memorandum
memorandum
Division of Health and Environment

Date
August 9, 2021

To
Tiffany DeFoe, David Valiante, and Greg Kuczura  -  OSHA

cc
Bob Blicksilver and Robert Stone  -  OSHA

From
Lauren Masatsugu and Matt LaPenta  -  Abt Associates

Subject
Estimated Number of Work-Related BLL Cases and Firms
Introduction
The purpose of this memo is to provide estimates for the annual number of work-related blood lead level tests and the number of cases and firms with workers with blood lead levels (BLLs) at or above various thresholds, by industry. We primarily draw on data provided by CDC's Adult Blood Lead Epidemiology and Surveillance (ABLES). ABLES coordinates with a number of state programs to conduct adult blood lead surveillance, collecting data that includes the number of tests conducted, blood lead level results, and NAICS codes for occupational-related exposures. While these data are limited to those states that report testing results to ABLES, our approach uses U.S. Census data to extrapolate the national number of cases from the ABLES state data.

One challenge with the ABLES data is that detailed breakouts of case and test counts by NAICS are limited. Furthermore, due to different BLL thresholds at which states report case and testing data to ABLES, establishing an estimate for national numbers of tests and cases at different BLL thresholds requires an approach involving several analytical steps. Our approach to estimating the number of BLL tests and cases at or above 5 ug/dL, 10 ug/dL, 25 ug/dL, and OSHA's medical removal levels (50 ug/dL for construction and 60 ug/dL for general industry) includes the following steps:

 Estimate the annual number of BLL >= 10 ug/dL cases in ABLES states, by NAICS

 Extrapolate to a national estimate of the annual number of cases of BLL >= 10 ug/dL based on the numbers of employees in affected NAICS nationally relative to the number on the ABLES states.

 Estimate the annual number of employees tested and the number of BLL >= 5, 10, 25, 50, and 60 ug/dL cases nationwide, by NAICS using the overall ratio of BLL cases above 10 ug/dL to the number of tests and cases at or above 5 ug/dL, 25 ug/dL, 50 ug/dL, and 60 ug/dL.

 Use CDPH estimated number of cases per firm by NAICS to estimate the number of affected firms by NAICS from the number of cases

Methodology and Results
Step 1: Estimate the annual number of BLL >= 10 ug/dL cases above the 10 ug/dL threshold in ABLES states, by NAICS
The California Department of Public Health (CDPH) provided Abt with 2015-2018 data on the number of cases and the number of employers with cases above the 10 ug/dL threshold (CDPH 2020a; 2020b).

However, only a subset of all reports received by CDPH provided an associated NAICS code. Testing for elevated blood lead levels in adults is generally not done as part of routine medical screening, and therefore it seems likely that most blood tests in adults are performed for individuals with potential occupational exposures. Thus, while some reports without a NAICS code may be associated with a non-occupational exposure, we believe that the vast majority of tests are due to occupational exposures where the reporting state did not identify the industry. Thus, the number of BLL >=10 ug/dL cases reported at the NAICS level is likely an underestimate of the true number of cases in each industry.

Therefore, we instead use the number of reported BLL >=10 ug/dL cases by NAICS to estimate the distribution of cases across NAICS (see Columns A and B; Table 2). We then combine our estimated distribution of BLL >=10 ug/dL cases by NAICS with the published total of 18,093 BLL >=10 ug/dL cases in 2016 from ABLES (2019). As this total encompasses all ABLES states and both reported and unreported NAICS codes, we believe it is a more reasonable estimate of the total number of BLL >=10 ug/dL cases. We further multiply this estimate by the 93.4% of cases reported in ABLES (2019) that are either known occupational exposures or unknown exposures (i.e. we exclude the known non-occupational exposures) to estimate the annual number of BLL >=10 ug/dL cases in ABLES states, by NAICS (see Column C; Table 2).

Step 2: Extrapolate to a national estimate of the annual number of cases of BLL >= 10 ug/dL
We then extrapolate the national number of cases where BLL >=10 ug/dL using the counts from the states reporting to ABLES and the U.S. Census's 2016 County Business Patterns (CBP) (U.S. Census Bureau 2018). This extrapolation involves using the CBP data to estimate the ratio of the number of employees in each industry across all states (Column E; Table 2) to the number of employees in each industry among just the states reporting to ABLES (Column D; Table 2). We then multiply this ratio by the number of BLL >=10 ug/dL cases reported to ABLES to estimate the annual number of cases nationally where BLLs are at or above 10 ug/dL (Column F; Table 2). Note that for some state/NAICS combinations, the CBP reports a range of employees (e.g. 0-19 employees; 20-99 employees) rather than an exact employment count. In these instances, we use the median value from the reported ranges for our employment estimates.

We also note that there are several NAICS that do not have employment data reported to the CBP. In Table 1 below, we list these NAICS along with the datasets we instead used to estimate the ratio of the number of employees nationally to the number of employees in ABLES states.

Table 1: Alternate Employment Data Sources
                                     NAICS
                               NAICS Description
                                    Source
                                   Comments
1119
Other Crop Farming
U.S. Census Bureau 2018
The CBP does not cover crop production (NAICS 111), so we use employment data from NAICS 11 (Agriculture, Forestry, Fishing, and Hunting).
2399
Construction (specific industry unknown)

Payne et al. (2017) coded tests in unspecified sectors of the construction industry under this NAICS. We therefore use CBP employment data from NAICS 23 (Construction).
4821
Rail Transportation
BLS 2016
The CBP does not cover rail transportation, so we use employment data from the Bureau of Labor Statistics' (BLS) May 2016 Occupational Employment Statistics (OES) Research Estimates for NAICS 4821.
9211
Executive, Legislative, and Other General Government Support
U.S. Census Bureau 2017
The CBP does not cover NAICS 92 (Public Administration), so we use the 2016 Annual Survey of Public Employment and Payroll (ASPEP) for employment function 1040 Other Government Administration.
9221
Justice, Public Order, and Safety Activities

We use ASPEP employment function 1100 Police Protection, total.
9231
Administration of Human Resource Programs

We use ASPEP employment function 1040 Other Government Administration
9241
Administration of Environmental Quality Programs

We use ASPEP employment functions 1300 (Solid Waste Management), 1320 (Sewerage), 1340 (Parks and Recreation), 1380 (Natural Resources), and 1400 (Water Supply)
9251
Administration of Housing Programs, Urban Planning, and Community Development

We use ASPEP employment function 1360 Housing and Community Development
9261
Administration of Economic Programs

Payne et al. (2017) specifies transportation programs (Coast Guard and ports) and utilities as relevant subsectors in this industry. We therefore use ASPEP employment functions 1200 (Water Transport and Terminals), 1420 (Electric Power), and 1440 (Gas Supply).
9281
National Security and International Affairs
Defence Manpower Data Center (DMDC) 2016
We use data from the Department of Defense's Defense Manpower Data Center (DMDC) on the numbers of active duty, National Guard/reserve, and civilian personnel.

Table 2: Annual Number of BLL >= 10 ug/dL Cases
                                     NAICS
                               NAICS Description
Average Annual Number of BLL >=10 ug/dL Cases in CA 2015-2018 (with known NAICS)
                          Percent of Cases, by NAICS
            Annual Number of BLL >=10 ug/dL Cases
(ABLES States)
                   Total Number of Employees (ABLES States)
                    Total Number of Employees
(All States)
             Annual Number of BLL >=10 ug/dL Cases
(All States)

                                       A
                                B = A / sum(A)
                           C = B x 18,093 x  0.934
                                       D
                                       E
                                 F = C x E/ D
                                                                           1151
Support Activities for Crop Production
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        114,817
                                                                        160,410
                                                                              0
                                                                           2122
Metal Ore Mining
                                                                              5
                                                                          0.19%
                                                                             32
                                                                         74,981
                                                                        141,481
                                                                             59
                                                                           2123
Nonmetallic Mineral Mining and Quarrying
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        170,882
                                                                        328,640
                                                                              0
                                                                           2131
Support Activities for Mining
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        953,435
                                                                      1,165,459
                                                                              0
                                                                           2211
Electric Power Generation, Transmission and Distribution
                                                                              5
                                                                          0.19%
                                                                             32
                                                                      1,108,728
                                                                      1,823,599
                                                                             52
                                                                           2212
Natural Gas Distribution
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        198,370
                                                                        332,804
                                                                             11
                                                                           2213
Water, Sewage and Other Systems
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        110,839
                                                                        176,268
                                                                              0
                                                                           2361
Residential Building Construction
                                                                           21.4
                                                                          0.80%
                                                                            135
                                                                      1,830,751
                                                                      2,668,219
                                                                            196
                                                                           2362
Nonresidential Building Construction
                                                                             71
                                                                          2.65%
                                                                            447
                                                                      1,589,605
                                                                      2,567,452
                                                                            723
                                                                           2371
Utility System Construction
                                                                              6
                                                                          0.22%
                                                                             38
                                                                      1,485,844
                                                                      2,138,702
                                                                             54
                                                                           2373
Highway, Street, and Bridge Construction
                                                                             34
                                                                          1.27%
                                                                            214
                                                                        695,523
                                                                      1,111,146
                                                                            342
                                                                           2379
Other Heavy and Civil Engineering Construction
                                                                              5
                                                                          0.19%
                                                                             32
                                                                        240,661
                                                                        324,663
                                                                             42
                                                                           2381
Foundation, Structure, and Building Exterior Contractors
                                                                             12
                                                                          0.45%
                                                                             76
                                                                      2,162,388
                                                                      3,248,139
                                                                            114
                                                                           2382
Building Equipment Contractors
                                                                             30
                                                                          1.12%
                                                                            189
                                                                      5,022,634
                                                                      7,685,818
                                                                            289
                                                                           2383
Building Finishing Contractors
                                                                            304
                                                                         11.33%
                                                                          1,915
                                                                      2,092,103
                                                                      2,999,826
                                                                          2,746
                                                                           2389
Other Specialty Trade Contractors
                                                                             75
                                                                          2.80%
                                                                            473
                                                                      1,463,519
                                                                      2,288,423
                                                                            739
                                                                           2399
Construction (Specific industry unknown)
                                                                             17
                                                                          0.63%
                                                                            107
                                                                      4,795,494
                                                                      6,311,264
                                                                            141
                                                                           3231
Printing and Related Support Activities
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      1,011,642
                                                                      1,789,779
                                                                             11
                                                                           3241
Petroleum and Coal Products Manufacturing
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        281,773
                                                                        423,090
                                                                              0
                                                                           3251
Basic Chemical Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        354,116
                                                                        613,379
                                                                             11
                                                                           3252
Resin, Synthetic Rubber, and Artificial and Synthetic Fibers and Filaments Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        179,439
                                                                        382,122
                                                                             13
                                                                           3255
Paint, Coating, and Adhesive Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        134,212
                                                                        246,987
                                                                             12
                                                                           3259
Other Chemical Product and Preparation Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        174,829
                                                                        335,886
                                                                             12
                                                                           3271
Clay Product and Refractory Manufacturing
                                                                              2
                                                                          0.07%
                                                                             13
                                                                         65,508
                                                                        141,535
                                                                             27
                                                                           3272
Glass and Glass Product Manufacturing
                                                                             52
                                                                          1.94%
                                                                            328
                                                                        201,401
                                                                        363,758
                                                                            592
                                                                           3279
Other Nonmetallic Mineral Product Manufacturing
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        170,490
                                                                        311,837
                                                                              0
                                                                           3311
Iron and Steel Mills and Ferroalloy Manufacturing
                                                                             16
                                                                          0.60%
                                                                            101
                                                                         95,473
                                                                        354,806
                                                                            375
                                                                           3312
Steel Product Manufacturing from Purchased Steel
                                                                              1
                                                                          0.04%
                                                                              6
                                                                         87,578
                                                                        195,241
                                                                             14
                                                                           3314
Nonferrous Metal (except Aluminum) Production and Processing
                                                                            303
                                                                         11.29%
                                                                          1,909
                                                                        126,116
                                                                        251,965
                                                                          3,814
                                                                           3315
Foundries
                                                                             20
                                                                          0.75%
                                                                            126
                                                                        213,789
                                                                        492,958
                                                                            291
                                                                           3323
Architectural and Structural Metals Manufacturing
                                                                             41
                                                                          1.53%
                                                                            258
                                                                        766,720
                                                                      1,385,091
                                                                            467
                                                                           3324
Boiler, Tank, and Shipping Container Manufacturing
                                                                              3
                                                                          0.11%
                                                                             19
                                                                        187,415
                                                                        347,070
                                                                             35
                                                                           3325
Hardware Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                         59,377
                                                                        119,804
                                                                             13
                                                                           3327
Machine Shops; Turned Product; and Screw, Nut, and Bolt Manufacturing
                                                                              7
                                                                          0.26%
                                                                             44
                                                                        885,582
                                                                      1,494,874
                                                                             74
                                                                           3328
Coating, Engraving, Heat Treating, and Allied Activities
                                                                              5
                                                                          0.19%
                                                                             32
                                                                        301,934
                                                                        516,116
                                                                             54
                                                                           3329
Other Fabricated Metal Product Manufacturing
                                                                             51
                                                                          1.90%
                                                                            321
                                                                        553,317
                                                                      1,041,387
                                                                            605
                                                                           3333
Commercial and Service Industry Machinery Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        185,661
                                                                        300,780
                                                                             10
                                                                           3336
Engine, Turbine, and Power Transmission Equipment Manufacturing
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        189,255
                                                                        375,213
                                                                              0
                                                                           3339
Other General Purpose Machinery Manufacturing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        631,972
                                                                      1,168,609
                                                                             12
                                                                           3341
Computer and Peripheral Equipment Manufacturing
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        120,598
                                                                        173,383
                                                                              0
                                                                           3342
Communications Equipment Manufacturing
                                                                              2
                                                                          0.07%
                                                                             13
                                                                        248,988
                                                                        330,454
                                                                             17
                                                                           3343
Audio and Video Equipment Manufacturing
                                                                              0
                                                                          0.00%
                                                                              0
                                                                         31,073
                                                                         43,406
                                                                              0
                                                                           3344
Semiconductor and Other Electronic Component Manufacturing
                                                                             35
                                                                          1.30%
                                                                            221
                                                                        782,039
                                                                      1,030,588
                                                                            291
                                                                           3345
Navigational, Measuring, Electromedical, and Control Instruments Manufacturing
                                                                              6
                                                                          0.22%
                                                                             38
                                                                        940,097
                                                                      1,374,346
                                                                             55
                                                                           3359
Other Electrical Equipment and Component Manufacturing
                                                                            609
                                                                         22.70%
                                                                          3,837
                                                                        298,111
                                                                        535,036
                                                                          6,887
                                                                           3363
Motor Vehicle Parts Manufacturing
                                                                             35
                                                                          1.30%
                                                                            221
                                                                        940,808
                                                                      2,217,179
                                                                            520
                                                                           3364
Aerospace Product and Parts Manufacturing
                                                                             28
                                                                          1.04%
                                                                            176
                                                                        838,390
                                                                      1,314,967
                                                                            277
                                                                           3366
Ship and Boat Building
                                                                              5
                                                                          0.19%
                                                                             32
                                                                        195,338
                                                                        407,569
                                                                             66
                                                                           3369
Other Transportation Equipment Manufacturing
                                                                              0
                                                                          0.00%
                                                                              0
                                                                         55,313
                                                                        131,895
                                                                              0
                                                                           3399
Other Miscellaneous Manufacturing
                                                                              6
                                                                          0.22%
                                                                             38
                                                                        628,400
                                                                      1,055,510
                                                                             63
                                                                           4231
Motor Vehicle and Motor Vehicle Parts and Supplies Merchant Wholesalers
                                                                              3
                                                                          0.11%
                                                                             19
                                                                        975,492
                                                                      1,604,622
                                                                             31
                                                                           4236
Household Appliances and Electrical and Electronic Goods Merchant Wholesalers
                                                                              4
                                                                          0.15%
                                                                             25
                                                                      1,609,937
                                                                      2,153,589
                                                                             34
                                                                           4237
Hardware, and Plumbing and Heating Equipment and Supplies Merchant Wholesalers
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        616,845
                                                                        971,393
                                                                             10
                                                                           4238
Machinery, Equipment, and Supplies Merchant Wholesalers
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,881,383
                                                                      3,050,249
                                                                              0
                                                                           4239
Miscellaneous Durable Goods Merchant Wholesalers
                                                                             93
                                                                          3.47%
                                                                            586
                                                                        869,839
                                                                      1,302,395
                                                                            877
                                                                           4244
Grocery and Related Product Merchant Wholesalers
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      2,234,267
                                                                      3,290,663
                                                                              0
                                                                           4247
Petroleum and Petroleum Products Merchant Wholesalers
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        256,087
                                                                        407,242
                                                                              0
                                                                           4413
Automotive Parts, Accessories, and Tire Stores
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      1,285,156
                                                                      2,120,534
                                                                             10
                                                                           4441
Building Material and Supplies Dealers
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      2,509,987
                                                                      4,071,441
                                                                             10
                                                                           4451
Grocery Stores
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      7,219,064
                                                                     11,016,106
                                                                              0
                                                                           4483
Jewelry, Luggage, and Leather Goods Stores
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        335,741
                                                                        510,288
                                                                             10
                                                                           4511
Sporting Goods, Hobby, and Musical Instrument Stores
                                                                              6
                                                                          0.22%
                                                                             38
                                                                      1,215,585
                                                                      1,919,925
                                                                             60
                                                                           4821
Rail Transportation
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        118,430
                                                                        174,380
                                                                              9
                                                                           4841
General Freight Trucking
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      2,022,090
                                                                      3,878,324
                                                                              0
                                                                           4842
Specialized Freight Trucking
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,112,410
                                                                      1,928,170
                                                                              0
                                                                           4851
Urban Transit Systems
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        164,144
                                                                        218,105
                                                                              8
                                                                           4881
Support Activities for Air Transportation
                                                                              7
                                                                          0.26%
                                                                             44
                                                                        527,569
                                                                        736,499
                                                                             62
                                                                           4883
Support Activities for Water Transportation
                                                                              4
                                                                          0.15%
                                                                             25
                                                                        267,338
                                                                        347,344
                                                                             33
                                                                           4884
Support Activities for Road Transportation
                                                                            1.4
                                                                          0.05%
                                                                              9
                                                                        233,889
                                                                        360,284
                                                                             14
                                                                           4911
Postal Service
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        344,896
                                                                             20
                                                                              0
                                                                           4921
Couriers and Express Delivery Services
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        961,005
                                                                      1,511,999
                                                                              0
                                                                           5111
Newspaper, Periodical, Book, and Directory Publishers
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        921,712
                                                                      1,462,282
                                                                             10
                                                                           5173
Wired and Wireless Telecommunications Carriers
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,953,244
                                                                      2,970,961
                                                                              0
                                                                           5182
Data Processing, Hosting, and Related Services
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,272,532
                                                                      1,846,726
                                                                              0
                                                                           5211
Monetary Authorities-Central Bank
                                                                              1
                                                                          0.04%
                                                                              6
                                                                         45,183
                                                                         71,668
                                                                             10
                                                                           5242
Agencies, Brokerages, and Other Insurance Related Activities
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      2,538,472
                                                                      3,901,214
                                                                              0
                                                                           5311
Lessors of Real Estate
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,646,018
                                                                      2,308,342
                                                                              0
                                                                           5313
Activities Related to Real Estate
                                                                              2
                                                                          0.07%
                                                                             13
                                                                      1,947,824
                                                                      2,728,454
                                                                             18
                                                                           5323
General Rental Centers
                                                                              2
                                                                          0.07%
                                                                             13
                                                                         50,456
                                                                         81,324
                                                                             20
                                                                           5324
Commercial and Industrial Machinery and Equipment Rental and Leasing
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        528,907
                                                                        723,159
                                                                              9
                                                                           5413
Architectural, Engineering, and Related Services
                                                                              7
                                                                          0.26%
                                                                             44
                                                                      3,800,962
                                                                      5,644,813
                                                                             65
                                                                           5415
Computer Systems Design and Related Services
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      4,904,613
                                                                      7,228,915
                                                                              9
                                                                           5416
Management, Scientific, and Technical Consulting Services
                                                                              4
                                                                          0.15%
                                                                             25
                                                                      3,264,158
                                                                      4,829,052
                                                                             37
                                                                           5417
Scientific Research and Development Services
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      1,953,363
                                                                      2,622,173
                                                                              8
                                                                           5419
Other Professional, Scientific, and Technical Services
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      1,655,044
                                                                      2,516,054
                                                                             10
                                                                           5611
Office Administrative Services
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      1,255,496
                                                                      1,804,174
                                                                              9
                                                                           5613
Employment Services
                                                                            6.4
                                                                          0.24%
                                                                             40
                                                                     18,585,029
                                                                     25,392,656
                                                                             55
                                                                           5614
Business Support Services
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,958,466
                                                                      3,135,514
                                                                              0
                                                                           5616
Investigation and Security Services
                                                                              4
                                                                          0.15%
                                                                             25
                                                                      2,561,696
                                                                      3,689,093
                                                                             36
                                                                           5617
Services to Buildings and Dwellings
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      4,805,711
                                                                      7,384,659
                                                                             10
                                                                           5621
Waste Collection
                                                                              2
                                                                          0.07%
                                                                             13
                                                                        545,476
                                                                        826,957
                                                                             19
                                                                           5622
Waste Treatment and Disposal
                                                                              3
                                                                          0.11%
                                                                             19
                                                                        118,348
                                                                        206,918
                                                                             33
                                                                           5629
Remediation and Other Waste Management Services
                                                                            131
                                                                          4.88%
                                                                            825
                                                                        356,879
                                                                        538,638
                                                                          1,246
                                                                           6111
Elementary and Secondary Schools
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      2,728,975
                                                                      4,071,980
                                                                              9
                                                                           6112
Junior Colleges
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        171,987
                                                                        304,590
                                                                             11
                                                                           6113
Colleges, Universities, and Professional Schools
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      4,581,057
                                                                      7,427,851
                                                                              0
                                                                           6115
Technical and Trade Schools
                                                                              6
                                                                          0.22%
                                                                             38
                                                                        306,640
                                                                        442,885
                                                                             55
                                                                           6116
Other Schools and Instruction
                                                                             15
                                                                          0.56%
                                                                             95
                                                                      1,233,171
                                                                      1,700,627
                                                                            130
                                                                           6211
Offices of Physicians
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      6,410,440
                                                                     10,087,566
                                                                              0
                                                                           6214
Outpatient Care Centers
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      2,408,504
                                                                      3,732,486
                                                                              0
                                                                           6215
Medical and Diagnostic Laboratories
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        785,429
                                                                      1,138,391
                                                                              0
                                                                           6219
Other Ambulatory Health Care Services
                                                                              2
                                                                          0.07%
                                                                             13
                                                                        728,746
                                                                      1,193,346
                                                                             21
                                                                           6221
General Medical and Surgical Hospitals
                                                                              0
                                                                          0.00%
                                                                              0
                                                                     12,870,416
                                                                     20,879,753
                                                                              0
                                                                           6222
Psychiatric and Substance Abuse Hospitals
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        563,390
                                                                        929,741
                                                                              0
                                                                           6232
Residential Intellectual and Developmental Disability, Mental Health, and Substance Abuse Facilities
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      1,854,137
                                                                      3,056,829
                                                                              0
                                                                           6241
Individual and Family Services
                                                                              1
                                                                          0.04%
                                                                              6
                                                                      4,409,126
                                                                      6,761,077
                                                                             10
                                                                           6243
Vocational Rehabilitation Services
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        787,830
                                                                      1,291,934
                                                                              0
                                                                           7115
Independent Artists, Writers, and Performers
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        150,998
                                                                        190,538
                                                                              0
                                                                           7121
Museums, Historical Sites, and Similar Institutions
                                                                           11.3
                                                                          0.42%
                                                                             71
                                                                        386,132
                                                                        604,927
                                                                            112
                                                                           7131
Amusement Parks and Arcades
                                                                              0
                                                                          0.00%
                                                                              0
                                                                        642,928
                                                                        770,969
                                                                              0
                                                                           7139
Other Amusement and Recreation Industries
                                                                            349
                                                                         13.01%
                                                                          2,199
                                                                      3,464,172
                                                                      5,231,982
                                                                          3,321
                                                                           8111
Automotive Repair and Maintenance
                                                                          38.86
                                                                          1.45%
                                                                            245
                                                                      2,323,936
                                                                      3,575,280
                                                                            377
                                                                           8112
Electronic and Precision Equipment Repair and Maintenance
                                                                              6
                                                                          0.22%
                                                                             38
                                                                        272,169
                                                                        420,673
                                                                             58
                                                                           8113
Commercial and Industrial Machinery and Equipment (except Automotive and Electronic) Repair and Maintenance
                                                                              3
                                                                          0.11%
                                                                             19
                                                                        490,044
                                                                        787,934
                                                                             30
                                                                           8114
Personal and Household Goods Repair and Maintenance
                                                                             20
                                                                          0.75%
                                                                            126
                                                                        204,613
                                                                        289,282
                                                                            178
                                                                           8122
Death Care Services
                                                                              1
                                                                          0.04%
                                                                              6
                                                                        322,596
                                                                        567,839
                                                                             11
                                                                           8131
Religious Organizations
                                                                              0
                                                                          0.00%
                                                                              0
                                                                      4,060,992
                                                                      6,696,336
                                                                              0
                                                                           8139
Business, Professional, Labor, Political, and Similar Organizations
                                                                             15
                                                                          0.56%
                                                                             95
                                                                      1,255,750
                                                                      1,982,551
                                                                            149
                                                                           9211
Executive, Legislative, and Other General Government Support
                                                                             15
                                                                          0.56%
                                                                             95
                                                                        102,594
                                                                              6
                                                                              0
                                                                           9221
Justice, Public Order, and Safety Activities
                                                                             72
                                                                          2.68%
                                                                            454
                                                                        202,842
                                                                             12
                                                                              0
                                                                           9231
Administration of Human Resource Programs
                                                                              2
                                                                          0.07%
                                                                             13
                                                                        102,594
                                                                              6
                                                                              0
                                                                           9241
Administration of Environmental Quality Programs
                                                                              2
                                                                          0.07%
                                                                             13
                                                                        348,334
                                                                             21
                                                                              0
                                                                           9251
Administration of Housing Programs, Urban Planning, and Community Development
                                                                              1
                                                                          0.04%
                                                                              6
                                                                          1,290
                                                                              0
                                                                              0
                                                                           9261
Administration of Economic Programs
                                                                              1
                                                                          0.04%
                                                                              6
                                                                         17,310
                                                                              1
                                                                              0
                                                                           9281
National Security and International Affairs
                                                                              4
                                                                          0.15%
                                                                             25
                                                                      2,483,122
                                                                            147
                                                                              0

Sources: CDPH 2020a; 2020b, U.S. Census Bureau 2018, U.S. Census Bureau 2017.

Step 3: Estimate the annual number of employees tested and the number of BLL >= 5, 10, 25, 50, and 60 ug/dL cases nationwide, by NAICS

ABLES provided Abt with the number of tests and the number of cases at or above 5, 10, 25, 50, and 60 ug/dL (ABLES 2020). These counts are not disaggregated by NAICS, and they also only include states that reported BLLs at all levels (BLL >=0 ug/dL). In other words, they exclude states that only reported to ABLES if cases were above a given threshold (e.g. BLL >=10 ug/dL). Because test results below the state's threshold are not reported, ABLES did not have complete test counts for these states and thus excluded them. Thus, the number of tests and the number of BLL cases at the 5, 25, 50, and 60 ug/dL thresholds as provided by ABLES are an underestimate of the true numbers in ABLES states.

However, because we have already estimated the national number of BLL >=10 ug/dL cases by NAICS in Steps 1 and 2 above, we can use ratios between the number of tests and the number of cases at the various BLL thresholds in ABLES states reporting BLLs at all levels to estimate national numbers of tests and BLL cases by NAICS at each threshold. These ratios are presented in Table 3.

Table 3: Ratios Used to Estimate Number of Tests and Number of BLL >= 5, 25, 50, and 60 ug/dL Cases
                                    Metric
                               Reports to ABLES
                                (2014-2018)[1]
                            Ratio of Cases : Tests
Number of tests
                                                                        645,761
                                                                              -
BLL >=5 ug/dL cases
                                                                         90,292
                                                                           0.14
BLL >=10 ug/dL cases
                                                                         49,408
                                                                         0.0765
BLL >=25 ug/dL cases
                                                                          9,404
                                                                          0.015
BLL >=50 ug/dL cases
                                                                            611
                                                                         0.0009
BLL >=60 ug/dL cases
                                                                            172
                                                                         0.0003
1 Only includes ABLES states reporting BLLs at all levels (BLL >= 0 ug/dL)
Source: ABLES 2020

We derive national estimates for the number of employees tested in each industry by dividing the number of BLL >=10 ug/dL cases from Table 2 by the ratio between the number of tests and the number of BLL >=10 ug/dL cases from Table 3 (see Column G; Table 4). We then multiply the resulting estimate for the number of employees tested by the ratios between the number of tests and the number of BLL >=5, 25, 50, and 60 ug/dL cases to estimate the national number of cases at each BLL threshold, by NAICS (see Columns H, I, and J; Table 4). Note that because current medical removal levels are BLL >=50 ug/dL in Construction and BLL >=60 ug/dL in General Industry, we use the BLL >=50 ug/dL ratio to estimate medical removal cases only in the construction industry (NAICS 2361, 2362, 2373, 2383, 2389), and the BLL >=60 ug/dL ratio to estimate cases in all other industries.

Table 4 presents a summary of the estimated annual number of employees tested and the number of cases nationwide with BLLs at or above 5 ug/dL, 10 ug/dL, 25 ug/dL, and medical removal values, by NAICS. We also note a few areas of uncertainty and limitations to the approaches described in this memo as follows:
 The majority of reports used to estimate the ratios in Table 3 do not have an identified NAICS. We attribute these unknown sources to occupational exposures, but this may overestimate the number of cases and tests to the extent that they are actually due to non-occupational exposures.

 Because the number of BLL >= 5, 25, 50 and 60 ug/dL cases reported by ABLES are not disaggregated by NAICS, we make the simplifying assumption that the overall test to case ratios observed in the ABLES states are the same for each industry. To the extent that the distributions of blood lead levels across industries differ from each other, this assumption may over- or under- estimate the number of cases in an industry at a given BLL.

 Our approach assumes the relative number of cases at each BLL threshold observed in the states that report to ABLES to be nationally representative. For example, we assume that both the ratio of BLL >=10 ug/dL cases to the total number of employees and the ratio of BLL >=10 ug/dL cases to employees tested are consistent between the ABLES states and the national population of workers.

Table 4: Summary of Annual Number of BLL Cases and Tests
                                     NAICS
                               NAICS Description
                       Annual Number of Employees Tested
                            Annual Number of Cases

                                   BLL >=5
                                 BLL >=10 [1]
                                   BLL >=25
                                BLL >= MRL [2]

                                G = F / 0.0765
                                 H = G x 0.14
                                       F
                                 I = G x 0.015
J = G x 0.0009 or
J = G x 0.0003
                                                                           1151
Support Activities for Crop Production
                                                                             10
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                           2122
Metal Ore Mining
                                                                            777
                                                                            109
                                                                             59
                                                                             11
                                                                              0
                                                                           2123
Nonmetallic Mineral Mining and Quarrying
                                                                             17
                                                                              2
                                                                              0
                                                                              0
                                                                              0
                                                                           2131
Support Activities for Mining
                                                                             35
                                                                              5
                                                                              0
                                                                              1
                                                                              0
                                                                           2211
Electric Power Generation, Transmission and Distribution
                                                                            677
                                                                             95
                                                                             52
                                                                             10
                                                                              0
                                                                           2212
Natural Gas Distribution
                                                                            138
                                                                             19
                                                                             11
                                                                              2
                                                                              0
                                                                           2213
Water, Sewage and Other Systems
                                                                            117
                                                                             16
                                                                              0
                                                                              2
                                                                              0
                                                                           2361
Residential Building Construction
                                                                          2,563
                                                                            358
                                                                            196
                                                                             37
                                                                              2
                                                                           2362
Nonresidential Building Construction
                                                                          9,443
                                                                          1,320
                                                                            723
                                                                            138
                                                                              9
                                                                           2371
Utility System Construction
                                                                            711
                                                                             99
                                                                             54
                                                                             10
                                                                              1
                                                                           2373
Highway, Street, and Bridge Construction
                                                                          4,473
                                                                            625
                                                                            342
                                                                             65
                                                                              4
                                                                           2379
Other Heavy and Civil Engineering Construction
                                                                            555
                                                                             78
                                                                             42
                                                                              8
                                                                              1
                                                                           2381
Foundation, Structure, and Building Exterior Contractors
                                                                          1,484
                                                                            208
                                                                            114
                                                                             22
                                                                              1
                                                                           2382
Building Equipment Contractors
                                                                          3,780
                                                                            529
                                                                            289
                                                                             55
                                                                              4
                                                                           2383
Building Finishing Contractors
                                                                         35,896
                                                                          5,019
                                                                          2,746
                                                                            523
                                                                             34
                                                                           2389
Other Specialty Trade Contractors
                                                                          9,657
                                                                          1,350
                                                                            739
                                                                            141
                                                                              9
                                                                           2399
Construction (Specific industry unknown)
                                                                          1,842
                                                                            258
                                                                            141
                                                                             27
                                                                              0
                                                                           3231
Printing and Related Support Activities
                                                                            146
                                                                             20
                                                                             11
                                                                              2
                                                                              0
                                                                           3241
Petroleum and Coal Products Manufacturing
                                                                            171
                                                                             24
                                                                              0
                                                                              2
                                                                              0
                                                                           3251
Basic Chemical Manufacturing
                                                                            143
                                                                             20
                                                                             11
                                                                              2
                                                                              0
                                                                           3252
Resin, Synthetic Rubber, and Artificial and Synthetic Fibers and Filaments Manufacturing
                                                                            175
                                                                             25
                                                                             13
                                                                              3
                                                                              0
                                                                           3255
Paint, Coating, and Adhesive Manufacturing
                                                                            152
                                                                             21
                                                                             12
                                                                              2
                                                                              0
                                                                           3259
Other Chemical Product and Preparation Manufacturing
                                                                            158
                                                                             22
                                                                             12
                                                                              2
                                                                              0
                                                                           3271
Clay Product and Refractory Manufacturing
                                                                            356
                                                                             50
                                                                             27
                                                                              5
                                                                              0
                                                                           3272
Glass and Glass Product Manufacturing
                                                                          7,734
                                                                          1,081
                                                                            592
                                                                            113
                                                                              2
                                                                           3279
Other Nonmetallic Mineral Product Manufacturing
                                                                             24
                                                                              3
                                                                              0
                                                                              0
                                                                              0
                                                                           3311
Iron and Steel Mills and Ferroalloy Manufacturing
                                                                          4,897
                                                                            685
                                                                            375
                                                                             71
                                                                              1
                                                                           3312
Steel Product Manufacturing from Purchased Steel
                                                                            184
                                                                             26
                                                                             14
                                                                              3
                                                                              0
                                                                           3314
Nonferrous Metal (except Aluminum) Production and Processing
                                                                         49,851
                                                                          6,970
                                                                          3,814
                                                                            726
                                                                             13
                                                                           3315
Foundries
                                                                          3,798
                                                                            531
                                                                            291
                                                                             55
                                                                              1
                                                                           3323
Architectural and Structural Metals Manufacturing
                                                                          6,099
                                                                            853
                                                                            467
                                                                             89
                                                                              2
                                                                           3324
Boiler, Tank, and Shipping Container Manufacturing
                                                                            458
                                                                             64
                                                                             35
                                                                              7
                                                                              0
                                                                           3325
Hardware Manufacturing
                                                                            166
                                                                             23
                                                                             13
                                                                              2
                                                                              0
                                                                           3327
Machine Shops; Turned Product; and Screw, Nut, and Bolt Manufacturing
                                                                            973
                                                                            136
                                                                             74
                                                                             14
                                                                              0
                                                                           3328
Coating, Engraving, Heat Treating, and Allied Activities
                                                                            704
                                                                             98
                                                                             54
                                                                             10
                                                                              0
                                                                           3329
Other Fabricated Metal Product Manufacturing
                                                                          7,904
                                                                          1,105
                                                                            605
                                                                            115
                                                                              2
                                                                           3333
Commercial and Service Industry Machinery Manufacturing
                                                                            133
                                                                             19
                                                                             10
                                                                              2
                                                                              0
                                                                           3336
Engine, Turbine, and Power Transmission Equipment Manufacturing
                                                                            359
                                                                             50
                                                                              0
                                                                              5
                                                                              0
                                                                           3339
Other General Purpose Machinery Manufacturing
                                                                            152
                                                                             21
                                                                             12
                                                                              2
                                                                              0
                                                                           3341
Computer and Peripheral Equipment Manufacturing
                                                                              6
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                           3342
Communications Equipment Manufacturing
                                                                            219
                                                                             31
                                                                             17
                                                                              3
                                                                              0
                                                                           3343
Audio and Video Equipment Manufacturing
                                                                              9
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                           3344
Semiconductor and Other Electronic Component Manufacturing
                                                                          3,798
                                                                            531
                                                                            291
                                                                             55
                                                                              1
                                                                           3345
Navigational, Measuring, Electromedical, and Control Instruments Manufacturing
                                                                            722
                                                                            101
                                                                             55
                                                                             11
                                                                              0
                                                                           3359
Other Electrical Equipment and Component Manufacturing
                                                                         90,008
                                                                         12,585
                                                                          6,887
                                                                          1,311
                                                                             24
                                                                           3363
Motor Vehicle Parts Manufacturing
                                                                          6,792
                                                                            950
                                                                            520
                                                                             99
                                                                              2
                                                                           3364
Aerospace Product and Parts Manufacturing
                                                                          3,616
                                                                            506
                                                                            277
                                                                             53
                                                                              1
                                                                           3366
Ship and Boat Building
                                                                            859
                                                                            120
                                                                             66
                                                                             13
                                                                              0
                                                                           3369
Other Transportation Equipment Manufacturing
                                                                             55
                                                                              8
                                                                              0
                                                                              1
                                                                              0
                                                                           3399
Other Miscellaneous Manufacturing
                                                                            830
                                                                            116
                                                                             63
                                                                             12
                                                                              0
                                                                           4231
Motor Vehicle and Motor Vehicle Parts and Supplies Merchant Wholesalers
                                                                            406
                                                                             57
                                                                             31
                                                                              6
                                                                              0
                                                                           4236
Household Appliances and Electrical and Electronic Goods Merchant Wholesalers
                                                                            441
                                                                             62
                                                                             34
                                                                              6
                                                                              0
                                                                           4237
Hardware, and Plumbing and Heating Equipment and Supplies Merchant Wholesalers
                                                                            130
                                                                             18
                                                                             10
                                                                              2
                                                                              0
                                                                           4238
Machinery, Equipment, and Supplies Merchant Wholesalers
                                                                             12
                                                                              2
                                                                              0
                                                                              0
                                                                              0
                                                                           4239
Miscellaneous Durable Goods Merchant Wholesalers
                                                                         11,467
                                                                          1,603
                                                                            877
                                                                            167
                                                                              3
                                                                           4244
Grocery and Related Product Merchant Wholesalers
                                                                              7
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                           4247
Petroleum and Petroleum Products Merchant Wholesalers
                                                                             14
                                                                              2
                                                                              0
                                                                              0
                                                                              0
                                                                           4413
Automotive Parts, Accessories, and Tire Stores
                                                                            136
                                                                             19
                                                                             10
                                                                              2
                                                                              0
                                                                           4441
Building Material and Supplies Dealers
                                                                            134
                                                                             19
                                                                             10
                                                                              2
                                                                              0
                                                                           4451
Grocery Stores
                                                                              8
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                           4483
Jewelry, Luggage, and Leather Goods Stores
                                                                            125
                                                                             18
                                                                             10
                                                                              2
                                                                              0
                                                                           4511
Sporting Goods, Hobby, and Musical Instrument Stores
                                                                            780
                                                                            109
                                                                             60
                                                                             11
                                                                              0
                                                                           4821
Rail Transportation
                                                                            121
                                                                             17
                                                                              9
                                                                              2
                                                                              0
                                                                           4841
General Freight Trucking
                                                                             98
                                                                             14
                                                                              0
                                                                              1
                                                                              0
                                                                           4842
Specialized Freight Trucking
                                                                             25
                                                                              3
                                                                              0
                                                                              0
                                                                              0
                                                                           4851
Urban Transit Systems
                                                                            109
                                                                             15
                                                                              8
                                                                              2
                                                                              0
                                                                           4881
Support Activities for Air Transportation
                                                                            805
                                                                            113
                                                                             62
                                                                             12
                                                                              0
                                                                           4883
Support Activities for Water Transportation
                                                                            428
                                                                             60
                                                                             33
                                                                              6
                                                                              0
                                                                           4884
Support Activities for Road Transportation
                                                                            183
                                                                             26
                                                                             14
                                                                              3
                                                                              0
                                                                           4911
Postal Service
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                              0
                                                                           4921
Couriers and Express Delivery Services
                                                                              8
                                                                              1
                                                                              0
                                                                              0
                                                                              0
                                                                           5111
Newspaper, Periodical, Book, and Directory Publishers
                                                                            131
                                                                             18
                                                                             10
                                                                              2
                                                                              0
                                                                           5173
Wired and Wireless Telecommunications Carriers
                                                                             10
                                                                              1
                                                                              0
                                                                              0
                                                                              0