DRAFT TABLE 13 PARAMETERS ( SACF, AR, PUF, FOL, AND TOXICITY VALUES) USED TO CALCULATE THE RISK BASED CONCENTRATIONS ( RBCs) ( a, b)

Parameter ( c) Units Parameter Values SACF Soil Accumulation Factor m 2 yr/ g  Arsenic 2.4E 05 Cadmium 2.4E 05 Chromium 1.6E 04 Cobalt 1.1E 04 Copper 6.9E 05 Lead 3.0E 04 Mercury 1.6E 04 Molybdenum 6.5E 05 Nickel 1.2E 04 Selenium 1.0E 05 Vanadium 3.9E 05 Zinc 5.4E 05 AR ( d) Application Rate g/ m 2 yr Vegetable ( v) Root ( r) Grain ( g) Phosphate 13 17 6.9 Zinc Micronutrient 1.1 1.1 1.1 PUF Plant Uptake Factor unitless Vegetable Root Grain Arsenic 0.03 0.0061 0.03 Cadmium 0.17 0.11 0.12 Chromium 0.00014 0.00018 0.037 Cobalt 0.005 0.0037 0.02 Copper 0.0034 0.027 0.31 Lead 0.008 0.0061 0.05 Mercury 0.061 0.082 0.26 Molybdenum 0.11 0.018 0.22 Nickel 0.015 0.0086 0.05 Selenium 0.088 0.093 0.57 Vanadium 0.0007 0.00086 0.007 Zinc 0.17 0.056 0.58 FOL ( e) Fraction of Land unitless Vegetable Root Grain 0.4 0.1 0.5 Toxicity Value Oral ( o) Dermal ( d)

SF Slope Factor ( mg/ kg day) 1 Arsenic 1.5E+ 00 1.5E+ 00 RfD Reference Dose mg/ kg day Arsenic 3.0E 04 2.9E 04 Cadmium 1.0E 03 1.0E 03 Chromium 1.5E+ 00 3.0E 02 Cobalt 6.0E 02 2.6E 02 Copper 4.0E 02 3.9E 02 Lead   Mercury 3.0E 04 2.1E 05 Molybdenum 5.0E 03 5.0E 03 Nickel 2.0E 02 1.4E 04 Selenium 5.0E 03 5.0E 03 Vanadium 7.0E 03 2.1E 04 Zinc 3.0E 01 2.4E 01 Notes:

 Not Applicable ( a) The equations used to calculate the RBCs are presented below.

( b) Summary Intake Factors ( SIFs) are presented in Table 12.

( c) All of the parameters are presented in Section 2.0.

( d) AR is adjusted so that the RBC is based on 1% fraction of nutrient ( FON), resulting in unit RBCs.

The AR is inversely proportionate to the FON, therefore, AR is adjusted to 1% FON by dividing by 1%.

( e) FOL is only needed for the calculation of the multiple crop RBCs.

RBC Calculations for Single Crop Farm ( equations adopted from CDFA 1998):

Cancer RBC = TR/{ SACF*[ AR*( SIFsi* SFo* RAFs+ SIFd* SFd+ PUF* SIFc* SFo* RAFc)]}

Noncancer RBC = THI/{ SACF*[ AR*( SIFsi* 1/ RfDo* RAFs+ SIFd* 1/ RfDd+ PUF* SIFc* 1/ RfDo* RAFc)]}

RBC Calculations for Multiple Crop Farm ( equations adopted from CDFA 1998):

Cancer RBC =

TR/( SACF*{ ARv*[(( SIFsi* SFo+ SIFd* SFd)* FOLv)+ PUFv* SIFv* SFo]}+{ ARr*[(( SIFsi* SFo+

SIFsd* SFd)* FOLr)+ PUFr* SIFr* SFo]}+{ ARg*[(( SIFsi* SFo+ SIFd* SFd)* FOLg)+ PUFg* SIFg* SFo]})

Noncancer RBC =

THI/( SACF*{ ARv*[(( SIFsi* 1/ RfDo+ SIFd* 1/ RfDd)* FOLv)+ PUFv* SIFv* 1/ RfDo]}+{ ARr*[(( SIFsi * 1/ RfDo+ SIFd* 1/ RfDd)* FOLr)+ PUFr* SIFr* 1/ RfDo]}+{ ARg*[(( SIFsi* 1/ RfDo+ SIFd* 1/ RfDd)* FOLg)+

PUFg* SIFg* 1/ RfDo]})

DRAFT TABLE 14 UNIT RISK BASED CONCENTRATIONS ( RBCs) ( a) FOR ALL SCENARIOS Adult Farm Resident RBC Child Farm Resident RBC Lowest Unit RBC ( b)

MOPC Vegetable Roots Grains Multi crop Vegetable Roots Grains Multi crop Scientific Notation Standard Notation Phosphate Fertilizer Arsenic ( c) 9.9E+ 00 5.4E+ 01 9.4E+ 00 4.5E+ 00 2.7E+ 01 9.7E+ 01 1.7E+ 01 9.8E+ 00 4.5E+ 00 4.5 Cadmium 1.1E+ 02 2.0E+ 02 1.5E+ 02 4.9E+ 01 6.4E+ 01 9.8E+ 01 5.4E+ 01 2.3E+ 01 2.3E+ 01 23 Chromium ( III) 1.8E+ 06 1.4E+ 06 1.1E+ 05 1.0E+ 05 1.7E+ 05 1.3E+ 05 3.6E+ 04 3.4E+ 04 3.4E+ 04 34,000 Cobalt 4.5E+ 04 6.6E+ 04 1.2E+ 04 8.4E+ 03 1.5E+ 04 1.5E+ 04 4.0E+ 03 3.1E+ 03 3.1E+ 03 3,100 Copper 7.0E+ 04 1.1E+ 04 8.2E+ 02 7.6E+ 02 2.0E+ 04 5.0E+ 03 3.0E+ 02 2.8E+ 02 2.8E+ 02 280 Lead 1.3E+ 03 2.0E+ 03 2.1E+ 02 1.6E+ 02 7.7E+ 02 9.3E+ 02 8.5E+ 01 7.3E+ 01 7.3E+ 01 73 Mercury 1.5E+ 01 1.3E+ 01 3.3E+ 00 2.2E+ 00 7.8E+ 00 6.1E+ 00 1.2E+ 00 9.0E 01 9.0E 01 0.9 Molybdenum 3.3E+ 02 2.2E+ 03 1.6E+ 02 1.0E+ 02 1.8E+ 02 9.0E+ 02 5.6E+ 01 4.2E+ 01 4.2E+ 01 42 Nickel 3.8E+ 03 5.4E+ 03 1.4E+ 03 1.0E+ 03 9.9E+ 02 9.3E+ 02 4.5E+ 02 3.5E+ 02 3.5E+ 02 350 Selenium 2.6E+ 03 2.9E+ 03 3.8E+ 02 3.0E+ 02 1.5E+ 03 1.4E+ 03 1.4E+ 02 1.2E+ 02 1.2E+ 02 120 Vanadium 3.6E+ 04 2.9E+ 04 1.0E+ 04 8.3E+ 03 4.2E+ 03 3.2E+ 03 2.8E+ 03 2.2E+ 03 2.2E+ 03 2,200 Zinc 1.5E+ 04 5.3E+ 04 4.2E+ 03 3.1E+ 03 8.8E+ 03 2.5E+ 04 1.5E+ 03 1.2E+ 03 1.2E+ 03 1,200 Micronutrient Fertilizer Arsenic ( c) 1.2E+ 02 8.4E+ 02 5.9E+ 01 3.8E+ 01 3.2E+ 02 1.5E+ 03 1.0E+ 02 7.4E+ 01 3.8E+ 01 38 Cadmium 1.3E+ 03 3.1E+ 03 9.5E+ 02 4.7E+ 02 7.6E+ 02 1.5E+ 03 3.4E+ 02 2.1E+ 02 2.1E+ 02 210 Chromium ( III) 2.1E+ 07 2.1E+ 07 6.7E+ 05 6.7E+ 05 2.1E+ 06 2.1E+ 06 2.2E+ 05 2.2E+ 05 2.2E+ 05 220,000 Cobalt 5.4E+ 05 1.0E+ 06 7.3E+ 04 6.2E+ 04 1.8E+ 05 2.3E+ 05 2.5E+ 04 2.3E+ 04 2.3E+ 04 23,000 Copper 8.3E+ 05 1.8E+ 05 5.2E+ 03 5.0E+ 03 2.3E+ 05 7.8E+ 04 1.9E+ 03 1.8E+ 03 1.8E+ 03 1,800 Lead 1.6E+ 04 3.1E+ 04 1.3E+ 03 1.2E+ 03 9.1E+ 03 1.5E+ 04 5.4E+ 02 5.0E+ 02 5.0E+ 02 500 Mercury 1.7E+ 02 2.0E+ 02 2.1E+ 01 1.7E+ 01 9.3E+ 01 9.5E+ 01 7.4E+ 00 6.5E+ 00 6.5E+ 00 6.5 Molybdenum 3.9E+ 03 3.5E+ 04 9.8E+ 02 7.6E+ 02 2.2E+ 03 1.4E+ 04 3.5E+ 02 3.0E+ 02 3.0E+ 02 300 Nickel 4.6E+ 04 8.4E+ 04 9.0E+ 03 7.5E+ 03 1.2E+ 04 1.4E+ 04 2.9E+ 03 2.6E+ 03 2.6E+ 03 2,600 Selenium 3.1E+ 04 4.6E+ 04 2.4E+ 03 2.1E+ 03 1.7E+ 04 2.2E+ 04 8.7E+ 02 8.0E+ 02 8.0E+ 02 800 Vanadium 4.2E+ 05 4.5E+ 05 6.4E+ 04 5.9E+ 04 5.0E+ 04 5.1E+ 04 1.7E+ 04 1.7E+ 04 1.7E+ 04 17,000 Zinc 1.8E+ 05 8.3E+ 05 2.6E+ 04 2.3E+ 04 1.0E+ 05 4.0E+ 05 9.6E+ 03 8.6E+ 03 8.6E+ 03 8,600 Notes: Bold = Lowest RBC MOPC = Metal of Potential Concern ( a) The units for all RBCs are mg MOPC/ kg product ( i. e., ppm). The lowest unit RBC for each metal is shown in the two far right columns.

This is the value used for screening ( presented in Section 4.0).

( b) The lowest unit RBC is the lowest for child and adult farm residents.

( c) The RBCs presented for arsenic are based on cancer. All other RBCs are based on non cancer. DRAFT 34 DRAFT SECTION 4.0 ¾ SCREENING HEALTH EVALUATION: COMPARISON OF THE RISK BASED CONCENTRATIONS ( RBC) WITH THE CONCENTRATION OF THE METAL OF POTENTIAL CONCERN ( MOPC) IN FERTILIZER PRODUCTS A screening level determination of whether a particular fertilizer product poses a potential health risk is accomplished by comparing the measured concentration of a MOPC ( e. g. arsenic) in the product to the RBC for that same MOPC. The RBCs for this assessment are derived in this report and presented in Table 14. The lowest RBCs are the most appropriate to use in a screening level health risk evaluation. The measured concentrations of MOPC are obtained from the published literature, from a survey of fertilizer manufacturers, and from monitoring programs being conducted by a number of states. This database has been compiled by TWG. 33 The concentrations of the MOPC in products must be in the same units as the RBCs to make a direct comparison. The RBCs and the product concentration database are reported in mg MOPC/ kg product ( i. e., part per million or ppm). Comparisons can be made on a product byproduct basis, or if there are multiple reported concentrations of a MOPC for the same fertilizer ( e. g., samples from different batches or from different manufacturers), the maximum MOPC concentration can be compared to the RBC as an initial screen. Comparing the lowest RBC to the maximum MOPC concentration provides the most health protective estimate of health risk. If the concentration of the MOPC in the fertilizer is below the RBC, there is no health risk. If the concentration of the MOPC in the fertilizer is above the RBC, further evaluation is warranted. An exceedence of a screening level RBC does not necessarily indicate there is a health risk because the RBCs are health protective derived to ensure that health risks are not underestimated ( but they may be overestimated). A firm conclusion regarding health risks, in the case of a RBC exceedence, therefore, requires a closer evaluation.

Before the RBCs can be compared to the measured levels of MOPC in a product, however, the unit RBCs ( i. e., RBCs derived for 1% of the nutrient in a product; reported in Table 14) need to be adjusted for the actual fraction of nutrient ( FON) in the product. The unit RBC is adjusted by multiplying the RBC by the percent FON. For phosphate fertilizers, the FON is the phosphate ( or P2O5) component; for micronutrient fertilizers, it is the principal micronutrient component ( e. g. zinc or iron). The representative FON is determined using both the TWG fertilizer database and information reported in USEPA ( 1999a). The FONs for each product category are best estimates and are presented in Table 15 ( for phosphate) and Table 16 ( for micronutrients).

The comparisons of FON adjusted RBCs to maximum measured concentrations of MOPC in products ( by fertilizer type or product category) are presented in Tables 17 and 18 for phosphate and micronutrient fertilizers, respectively. Phosphate product categories include, for example, diammonium phosphate or urea ammonium phosphate. There are also a number of product samples that were reported as ` agricultural blends'; they contain N, P and K but with no micronutrients added. The micronutrient product categories are boron, iron, manganese, and zinc micronutrient fertilizers.

33 TWG fertilizer database consists of state, literature, and industry data on inorganic fertilizers. A summary of this database is presented in TWG ( 1999c). This database is updated as new data become available. 35 DRAFT Results There were no RBC exceedances for any of the 12 MOPC in phosphate fertilizers ( see Table 17). There were comparisons made for 15 categories of phosphate fertilizers ( including the agricultural blends) and for a total of approximately 925 individual fertilizer samples.

There were RBC exceedances among the four categories of micronutrient fertilizers, primarily for the MOPC arsenic and lead. A total of approximately 140 individual fertilizer samples were evaluated. The exceedances include:

· 2 for arsenic in boron micronutrient fertilizers; · 8 for arsenic in iron micronutrients; · 2 for arsenic in manganese micronutrient fertilizers; · 1 for lead in iron micronutrient fertilizers; · 1 for lead in manganese micronutrient fertilizers; · 6 for lead in zinc micronutrient fertilizers; · and 2 for zinc in zinc micronutrient fertilizers.

A closer evaluation of the exceedances, to determine if these fertilizers pose a health risk, would involve several steps, including: ( 1) replacing the default FON developed for the fertilizer category with the FON for the individual fertilizer sample ( not always reported in the database) 34, ( 2) confirmation that the product is still on the market ( a number of the samples reported in the database are years old), and ( 3) determine the exact usage ( including application rate, crop types, etc.) for the product of interest, then adjust the RBC value to more closely reflect the actual exposure scenario conditions.

34 Six of these 22 exceedances become non exceedances when the unit RBC is adjusted by a sample specific FON in place of the default FON for the product category. FONs were reported for most of the samples. TABLES TABLE 15 PERCENT FRACTION OF NUTRIENT ( FON) ESTIMATES FOR PHOSPHATE FERTILIZER PRODUCT CATEGORIES TWG Database ( a) USEPA ( b)

Product Reported Best Category N ( c) Minimum Maximum Median Mean % P2O5 Estimate ( d)

Agricultural Blends 59 2 60 15 18  18 Ammonium Phosphate Sulfate 1 20 20   20.0 20 Ammonium Polyphosphate 1 34 34   60.0 34 Diammonium Phosphate 4 46 53 46 48 46.0 46 Monoammonium Phosphate 8 50 52 52 51 51.8 52 Nitrophosphate 1 20 20    20 Orthophosphate 1 30 30    30 Phosphate 5 15 37 30 27  30 Phosphoric Acid 2 52 60 56 56 53.3 56 Superphosphate 2 18 20 19 19 20.7 20 Superphosphoric acid 4 61 70 69 67 70.1 70 Triple Superphosphate 7 44 46 46 45 45.7 46 Urea Ammonium Polyphosphate  KCl 1 19 19    19 Urea Ammonium Phosphate 1 45 45    45 Urea Diammonium Phosphate  KCl 1 15 15    15 Notes:  = Not Applicable N = Number of Samples % P2O5 = Phosphate ( Phosphorous)

TWG = The Weinberg Group Inc.

USEPA = United States Environmental Protection Agency ( a) All values are the % P2O5 of the product category. TWG database is compiled from industry, literature, and states'

monitoring data ( TWG 1999c).

( b) Numbers are from Table 3 4 of USEPA ( 1999a).

( c) Reflects the number of samples of a product with a reported % P2O5.

( d) The best estimate is the % FON that is used to adjust the unit RBC. DRAFT TABLE 16 PERCENT FRACTION OF NUTRIENT ( FON) ESTIMATES FOR MICRONUTRIENT FERTILIZER PRODUCT CATEGORIES TWG Database( a) USEPA ( 1999a) ( b)

Product Best Category N ( c) Minimum Maximum Median Mean N Minimum Maximum Mean Estimate ( d)

Boron 5 10 21 15 15 2 10 21 15.5 15 Iron 16 2 58 20 24 3 12 15 14 24 Manganese 7 28 40 12 12 2 24.7 29.5 27.1 12 Zinc 29 7 89 25 27 63 7 89 26.5 27 Notes: `

 = Not Applicable N = Number of Samples TWG = The Weinberg Group Inc.

USEPA = United States Environmental Protection Agency ( a) TWG database is compiled from industry, literature, and states' monitoring data ( TWG 1999c).

( b) All values are the % micronutrient of the product category. Statistics are calculated from the data set found in Appendix G of USEPA ( 1999a).

( c) Reflects the number of products for which a % micronutrient is reported.

( d) The best estimate is the % FON that is used to adjust the unit RBC. DRAFT TABLE 17 SCREENING LEVEL EVALUATION:

COMPARISON OF THE CONCENTRATION OF METAL OF POTENTIAL CONCERN ( MOPC) IN PHOSPHATE FERTILIZERS TO THE ADJUSTED RISK BASED CONCENTRATION ( RBC)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Agricultural Blends Arsenic 84 0.15 42 2.6 3.6 3.2 4.5 81 42 No

Cadmium 83 0.015 160 3.2 7.1 4.6 23 410 160 No

Chromium 84 0.25 5,100 49 4.2 64 34,000 610,000 5,100 No

Cobalt 35 0.65 22 3.3 2.9 4.5 3,100 56,000 22 No

Copper 55 0.14 540 15 5.1 22 280 5,000 540 No

Lead 79 0.1( h) 650 4.8 9.3 7.3 73 1,300 650 No

Mercury 46 0.0025 1.1 0.036 6.5 0.058 0.9 16 1.1 No

Molybdenum 10 0.69 6 3.4 1.9 4.9 42 760 6 No

Nickel 52 0.54 54 8.6 3 11 350 6,300 54 No

Selenium 26 0.025 5.7 0.22 2.9 0.32 120 2,200 5.7 No

Vanadium 52 0.28 350 42 3.7 56 2,200 40,000 350 No

Zinc 57 0.85 6,300 107 7.8 130 1,200 22,000 6,300 No

Ammonium Phosphate Sulfate Arsenic 2 4.1 4.2 4.1 1  4.5 90 4.2 No

Cadmium 2 150 150 150 1  23 460 150 No

Chromium 2 210 250 230 1.1  34,000 680,000 250 No

Cobalt 2 2.5 3.2 2.8 1.2  3,100 62,000 3.2 No

Copper 2 11 16 13 1.3  280 5,600 16 No

Lead 2 2.1 4.4 3 1.7  73 1,500 4.4 No

Mercury 2 0.01 0.024 0.015 1.9  0.9 18 0.024 No

Molybdenum 2 5 5.7 5.3 1.1  42 840 5.7 No

Nickel 2 200 220 208 1.1  350 7,000 220 No

Selenium 2 0.13 2 0.5 7.1  120 2,400 2 No

Vanadium 1 400 400    2,200 44,000 400 No

Zinc 2 1,500 2,400 1,900 1.4  1,200 24,000 2,400 No

Foot notes are presented at the end of the table. DRAFT TABLE 17 ( continued)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Ammonium Polyphosphate Arsenic 7 0.6 21 7.7 3.5 19 4.5 150 21 No

Cadmium 11 4 56 15 2.2 23 23 780 56 No

Chromium 9 57 400 150 2 240 34,000 1,200,000 400 No

Cobalt 3 0.15 1.4 0.53 3.1  3,100 110,000 1.4 No

Copper 10 0.5 14 3 3.6 6.4 280 9,500 14 No

Lead 10 0.17 150 2.7 10 10 73 2,500 150 No

Mercury 1 0.0025 0.0025    0.9 31 0.0025 No

Molybdenum 2 3.1 6.5 4.5 1.7  42 1,400 6.5 No

Nickel 5 0.5 14 5.9 4.1  350 12,000 14 No

Selenium 2 2 2.1 2 1  120 4,100 2.1 No

Vanadium 5 49 230 94 1.8  2,200 75,000 230 No

Zinc 10 46 820 180 2.3 290 1,200 41,000 820 No

Diammonium Phosphate Arsenic 114 0.05 21 10 1.9 11 4.5 210 21 No

Cadmium 347 0.25 190 5.1 1.8 5.3 23 1,100 190 No

Chromium 117 1 620 69 1.8 76 34,000 1,600,000 620 No

Cobalt 106 0.25 10 3.8 1.8 4.1 3,100 140,000 10 No

Copper 115 0.45 98 1.8 2.9 2.1 280 13,000 98 No

Lead 344 0.5 150 3.4 2.5 3.7 73 3,400 150 No

Mercury 167 0.001 0.5 0.046 6.4 0.058 0.9 41 0.5 No

Molybdenum 103 2.5 47 11 1.4 11 42 1,900 47 No

Nickel 127 1.1 160 17 1.8 18 350 16,000 160 No

Selenium 103 0.025 5 1.2 5 1.6 120 5,500 5 No

Vanadium 78 11 280 130 1.4 130 2,200 100,000 280 No

Zinc 115 0.83 2,300 82 2.9 96 1,200 55,000 2,300 No

Foot notes are presented at the end of the table. DRAFT TABLE 17 ( continued)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Monoammonium Phosphate Arsenic 84 0.05 25 10 2.6 12 4.5 230 25 No

Cadmium 233 0.15 210 6.2 2 6.6 23 1,200 210 No

Chromium 83 0.5 730 69 2.5 82 34,000 1,800,000 730 No

Cobalt 79 0.78 12 4.3 1.9 4.8 3,100 160,000 12 No

Copper 80 0.44 76 1.8 2.9 2.2 280 15,000 76 No

Lead 231 0.05 150 4.9 2.5 5.4 73 3,800 150 No

Mercury 98 0.002 1.5 0.044 6.5 0.061 0.9 47 1.5 No

Molybdenum 75 4 38 12 1.4 13 42 2,200 38 No

Nickel 82 1.3 240 17 1.7 19 350 18,000 240 No

Selenium 74 0.05 20 1.1 4.4 1.4 120 6,200 20 No

Vanadium 52 35 1,100 160 1.6 170 2,200 110,000 1,100 No

Zinc 80 10 3,400 75 2.1 86 1,200 62,000 3,400 No

Nitrophosphate ( i)

Arsenic 5 3.6 7.4 6.1 1.3  4.5 90 7.4 No

Cadmium 5 2.6 4.3 3.2 1.2  23 460 4.3 No

Chromium 5 39 200 66 1.9  34,000 680,000 200 No

Cobalt 5 2.7 12 6.4 1.7  3,100 62,000 12 No

Copper 5 11 71 21 2.1  280 5,600 71 No

Lead 5 2.5 20 4.5 2.3  73 1,100 20 No

Mercury 1 0.38 0.38    0.9 18 0.38 No

Nickel 5 5.7 86 15 2.9  350 7,000 86 No

Vanadium 4 65 83 71 1.1  2,200 44,000 83 No

Zinc 5 0.48 140 19 8.8  1,200 24,000 140 No

Foot notes are presented at the end of the table. DRAFT TABLE 17 ( continued)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Orthophosphate ( i)

Arsenic 2 21 21 21   4.5 140 21 No

Cadmium 2 20 20 19   23 690 20 No

Lead 2 150 150 150   73 2,200 150 No

Phosphate ( i)

Arsenic 5 0.2 25 2.1 10  4.5 130 25 No

Cadmium 4 3 69 10 4.6  23 690 69 No

Lead 3 1 110 11 10  73 2,200 110 No

Phosphoric Acid Arsenic 14 0.5 19 7.5 3.3 13 4.5 250 19 No

Cadmium 10 0.15 160 18 11 75 23 1,300 160 No

Chromium 3 62 900 160 4.4  34,000 1,900,000 900 No

Cobalt 3 0.15 4 1.2 6.2  3,100 170,000 4 No

Copper 3 0.2 0.5 0.37 1.7  280 16,000 0.5 No

Lead 10 0.5 10 1.6 2.4 2.7 73 4,100 10 No

Mercury 3 0.0025 0.25 0.054 14  0.9 50 0.25 No

Molybdenum 3 5.9 11 8.7 1.4  42 2,400 11 No

Nickel 3 0.5 15 4.6 6.8  350 20,000 15 No

Selenium 3 2 2.5 2.3 1.1  120 6,700 2.5 No

Vanadium 3 57 140 97 1.6  2,200 120,000 140 No

Zinc 3 31 63 45 1.4  1,200 67,000 63 No

Superphosphate Arsenic 4 7 21 11 1.7  4.5 90 21 No

Cadmium 4 2 4.9 3.8 1.5  23 460 4.9 No

Chromium 3 32 40 34 1.1  34,000 680,000 40 No

Cobalt 1 2.5 2.5    3,100 62,000 2.5 No

Copper 1 6.9 6.9    280 5,600 6.9 No

Lead 4 1 17 6.2 3.5  73 1,500 17 No

Mercury 1 0.0025 0.0025    0.9 18 0.0025 No

Molybdenum 2 3.9 27 10 3.9  42 840 27 No

Nickel 4 8.8 14 11 1.2  350 7,000 14 No

Selenium 1 2 2    120 2,400 2 No

Vanadium 2 49 190 97 2.7  2,200 44,000 190 No

Zinc 2 43 56 49 1.2  1,200 24,000 56 No

Foot notes are presented at the end of the table. DRAFT TABLE 17 ( continued)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Superphosphoric Acid ( i)

Arsenic 9 0.2 31 6.9 4.7 18 4.5 320 31 No

Cadmium 9 0.5 160 33 8.3 120 23 1,600 160 No

Chromium 2 300 840 500 2.1  34,000 2,400,000 840 No

Copper 2 2.5 30 8.6 5.8  280 20,000 30 No

Lead 5 0.05 8.5 1.3 7.3  73 5,100 8.5 No

Molybdenum 2 6 6.8 6.4 1.1  42 2,900 6.8 No

Nickel 2 22 27 24 1.2  350 25,000 27 No

Selenium 1 4.3 4.3    120 8,400 4.3 No

Vanadium 2 52 200 100 2.6  2,200 150,000 200 No

Zinc 2 30 240 85 4.4  1,200 84,000 240 No

Triple Superphosphate Arsenic 68 0.05 21 9.8 2.4 10 4.5 210 21 No

Cadmium 204 1.8 180 8 2 8.6 23 1,100 180 No

Chromium 63 3.5 550 84 1.9 96 34,000 1,200,000 550 No

Cobalt 56 1.8 15 6.1 2 7.1 3,100 140,000 15 No

Copper 58 1 55 4.2 2.2 5 280 13,000 55 No

Lead 201 1 1,900 8.4 2 9.1 73 3,400 1,900 No

Mercury 85 0.0025 1.3 0.056 4.8 0.074 0.9 41 1.3 No

Molybdenum 53 6 72 12 1.4 13 42 1,900 72 No

Nickel 64 10 150 19 1.6 21 350 16,000 150 No

Selenium 54 0.025 21 2 3.2 2.6 120 5,500 21 No

Vanadium 33 87 720 140 1.4 160 2,200 100,000 720 No

Zinc 57 42 1,600 100 2 120 1,200 55,000 1,600 No

Urea Ammonium Polyphosphate KCl ( i)

Arsenic 4 5.2 7.8 6.7 1.2  4.5 86 7.8 No

Cadmium 5 1.6 24 4.1 2.9  23 440 24 No

Chromium 5 44 160 63 1.7  34,000 650,000 160 No

Cobalt 2 3.5 3.9 3.7 1.1  3,100 59,000 3.9 No

Copper 4 3.9 26 10 2.2  280 5,300 26 No

Lead 5 1.1 3.8 2.2 1.7  73 1,400 3.8 No

Nickel 4 9.2 27 13 1.6  350 6,700 27 No

Vanadium 5 47 98 76 1.3  2,200 42,000 98 No

Zinc 4 6.9 75 28 2.7  1,200 23,000 75 No

Foot notes are presented at the end of the table. DRAFT TABLE 17 ( continued)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Urea Ammonium Phosphate ( i)

Arsenic 1 1 1    4.5 200 1 No

Cadmium 1 110 110    23 1,000 110 No

Chromium 1 380 380    34,000 1,500,000 380 No

Lead 1 3.2 3.2    73 3,300 3.2 No

Mercury 1 0.0025 0.0025    0.9 41 0.0025 No

Selenium 1 0.15 0.15    120 5,400 0.15 No

Urea Diammonium Phosphate KCl ( i)

Arsenic 2 4.7 4.9 4.8 1  4.5 68 4.9 No

Cadmium 2 2 2.1 2 1  23 350 2.1 No

Chromium 2 28 43 34 1.3  34,000 510,000 43 No

Cobalt 1 7.2 7.2    3,100 47,000 7.2 No

Copper 2 3.9 7.2 5.3 1.5  280 4,200 7.2 No

Lead 2 1.8 2.1 1.9 1.1  73 1,100 2.1 No

Nickel 2 6.2 11 8.4 1.5  350 5,300 11 No

Vanadium 2 49 73 60 1.3  2,200 33,000 73 No

Zinc 2 0.3 0.55 0.41 1.5  1,200 18,000 0.55 No

Notes:  = Not Applicable GM = Geometric Mean GSD = Geometric Standard Deviation N = Number of Samples ( or Exceedances)

90% UCL = 90% Upper Confidence Limit ( a) All concentrations are in mg MOPC/ kg product ( or ppm). Data is from industry, literature, and states' monitoring data [ compiled and maintained by The Weinberg Group Inc. ( TWG 1999c)].

( b) A 90 % UCL is provided when the number of samples for the MOPC is greater than five. The 90% UCL is considered a good upper end estimate of the mean.

( c) Unit RBC is based on a 1% fraction of nutrient ( FON). All RBCs are in mg MOPC/ kg product.

( d) % FON for each product category is a best estimate. The determination of FON is presented in Table 15.

% FON for each product category is:

agricultural blends = 18; ammonium phosphate sulfate = 20; ammonium polyphosphate = 34; diammonium phosphate = 46; monoammonium phosphate = 52;

nitrophosphate = 20; orthophosphate = 30; phosphate = 30; phosphoric acid = 56; superphosphate = 20; superphosphoric acid = 70;

triple superphosphate = 46; urea ammonium polyphosphate  KCl = 19; urea ammonium phosphate = 45; and urea  diammonium phosphate  KCl = 15.

( e) Adjusted RBC equals the unit RBC multiplied by the % FON.

For example, arsenic unit RBC for agricultural blends = 4.5 and the % FON for agricultural blends is 18. Therefore, the adjusted RBC for arsenic in agricultural blends = 4.5* 18 = 81 mg of arsenic/ kg product.

( f) If the maximum concentration is greater than the adjusted RBC, there is an exceedance.

( g) The number of exceedances is the number of samples ( within each product category) with a concentration greater than the adjusted RBC.

( h) All numbers have two significant figures. When only one digit is presented, a zero ( to the right of the decimal) is the last digit. For example, 6 = 6.0 and 0.05 = 0.050.

( i) TWG ( 1999c) does not have data for all MOPC for the following product categories: nitrophosphate, orthophosphate, phosphate, superphosphoric acid,

urea ammonium polyphosphate  KCl, urea ammonium phosphate, and urea diammonium phosphate. DRAFT TABLE 18 SCREENING LEVEL EVALUATION:

COMPARISON OF THE CONCENTRATION OF METAL OF POTENTIAL CONCERN ( MOPC) IN MICRONUTRIENT FERTILIZERS TO THE ADJUSTED RISK BASED CONCENTRATION ( RBC)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product 90% Unit Adjusted Maximum Yes or Category N Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Boron Micronutrient Arsenic 8 1.8 1,000 42 8.6 180 38 570 1,000 Yes 2 Cadmium 5 0.75 20 10 4.3  210 3,200 20 No

Chromium 1 1.3 1.3    220,000 3,300,000 1.3 No

Cobalt 1 1.8 1.8    23,000 350,000 1.8 No

Copper 1 0.5 ( h) 0.5    1,800 27,000 0.5 No

Lead 7 1 150 21 12 130 500 7,500 150 No

Mercury 1 0.0025 0.0025    6.5 98 0.0025 No

Molybdenum 1 0.25 0.25    300 4,500 0.25 No

Nickel 3 0.5 4 1.8 3  2,600 39,000 4 No

Selenium 1 2 2    800 12,000 2 No

Vanadium 1 17 17    17,000 260,000 17 No

Zinc 1 7.7 7.7    8,600 130,000 7.7 No

Iron Micronutrient ( i)

Arsenic 35 0.6 6,200 67 13 140 38 910 6,200 Yes 8 Cadmium 31 0.3 3,900 17 5.4 28 210 5,000 3,900 No

Chromium 10 2 120 8.9 3.9 20 220,000 5,300,000 120 No

Lead 37 0.37 18,000 330 12 660 500 12,000 18,000 Yes 1 Nickel 10 3.4 210 31 4.2 71 2,600 6,200 210 No

Manganese Micronutrient Arsenic 14 0.1 2,000 19 16 70 38 460 2,000 Yes 2 Cadmium 13 0.16 55 3.1 6 7.4 210 2,500 55 No

Chromium 8 3.1 460 17 5.8 57 220,000 2,600,000 460 No

Cobalt 5 11 290 74 3.4  23,000 280,000 290 No

Copper 3 21 40,000 2,500 65  18,000 220,000 40,000 No

Lead 14 0.55 13,000 62 30 310 500 6,000 13,000 Yes 1 Mercury 5 0.0025 0.23 0.01 7.6  6.5 78 0.23 No

Molybdenum 5 2.5 850 15 12  300 3,600 850 No

Nickel 11 1.5 560 43 5.4 110 2,600 31,000 560 No

Selenium 5 2 20 6.2 2.9  800 9,600 20 No

Vanadium 3 0.55 33 3 8.4  17,000 200,000 33 No

Zinc 5 61 94,000 4,700 25  8,600 100,000 94,000 No

Foot notes are presented at the end of the table. DRAFT TABLE 18 ( continued)

Statistical Summary of Concentration Data ( a) Comparison Exceed?

Product N of 90% Unit Adjusted Maximum Yes or Category Samples Minimum Maximum GM GSD UCL ( b) RBC ( c, d) RBC ( e) Concentration No ( f) N ( g)

Zinc Micronutrient Arsenic 56 0.1 130 4.5 8.8 7.4 38 1,000 130 No

Cadmium 74 0.095 2,300 24 8.5 36 210 5,700 2,300 No

Chromium 24 0.25 8,100 24 17 65 1,800,000 49,000,000 8,100 No

Cobalt 6 0.25 790 17 36 330 23,000 620,000 790 No

Copper 4 4.4 1,700 170 14  1,800 49,000 1,700 No

Lead 72 0.32 28,000 180 23 320 500 14,000 28,000 Yes 6 Mercury 16 0.0025 12 0.03 31 0.14 6.5 180 12 No

Molybdenum 5 0.25 14 1.2 5.6  300 8,100 14 No

Nickel 14 4.3 450 47 4.4 96 2,600 70,000 450 No

Selenium 15 0.013 25 0.77 9.1 2.1 800 22,000 25 No

Vanadium 4 0.5 47 14 9.3  17,000 460,000 47 No

Zinc 6 22,000 350,000 160,000 2.8 380,000 8,600 230,000 350,000 Yes 2 Notes:  = Not Applicable GM = Geometric Mean GSD = Geometric Standard Deviation N = Number of Samples ( or Exceedances)

90% UCL = 90 percent Upper Confidence Limit ( a) All concentrations are in mg MOPC/ kg product ( or ppm). Data is from industry, literature, and states' monitoring data [ compiled and maintained by The Weinberg Group Inc. ( TWG 1999c)].

( b) A 90 % UCL is provided when the number of samples for the MOPC is greater than five. The 90% UCL is considered a good upper end estimate of the mean.

( c) Unit RBC is based on a 1% fraction of nutrient ( FON). All RBCs are in mg MOPC/ kg product.

( d) % FON for each product category is a best estimate. The determination of FON is present in Table 16.

% FON for each product category is:

boron micronutrient = 15; iron micronutrient = 24; manganese micronutrient = 12; and zinc micronutrient = 27.

( e) Adjusted RBC equals the unit RBC multiplied by the % FON.

For example, arsenic unit RBC for micronutrient = 38, % FON for boron miconutrient = 15, therefore, the adjusted RBC for arsenic in boron micronutrient = 38* 15 = 570 mg arsenic/ kg product.

( f) If the maximum concentration is greater than the adjusted RBC, there is an exceedance.

( g) The number of exceedances is the number of samples ( within each product category) with a concentration greater than the adjusted RBC.

( h) All numbers have two significant figures. When only one number is presented, a zero ( to the right of the decimal) is the last digit.

For example, 6 = 6.0 and 0.05 = 0.050.

( i) TWG ( 1999c) does not have data for all MOPC for the iron micronutrient category. DRAFT 36 DRAFT SECTION 5.0 ¾ DERIVATION OF THE RISK BASED CONCENTRATION ( RBC) FOR RADIONUCLUDE ( RADIUM226) AND SCREENING LEVEL HEALTH EVALUATION: COMPARISON OF THE RBC WITH PRODUCT DATA Several radionuclides have been detected in phosphate fertilizers, namely uranium238, radium226, and thorium232. This section derives a RBC for one of the radionuclides, radium226. Radium226 is selected as the radionuclide to develop a RBC based on relative toxicity, relative product concentration, and evaluation precedence. The RBC for radium226 is used to conduct a screening level health evaluation.

Relative Toxicity A radionuclide is the radioactive species of a specific element. Radionuclides exert a toxic effect by transferring energy from the electric field of their nucleus thereby destroying surrounding cells and producing free radicals. Toxicity is measured as activity. Radionuclides are classified by USEPA as Group A carcinogens ( USEPA 1999d), and as such, the RBCs are developed based on carcinogenic risk. Radium226 has higher relative toxicity, based on the ingestion slope factors ( USEPA 1999d), compared to the other radionuclides under consideration. The ingestion slope factors for radium226, thorium232, and uranium238 are 2.96E 10 ( for radium and its shortlived decay products), 3.28E 11, and 4.27E 11, respectively. The slope factors are expressed as age average lifetime oral radiation cancer incidence risk per unit intake or exposure; the units are risk/ pCi ( picoCurie, discussed below).

Relative Concentration in Product The amount ( or concentration) of a radionuclide is also measured as activity. Typically, the unit of activity is expressed as becqueral ( Bq). Bq is the quantity of a radionuclide where one atom is transferred per second. In the derivation of the RBC, Bq are converted to more conventional units, picoCurie ( pCi), in order to match the units of the toxicity value. There is limited data on the concentration of radionuclides in phosphate fertilizers. During processing, the concentration of uranium238 and thorium232 will generally remain in the phosphate component of the fertilizer ( USEPA 1999a). Uranium238 decays to form radium226 ( USEPA 1999e). The halflife for radium226 is 1,600 years. Radium226 then decays to form radon 222 gas, which has a half life of 3.8 days ( USEPA 1999e). Radium226 in phosphate ore will be contained in the phosphogypsum by product ( USEPA 1999a). Thorium232 is at lower levels in phosphate fertilizer than uranium238 and radium226 ( USEPA 1999a and TWG 1999c). The level of uranium238 and radium226 measured in various phosphate fertilizers varies.

Evaluation Precedence Radium226 is selected as a good example radionuclide to develop a RBC. This selection is based largely on evaluation precedence. Currently, the USEPA ( 1999e) has established strict regulatory limits on phosphogypsum, including a ban on its use in building roads in Florida due to radium content. The ban is based on the potential risk to a resident if the road is abandoned and a house is built on the road. Under USEPA regulation, the agricultural use of phosphogypsum is permitted if a stack ( pile) has less than 10 pCi/ g of radium226. 37 DRAFT Derivation of the Risk Based Concentration ( RBC)

A RBC is derived for radium226 for the exposure scenario defined in Section 1.0, the farm family and unintentional ingestion of fertilized soil and ingestion of crops. 35 The dermal contact exposure route is not included in the RBC because of the low risk potential from dermal exposure.

The RBC is calculated using a similar approach and many of the same parameters that are used to derive the MOPC RBCs. However, because of the difference in toxicity ( e. g., slope factors are expressed as activity other than concentration) of radionuclides, the RBC for radium226 is calculated in a slightly different way than the RBCs for the MOPC. In addition, radium specific parameters are needed for several parameters. Deviations from the derivation of the RBCs for the MOPC are:

( 1) radionuclide slope factors are not expressed as a function of body weight and time, therefore, these parameters are not included in the intake equation; ( 2) radium226 specific parameters for PUF and Kd; and ( 3) radionuclide slope factors are expressed as an activity.

Radium226 specific parameters are:

· Kd of 214  470 mL/ g ( USDHHS 1989b); · PUF ( unitless) for vegetable crops is 0.012, root crops is 0.012, and for grain is 0.001   0.6 ( Post, Buckley, Schuh, & Jernigan, Inc. [ PBS& J] 1990, Watson et al., 1983); and · Oral Slope Factor 2.96E 10 risk/ pCi ( USEPA 1999d).

The PUFs values for vegetable and root crops are consistent. However, there is a wide range of PUFs for grain ( Watson et al., 1983). In a report by PBS& J ( 1990) the authors suggest that the 0.6 PUF for grain is too high; they suggest a more realistic PUF for grain ( 0.01 for " control" soils or 0.001 for grain grown on phosphate clay settling areas). The grain PUF value that is similar to the PUFs for vegetable and root is used to calculate the RBC ( 0.01).

In addition, given the consideration of only one loss pathway, the low end Kd value is used to calculate the RBC.

The amount of radium226 that is taken into the body through unintentional ingestion of fertilized soil and ingestion of crops is adjusted by the percent of radium226 that is expected to be absorbed in the gastrointestinal tract ( GI), which is 20% ( USDHSS 1989b).

35 The decay of radium226 to radon 222 gas and potential for inhalation exposure is recognized. However, under the farm family exposure scenario, the contribution of exposure from inhalation is expected to be much lower than the other routes of exposure. The exposure for this route is expected to be low because ( 1) the limited time of exposure ( time spent in the filed) and ( 2) because the exposure is not in a confined space but in open field, which will allow the radionuclide to dissipate. 38 DRAFT Presentation of the Risk Based Concentration ( RBC) and Health Screening Evaluation The unit RBCs for radium226 are presented below, the lowest unit RBC is 21 pCi/ g and is based on the multi crop farm and the adult.

RBC ( pCi/ g) Vegetable Root Grain Multiple Crop Adult 55 70 64 21 Child 540 520 460 200 The unit RBC is adjusted by the appropriate FON for screening and compared with the activity measured in select phosphate products. The screening evaluation is presented below. There are no exceedances of the radium226 RBC by measured activity levels of radium 226 in phosphate fertilizers.

Activity Level in Product ( pCi/ g) ( a) Product FON Adjusted RBC Minimum Maximum Exceedances DAP 46 966 0.7  None MAP 52 1,100 0.6 12.8 None TSP 46 970 84  None SP 20 420 92  None NPK 18 380 0.4 124 None  Indicates one sample. ( a) Activity level in phosphate products is from TWG ( 1999c) and several world wide samples from USEPA ( 1999a). 39 DRAFT SECTION 6.0 ¾ DISCUSSION OF UNCERTAINTY Each step in establishing the scope of the evaluation and in developing the RBCs has some inherent uncertainty associated with it. The major uncertainties in this evaluation of fertilizers are described in this section in order to provide an indication of the relative degree to which the uncertainty may underestimate or overestimate exposure, the RBCs, and/ or the conclusions of the screening evaluation. Note, an overestimate of exposure will result in a RBC that is lower, a lower RBC is more health protective. An assessment of the major uncertainties associated with establishing the scope of the evaluation and developing the RBCs is presented in Table 19. In addition, an assessment of the magnitude of relative impact in the RBC equation associated with each parameter is presented in Table 20.

The purpose of this document is to provide fertilizer manufacturers and interested regulators with an easy tool to evaluate whether the concentrations of select elements ( MOPC), in a particular commercial inorganic fertilizer, may pose a health risk to the humans following its application to agricultural soil. The tool is a screening level RBC that defines a health protective exposure limit. RBCs are calculated based on a reasonable maximum exposure ( RME) and " high end values" purposely selected to account for the inherent uncertainty associated with each parameter. RBCs are intended to be an evaluation tool. More specifically, the RBC is an evaluation threshold above which further evaluation ( more product specific) are necessary to determine if there is, in fact, a risk. The RBCs are therefore, more likely to be over rather than under protective of human health, and the uncertainty analysis supports this conclusion.

The information presented in Tables 19 and 20 follow the organization of the information as presented in the report and are discussed below by major category.

Scope of the Evaluation The scope of the evaluation is narrowed to focus on the products, MOPC, exposed population, and exposure pathways of greatest concern. As a result, the RBCs are focused on the highest potential exposure and are intended to be health protective of all other exposure scenarios. The RBCs may result in an overestimate of potential risk but are not likely to underestimate risk.

Based on ( 1) the available MOPC concentration data in a wide range of inorganic fertilizer products, ( 2) the relative toxicity of the MOPC, and ( 3) the precedence for health risk evaluation, the selection of phosphate fertilizers and micronutrient fertilizers and the 12 metals ( plus radium 226) there is very little uncertainty that there are higher risks for other products or metals.

Fertilizer applicators are at minimal risk from MOPC in inorganic fertilizers ( TWG 1999a, b). Ingestion is the major exposure pathway and therefore a crop consumer who lives on a farm ( i. e., farm adult and child) has the highest expected exposure to MOPC ( USEPA 1999b, CDFA 1998). Exposure is from both ingestion of crops plus incidental dermal and soil ingestion. The added exposure from applying fertilizer is not expected to add significantly to the risk to the farm adult.

Several exposure pathways ( transport pathways and exposure routes) are not major exposure pathways and are excluded from the development of the RBCs. The exclusion of these exposure 40 DRAFT pathways is not likely to significantly underestimate risk, since the exposure pathways and exposure routes of greatest concern ( the primary drivers of the RBC) are the basis of the RBC ( USEPA 1999b, CDFA 1998). In particular, the ingestion of animal products is not considered in the RBC. The exclusion of this exposure route is not likely to underestimate risk because all of the MOPC that is taken up into grains is assumed to be directly consumed by humans ( rather than splitting the MOPC exposure into direct consumption of crops and indirect consumption of animals that ate the crops). Similarly, the assumption that the form of mercury is mercuric chloride ( that accumulates in soil), and not methyl mercury ( that bioaccumulates in fish), is very unlikely to significantly change the final evaluation of risk. 36 Again, it is a matter of splitting the total MOPC added to soil into two exposure pathways versus considering the total MOPC added to soil in a single exposure pathway.

Several exposure routes that are not considered " environmental acceptable end points" ( Chaney et al., 1999) for specific MOPC were included in the RBC. For example, several MOPC may be toxic ( phytotoxic) to the plant ( e. g. zinc) before reaching levels that could be toxic to humans that ingest the plant ( or crop). The inclusion of the ingestion of crops in the RBC for these MOPC may overestimate risk.

Derivation of the Risk Based Concentration ( RBC)

The RBCs are intended to represent a RME scenario; therefore, they are expected to be reasonably and maximally health protective. The lower RBC is the more health protective. Many of the parameters are statistical estimates recommended by USEPA for the RME scenario. An assessment of the magnitude of relative impact in the RBC equation for each of these parameters is presented in Table 20. The magnitude of impact considers ( 1) the possible range of values ( e. g., EF of 350 days/ year   1 day / year, or soil ingestion for a child of 100 mg/ day   400 mg/ day) and ( 2) the weight that each of the parameters has on the RBC ( e. g., SACF, AR, and PUF can significantly influence the RBC). Two parameters in particular, AR and PUF, that have upper end estimates, are particularly influential on the RBC derivation. The use of an RME scenario and upper end estimates for AR and PUF is more likely to underestimate rather than overestimate the RBCs ( i. e., overestimate rather than underestimate risk), as discussed below. Several additional assumptions are made that may further underestimate the RBC ( overestimate risk); these assumptions are also discussed below.

The biological exposure parameters ( e. g., BW [ body weight], IR [ ingestion rate], and SA [ exposed skin surface area]) are recommended RME estimates. These parameters may underestimate the RBC, but are considered reasonable for a screening level evaluation. In addition, they have a low relative impact on the RBC equation. The use of an FI of 1 assumes that 100% of the crops that a person consumes is from the farm. This is the highest FI and assumes that all of the crops that are ingested are fertilized. Also, the effect of preparing and/ or cooking crops for consumption is not evaluated in the RBC. The exclusion of this factor may 36 In soil, mercury is reactive and may form several different complexes. Although the transport of mercury into a nearby water body, formation of methyl mercury, and uptake into fish may occur, it is expected that this pathway will occur less frequently, and result in less exposure than the complexing of mercury with chlorine in soil ( especially since chlorine ions may be the most persistent complexing agent for mercury in soil) ( McLaughlin et al. 1996). 41 DRAFT overestimate risk and underestimate the RBC because it is likely that cooking will result in less concentration of a MOPC in the crop by causing the release of some of the MOPC.

The use of high end estimates for AR and PUF may result in RBCs that are underestimated for a " typical" scenario. However, the use of high end estimates for these parameters ensures that the RBCs are health protective of possible high end exposures. For example, plant uptake of an MOPC is generally higher in acidic soil. The use of an upper end estimate of PUF results in RBCs that are health protective of this potential scenario. In addition, the PUFs may be further overestimated by the inclusion of greenhouse or pot studies. MOPC uptake is typically greater in pot studies than field studies; still pot studies were included in the database. Conversely, the PUFs may be underestimated by the use of total compared to extractable MOPC soil concentration in the denominator of the PUF. Lastly, the PUFs are based on all of the plant parts, not just the edible portion. The magnitude of uncertainty on the use of data from the whole plant in developing the PUFs is unknown. In general, the PUFs are probably overestimates of MOPC plant uptake rather than underestimates.

Another parameter that may further underestimate rather than overestimate the RBC is the assumption of 100% relative absorption factor ( RAF) from the ingestion of MOPC in soil and crops for most of the MOPC. Again, this is selected as a conservative parameter for a screeninglevel evaluation. RAF adjusts the estimated intake and toxicity value to an absorbed dose resulting in a RBC that is more realistic and representative of actual exposure, intake, and absorption. The absorbed dose is likely to be less than the administered dose, especially when the MOPC is sorbed to soil or in plant tissue. For all MOPC, except arsenic, RAF is assumed to be 1. In addition, lead intake is adjusted by percent absorption values. A RAF of 1 can have different magnitudes of effect on the RBC depending on the MOPC and the basis of the toxicity value. For example, most of the toxicity values are based on an administered dose in the diet or food. The absorbed dose may be lower than the administered dose. In this case toxicity would occur at a lower dose, resulting in a lower toxicity value. Therefore, a toxicity value based on an administered dose may be greater than the a toxicity value based on an absorbed dose. Conversely, an estimated intake that is also based on an administered intake, rather than an absorbed intake, may be over estimated, especially depending on the medium of exposure. Therefore, if possible toxicity values and intake should both be based on administered dose or an absorbed dose and the same ( or similar) medium of exposure.

When the toxicity value is based on an absorbed dose and the estimated intake is based on administered dose, as is the case for cadmium, the RBC may be underestimated. The toxicity value for cadmium is based on food and is derived using a pharmacokinetic model that considers the percent of cadmium that is absorbed into the blood stream from the diet. Yet, the estimated intake of cadmium from the crop and incidental soil ingestion is based on the amount of food or soil ingested and not the actual amount of cadmium absorbed into the bloodstream. The absorption of cadmium in these media is assumed to be 100%, whereas, cadmium absorption from food or soil in the gut is expected to be much lower ( less than 5%).

The magnitude of the effect of soil accumulation factor ( SACF) on the RBC is unknown. SACF may overestimate or underestimate accumulation and bioavailability of the MOPC in soil following application. The consideration of MOPC loss through leaching as the only loss 42 DRAFT pathway is likely to underestimate the RBC because it is likely that loss of MOPC through other loss pathways could occur. Conversely however, the Kd values used in the development of the RBC may overestimate the leaching of the MOPC into groundwater and underestimate the exposure in soil. The lower the Kd, the more available the MOPC is for leaching into groundwater and the less remains in the soil. There is a very wide range of Kd values ( both measured and estimated) in the literature. The Kds selected for this evaluation are based on measured data and come from a single literature source, but are on the lower end of the Kd range.

The USEPA toxicity values used in the development of the RBCs are purposely conservative. For instance, the toxicity value for arsenic is based on a nutrient deficient population. The agency has built in considerable safety factors. In addition, for this evaluation in particular, the use of the oral cancer slope factor for arsenic may overestimate risk since the cancer toxicity value for arsenic is based on ( 1) inhalation and lung cancer and ( 2) drinking water and skin cancer, neither being directly related to the ingestion of food.

Also, toxicity values for several forms of chromium are available. In order to select the most appropriate toxicity value to use in developing the RBCs, assumptions are made about the form of the MOPC that is likely to accumulate in soil and be available for uptake into crop and human exposure. In particular, chromium III is assumed to accumulate in soil and be available for uptake, not chromium VI. This assumption about the form of chromium may underestimate risk from exposure because chromium III is less toxic than chromium VI. However, chromium III is the form expected to accumulate in soil over a long period of time.

The presence and effect of other MOPC on toxicity ( synergism, antagonism) or uptake ( e. g., cadmium and zinc) are not considered and may underestimate or overestimate risks. More than one MOPC is often present in a fertilizer. In addition, the contribution of MOPC in soil from natural background levels is also not accounted for in the RBC. The exclusion of contribution from background may overestimate the RBC and underestimate exposure and risk. The potential for underestimating exposure and risk from these factors is assumed to be offset by the overall high end parameters and assumptions used in the derivation of the RBCs.

Overall Assessment of Uncertainty on the RBC and Health Risk Screening Evaluation The approach used in this evaluation is consistent with the generally accepted practice in screening level health risk assessments. To this end, the products, MOPC, exposed population, and exposure scenario are selected and the RBCs are derived to ensure they are sufficiently health protective. Despite several uncertainties that may overestimate the RBC ( underestimate risk), the scope, the RBCs and the health screening evaluation ( comparison of RBCs to measured MOPC concentrations in products) are considered to be health protective. In addition, most of the parameters, in particular parameters that have a relative high impact on the RBC equation ( e. g., AR, PUF), are high end estimates. TABLES TABLE 19 MAJOR ASSUMPTIONS AND UNCERTAINTIES ASSOCIATED WITH THE RISK BASED CONCENTRATIONS ( RBCs) AND THE SCREENING LEVEL HEALTH RISK EVALUATION DRAFT Assumption Magnitude of Uncertainty and Effect on the Risk Based Concentration ( RBC) and Estimate of Risk Rationale Scope of the Evaluation Focuses on phosphate and select micronutrient fertilizers. Low   may underestimate risk ( overestimate RBC) if other classes had higher metal levels, but not likely. These classes of inorganic fertilizers tend to contain higher levels of the metals of potential concern ( MOPC). Phosphate fertilizers have the highest levels of metals compared to other macronutrient fertilizers. Also, micronutrient fertilizers that are evaluated have the highest metal concentrations.

Focuses on twelve metals of potential concern ( MOPC) and one radionuclide ( radium 226) considered to have toxicological significance compared to other metals found in inorganic fertilizers. Low   may underestimate risk and overestimate the RBC if the other metals are more toxic or were at significantly higher levels, but not likely. Other metals found in inorganic fertilizers have lower comparative toxicity. Also, since the metals with high toxicity are generally not found to a health concern ( arsenic, mercury and lead), then the other metals are not expected to be a health concern.

Focuses on farmer family and select exposure pathways   unintentional ingestion of fertilized soil, dermal contact fertilized soil and ingestion of crops. Low   may overestimate risk and underestimate the RBC. Health protective of all other scenarios because considered the scenario with highest exposure, and therefore, expected to have the lowest RBC.

Exclusion of several exposure pathways and routes, such as, ingestion of animal products that have taken up MOPC, and bioaccumulation of methyl mercury in fish. Low   may underestimate risk and overestimate the RBC. Not likely to underestimate risk because the highest exposure routes are the basis of the RBC. In particular, the RBC for grains is based on the assumption that all of the MOPC that is taken up into grain is directly consumed by humans.

Lack of the consideration of environmentally acceptable endpoints. For example, MOPC may be toxic to the plant before reaching levels that could toxic to humans. Low   Medium   may overestimate risk and underestimate RBC. Plant toxicity is not considered in this evaluation. The RBCs are intended to be health protective of the ingestion of MOPC in crops for any scenario.

Derivation of the Risk Based Concentration ( RBC)

Development of a RME scenario. Low   Medium   may overestimate risk and underestimate the RBC. Standard screening level guidance to ensure the RBCs are sufficiently health protective.

Exposures are based on granular fertilizer. Low   may under or overestimate risk and RBC. Exposure to fertilizer in the granular form is assumed to be similar to soil and exposure to liquid fertilizer is assumed to result in similar exposure as to granular fertilizer. Sufficiently health protective.

Upper   end estimates for AR and PUF. Low   Medium   may overestimate risk and underestimate the RBC. Ensures the RBCs are health protective of scenario were high accumulation, uptake, and exposure may occur. TABLE 19 ( continued)

DRAFT Assumption Magnitude of Uncertainty and Effect on the Risk Based Concentration ( RBC) and Estimate of Risk Rationale Development of PUFs ( 1) includes greenhouse and pot studies and ( 2) is based on total MOPC concentration in soil. Low   Medium   may under or overestimate risk and RBC. Uptake of MOPC by plants in greenhouse and pot studies is greater than in filed studies. PUFs based on total MOPC concentration in soil are lower than PUFs based on extractable MOPC concentration in soil.

RAF of 1 ( or 100%). Low   Medium   may overestimate exposure and risk and underestimate the RBC. Conservative assumption given the lack of information needed to develop appropriate and applicable RAF. RAF is probably lower than 100%.

Development of SACF   consideration of limited loss pathways and use of low end Kds. Low   Medium   may over or underestimate risk and RBC. An SACF based on limited loss pathways may result in more MOPC accumulating in soil. Conversely, low end Kds may overestimate the availability of MOPC to transport and leach into groundwater.

Conservatively derived USEPA cancer slope factors, chronic reference doses, and lead biokinetic slope factor are used to evaluate risk. Medium   may overestimate risk and underestimate RBC. For noncancer effects, combinations of uncertainty factors along with doseresponse data, often from laboratory animals, are used to derive criteria to protect the most sensitive human receptors. For cancer effects, doseresponse data are used to derive slope factors that estimate an upper limit on risk associated with a given exposure. Actual risk could be much lower ( especially for arsenic).

Toxicity criteria for the dermal exposure of exposure were derived using route to route extrapolation and an adjustment to an absorbed dose. Medium   may over or underestimate risk and RBC. Depending on the MOPC, the route of administration or exposure may change the toxicity.

Toxicity value for chromium III, not chromium VI is used. Low   may underestimate risk and overestimate the RBC. Chromium VI is more toxic than chromium, however, chromium III is expected to accumulate in soil over a long time period.

Factors not considered when developing the RBC · Contribution of MOPC from background · The presence and effect of other MOPC on toxicity ( synergism antagonism) or uptake ( e. g. cadmium and zinc) Low   Medium   may over or underestimate risk and RBC. Impossible to assess each of the factors because of lack of information that is needed. Overall conservative approach is considered health protective. TABLE 20 MAGNITUDE OF RELATIVE IMPACT ASSOCIATED WITH EACH PARAMETER IN THE RISK EQUATION DRAFT Parameter Statistical Descriptor Magnitude of Relative Impact ( High, Low) in Risk Equation ( a)

Biological Exposure Parameters Exposure Duration ( ED) 95th percentile, upper end estimate High ( for arsenic, the only carcinogen)

Exposure Frequency ( EF) Very high end, assumes exposure every day of the year except for 2 weeks away from home High Averaging Time ( AT) Standard default, but high end, based on lifetime exposure for cancer and length of exposure ( exposure duration) for noncancer High Body Weight ( BW) Mean estimate Low Ingestion Rates for Soil and Crops ( IR) Mean estimates Low Fraction Ingested ( FI) Highest possible percent High Skin Surface Area ( SA) Central tendency Low Adherence Factor ( AF) Central tendency Low Crops Specific Parameters Application Rate ( AR) 95% upper confidence limit of the arithmetic mean   upper end estimate High Plant Uptake Factors ( PUFs) 90% confidence limit of the geometric mean   upper end estimate High Fraction of Land ( FOL) Reasonable estimates Low Soil Accumulation Factor ( SACF) Reasonable estimate, combination of high, central and low end values High Metal of Potential Concern ( MOPC) Specific Parameters Toxicity Values ( Tox) High end, standard health protective values High Relative Absorption Factor ( RAF) Mostly 100%, high end percent ( except for arsenic and lead) Low   High ( MOPC dependent)

( a) The magnitude of impact considers ( 1) the possible range of values ( e. g., EF of 350 days/ year   1 day / year or soil ingestion for a child of 100 mg/ day   400 mg/ day) and ( 2) the weight that each of the parameters has in the RBC equation ( e. g., SACF, AR, and PUF have significant weight). 43 DRAFT SECTION 7.0 ¾ CONCLUSIONS OF EVALUATION The screening evaluation indicates there are no exceedances for any of the phosphate fertilizer RBCs and therefore no post application health risks from exposure to metals in NPK types of fertilizers. With regard to micronutrient fertilizers, there are exceedances of arsenic and lead RBCs for several micronutrient fertilizer products. These products contain relatively high levels of arsenic and lead in some samples. Because of the health protective nature of screening level evaluations, and because exceedances occur only at the maximum metal concentration in some of the samples, a firm conclusion regarding health risks from micronutrient products or product categories requires a closer, product by product evaluation. A refined evaluation would take into account the exact uses and use conditions of the specific products, as well as monitoring data for arsenic and lead concentrations in additional samples of these products.

As with all risk assessments there is some level of uncertainty associated with this evaluation. The major uncertainties are identified and described in the report. The uncertainty is more likely to err on the side of overestimating the potential for risk rather than underestimating the potential risk for both the NPK and micronutrient fertilizer products. 44 DRAFT SECTION 8.0 ¾ COMPARISON TO OTHER EVALUATIONS In addition to this evaluation, evaluations of inorganic fertilizers have been conducted and are presented in two previous reports: CDFA ( 1998) and USEPA ( 1999b). 37 These reports are used throughout this evaluation to assist in establishing health protective assumptions and in focusing the scope of this evaluation. A comparison of the ( 1) purpose and general approach ( 2) scope ( 3) specific key parameters and ( 4) the conclusions among these three evaluations is made in this section.

Purpose and General Approach The purpose and general approach of each of the evaluations is presented in Table 21. All three evaluations are intended to assist in answering the question: are inorganic fertilizers safe, or more specifically, does the use of inorganic fertilizer on agricultural soils pose a health risk? Each of these evaluations provides valuable information to answer this question. However, each assessment has a somewhat different approach and thus provides unique as well as complimentary information and conclusions.

The purpose of this evaluation is to develop a flexible screening tool that can be used to evaluate inorganic fertilizer products. In addition, this assessment evaluates a fairly comprehensive fertilizer product database ( TWG 1999c). Because the purpose of this evaluation is to provide a flexible screening tool, that can be used to evaluate many products now and in the future, this evaluation uses a back calculation, risk based approach and develops RBCs. This evaluation uses a deterministic and high end exposure estimate approach to develop health protective RBCs, or levels of metals in products. In addition, this evaluation is intended to be nationwide in its application.

As stated in USEPA ( 1999b), the purpose of USEPA's assessment is to estimate potential risks posed to human health and the environment by contaminants in ( 23) fertilizer products. Such a determination of risk requires a forward risk assessment approach. That is, USEPA determines risks for a range of product types that are currently in commerce. A summary of this product database is presented in USEPA ( 1999a). USEPA uses a probabilistic approach to estimate the distribution of individual lifetime risk from exposure to metals in inorganic fertilizer following application. USEPA's evaluation has nationwide application.

The purpose of the CDFA ( 1998) evaluation is to develop RBCs for three metals in inorganic fertilizers, arsenic, mercury, and lead, that are based on application and exposure in California. Of all the metals that are present in inorganic fertilizers, these three were chosen ( based on a screening evaluation) because they are considered to pose the highest risk. CDFA ( 1998) offers a method but does not evaluate actual product data and therefore does not make conclusions with regard to health risks. California uses a probabilistic approach to develop the RBCs.

37 The USEPA fertilizer risk assessment relies on the information provided in a companion report, USEPA 1999a. 45 DRAFT Scope The scope of each of these evaluations varies; a comparison of the scope is also presented in Table 21.

The scope of this evaluation is narrowed to focus on the products, MOPC, populations and exposure pathways of greatest concern. The products evaluated are phosphate fertilizers and select micronutrient fertilizers ( boron, iron, manganese, and zinc). The MOPC for which RBCs are developed and products are evaluated are: arsenic, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, selenium, vanadium, and zinc and one radionuclide, radium 226. The exposure scenario is the farm family, including adults and children, and exposure pathways that contribute the most to risk including direct contact with fertilized soil ( i. e., unintentional ingestion and dermal contact) and uptake of MOPC into crops and subsequent ingestion of crops. The RBCs are intended to be nationally representative. The crops are grouped into like physiological groups ( vegetable, root, and grain); each of these groups is evaluated independently.

USEPA ( 1999b) evaluates all of the general categories of inorganic fertilizer products ( e. g., NPK for P, NPK for N, phosphate fertilizers, nitrogen fertilizers, potash fertilizers, etc.), farm workers and farm residents ( both adults and children), most of the potential exposure pathways ( all three evaluations exclude drinking water), and 29 geographic locations. Crops are grouped as ingested by animals ( grain and forage) and crops ingested by humans ( fruit, herb or above ground vegetables, and root). USEPA ( 1999b) evaluates nine MOPC: arsenic, cadmium, cobalt, copper, lead, mercury, nickel, vanadium, and zinc, as well as dioxin. USEPA ( 1999b) also evaluates risk to the environment.

The scope of CDFA ( 1998) is focused on the development of RBCs for phosphate and zinc micronutrient fertilizers and three MOPC: arsenic, cadmium, and lead. In addition, as mentioned above, the CDFA ( 1998) evaluation focuses on California. The exposure scenario that the RBCs are based on is narrowed to focus on the exposure scenario of greatest concern through a deterministic, forward risk assessment screening evaluation. The focused exposure scenario consists of the farm family ( adults and children) and direct contact with fertilized soil ( i. e., unintentional ingestion and dermal contact) and the uptake of the MOPC through the ingestion of crops. Crops are grouped and evaluated similar to this evaluation.

Key Parameters Whether the assessment uses a forward risk based approach ( determination of risk for a specific group of products) or a back calculation risk based approach ( development of RBCs and a screening evaluation of current and future products), there are " key" parameters in common. Key parameters are those that can significantly influence the estimation of the RBC or risk; they are also called sensitive parameters. A comparison of the parameters used in each of the three evaluations is presented in Table 22. The key parameters include application rate ( AR), soil accumulation factor ( specifically related to loss and bioavailability), plant uptake factor ( PUF), 46 DRAFT and representative MOPC concentration in product. Other parameters are also presented in Table 22 ( i. e., biological exposure parameters and toxicity values); however, these parameters are generally similar among the three evaluations and therefore do not influence the estimation of the RBC or risk as much as the key parameters.

Application Rate ( AR)

The application rates used in this evaluation are developed from information presented in USEPA ( 1999a). ARs for each of the three crop groups are developed for both phosphate fertilizers and zinc micronutrient fertilizers. The ARs are upper end estimates of the data set for each crop group ( they are the 95 percent upper confidence limit, 95UCL of the mean, based on a normal distribution). The ARs for phosphate fertilizers are 118, 154, and 63 lbs/ acre year for vegetable, root, and grain crops, respectively. The AR for zinc micronutrient fertilizer is 10 lbs/ acre for all 3 crop groups, and is an estimate from industry experts ( USEPA 1999a).

The ARs used in USEPA ( 1999b) are taken directly from USEPA report ( 1999a) where the consumption and use of inorganic fertilizers is presented. The ARs for each generic fertilizer category are based on a distribution of percentile ( 50th, 85th, and 95th) ARs. For the purposes of comparing, the high end ( 85%) estimate from USEPA ( 1999a) for phosphate fertilizer is 173 lbs/ acre and the maximum AR ( 95%) is 252 lbs/ acre year. The high end ARs for micronutrient fertilizers are 10 lbs/ acre year for zinc and 20 lbs/ acre year for iron micronutrient fertilizers ( USEPA 1999a). The distribution of ARs is combined with varying FONs in determining the distribution of risk.

ARs used in developing the RBC in CDFA ( 1998) are also represented as a distribution. For comparison purposes, phosphate fertilizer ARs values ( mean) reported in CDFA ( 1998) are 60.0, 67.4, and 38.2 lb/ acre year for vegetable, root, and grain crop groups, respectively ( CDFA 1998). The AR for micronutrient fertilizers is 6.1 lb/ acre year for all crop groups.

Soil Accumulation The accumulation of MOPC soil following application is estimated in each of the three evaluations using similar models. However, assumptions that are made regarding soil accumulation, loss from soil, and the Kd values are different.

In this evaluation, SACF considers only the loss of MOPC through leaching, thereby, most of the MOPC that is applied is assumed to accumulate in soil. SACF is primarily based on generic USEPA default parameters. The Kd values are measured values published in the literature. These Kd values are on the lower end of the Kd range.

The accumulation of MOPC in soil in USEPA's evaluation is more complex because it considers the loss of MOPC through several loss pathways. Also, accumulation and loss is determined for each of the 29 geographic locations using geographic specific parameters. The Kd distributions in USEPA ( 1999b) are from derived from a database of Kds compiled by USEPA. 47 DRAFT The accumulation of MOPC in soil in CDFA ( 1998) considers several loss pathways however only leaching is determined to contribute substantially to loss. The other loss pathways are determined to be negligible. The Kd values used in CDFA ( 1998) are the same as the Kd values used in this evaluation.

Plant Uptake Factor ( PUF)

The plant uptake factors ( PUFs) used in this evaluation are based primarily on field studies, however, some data are from greenhouse or pot studies ( in the instance of insufficient field data). Also, any studies that applied organic fertilizer are generally excluded from the PUF database. The PUF data are grouped by crop: vegetable, root, and grain. PUF estimates are the 90 percent upper confidence limit ( UCL) assuming a log normal distribution ( or the 95% UCL, based on a normal distribution). PUFs are presented in Table 23.

The plant uptake factors ( defined as Br in USEPA's evaluation) in USEPA ( 1999b) are presented as distributions and are developed from a comprehensive literature search. All of the PUF data used in CDFA ( 1998) is included in this database as well as additional data. The majority of PUF data is from field studies; however, some data is from greenhouse studies ( used to supplement data set in the instance of insufficient field data). Studies that use organic fertilizer are not included in the database. PUFs are developed for herbs ( exposed vegetables consumed by humans), roots, grains, fruits, and forage crops. The mean value of the distribution is presented in Table 23 for comparison purposes.

The PUF distributions developed in CDFA ( 1998) also exclude studies that apply organic fertilizer, however, unlike the data in USEPA or this report, most of the data in CDFA ( 1998) is from greenhouse and pot studies. The mean PUF is also presented in Table 23 for comparison purposes.

Other parameters, biological exposure parameters ( e. g., IRs, BW, and SA), absorption values, and toxicity values, are generally developed from standard USEPA resources. Some of these parameters are represented as distributions and not point estimates in USEPA ( 1999b) and CDFA ( 1998). Nevertheless, these parameters are generally similar.

MOPC Concentration in Product MOPC concentration in product is only considered in this evaluation and in USEPA ( 1999b). A comparison of MOPC concentrations is presented in Table 24. CDFA ( 1998) does not conduct a health evaluation of products and therefore does not consider product information.

The product database used in this evaluation is a fairly comprehensive database and consists of industry, state, and literature data ( TWG 1999c). Products for which there are reported MOPC concentrations are evaluated as product groups or types, but can also be evaluated separately.

The product database for USEPA's risk assessment ( 1999b) is based on a recent USEPA report on inorganic fertilizers ( USEPA 1999a) that summarizes the literature data. MOPC concentrations for a product type ( e. g. diammonium phosphate) are evaluated as a distribution. 48 DRAFT However, for several products, limited product data are available and distributions could not be developed.

Conclusion Regarding Determination of Risk Only this evaluation and USEPA ( 1999b) evaluate potential risk from exposure to MOPC following application. However, the RBC values for arsenic, cadmium and lead are similar for this evaluation and the CDFA ( 1998) evaluation. Both this evaluation and USEPA ( 1999b) evaluation conclude that there is no significant post application human health risk from exposure to NPK types of inorganic fertilizers. The CDFA ( 1998) evaluation would give the same conclusion if its RBC values were compared to MOPC concentrations in the fertilizer product database. With regard to micronutrient fertilizers, both this evaluation and USEPA ( 1999b) identified several micronutrient fertilizers that contain levels of certain MOPC, in particular arsenic, that pose a possible health risk. While it is a basic tenant of health risk assessment that exposure to a high enough concentration of a chemical can pose an unacceptable risk, a closer look at these relatively few micronutrient product samples is warranted before a firm conclusion of risk for these specific samples, and even more so for product types or categories, can be made. USEPA ( 1999b) concluded that hazardous constituents in fertilizers generally do not pose harm to human health or the environment. 38 This evaluation, and by similarity in RBCs, the CDFA ( 1998) evaluation are in general agreement with this conclusion.

38 Based on a screening level ecological risk evaluation of metals in fertilizer runoff into streams, USEPA ( 1999b) concluded that no exceedances of water quality criteria are projected. TABLES DRAFT TABLE 21 COMPARISON OF THE PURPOSE, GENERAL APPROACH, AND SCOPE OF THIS EVALUATION TO USEPA ( 1999b) INORGANIC FERTILIZER RISK ASSESSMENT AND CDFA ( 1998) DEVELOPMENT OF RISK BASED CONCENTRATIONS ( RBCs) FOR ARSENIC, CADMIUM, AND LEAD Factor This Evaluation USEPA CDFA General Purpose Develop flexible risk based screening tool and to evaluate available product data. Estimate distribution of individual lifetime risk based on available product information. Develop RBCs for arsenic, cadmium and lead.

Back calculation, risk based approach   development of risk based concentrations ( RBCs) Forward risk assessment Back calculation, risk based approach   development of RBCs Approach Deterministic based on a reasonable maximum exposure ( RME) scenario Probabilistic presents risks at 50, 90, 95, and 99 percentile Probabilistic develop RBCs ( protective of 90 percentile risks)

Perspective National ( health protective) National ( 29 geographic locations) California Scope Fertilizers Œ Phosphate ( blends and phosphate)

Œ Select micronutrients ( boron, iron,

manganese, and zinc) Œ Macronutrient ( phosphate, NPK for phosphate,

NPK for nitrogen, potash)

Œ Amendments ( sulfur for nutrient, sulfur for pH,

lime, and gypsum)

Œ Micronutrient ( boron, iron, manganese, zinc,

and mixes) Œ Phosphate Œ Zinc micronutrients Metals of Potential Concern ( MOPC) Arsenic, Cadmium, Chromium, Cobalt,

Copper, Lead, Mercury, Molybdenum,

Nickel, Selenium, Vanadium, and Zinc ( radium 226 is also evaluated) Arsenic, Cadmium, Chromium, Copper, Lead,

Mercury, Nickel, Vanadium, and Zinc ( dioxin is also evaluated) Arsenic, Cadmium, and Lead Populations and Exposure Routes Farm family  adult and child Œ unintentional ingestion of fertilized soil Œ dermal contact with fertilized soil Œ crop ingestion on a single and multicrop farm ( vegetable, root, and grains)

note: a worker is evaluated in previous reports ( TWG 1999a, b) Farm family  adult and child Œ inhalation Œ ingestion of animal products ( milk and beef)

following ingestion of forage crops and grain Œ ingestion of crops ( fruit, vegetable, and root)

( multiple only)

Œ unintentional ingestion of fertilized soil ( not added to indirect pathways)

Œ ingestion fish Œ direct ingestion fertilizer ( adult worker only) Farm family  adult and child Œ unintentional ingestion of fertilized soil Œ dermal contact with fertilized soil Œ crop ingestion on a single and multi crop farm ( vegetable, root,

and grain)

note: focused on this exposure scenario through a deterministic risk based forward screen DRAFT TABLE 22 COMPARISON OF KEY PARAMETERS USED IN THIS EVALUATION TO THESE PARAMETERS IN USEPA ( 1999b) INORGANIC FERTILIZER RISK ASSESSMENT AND CDFA ( 1998) DEVELOPMENT OF RISK BASED CONCENTRATIONS ( RBCs) FOR ARSENIC,

CADMIUM, AND LEAD Key Parameters This Evaluation USEPA CDFA Application Rate ( AR) Upper end point estimates based on information from USEPA ( 1999a) ( a)

Phosphate 118 lb/ acre   yr   vegetable 154 lb/ acre   yr   root 63 lb/ acre   yr   grain Micronutrient 10 lbs/ acre   yr Distribution based on information from USEPA ( 1999a) ( a)

High end estimates:

Phosphate 173 lb/ acre   yr   all crops Micronutrient 10 lb/ acre   yr ( for zinc)

20 lb/ acre   yr ( for iron) Based on California data and distribution based Representative value:

Phosphate 60.1 lb/ acre   yr   vegetable 66.2 lb/ acre   yr   root 37.4 lb/ acre   yr   grain Micronutrient 6 lbs/ acre   yr Soil Accumulation Factor ( SACF) Œ Based on national default values and only one loss pathway ( leaching)

Œ 50 yrs application duration ( 200 for lead)

Œ Low end Kd values Œ Based on regional information and several default values and several loss pathways Œ 100 yrs application duration ( followed by 40 years of inactive use)

Œ Distribution of Kd values that includes high end values Œ California specific and several loss pathways Œ 50 yrs application duration ( 200 for lead)

Œ Low end Kd values Plant Uptake Factors ( PUFs) ( a) Œ Upper end point estimate Œ Database consists of field studies and limited greenhouse and potted Œ Represented as a distribution Œ Database consists of all data in CDFA plus additional data Œ Primarily field studies, except when insufficient field data, then greenhouse and potted studies Œ Represented as a distribution Œ Mostly pot and greenhouse studies; few field studies Toxicity Values Standard USEPA Standard USEPA Standard USEPA and DTSC General Exposure Parameters ( e. g., ingestion rates, exposure duration, exposed skin surface area, and body weight and relative absorption factors and fraction ingested) Œ Based on USEPA default, RME recommended point estimates Œ 100% fraction ingested Œ 100% ( or 1) relative absorption factor ( except for arsenic and lead) Œ Generally based on USEPA standard default,

several represented as a distribution Œ IRs developed differently considers a fraction ingested of less than 100%

Œ Relative absorption of 100% Œ Generally based on USEPA default, some California, Department of Toxic Substance Control ( DTSC) specific information Œ 100% fraction ingested Œ Similar relative absorption factor as this evaluation MOPC Concentration in Product ( b) Œ Comprehensive product database Œ Maximum product concentration used for screening Œ Concentration data obtained from USEPA ( 1999a)

Œ Represented as a distribution except for when limited number of samples available ( e. g., iron micronutrient) NA Notes: NA Not Applicable ( a) PUFs are presented in Table 23.

( b) MOPC concentrations in product are presented in Table 24 and Table 25. DRAFT TABLE 23 COMPARISON OF PLANT UPTAKE FACTORS ( PUFs) USED IN THIS EVALUATION TO THE PUFs DEVELOPED IN USEPA ( 1999b)

INORGANIC FERTILIZER RISK ASSESSMENT AND CDFA ( 1998) DEVELOPMENT OF RISK BASED CONCENTRATIONS ( RBCs) FOR ARSENIC, CADMIUM, AND LEAD PUFs ( a)

This Evaluation ( upper end estimate, 95 UCL) USEPA ( mean, although estimated as a distribution) CDFA ( mean, although estimated as a distribution)

Metal of Potential Concern ( MOPC) Vegetable Root Grain Herbage Root Grain Vegetable Root Grain Arsenic 0.30 0.05 0.03 0.065 0.099 0.005 0.024 0.011 0.02 Cadmium 1.7 0.93 0.12 0.81 0.75 0.54 0.68 0.31 0.092 Chromium 0.0014 0.0014 0.0037 0.032 0.0011 0.000093

Cobalt 0.05 0.03 0.02

Copper 0.034 0.22 0.31 0.28 0.45 1.7

Lead 0.08 0.05 0.05 0.12 0.046 0.11 0.014 0.026 0.0096 Mercury 0.61 0.67 0.26 0.52 0.036 0.57

Molybdenum 1.1 0.15 0.22

Nickel 0.15 0.07 0.05 0.0086

Selenium 0.88 0.76 0.57

Vanadium 0.007 0.007 0.007

Zinc 1.7 0.46 0.58 0.77 0.13 0.97

Notes:  Not applicable or not available ( a) PUFs are based on dry weight and are unitless. TABLE 24 COMPARISON OF THE METAL OF POTENTIAL CONCERN ( MOPC) CONCENTRATIONS IN PHOSPHATE FERTILIZER PRODUCTS USED IN THIS EVALUATION TO THE MOPC CONCENTRATIONS USED IN USEPA ( 1999b) INORGANIC FERTILIZER RISK ASSESSMENT Concentrations ( a) This Evaluation USEPA MOPC Minimum Maximum Mean ( b) Minimum Maximum Mean Arsenic 0.05 42 10 0.05 155 12 Cadmium 0.015 205 13 0.03 250 44 Chromium 0.25 5,060 120 4.3 896 110 Cobalt 0.04 58 5.6 NE NE NE Copper 0.14 544 14 0.2 1,170 41 Lead 0.05 1,860 13 0.1 5,425 140 Mercury 0.001 1.5 0.16 0.003 0.2 0.1 Molybdenum 0.69 72 12 NE NE NE Nickel 0.5 351 22 0.5 195 28 Selenium 0.03 27 2.6 NE NE NE Vanadium 0.28 1,106 128 25 721 180 Zinc 0.30 6,270 260 1 2,193 240 Notes:

NE Not Evaluated ( a) Concentrations are presented as ppm ( or mg MOPC/ kg product).

( b) For comparison purposes, the mean values assume a normal distribution, the mean values presented in Section 4.0 assume a log normal distribution.

DRAFT TABLE 25 COMPARISON OF THE METAL OF POTENTIAL CONCERN ( MOPC) CONCENTRATIONS IN MICRONUTRIENT FERTILIZER PRODUCTS USED IN THIS EVALUATION TO THE MOPC CONCENTRATIONS USED IN USEPA ( 1999b) INORGANIC FERTILIZER RISK ASSESSMENT Concentrations ( a) This Evaluation ( b) USEPA MOPC Minimum Maximum Mean Minimum Maximum Mean Arsenic 0.1 6,200 400 0.5 4,950 560 Cadmium 0.095 3,900 120 0.75 2,165 340 Chromium 0.25 8,100 290 1.3 580 170 Cobalt 0.25 790 200 NE NE NE Copper 0.5 40,000 7,700 1.5 2,050 640 Lead 0.32 28,000 2,400 5 52,000 9,400 Mercury 0.0025 12 1 0.01 3.36 1.3 Molybdenum 0.25 850 83 NE NE NE Nickel 0.5 560 88 2.5 8,950 760 Selenium 0.013 25 6 NE NE NE Vanadium 0.5 47 23 0.5 41 15 Zinc 8 350,000 120,000 6 60.8 33 Notes: NE Not Evaluated ( a) Concentrations are presented as ppm ( or mg MOPC/ kg product). ( b) For comparison purposes, the mean values assume a normal distribution, the mean values presented in Section 4.0 assume a log normal distribution.

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