Mechanic welder; welder; car man welder; arc welding and cutting; welder cutter
                                  0.01 - 0.01
                                     0.01
                                     0.01
50-67
Wholesale and retail trade; finance, insurance, and real estate
                                     0/41
                                 (0% positive)
Welder; welding; iron worker/welder; maintenance welder; MIG steel welder; sheet metal welder; welder/fabricator; machinist welder; head welder; welding technician
                                     None
                                     None
                                     None
70-89
Services
                                    28/152
                                (18% positive)
Welder(s); welder/metal finisher; welder supervisor; drive shaft welder; F/T welder; machinist welder; P/T welder; welder/cutter; welder/fabricator; welder laborer; welding head leather
                                  0.01 - 0.4
                                     0.06
                                     0.04
91-99
Public administration
                                     0/18
                                 (0% positive)
Welder, welder-student; apprentice welder
                                     None
                                     None
                                     None
N/A
OSHA On-Site Consultation Services
                                     7/19
                                (37% positive)
Welder
                                  0.05 - 32.0
                                     16.8
                                     11.0
Total

                                   322/4,148
                                 (8% positive)

                                 0.002 - 4,800
                                     17.2
                                     0.05
[a]	OSHA uses the term "general industry" to refer to all industries not included in agriculture, construction, or maritime.
[b]	Includes all welding-related PBZ samples by SIC code.
[c]	The range, mean, and median results are based on positive sample results only. All positive results are included. Note that sampling limits of detection for nondetectable samples are not available in the IMIS database.

PBZ: personal breathing zone
N/A: not available

Source: OSHA, 2009

Table IV-76 -- Distribution of Positive OSHA IMIS PBZ Total Beryllium Air Sampling
Results  for Welding Operations in General Industry
                                 Job Category
                     Number of Results in Range (ug/m[3])
                                     Total

<0.1
>=0.1 to <= 0.2
> 0.2 to <= 0.5
> 0.5 to <= 1.0
> 1.0 to <= 2.0
> 2.0

Welders
                                      204
                                    (63.4%)
                                      78
                                    (24.2%)
                                      14
                                    (4.3%)
                                      11
                                    (3.4%)
                                       5
                                    (1.6%)
                                      10
                                    (3.1%)
                                      322
                                    (100%)
Source: OSHA, 2009 (see Table IV-75)

SECTION 10 -- Welding, Appendix 2 -- FULL-SHIFT EXPOSURE RESULTS FOR WELDERS AT U.S. NAVAL FACILITIES, SHIPYARDS, CONSTRUCTION INDUSTRY WORKSITES, AND WELDING SCHOOLS
U.S. NAVAL FACILITIES AND SHIPYARDS: One hundred twenty-seven PBZ samples collected on welders welding non-specified or non-beryllium-containing materials in U.S. shipyards and Navy facilities range from 0.02 μg/m[3] to 0.74 μg/m[3], with a mean of 0.13 μg/m[3] and a median of 0.08 μg/m[3] (OSHA Shipyards, 2005; U.S. Navy, 2003). Of the 127 samples, 123 samples (97 percent) are nondetectable for beryllium. This pattern was also confirmed in an observation by the Navy Environmental Health Center, which indicated that beryllium has not generally been found in welding fumes (NEHC_Jan24, 2005). The four positive results include values of 0.1 μg/m[3], 0.15 μg/m[3], 0.66 μg/m[3], and 0.74 μg/m[3]. For three of the results (0.1 μg/m[3], 0.15 μg/m[3], and 0.66 μg/m[3]) the base material welded was not mentioned; for the remaining value, which is also the highest result (0.74 μg/m[3]), a shipyard employee was working with scrap metal.
CONSTRUCTION INDUSTRY: In the construction industry, NIOSH evaluated employee exposures to particulates from arc welding operations at the site of the Honda Motor Company of America plant in Marysville, Ohio (NIOSH HETA 82-106-1366, 1983). NIOSH investigators collected 47 PBZ and general area air samples for total particulates and metals inside the building at the construction site. The investigators analyzed 28 of the samples for iron, lead, nickel, zinc, beryllium, and copper. Of the metals, only iron was detected, in concentrations ranging from 20 μg/m[3] to 2,580 μg/m[3]. All results for beryllium, copper, lead, nickel, and zinc were nondetectable (sampling LOD concentrations not provided). Engineering controls consisted of several ceiling exhaust fans specifically installed to reduce the levels of air contaminants associated with welding and diesel vehicular traffic. No information was provided about the type of arc welding performed, the base metals welded, or the sampling and analytical methods employed.
WELDING SCHOOLS: Studies in welding schools also show that beryllium exposures are limited when workers are not welding with beryllium-containing materials. During a simulation study (NIOSH ECTB 214-13a, 1997) of arc welding (shielded metal arc welding) on stainless steel at the boilermaker's National Apprenticeship Training School in Kansas City, Kansas, beryllium was not detected in 45 short-term (15-minutes) PBZ samples and six full-shift general area samples collected under various study conditions (e.g., with and without LEV, indoors, outdoors in a semi-enclosed tank). Investigators collected the general area samples at a flow rate of 3 liters per minute to determine the background level of air contaminants on each day of the study. They collected PBZ samples at a flow rate of 13 liters per minute, by using a length of tubing to connect the filter on the welder to a high-volume air sampling pump placed on the floor. Samples were analyzed for total welding fume and elements according to NIOSH Methods 0500 and 7300, respectively. The laboratory analytical detection and quantitation limits for beryllium varied depending on the analysis date of the filters. The sampling LOD concentrations were 0.01 ug or 0.03 ug per sample and the limits of quantitation were either 0.035 ug or 0.075 ug.
In another study, NIOSH investigators evaluated student exposures in the welding shop of a vocational school located in the Midwest (Wallace et al., 1997). During the study, most students performed stick welding on mild steel, and one student performed MIG welding. In addition to welding, students also performed cutting and grinding operations. Investigators collected 12 air samples (10 PBZ and two general area samples) in the welding shop to determine total welding fumes (NIOSH Method 0500) and perform elemental analysis (NIOSH Method 7300). Sampling durations ranged from 80 to 109 minutes for PBZ samples and 264 and 268 minutes for the general area samples. Beryllium was detected in one sample at a concentration of 0.48 ug/m[3] for the only student who was MIG welding. The remaining 11 samples were all nondetectable for beryllium (sampling LOD concentrations not provided). No information was provided to indicate the potential source of beryllium. Although mild steel was used during the study, the students also learned to weld aluminum (a potential source of beryllium exposure during welding) and stainless steel during the year. Investigators noted that the ventilation system in the welding shop was not functioning properly during the study. An inspection of the fans on the roof revealed that two of the three exhaust fans servicing the welding shop were not operational. Additionally, no preventive maintenance program for the fans was in place at the school.

SECTION 10 -- Welding, Appendix 3 -- BERYLLIUM EXPOSURES WHILE WELDING ALUMINUM ALLOYS
Table IV-77 -- Beryllium Emissions During Experimental Uncontrolled Aluminum Arc Welding and Cutting Using Base and Filler (Electrode) Alloy of Varying Beryllium Content[a]
                              ALUMINUM BASE ALLOY
                             ALUMINUM FILLER ALLOY
                                  (electrode)
                        Beryllium Emissions (ug/m[3])
                                  Designation
                                Be Content (%)
                                  Designation
                                Be Content (%)

MIG Welding
(1/4)" 2219
                                     0.00
                                  1/16" 4145
                                     0.00
                                   < 0.2
(1/4)" 5456
                                    0.0002
                                  1/16" 5556
                                    0.0001
                                   < 1.0
(1/2)" 5456 (with high current)
                                    0.0004
                                  3/32" 5556
                                    0.0001
                                   < 1.0
5456 (with argon shield gas)[c]
                                     0.00
                                     5356
                                    0.0007
                                  < 0.2[B]
5456 (with helium-argon shield gas)[c]
                                     0.00
                                     5356
                                    0.0007
                                  < 0.2[B]
6061 (with argon shield gas)[c]
                                     0.00
                                     5356
                                    0.0007
                                  < 0.2[B]
(1/4)" 7039
                                    0.0001
                                  1/16" 5039
                                    0.0001
                                   < 1.0
A356.0
                                     0.002
                                     4043
                                     0.00
                                   < 0.63
A356.0
                                     0.006
                                     4043
                                     0.00
                                   < 0.99
A356.0
                                     0.008
                                     4043
                                     0.00
                                      9.3
(1/4)" A357.0
                                     0.054
                                  1/16" 4047
                                     0.00
                                     16.0
(1/4)" 358.0
                                     0.33
                                  1/16" 4047
                                     0.00
                                     31.9
(1/2)" 358.0 (with high current)
                                     0.25
                                  3/32" 4047
                                     0.00
                                     45.8
TIG Welding
6061 (with argon shield gas)[c]
                                     0.00
                                     5356
                                    0.0007
                                  < 0.2[b]
5456 (with argon shield gas)[c]
                                     0.00
                                     5356
                                    0.0007
                                  < 0.2[b]
5456 (with helium-argon shield gas)[c]
                                     0.00
                                     5356
                                    0.0007
                                   < 0.5
Plasma Arc Cutting
2090
                                     0.00
                                      NA
                                      NA
                                   < 0.5
[a]	Based on four laboratory investigations designed to estimate worst case emissions during the welding of aluminum alloys. One study was conducted at the Martin Marietta laboratories and three studies were completed at Alcoa laboratories.
[b]	Result is the geometric mean of five tests.
[c]	Tests were conducted in a high-bay production welding facility with natural ventilation. Welding areas of about 10 feet by 12 feet (with large open spaces overhead) were enclosed using flexible welding curtains. Cross-draft air movement was minimal, and the welding enclosures were designed to allow updraft convection currents. Sampling was conducted for 100 minutes of arc time, the estimated time a welder has an arc struck during an 8-hour shift at this type of facility.

Be = beryllium
<: means less than (i.e., the result is nondetectable)
NA: means "not applicable"

Source: Cole, 1997; Cole et al., 2007

Table IV-78 -- PBZ Total Beryllium Results for Aluminum Welding and Cutting
Operations in U.S. Shipyards and Navy Facilities[a]
                                  Base Metal
                                     Task
                                  Sample Time
                                   (minutes)
                                  8-Hour TWA
                                 Concentration
                                  (ug/m[3])
Aluminum
Welding, plasma arc and cutting
                                      19
                                    0.02[b]
Aluminum
Thermal flame spraying
                                      30
                                    0.01[b]
Aluminum
Thermal flame spraying
                                      39
                                    0.03[b]
Aluminum
Welding, gas tungsten arc
                                      108
                                    0.06[b]
Aluminum/steel
Welding, not otherwise classified
                                      124
                                    0.06[b]
Aluminum
Welding, shielded metal arc
                                      135
                                    0.02[b]
Aluminum
Welding, gas tungsten arc
                                      153
                                    0.04[b]
Aluminum
Welding, shielded metal arc
                                      200
                                    0.02[b]
Aluminum and steel plates
Hot work helper/Fire watch
(Burning steel/plasma arc aluminum)
                                      206
                                    0.03[b]
Aluminum
Welding, gas tungsten arc
                                      209
                                    0.03[b]
Aluminum and steel plates
Oxygen cutting/plasma arc welding
                                      299
                                    0.06[b]
Aluminum and steel plates
Oxygen and plasma cutting
                                      301
                                    0.06[b]
Aluminum
Welding, not otherwise classified
                                      390
                                    0.03[b]
Aluminum
Welding, not otherwise classified
                                      401
                                    0.06[b]
Aluminum
Welding, not otherwise classified
                                      523
                                     0.76
Aluminum
Welding, not otherwise classified
                                      533
                                     0.77
Aluminum
Welding, not otherwise classified
                                      534
                                     1.34
[a]	These data are characterized by a median of 0.04 ug/m[3], a mean of 0.2 ug/m[3], and a range from 0.01 ug/m[3] to 1.34 ug/m[3]. Eighty-two percent (14 samples) of the sample results are less than 0.1 ug/m[3] and are also nondetectable for beryllium.
[b]	Sampling limit of detection (LOD) concentration (i.e., the sample result is nondetectable or less than the analytical detection limit).

PBZ: means personal breathing zone
TWA: means time-weighted average

Source: OSHA Shipyards, 2005; U.S. Navy, 2003

SECTION 10 -- Welding, Appendix 4 -- WELDING STUDIES INDICATING THE EFFECTIVENESS OF LOCAL EXHAUST VENTILATION SYSTEMS
OSHA reviewed several studies submitted to the chromium VI rulemaking docket. These studies discuss the effectiveness of various LEV for controlling general welding fumes or other (non-beryllium) components of welding fumes.
A 1982 study by AWS showed that a welding fume reduction of 96 percent could be achieved with the use of a movable exhaust hood during steel welding (OSHA-H054A-2006-0064-2527). As with the work conducted by Susi and Meeker (2008), that AWS study showed that great exposure reductions can be achieved when ventilation systems are well designed and the workers using them are attentive to using the systems properly. Other studies also reviewed by OSHA have found the effectiveness of moveable exhaust hoods for controlling hexavalent chromium exposures to range from a 5 to 33 percent reduction, or 4 to 54 percent, depending on the type of welding performed (Kura, 1998). Hexavalent chromium is a potential occupational carcinogen with a PEL of 5 ug/m3 (8-hour TWA). The use of chromium alloy electrodes during arc welding could lead to exposure to hexavalent chromium, which is also a component of stainless steel welding fumes. Recent OSHA research on the control of hexavalent chromium estimated the effectiveness of well-positioned, flexible LEV systems for welding, such as the Neiderman Filterbox (a portable exhaust blower with a flexible welding fume collection duct), at 50 percent (OSHA-H054A-2006-0064-2527).
OSHA also reviewed additional studies on the same topic:
The Center for Construction Research and Training (formerly the Center for the Protection of Workers' Rights) (CPWR) investigated welders' exposure to hexavalent chromium with and without the use of LEV in a controlled setting (union training facility) and during two large coal-fired power plant rehabilitation projects (BCTD_CPWR, 2009). In the controlled setting, the use of LEV was associated with a 55-percent reduction in hexavalent chromium levels in trials involving TIG and stick welding. During the power plant rehabilitation projects, use of a portable LEV system for stick welding at one plant resulted in hexavalent chromium exposures 76 percent lower than when no LEV was used. The second power plant survey involved the use of a large central LEV unit with up to eight main branches and smaller terminal bifurcating ducts with hoods. Samples collected at this site when the central LEV system was in use during MIG or stick welding had 79 percent lower hexavalent chromium concentrations than when the system was not used.
NIOSH performed a controlled study of welding fume exposures in which it was demonstrated that correctly used ventilation could substantially reduce exposures to welding fumes. In this 1996 study, NIOSH examined two portable LEV systems and found that total welding fume concentrations with the use of LEV could be reduced by 80 percent, from a maximum of 60 mg/m[3] to a maximum of 13 mg/m[3] (CPWR, 1997). PBZ hexavalent chromium exposures were reduced from a maximum of 2,615 ug/m[3] to a maximum of 1,077 ug/m[3], an exposure reduction of about 59 percent (NIOSH ECTB 214-13a, 1997).
In another study of 20 MIG welders in a Tennessee plant, a new general ventilation system combined with portable LEV units (exhausting 740 cubic feet per minute and positioned to pull the fumes out of the welder's breathing zone) reduced the amount of welding fume exposure by 51 percent (Ashby, 2002). Individual sample results were not provided.

SECTION 11 -- DENTAL LABORATORIES
Industry Profile
Dental laboratory technicians cast and form the metal framework for prosthetic devices. These technicians and other dental workers may be exposed to beryllium, primarily while performing induction casting and finishing beryllium-containing metal alloys used in some dental prostheses, specifically crowns, bridges, and cast partial dentures.  Beryllium is added to some dental alloys (typically in quantities of 0.5 to 2.0 percent) to improve strength, corrosion resistance, and elasticity, and is considered a less expensive alternative to silver and gold (Kotloff et al., 1993; Rom et al., 1984; Materion MSDS A11, 2011; ERG Beryllium Site 5, 2003).
According to the 2010 County Business Patterns, there are 6,995 establishments in the NAICS industry classification 339116, Dental Laboratories (U.S. Census Bureau, 2010).  These establishments employ a total of 44,030 people.  Of these, OSHA estimates that 1,749 establishments and 11,008 employees will be affected by beryllium exposures.  Refer to Preliminary Economic Analysis (PEA) Chapter IV.III, Industrial Profile, for details of OSHA's methodology in obtaining this estimate.
Occasionally, a dentist office (NAICS 621200, Offices of Dentists) may contain a captive dental laboratory that performs the activities of dental laboratories in NAICS 339116.  The 2010 County Business Patterns reports 129,830 establishments and 846,092 employees in NAICS 621200.  While no data exist on the number dentist offices that contain captive dental laboratories, a representative of the National Association of Dental Laboratories estimates that 950 dental practices include a captive dental laboratory (Napier, 2004).  OSHA estimates that approximately 25% of these dental practices (238) use beryllium alloys.  Refer to PEA Chapter IV.III, Industrial Profile, for details of OSHA's methodology in obtaining this estimate.
Table IV-79 shows the number of affected establishments and affected employees by NAICS code.
Table IV-79 -- Dental Laboratories
                                     NAICS
                                   Industry
                            Affected Establishments
                              Affected Employees
                                    339116
                              Dental Laboratories
                                     1,749
                                    11,008
                                    621210
                Dentists Offices with "captive" dental labs
                                      238
                                     1,548

                                     Total
                                     1,986
                                    12,555
Sources: U.S. Census Bureau, 2010; BLS 2008; OSHA Office of Regulatory Analysis

Process Description
Dental laboratory technicians produce custom dental appliances (a device to repair teeth or replace missing teeth), first by constructing plaster models of dental impressions, and then using the models as templates to make metal castings.  Dental laboratory technicians manually handle and work in close proximity to the dental appliances (within about 8 inches) (Kim et al., 2002).  Beryllium exposure can occur during the melting and casting of beryllium-containing alloys and during abrasive blasting, cutting, grinding, or polishing of the resulting casting.  As noted, not all dental laboratories use beryllium alloys.  Precious metal alloys and beryllium-free non-precious metal alloys are both widely used.
Most dental laboratories include some form of local exhaust ventilation (LEV); typically a recirculating filtration unit is used with the grinding tools.  LEV is not, however, present in all dental laboratories.  For example, Koltoff et al. (1993) described a laboratory where a dental technician produced dental appliances using beryllium alloy in a 10-foot by 12-foot room with one window, which remained closed, and no ventilation hoods.  The dental technician developed chronic beryllium disease.  Other reports suggest that the few laboratories without adequate exhaust ventilation are "mom and pop" operators who are unaware of the safety and health regulations (OSHA-H005C-2006-0870-0345).
The process description presented below is based primarily on observations made by ERG during a site visit to a dental laboratory conducted as part of an analysis of crystalline silica exposure, as well as interviews with dental laboratory staff regarding the handling of beryllium alloys (ERG Dental Lab A, 2000; Dental Laboratory A, 2004; ERG Beryllium Site 5, 2004).
The steps in dental product manufacture include:
Plaster Model and Mold Production: The technician produces plaster by mixing dry ingredients and water in a small container.  He then pours the plaster into an impression of the patient's mouth or teeth taken by a dentist.  After the plaster has set, the technician removes the model from the impression, grinds it to the proper shape, and uses it to form a wax pattern of the dental appliance.  Although the modeling and mold production steps are not associated with beryllium alloy handling or exposures, these steps can influence a potential source of exposure during later production phases.  By using extra care to produce a precise pattern, technicians can minimize excess metal and blemishes that must be removed using grinding equipment during subsequent finishing processes.  Because beryllium alloy is a hard metal and difficult to grind, dental technicians have an incentive to produce quality patterns rather than spend extra time grinding (Dental Laboratory A, 2004).
Casting: To cast metal portions of dental appliances, including those made of beryllium alloy, the technician constructs a high-temperature mold by mixing ceramic material and applying it to the wax pattern to form the mold.  The piece is placed in a furnace, and after the wax is burned off, the technician melts the dental alloy and pours molten metal into the mold. Technicians can melt alloy using a small burner (heating until metal appears melted) or specialized, temperature-controlled equipment.
Beryllium alloy releases beryllium fumes during heating and casting.  Castings often involve less than an ounce of metal, and the casting process can be completed in a few minutes. Once the casting cools, the technician cracks the mold and manually removes the casting.  Due to the small volume of metal and short task duration, OSHA considers the melting and casting process to be a relatively modest source of exposure compared to the subsequent finishing process.
Finishing: The technician grinds, polishes, or abrasively blasts the casting to remove any remaining mold material, sprues (metal left in the channels through which alloy was poured into the mold), or blemishes, and to achieve the required finish.  Technicians can be exposed to beryllium when the resulting dust becomes airborne.  This dust is also the primary source of surface and hand contamination.
Blasting is typically performed using silica sand or aluminum oxide inside an enclosed, ventilated glove-box-type blasting cabinet.  Grinding, polishing and abrasive blasting all remove fine particles of beryllium alloy from the casting.
Another finishing step involves heat treating the casting to improve durability of the resulting dental appliance.  The technician "fires" the casting in a temperature-controlled oven for a prescribed period of time before applying the coatings that form the white teeth on the appliance.  Heating can induce the formation of an oxide (with a higher concentration of beryllium than the base metal) on the surface of beryllium alloys (Covington et al., 1985).  A technical representative of a beryllium dental alloy manufacturer indicated, however, that oxide formation is minimal when dental alloys are handled properly (Pentron, 2004).  The MSDS for this dental alloy specifies that the alloy should not be handled or stored with oxidizing agents. This would reduce the amount of beryllium oxide formed on the surface of the alloy.
Coating: The technician may manually apply a coating (often porcelain) to the casting, which is then oven-fired again to set the coating.  The technician also uses a hand-held grinder and abrasive blasting technique to achieve the desired shape and finish.  Finally, the metal portion of the appliance is polished with a soft brush fitting on the grinding tool.
Depending on the size and configuration of the facility, a single dental laboratory technician may perform all the steps in dental product manufacture or just one particular activity repeatedly, such as abrasive finishing or applying coatings (ERG Dental Lab A, 2000; Dental Laboratory C, 2004).  The layout of one of the dental laboratories visited by ERG is illustrated in Figure IV-4 below.
Dental technicians in laboratories that use beryllium-free alloys for casting can still experience limited beryllium exposure if the laboratory performs repair work on dental appliances that were produced using beryllium-containing alloys.  This could include any non-precious metal appliance that may have been made by another laboratory or by the same laboratory using another alloy. It is not possible for dental technicians to tell (visually or by a simple test) whether a non-precious metal alloy contains beryllium (Cardinal Dental Laboratory, 2004).
Two laboratories that consider themselves typical of the industry in this respect report that about 1 percent of the crowns and bridges they handle are items sent to the laboratory for repair (Dental Laboratory A, 2004; Cardinal Dental Laboratory, 2004).  Technicians typically spend less than 10 minutes per week grinding (to prepare the metal surface) and polishing these items, usually with a hand-piece grinder (i.e., hand-held), and beryllium exposure can occur during these steps (Hinman et al., 1975; Rom et al., 1984; Materion MSDS A11, 2011).  It is important to note, however, that the amount of metal removed during surface preparation of repaired items (usually lightly roughing an area a few millimeters square) is substantially less than the amount removed during production of a new casting (when casting sprues must be removed and the whole casting must be polished).  OSHA assumes that a technician exposed only to beryllium during surface preparation associated with appliance repair is likely to have substantially lower beryllium exposure than a technician who grinds newly cast beryllium alloy appliances to remove excess metal from the casting process and shape the appliance.

Figure IV-4. ERG Beryllium Site visit 5.
ERG Beryllium Site 5, a university-associated dental laboratory with one employee during the day shift. Layout shows grinder and casting oven where the technician worked. Approximate size of the laboratory is 15 feet wide by 20 feet long. The common laboratory area has a work bench (shown in gray) in the center. The grinder is on a laboratory bench, and the technician sits on a chair to do the grinding and polishing. Most of the technician's time is spent in the grinding room. Occasionally, several other technicians work in the common laboratory area (i.e., area where no beryllium work is done). No physical separation exists between the rooms, and they share the same ventilation system. (Source: ERG Beryllium Site 5, 2003)
Exposure Profile
Data Sources
Several sources report workplace beryllium exposure results for technicians working in dental laboratories.  The five sources OSHA identified include a site visit conducted by ERG (ERG Beryllium Site 5, 2003), a published article by Rom et al. (1984), two datasets submitted to the OSHA Beryllium Docket, and OSHA's Integrated Management Information System (IMIS) (OSHA, 2009).  These sources are discussed below:
ERG obtained two full-shift personal breathing zone (PBZ) total beryllium air samples (as well as surface and hand wipe samples) during a 2003 site visit to a dental laboratory (ERG Beryllium Site 5, 2003).  At this facility, a technician used 0.5 percent beryllium alloy to produce partial dentures.  The laboratory was fitted with a canopy hood over the casting area and a recirculating high-efficiency particulate air (HEPA)-filtered ventilation system at the grinding bench.  Other technicians at this laboratory worked in other rooms and did not handle beryllium alloy.  Both air sampling results from this source are included in the dental technician exposure profile; one result is positive for beryllium (0.59 μg/m[3]) and one is nondetectable (0.02 μg/m[3]).  The samples were analyzed by OSHA Method ID-125G (Metal and Metalloid Particulates in Workplace Atmospheres) using inductively coupled argon plasma-atomic emission spectroscopy (ICAP-AES).  The laboratory analytical reporting limit was 0.02 ug per sample.
Rom et al. (1984) obtained seven full-shift (all results were obtained from sampling times greater than seven hours) PBZ total beryllium air samples in six dental laboratories in Utah that used non-precious metal alloys containing beryllium. Samples were collected on mixed cellulose ester filters (0.8-micrometer diameter pore size) and analyzed by atomic absorption spectroscopy.  The analytical limit of detection (LOD) was not reported; however, for other methods using this technique, such as National Institute for Occupational Safety and Health (NIOSH) Method 7102, the estimated LOD is 0.005 ug per sample.  The Rom et al. data are included in the dental laboratory technician exposure profile and contain three positive results of 1.5 μg/m[3], 2.7 μg/m[3], and 4.4 μg/m[3] and four nondetectable results with sampling LOD concentrations of 0.23 μg/m[3], 0.29 μg/m[3], 0.34 μg/m[3], and 0.72 μg/m[3].  General information on exposure controls is limited to the two positive results with values exceeding the current Permissible Exposure Limit (PEL) of 2.0 μg/m[3]. In both cases, the beryllium overexposures were primarily associated with grinding tasks, inadequate LEV, and improper use of available LEV (no other details are available). Rom et al. also commented on a dental laboratory technician diagnosed with acute berylliosis (and not affiliated with the six laboratories investigated).  This technician ground beryllium-containing metal alloys four to six hours a week for three months with only a dust mask and no LEV on his grinder.  In an effort to estimate the dental worker's beryllium exposure, Rom et al. recreated the grinding task in the actual laboratory in which the technician worked and measured 2.6 μg/m[3] of beryllium during a 30-minute grinding task.
The U.S. Navy submitted a large beryllium dataset to OSHA's Beryllium Docket (OSHA-H005C-2006-0870-0145).  The dataset includes 134 PBZ results, obtained from 1987 to 2001, for dental technicians primarily grinding dental prosthetics or castings that have been time-weighted for eight hours (TWA); however, only 12 of the results are regarded as full-shift samples (approximately 360 minutes in duration or greater) and are included in the dental laboratory technician exposure profile. The full-shift samples range from 0.02 μg/m[3] to 3.0 μg/m[3], and five of the 12 results (42 percent) are nondetectable for beryllium.  The Navy samples were analyzed by either NIOSH Method 7102 (Beryllium and Compounds, as Be) or Method 7300 (Elements by ICP), and analysis was performed by one of the Navy's three consolidated industrial hygiene laboratories, which are accredited by the American Industrial Hygiene Association (AIHA).  Although it was not reported, the estimated LOD for Method 7102 and Method 7300 is 0.005 ug per sample.  These data represent an unknown number of naval facilities; location identifiers were not included in the docket submission (the data were drawn from a central database that consolidates exposure results from a number of naval installations).  The Navy also reported that "Dental prosthetics operations are enclosed (glove box) and ventilated as much as possible with grinding and polishing operations requiring dust collecting systems or vacuums fitted with high efficiency particulate air (HEPA) filters" (OSHA-H005C-2006-0870-0144).
A second docket submission from CMP Industries (OSHA-H005C-2006-0870-0346) provided two nondetectable (0.2 ug/m[3]) PBZ results for dental technicians in a commercial dental laboratory that was described as a large user of nickel-beryllium alloy (Ticonium) for cast partials.  CMP Industries obtained these samples in 2002 and provided them to OSHA in 2007.  The associated report describes the results as "representative of the highest exposures expected for the processes being performed. Local exhaust ventilation was present and running during the sampling."  The samples were analyzed using modified NIOSH Method 7300, and the level of quantitation was reported as 0.15 ug per sample.  The documentation does not indicate whether the results are full-shift samples; however, the air volumes listed in the laboratory analysis report (931.4 liters and 952.3 liters) are consistent with full-shift samples obtained using NIOSH Method 7300, and the results were compared to the current eight-hour TWA PEL for beryllium.  Therefore, both samples from this source are included in the dental technician exposure profile.
OSHA's IMIS entries for the years 1978 to 2008 contain 41 PBZ samples associated with dental technicians, of which 23 (56 percent) are positive for beryllium.  Table IV-82 (in Dental Laboratories Appendix 1) summarizes the results for dental technicians working either in dental laboratories or in other facilities that include dental laboratory operations.  The means, medians, and distribution of results represent positive IMIS samples.  Only positive IMIS results are used because the sampling LOD concentrations (i.e., analytical LOD/air volume sampled) for the nondetectable results are not included in the IMIS database.  As shown in Table IV-82, the IMIS contains three results (all nondetectable) for standard industrial classification (SIC) code 8071 (Medical Laboratories) and 32 results for SIC code 8072 (Dental Laboratories). Nineteen of the 32 samples (59 percent) for SIC code 8072 are positive for beryllium. Six of the positive results are coded as ceiling samples, with results ranging from 0.1 ug/m[3] to 0.2 ug/m[3].  Another four of the positive results are coded as short-term exposure limit (STEL) samples, each with a value of 0.1 ug/m[3].  The remaining nine positive samples are coded as TWA (eight-hour time-weighted average) samples, with results ranging from 0.03 ug/m[3] to 0.2 ug/m[3].
         In addition to dental and medical laboratories, the IMIS data include sample entries for dental technicians in four other industries, including SIC code 3843 (Dental Equipment and Supplies), SIC code 5160 (Chemicals and Allied Products), SIC code 8049 (Offices and Clinics of Health Practitioners, not elsewhere classified); and SIC code 8062 (General Medical and Surgical Hospitals).  Two of the four entries are positive for beryllium, with results of 0.01 ug/m[3] (SIC 3843) and 3.0 ug/m[3] (SIC 8049).  The IMIS data also include two positive samples obtained through OSHA's On-site Consultation Services Program that are consistent with dental technician job descriptions (e.g., crown grinder); however, the industries associated with these results are not available.  The consultation program results include values of 0.02 ug/m[3] and 0.03 ug/m[3].
         Overall, the IMIS results with detectable levels of beryllium are characterized by a mean of 0.22 ug/m[3], a median of 0.10 ug/m[3], and a range from 0.01 ug/m[3] to 3.0 ug/m[3].  Thirty percent of the positive results (7 of the 23 samples) are less than 0.1 ug/m[3], and 96 percent are less than or equal to 0.2 ug/m[3].  These results include all positive IMIS results regardless of the exposure type (i.e., ceiling, STEL, or TWA).  If the positive TWA samples are analyzed separately, the 11 results range from 0.02 ug/m[3] to 0.2 ug/m[3], with a mean of 0.08 ug/m[3] and a median of 0.09 ug/m[3].  Fifty-five percent of the TWA results (6 of the 11 samples) are less than 0.1 ug/m[3], and 100 percent are less than or equal to 0.2 ug/m[3]. Refer to Table IV-82 for details.
         The sample analysis methods for these samples are not included in the IMIS database; however, OSHA's laboratory analyzes compliance samples using the OSHA method in effect at the time the sample was collected (e.g., OSHA Method 125G -- Metal and Metalloid Particulates in Workplace Atmospheres).  The LOQ for this method is 0.043 ug per sample, and the analysis is by ICAP-AES. Beyond the short job description, no supporting information, such as the actual sampling duration, the exposure controls in use, or whether the dental technician was actually working with beryllium-containing alloys, is available for the IMIS results.  The IMIS data are therefore used in a supporting role to provide additional insight into the dental laboratory technician exposure profile.
Exposure Profile for Dental Technicians
Tables IV-80 and IV-81 summarize the exposure profile for workers in dental laboratories and report the distribution of the results relative to the current and proposed OSHA PELs for beryllium.  These tables summarize all of the available full-shift eight-hour TWA PBZ total beryllium sample results for dental technicians.
As shown in Table IV-80, the exposure profile for dental technicians is based on 23 PBZ samples and is characterized by a median of 0.20 ug/m[3], a mean of 0.74 ug/m[3], and a range from 0.02 ug/m[3] to 4.4 ug/m[3]. Table IV-81 shows that 13 percent of the results are less than 0.1, 52 percent are less than or equal to 0.2 ug/m[3], 70 percent are in the range from 0.1 ug/m[3] to 1.0 ug/m[3], and 17 percent (four values) exceed 1.0 ug/m[3].
Twelve of the 23 samples (52 percent) are nondetectable for beryllium and suggest that the exposure profile may be overestimating exposures for this group of workers.  This finding is supported by the positive IMIS results for dental technicians discussed in the subsection on Data Sources, above in this Dental Laboratories section. As noted, 30 percent of positive-value IMIS results are less than 0.1 ug/m[3], and 96 percent are less than or equal to 0.2 ug/m[3].  Note that the IMIS values may underestimate the population of workers experiencing levels below 0.1 ug/m3 since only positive values were considered.
      Table IV-80 -- Personal Exposure Profile for Workers in Dental Laboratories (NAICS 339116)[a,b]
                                 Job Category
                                No. of Samples
                               Range
(μg/m[3])
                                Mean
(μg/m[3])
                               Median
(μg/m[3])
Dental Technician
                                      23
                                  0.02 to 4.4
                                     0.74
                                     0.20
[a]	Samples represent eight-hour time-weighted average (TWA) personal breathing zone (PBZ) total beryllium exposure results.
[b]	Nondetectable results are reported as sampling limit of detection (LOD) concentrations. Twelve of the 23 samples (52 percent) are nondetectable for beryllium. Eight of those 12 have reported sampling limits of detection of 0.2 μg/m[3] or less, while the remaining four samples were nondetectable at sampling limits of detection of 0.23 μg/m[3], 0.29 μg/m[3], 0.34 μg/m[3], and 0.72 μg/m[3].

Source: ERG Beryllium Site 5, 2003; OSHA-H005C-2006-0870-0145; OSHA-H0005C-2006-0870-0346; Rom et al., 1984

      Table IV-81 -- Distribution of Full-Shift PBZ Total Beryllium Exposure Results
for Workers in Dental Laboratories (NAICS 339116)[a,b]
                                 Job Category
                     Number of Results in Range (ug/m[3])
                                     Total

                                   < 0.1
                              >= 0.1 to <= 0.2
                              > 0.2 to <= 0.5
                              > 0.5 to <= 1.0
                              > 1.0 to <= 2.0
                                   > 2.0

Dental Technician
                                    3
(13%)
                                    9
(39%)
                                    3
(13%)
                                    4
(18%)
                                    1
(4%)
                                    3
(13%)
                                   23
(100%)
[a]	Samples represent eight-hour time-weighted average (TWA) personal breathing zone (PBZ) total beryllium exposure results.
[b]	Nondetectable results are reported as sampling limit of detection (LOD) concentrations. Twelve of the 23 samples (52 percent) are nondetectable for beryllium. Eight of those 12 have reported sampling limits of detection of 0.2 μg/m[3] or less, while the remaining four samples were nondetectable at sampling limits of detection of 0.23 μg/m[3], 0.29 μg/m[3], 0.34 μg/m[3], and 0.72 μg/m[3].

Source: ERG Beryllium Site 5, 2003; OSHA-H005C-2006-0870-0145; OSHA-H0005C-2006-0870-0346; Rom et al., 1984

Three positive results in the exposure profile exceed the current OSHA PEL of 2.0 ug/m[3]. Two of these results (2.7 ug/m[3] and 4.4 ug/m[3]) are also the oldest samples and occurred during grinding operations with inadequate LEV (Rom et al., 1984).  The study investigators reported that improper use of available LEV may have contributed to the exposure levels.  Full-shift PBZ results for cobalt sampled at this dental laboratory also exceeded the OSHA PEL and were attributed to inadequate LEV during grinding.  The third result (3.0 ug/m[3]) exceeding the current beryllium PEL is a 1988 Navy sample obtained during casting operations in a prosthetics laboratory.  However, no information is available about the nature of this exposure.  In general, few details are available for the Navy results.  As noted, the Navy reports that dental prosthetics operations are enclosed and ventilated and that engineering controls such as glove boxes are used.  Grinding and polishing operations require dust collection systems or vacuums equipped with HEPA filters (OSHA-H005C-2006-0870-0144).
One of the lowest results in the exposure profile (nondetectable at 0.02 ug/m[3]) is one of two results (the other being 0.6 ug/m[3]) obtained on consecutive dates for a dental technician at ERG Beryllium Site 5.  The technician's typical work activities include casting frames for partial dentures using 0.5 percent beryllium alloy, sandblasting the frames after casting to remove powdered investment material, and deburring and polishing the frames.  The first two activities are performed for two to three minutes each, while the final activity consumes most of the technician's time (ERG Beryllium Site 5, 2003).  These were the technician's activities on the first sampling date, during which this worker completed four frames and experienced the higher of the two exposure levels in the 469-minute sampling period.  On the second date, however, when the lower, nondetectable result was obtained, the technician completed just two frames and performed paper work during the latter half of the 511-minute sampling period, indicating that only part of the shift was spent handling beryllium alloy.  The difference in exposure levels on the two dates (0.6 ug/m[3] versus 0.02 ug/m[3]) is greater than might be expected based strictly on the amount of work performed (four frames compared to two frames).  Additional information is not available to explain the difference, but a basic facility description is provided:  The casting furnace is equipped with an overhead canopy hood, and the grinding equipment is ventilated with a HEPA-filtered recirculating ventilation system.  Sandblasting is conducted in a small, enclosed sandblasting booth within the same room as the casting furnace (ERG Beryllium Site 5, 2003).
As noted previously, over half (52 percent) of the full-shift PBZ sample results incorporated into the exposure profile for dental laboratory technicians are nondetectable for beryllium.  Because these values have been assigned the LOD level -- the most protective option for handling nondetectable samples -- the true values are likely lower than the reported levels (i.e., somewhere between zero and the reported level).  OSHA's conservative approach to assigning values to nondetectable results leads to an exposure profile that might overestimate the exposures for this group of workers.  The data in the IMIS, summarized in Table IV-82 (in Dental Laboratories Appendix 1), supports this conclusion.  The IMIS data for this industry contain a lower percentage of results that exceed 0.2 ug/m[3] (one of 23 positive samples) compared to the exposure profile.  This could be a consequence of the way the IMIS samples were obtained (i.e., a metal scan involving beryllium as a standard analyte might have been performed during metal work regardless of whether a beryllium alloy was used on that date).  It could also signal that the exposure profile somewhat overestimates the typical daily beryllium exposure of dental technicians.
Technological Feasibility
Dental Laboratory Technician -- Baseline Controls
The primary baseline control in dental laboratories is exhaust ventilation during grinding operations (OSHA-H005C-2006-0870-0345).  One manufacturer of dental laboratory materials and equipment reports that all of its clients (dental laboratories) that grind beryllium-containing partial denture alloy use an exhaust system to remove dust (OSHA-H005C-2006-0870-0345). Common exposure control in dental laboratories involves bench-top recirculating ventilation (not HEPA-filtered) with conical hoods that are positioned by workers during hand grinding (with a hand-piece) (ERG Dental Lab A, 2000; Dental Laboratory A, 2004).  Bench-top grinders or lathes (for larger items and to remove larger amounts of metal -- such as casting sprues) are often fitted with basic recirculating dust collection units, primarily intended to capture medium and large particles (ERG Beryllium Site 5, 2004).  The grinding wheels are partially enclosed (perhaps less than a 50-percent enclosure), and exhaust air is filtered and recirculated, but usually not HEPA-filtered.  HEPA filtration and ventilation exhausted directly outdoors are rare in dental laboratories (ERG Dental Lab A, 2000; Dental Laboratory C, 2004).
Dental laboratory technicians also perform beryllium alloy metal casting using unvented furnaces, although a canopy hood is likely to be present; when a hood is present, the worker can typically stand under it next to the casting operation, which could cause contaminated air to be ventilated away from the worker's breathing zone (ERG Dental Lab A, 2000; ERG Beryllium Site 5, 2004).  Technicians perform abrasive blasting of the castings in enclosed and exhaust-ventilated blasting cabinets; however, at Dental Laboratory A, ERG investigators noted that the glove box used had an opening on the side (perhaps originally intended as a pass-through) and was therefore poorly sealed (ERG Dental Lab A, 2000).  Exhaust air from blasting cabinets is typically filtered (not HEPA) and released into the laboratory.  Other baseline practices include a minimal level of housekeeping, involving occasional cleaning of visible debris from surfaces, dry sweeping, wet mopping, and vacuuming (again, without HEPA filtration) (ERG Dental Lab A, 2000; ERG Beryllium Site 5, 2003).
Dental Laboratory Technician -- Additional Controls
The median exposure level associated with dental laboratory technicians is 0.2 ug/m[3]. Fifty-two percent of the available exposure results are less than or equal to 0.2 ug/m[3].  Based on the current exposure profile, 48 percent of dental laboratory technicians have exposures that can exceed 0.2 ug/m[3] and require additional controls.  Some dental laboratories may choose to eliminate all beryllium exposure by not repairing dental appliances that contain beryllium and by substituting beryllium-free alloys for beryllium-containing alloys.  Beryllium-free alternatives for casting dental appliances are readily available from commercial sources and some alloy suppliers have stopped carrying alloys that contain beryllium (Dental Alloy Manufacturer A, 2006; Dental Alloy Distributor A, 2006).  For crowns and bridges, alternatives include all precious metal alloys and certain non-precious metal alloys (Pentron Rex 4 MSDS, 2004; Dental Laboratory A, 2004; Dental Laboratory D, 2006; Dental Laboratory F, 2006; Dental Alloy Distributor A, 2006).
For those dental laboratories that continue to use beryllium alloys, the primary control options include 1) properly designed, installed, and maintained LEV systems (equipped with HEPA filters) and enclosures, 2) work practices that optimize LEV system effectiveness, and 3) housekeeping methods that prevent contamination from building up.  These controls work together to limit beryllium release and keep it from spreading (Thomas et al., 2009).
Appropriate LEV for dental laboratories grinding beryllium alloy dental appliances includes booth-type enclosures for both grinding wheels (see Figure VS-80-17 in ACGIH, 2010) and hand-held grinding tools.  To use this style of enclosure, the worker reaches into the ventilated booth interior to operate tools and manipulate the work piece while his breathing zone remains outside the booth.
For manual grinding tasks, regardless of the nature of the industry, the primary beryllium producer suggests a booth designed with both backdraft and downdraft exhaust ventilation inside the enclosure (Materion Information Meeting, 2012).  For example, such a booth would include a front opening and rear exhaust, as is available for abrasive cut-off saws (Figure VS-80-17 in ACGIH, 2010), and the downdraft table ventilation of a hand-grinding bench (Figure VS-80-18 in ACGIH, 2010).  An adaptation to provide a rear-slot exhaust (rather than plain rear takeoff) is preferable for hand grinding, which might not occur at a single fixed spot inside the booth.  The booth exhaust should be fitted with a HEPA air filter, and special precautions must be used when servicing the booth or blower and changing the filter (respiratory protection needed for these tasks).  The booth should also be equipped with alarms to indicate when filter performance falls outside an effective range.
The primary beryllium producer advocates grinding booths of this general backdraft-plus-downdraft design, paired with work practices and careful housekeeping methods, as an effective method for reducing exposure levels for workers performing manual grinding (and related tasks using powered or rotary tools, such as polishing and buffing) to concentrations of 0.2 ug/m[3] or less (Materion Information Meeting, 2012).  These control measures (i.e., engineering controls, work practices, and housekeeping) must be used together to ensure that exposure levels are reliably maintained below 0.2 ug/m[3] for most workers most of the time (Thomas et al., 2009). The primary beryllium producer's exposure reduction guidelines are generic and applicable to any industry where beryllium-containing particles are generated using powered or rotary hand tools.  Thus, these guidelines pertain equally to foundries and machining facilities as they do to dental laboratories.
Although no study specifically demonstrates the effectiveness of these controls for dental laboratories, several studies provide evidence that ventilation systems can reduce technician exposure levels substantially. 	 Two of the full-shift PBZ results included in the dental laboratory technician exposure profile are nondetectable (LOD 0.2 ug/m[3]) for beryllium (OSHA-H005C- 2006-0870-0346).  Both samples were obtained from a commercial laboratory known to use large quantities of nickel-beryllium alloy (Ticonium) for cast partials.  The associated study report contains limited information and states that LEV was operating during the sampling and that the samples are representative of the highest exposures expected for the processes performed.  No information is available regarding the workers' activities, however.  Two full-shift area samples obtained in the denture and plaster rooms were also nondetectable (0.2 ug/m[3]) for beryllium.  Although no other details are available, these results suggest that low beryllium exposures are associated with effective ventilation controls.
Other available supporting information on the benefits of LEV in dental laboratories is discussed below.  Although these studies lend support to the value of LEV, they are hampered by various issues, such as the high LOD in effect at the time of the studies.
In the early 1970s, NIOSH and the Dental Research Section of the United States Public Health Service Hospital in San Francisco, California, studied beryllium exposures from handling non-precious alloys in a large commercial laboratory (Pacific Dental Laboratory, San Francisco, California) (Moffa et al., 1973).  The alloy used in the laboratory (Ultratek) contained 1.6 percent beryllium (approaching the typical upper range for alloys used in dental laboratories). Investigators collected a total of 15 PBZ and six area samples over a two-day period during casting, finishing, and polishing operations.  Finishing operations included the use of dental lathes (with interchangeable grinding and polishing points and discs) ventilated by a LEV system equipped with a rooftop baghouse for dust collection.  Sampling times ranged from 12 to 120 minutes and the ventilation controls were reported to be operating normally.  Three PBZ samples were collected on the worker operating the casting machine, six PBZ samples were obtained on one worker performing finishing activities during an entire workday, and two additional PBZ samples were collected on a worker polishing beryllium-containing materials.  All PBZ samples, including two general area samples, were reported to be nondetectable for beryllium (individual sampling LOD concentrations were not provided).  Although no beryllium was detected during the casting and finishing operations when the LEV was functioning normally on the first sampling day, Kimball (1983) reported that the sampling LOD concentrations for beryllium (on the first sampling day) were all greater than the current PEL of 2.0 ug/m[3].
During the second day of the investigation, Moffa et al. (1973) evaluated the effectiveness of the finishing LEV system.  With the LEV system blocked (no other details are available), the investigators collected four general area samples and four PBZ samples on the same finishing employee who had been evaluated on the first day of sampling.  During this testing, the worker wore a respirator while grinding and polishing.  Sampling times were short, ranging from 34 to 68 minutes.  Beryllium was detected in three of the four PBZ samples, with positive values of 0.6 ug/m[3], 1.2 ug/m[3], and 1.6 ug/m[3].  Three of the four general area samples (collected within two feet of the worker) were also positive for beryllium, with results of 1.4 ug/m[3], 3.2 ug/m[3], and 5.6 ug/m[3].  Sampling LOD concentrations were not provided for the two nondetectable results.  Based on the results of the study, Moffa et al. concluded that beryllium-containing alloys can be used safely in dental laboratories that are equipped with adequate LEV control measures.  OSHA observes that although Moffa et al. base their conclusion on a PEL of 2.0 ug/m[3], the results of this study do show that LEV can have a large impact on dental technician exposure levels during peak periods of exposure.
In a study simulating the work of dental laboratory technicians finishing and polishing beryllium-containing dental alloy (Ticonium Premium 100, with an assayed beryllium content of 0.470 percent), Hinman et al. (1975) of the Naval Graduate Dental School in Bethesda, Maryland, evaluated airborne beryllium levels while an operator used a high-speed grinding and polishing lathe with and without LEV.  Samples were collected at four different locations (one PBZ and three area samples) in two different rooms.  At each location, three 10-minute air samples were collected during separate finishing and polishing operations.  With the lathe connected to a vacuum dust collector, PBZ results were below the sampling LOD concentrations (0.5 μg/m[3] for the 10-minute test periods).  By contrast, when the vacuum was disconnected, the mean PBZ values for two sets of three 10-minute samples were 22.0 μg/m[3] and 23.9 μg/m[3].  This represents at least a 98-percent reduction in the short-term exposure level due to the use of LEV.
In the Moffa and Hinman investigations, the sampling results are limited by either very high LODs (Moffa et al., 1973) or very short sampling periods that are not under actual work conditions (Hinman et al., 1975).  Despite these shortcomings, however, both studies clearly show the importance of adequate LEV in reducing beryllium exposures in dental laboratories.
In 1980, NIOSH evaluated a large dental laboratory (Walter Reed Army Medical Center, Washington, DC) using beryllium-containing dental alloy (Ticonium Premium 100) where all but one exhaust hood met or exceeded a minimum capture velocity of 100 feet per minute (fpm), with an average capture velocity of 500 fpm for operator-positioned scoop hoods on bench tops (NIOSH TA 80-60-756, 1980).  Additionally, windows and doors were open, and supplemental fans were used to help control heat.  Under these conditions, 12 PBZ air samples for laboratory technicians and six area samples indicated that beryllium, nickel, chromium, and molybdenum concentrations were all below the LODs (sampling LOD concentrations were not reported). NIOSH noted that most metal grinding was performed at the benchtop hood scoops and that an average capture velocity of 500 fpm was considered adequate for removal of fine dusts.
At a dental laboratory in Norway, investigators evaluated another toxic metal that laboratory technicians might be exposed to in addition to beryllium.  Brune and Beltesbrekke (1980) determined that the cobalt exposure levels of dental technicians cutting, grinding, and polishing cobalt-containing dental alloys (Vitallium and Wironium brands) were at least 12 times higher (approximately 1.0 to 1.2 mg/m[3] -- 10 times the allowable level in Norway at that time) when work was performed without LEV compared to the exposure levels measured with ventilation present (less than 0.1 mg/m[3] in this case).  These findings indicate that LEV during abrasive activities can achieve at least a 90-percent reduction (i.e., % reduction = (1.0 mg/m[3] -0.1 mg/m[3])/(1.0 mg/m[3])) in the cobalt exposure level.  Although not specific to beryllium, these results show that significant exposure reduction is possible with effective LEV, which is consistent with the findings of other studies that have evaluated beryllium.  Thus, this investigation further supports the effectiveness of LEV to lower dental laboratory technician exposures.
In addition to improving LEV, employee training should be augmented to ensure that all employees use engineering controls properly and routinely.  Housekeeping in laboratories that use beryllium alloys should be performed routinely and thoroughly to prevent the accumulation of dust that can be spread to other work areas or become airborne if disturbed.  Cleaning should be performed with HEPA vacuums instead of traditional vacuums, and the use of compressed air and dry sweeping should be avoided.
In this standard group of controls described above, the downdraft-plus-backdraft grinding bench will control the exposures of dental laboratory technicians while they manually grind dental appliances, but work practice and administrative controls are necessary to ensure that the bench ventilation is maintained in working order, kept clean, and that beryllium particles are not released when the ventilation system is serviced and the filter is changed.
In the event that exposures continued to remain elevated with the standard group of controls, additional control options are also available, such as providing improved exhaust ventilation for both the furnace and abrasive blasting units.  Furnaces should be fitted with close-capture hoods attached to the furnace whenever possible.  Abrasive blasting units should be upgraded to meet the specifications presented in ACGIH (2010) (see Figure VS-80-02, abrasive blasting cabinet, adapted to the scale of the benchtop blasting units typically used in dental laboratories).  The blasting media must be changed frequently -- using dust control precautions and respiratory protection -- to prevent buildup of beryllium in the sand or other medium. Ventilation systems must be discharged outdoors, or fit with HEPA or equivalent filtration.  The same precautions and alarms are required for this ventilation equipment as for the grinding booth.
Dental Laboratory Technician -- Conclusion
The median exposure level for dental laboratory technicians is 0.2 ug/m[3] (see Table IV-80).  Based on the findings of the exposure profile presented in Table IV-81, the proposed PEL of 0.2 ug/m[3] has already been achieved for 52 percent of dental technicians.  Additionally, 13 percent of dental laboratory technicians currently have exposures below an alternative PEL of 0.1 ug/m[3].  Roughly 48 percent of these workers will require additional controls to reduce exposures to or below the proposed PEL of 0.2 ug/m[3].  For those laboratories that continue to use beryllium alloys, the exposure of dental laboratory technicians can be substantially reduced through the combined use of appropriate enclosures and LEV systems; administrative and work practice controls to ensure that the ventilation systems are maintained and used so that they function effectively; and housekeeping to ensure that beryllium contamination is not spread should it occur.  A study simulating the work of dental laboratory technicians found that the proper use of adequate LEV was associated with exposure reductions of at least 98 percent (Hinman et al., 1975).  Other studies also show substantial exposure reductions associated with LEV.  Enclosed and ventilated cabinets or booths would be expected to further reduce exposure. By using these control methods in conjunction with effective work practices and housekeeping methods, nearly all dental laboratory technicians will achieve beryllium exposure levels below 0.1 μg/m3 ( Hinman et al., 1975;  Thomas et al., 2009).  OSHA therefore preliminarily concludes that both an alternative PEL of 0.1 μg/m[3] and the proposed PEL of 0.2 μg/m[3] are feasible for dental laboratory technicians.
References
ACGIH, 2010. Sections 6.2 (Enclosing Hoods -- Introduction) and 6.3 (Totally Enclosing Hoods), Chapter 5 (Design Issues -- Systems), Chapter 13 (Specific Operations), and Section 8.9 (Selection of Air Filtration Equipment), Industrial Ventilation: A Manual of Recommended Practice for Design, 27th Edition. American Conference of Governmental Industrial Hygienists. Cincinnati, Ohio.
Brune, D. and H. Beltesbrekke, 1980. Dust in Dental Laboratories. Part I: Types and Levels in Specific Operations. The Journal of Prosthetic Dentistry 43(6): 687 - 692. June.
BLS, 2008. 2008 Occupational Employment Statistics Survey.  U.S. Bureau of Labor Statistics. .  Available on the U.S. Bureau of Labor Statistics website at http://bls.gov/oes/tables.htm.
Cardinal Dental Laboratory, 2004. Personal communication between a representative of Cardinal Dental Laboratory and Eastern Research Group, Inc. December 6.
Covington, J.S., M.A. McBride, W.F. Slafle, and A.L. Disney, 1985. Beryllium Localization in Base Metal Dental Casting Alloys. Journal of Biomedical Materials Research 19: 747 - 750.
Dental Alloy Distributor A, 2006. Personal communication between a representative of Dental Alloy Distributor A and Eastern Research Group, Inc. October 25.
Dental Alloy Manufacturer A, 2006. Personal communication between a representative of Dental Alloy Manufacturer A and Eastern Research Group, Inc. October 16.
Dental Laboratory A, 2004. Personal communication between a representative of Dental Laboratory A and Eastern Research Group, Inc. December 7.
Dental Laboratory C, 2004. Personal communication between a representative of Dental Laboratory C and Eastern Research Group, Inc. December 8.
Dental Laboratory D, 2006. Personal communication between a representative of Dental Laboratory D and Eastern Research Group, Inc. October 17.
Dental Laboratory F, 2006. Personal communication between a representative of Dental Laboratory F and Eastern Research Group, Inc. October 13.
ERG Beryllium Site 5, 2003. Site visit to a dental laboratory. Eastern Research Group, Inc., Lexington, Massachusetts. January 28 - 29. Recorded as a supporting document at www.regulations.gov, under Document ID number OSHA-H005C-2006-0870-0341.
ERG Dental Lab A, 2000. Site visit report -- Dental Laboratory A. Eastern Research Group, Inc., Arlington, Virginia. August 3.
Hinman, R.W., T.A. Lynde, G.B. Pelleu and R.W. Gaugler, 1975. Factors Affecting Airborne Beryllium Concentrations in Dental Spaces. The Journal of Prosthetic Dentistry 33(2): 210 - 215.
Kimball, A.C., 1983. An Industrial Hygiene Field Study of Dental Laboratories in the Greater Salt Lake Area. Master of Science Thesis in Community Medicine, Department of Family and Community Medicine, The University of Utah. Salt Lake City, Utah. June.
Kim, T.S., H.A. Kim, Y. Heo, Y. Park, C.Y. Park, and Y.M. Roh, 2002. Level of Silica in the Respirable Dust Inhaled by Dental Technicians with Demonstration of Respirable Symptoms. Industrial Health 40: 260 - 265.
Kotloff, R.M., P.S. Richman, J.K. Greenare, and M. D. Rossman, 1993. Chronic Beryllium Disease in a Dental Laboratory Technician. American Review of Respiratory Disease 147: 205 - 207.
Materion Information Meeting, 2012. Meeting between Materion Corporation and the U.S. Occupational Safety and Health Administration. Elmore, Ohio. May 8 - 9.
Materion MSDS A11, 2011. Nickel Beryllium Dental Alloy. Material Safety Data Sheet - No. A11, revised March 8, 2011. Materion Brush Inc. Cleveland, Ohio. Available online at: http://materion.com/~/media/Files/PDFs/Corporate/MSDS/A11NickelBerylliumDentalAlloy.pdf.
Moffa, J.P., A.D. Guckes, M.T. Okawa, and G.E. Lilly, 1973. An Evaluation of Non-precious Alloys for Use with Porcelain Veneers. Part II. Industrial Safety and Biocompatibility. The Journal of Prosthetic Dentistry 30(4): 432 - 441.
Napier, B., 2004. Telephone communication between Eastern Research Group, Inc. and Bennett Napier, Executive Director, National Association of Dental Laboratories. December 16.
NIOSH TA 80-60-756, 1980. Technical Assistance Report TA 80-60-756. Walter Reed Army Medical Center, Washington, DC. U.S. Department of Health and Human Services, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health. October.
OSHA-H005C-2006-0870-0144. U.S. Department of Labor, Occupational Safety and Health Administration. OSHA Beryllium Docket No. OSHA-H005C-2006-0870. Document ID No. OSHA-H005C-2006-0870-0144. Document title: Navy response to Occupational Safety and Health Administration's Occupational Exposure to Beryllium. Request for Information.
OSHA-H005C-2006-0870-0145. U.S. Department of Labor, Occupational Safety and Health Administration. OSHA Beryllium Docket No. OSHA-H005C-2006-0870. Document ID No. OSHA-H005C-2006-0870-0145. Document title: Attachment (1). Navy Occupational Exposure Database (NOED) Query Report -- Personal Breathing Zone Air Sampling Results for Beryllium.
OSHA-H005C-2006-0870-0345. U.S. Department of Labor, Occupational Safety and Health Administration. OSHA Beryllium Docket No. OSHA-H005C-2006-0870. Document ID No. OSHA-H005C-2006-0870-0345. Document title: Small Business Advisory Review (SBAR) Panel Report with Appendices A, B, and D. Final Version. (Report of the Small Business Advocacy Review Panel on the OSHA Draft Proposed Standard for Occupational Exposure to Beryllium, January 15, 2008.)
OSHA-H005C-2006-0870-0346. U.S. Department of Labor, Occupational Safety and Health Administration. OSHA Beryllium Docket No. OSHA-H005C-2006-0870. Document ID No. OSHA-H005C-2006-0870-0346. Document title: Appendix C. Beryllium Small Business Advocacy Review (SBAR) Panel Report.
OSHA, 2009.  Integrated Management Information System (IMIS).  Beryllium exposure data, updated April 21, 2009, covering the period 1978 through September 2008.  Data provided to Eastern Research Group, Inc. by the U.S. Department of Labor, Occupational Safety and Health Administration, Washington, DC.  [Unpublished, electronic files]
Pentron, 2004. Personal communication between a technical representative of Pentron Corporation and Eastern Research Group, Inc. December 7.
Pentron Rex 4 MSDS, 2004. Material Safety Data Sheet (MSDS) for Rex 4 Alloy. Beryllium-free nickel-chromium ceramic alloy, January 12, 2004. Pentron Laboratory Technologies, LLC, Wallingford, Connecticut.
Rom, W.N., J.E. Lockey, J.S. Lee, A.C. Kimball, K.M. Bang, H. Leaman, R.E. Johns, D. Perrota, and H.L. Gibbons, 1984. Pneumoconiosis and Exposures of Dental Laboratory Technicians. American Journal of Public Health 74(11): 1252 - 1257. November.
Thomas, C.A., R.L. Bailey, M.S. Kent, D.C. Deubner, K. Kreiss, and C.R. Schuler, 2009.  Efficacy of a Program to Prevent Beryllium Sensitization Among New Employees at a Copper-Beryllium Alloy Processing Facility. Public Health Reports, 2009 Supplement 1, Volume 124: 112 - 124.
U.S. Census Bureau, 2010. 2010 County Business Patterns. Available on the U.S. Census Bureau website at http://www.census.gov/econ/cbp/index.html.

SECTION 11 -- Dental Laboratories, Appendix 1 -- OSHA IMIS PBZ TOTAL BERYLLIUM AIR SAMPLING RESULTS  FOR DENTAL TECHNICIANS
      Table IV-82 -- OSHA IMIS PBZ Total Beryllium Air Sampling Results for Dental Technicians[a]
                                      SIC
                                     Code
                                SIC Description
      No. PBZ samples with Positive Results / Total No. of PBZ Samples[b]
                           Example Job Descriptions
                              (as listed in IMIS)
                                   Range[c]
                                  (μg/m[3])
                                    Mean[c]
                                  (μg/m[3])
                                   Median[c]
                                  (μg/m[3])
                                     3843
                         Dental Equipment and Supplies
                              1/1
(100% positive)
                             Dental lab technician
                                    0.01[d]
                                     0.01
                                     0.01
                                     5160
                         Chemicals and Allied Products
                               0/1
(0% positive)
                                  Dental tech
                                     None
                                     None
                                     None
                                     8049
               Offices and Clinics of Health Practitioners, NEC
                              1/1
(100% positive)
                             Denture metal alloys
                                    3.0[e]
                                      3.0
                                      3.0
                                     8062
                    General Medical and Surgical Hospitals
                               0/1
(0% positive)
                                  Dental tech
                                     None
                                     None
                                     None
                                     8071
                             Medical Laboratories
                               0/3
(0% positive)
                                Dental lab tech
                                     None
                                     None
                                     None
                                     8072
                              Dental Laboratories
                             19/32
(59% positive)
Dental tech; dental technician; frame grinder; grinding partials; lab technician; metal fabricator; metal finisher; tech/denture polisher; metals grind etc.
                                0.03 to 0.20[f]
                                     0.10
                                     0.10
                                    N/A[e]
                      OSHA On-site Consultation Services
                              2/2
(100% positive)
                       Dental tech metal; crown grinder
                                0.02 to 0.03[g]
                                     0.025
                                     0.025

                                     Total

                             23/41
(56% positive)

                                  0.01 to 3.0
                                     0.22
                                     0.10
[a]	Information regarding worker activities, the engineering controls in place, personal protective equipment (PPE) worn during sampling, nondetectable limit of detection (LOD) sample concentrations, and sample duration is not available.
[b]	Includes all PBZ samples by SIC code.
[c]	The range, mean, and median results are based on positive sample results only. All positive results are included.
[d]	Coded as a ceiling sample.
[e]	Coded as a STEL (short-term exposure limit) sample.
[f]	Includes six samples coded as ceiling samples; four samples coded as STEL samples; and nine samples coded as time-weighted average (TWA) samples.
[g]	Coded as TWA samples.
[e]	 N/A: not available

Source: OSHA, 2009

SECTION 12 -- SHORT-TERM EXPOSURES
Introduction
This section of the Preliminary Economic Analysis (PEA) identifies the tasks or jobs and the industries in which elevated short-term exposures have been documented, describes the influence that short-term exposures have on daily full-shift exposure levels, and discusses the technological feasibility of reducing short-term exposures.
Defining Short-Term Exposures and Identifying Samples
Short-term exposure means the worker exposure level averaged over a 15-minute sampling period. A 15-minute averaging period for short-term exposure limits (STELs) has been a standard in OSHA's previous rulemakings for air contaminants, such as 1, 3-Butadiene (29 CFR 1910.1051) and Methylene chloride (29 CFR 1910.1052).  Elevated short-term exposures occur when tasks lasting 15 minutes or less, or short bursts of activity within longer tasks, result in peaks in airborne concentrations that significantly exceed background levels.  Thus, one or more intermittent peaks during a 15-minute sampling period can contribute to an elevated short-term exposure.
OSHA's current acceptable ceiling limit for beryllium is defined in Table Z-2 of 29 CFR 1910.1000 as airborne concentrations of beryllium no greater than 5 ug/m[3] during an 8-hour shift, except that exposures may be as high as 25 ug/m[3] for one 30-minute period during an 8-hour shift. For compliance purposes, exposure levels can exceed an acceptable ceiling value of 5 ug/m[3] only once for not more than one thirty-minute interval during which exposures cannot exceed an acceptable maximum peak of  25 ug/m[3]. In order to assess compliance with OSHA's ceiling concentrations, employers have the option of assessing the beryllium ceiling concentration as a 15-minute time-weighted average (TWA) (FR 40  202, 1975).
With this proposed beryllium standard, OSHA intends to replace the current acceptable ceiling limit of 5.0 ug/m[3] with a short-term exposure limit (STEL) of 2.0 ug/m[3] based on a 15-minutes averaging period.  OSHA is also considering an alternative STEL of 1.0 ug/m[3]. To evaluate the feasibility of these proposed STELs, OSHA gathered samples for short-term tasks sampled over 15 minutes. To supplement these data, OSHA also considered samples collected over a somewhat shorter or longer period of time (e.g., 5 minutes and 30 minutes). OSHA has used this time range because it allows the Agency to build a more comprehensive exposure profile, and the short-term tasks that may expose workers to beryllium are typically conducted within this time frame. The 15- and 30-minute samples are equally prevalent within the data provided by the United States Navy (NEHC, 2003). Among samples collected by OSHA personnel, however, the 15-minute sampling period has been the most common short-term sampling period for evaluating beryllium exposure (OSHA, 2009).
In some cases, such as with OSHA's IMIS dataset for beryllium, sample durations are not specified for the reported exposure levels; however, OSHA considered the sample relevant to this analysis if the data indicate that the compliance officer compared the result to OSHA's current ceiling or peak exposure limits, presented in 29 CFR 1910.1000 Table Z-2. OSHA considered this to be sufficient evidence that the investigator limited the sampling time to a relevant short period.  However, due to the limited nature of the available information OSHA could not discern exactly what the worker was doing during the sampling period.
Sources of Information
OSHA searched for relevant job categories and short-term beryllium sampling data in the sources of exposure information described in Sections 3 through 11, Beryllium Production through Dental Laboratories, of the PEA.  In general, short-term samples were less prevalent than full-shift samples. For example, all available personal breathing zone (PBZ) beryllium samples from Brush Wellman and the National Institute for Safety and Health (NIOSH) exceed 30 minutes, and most are reported as full-shift. However, two sources -- OSHA's IMIS database and the United States Navy's Naval Environmental Health Center (NEHC) database -- included short-term samples (OSHA, 2009; NEHC, 2003).
IMIS Short-Term Exposure Data
ERG reviewed IMIS data from June 1978 to September 2008 to identify all PBZ samples reported as ceiling (C), short-term (L), or peak exposures (P). Collectively, these three exposure types in the IMIS dataset are representative of exposures that occur during short-term tasks for this analysis.
The IMIS database presents information by SIC code classification. OSHA analyzed the short-term IMIS data by SIC codes corresponding to the industries and job titles included in this technological feasibility analysis. The IMIS data include 593 PBZ air samples positive for total beryllium and representative of exposures that result from short-term tasks ("C" samples, "L" samples, and "P" samples) in the application groups addressed by this feasibility analysis (Beryllium Production through Dental Laboratories, Sections 3 through 11 of this PEA).  However, the database does not provide details of the activities that the workers were performing during the time they were monitored.  As in Beryllium Production through Dental Laboratories, Sections 3 through 11 of this PEA, the nondetectable (ND) short-term samples have been excluded; thus, all the IMIS short-term sample results discussed here are positive for beryllium.
Other Short-Term Exposure Data
ERG also compiled and reviewed PBZ total beryllium air samples shorter than or equal to 30 minutes in duration that were submitted by the U.S. Navy in response to OSHA's request for information pertaining to occupational exposure to beryllium (NEHC, 2003). Fifty-eight short-term PBZ samples from the Navy docket submittal were utilized in this analysis. These samples represent the most relevant jobs/tasks with positive beryllium results or possible beryllium exposure.   The majority of these samples are associated with the following jobs or tasks: maintaining ventilation equipment (air-cleaning devices) that support beryllium operations; machining beryllium-containing materials (e.g., turning copper-beryllium bushings); and welding and cutting involving base materials (e.g., aluminum) or electrodes (e.g., resistance welding) that could contain beryllium.
Operations During Which Short-Term Exposures Occur
Elevated exposures can occur during intermittent or periodic activities that involve a brief period of increased potential for beryllium exposure. Activities that can cause intermittent increased exposure are concentrated within high-energy tasks that release beryllium particles (e.g., certain machining jobs, such as grinding); jobs that involve creating a substantial amount of fume for a short period of time (e.g., removing dross during furnace operations, pouring/casting beryllium alloys); jobs that require workers to handle beryllium products on which loose, friable oxides of beryllium are present (e.g., tasks involving containers of foundry dross or powdered beryllium oxide); and housekeeping or maintenance tasks that cause beryllium dusts or mists to become airborne (e.g., sweeping, maintaining exhaust ventilation systems used to capture beryllium).
Based on the IMIS and Navy samples, results exceeding 2.0 ug/m[3] appear to be associated with the following types of operations and job categories:
Beryllium production: Furnace operations (melting and casting); powdering/pebble plant operations.
Copper and aluminum foundries: Furnace operations (melting and casting).
Secondary smelting, refining, and alloying, including handling of scrap and recycled materials: Furnace operations (furnace charging, melting and casting, calcining); mechanical processing; machining; housekeeping (sweeping).
Welding: Welding and cutting.
Jobs similar to those listed above (furnace operations, machining, housekeeping), which are occasionally listed in association with other related industries (e.g., manufacturing of fabricated metal products).
Relationship Between STEL and PEL exposures
Elevated short-term exposures are included in calculations of a worker's daily 8-hour TWA. Although brief, the higher concentration of a short-term exposure can influence the 8-hour TWA. A short-term exposure exceeding the proposed STEL of 2.0 ug/m[3] can influence whether the proposed PEL of 0.2 ug/m[3] can be achieved for a worker. For example, the typical average daily exposure of 0.1 ug/m[3] for a worker will increase to 0.225 ug/m[3] (exceeding the proposed PEL of 0.2 ug/m[3]) if that worker is assigned a new task that adds two 15-minute periods at an exposure level of 2.1 ug/m[3] (slightly exceeding the proposed STEL of 2.0 ug/m[3]).
Even when the worker has no other source of beryllium exposure during the work shift, that worker's 8-hour TWA will exceed the proposed PEL if the STEL is exceeded during more than three 15-minute periods over the course of a work shift. For example, in the absence of any other exposure, a concentration of 2.1 ug/m[3] for 48 minutes will cause the 8-hour TWA for that worker to exceed the proposed PEL of 0.2 ug/m[3]. Similarly, even with no other source of beryllium exposure, a single 15-minute exposure of 6.4 ug/m[3] or greater will cause the worker's 8-hour TWA to exceed the PEL of 0.2 ug/m[3]. These values represent the short-term threshold above which the PEL cannot be achieved.
Table IV-83 demonstrates how various elevated short-term beryllium concentrations can cause the daily exposure level to exceed the PEL.
Table IV-83 -- Influence of Short-Term Beryllium Exposure Levels on a Worker's 8-hour TWA Exposure
             Number of Short (15 minute) Periods During the Shift
                 Short-Term Concentration for Cumulative Time
                    Concentration During Remainder of Shift
                                  8-hour TWA
                                 Concentration
Short-Term Exposure, With No Other Exposure
One
                                 2.1 ug/m[3]
                                for 15 minutes
                                  0 ug/m[3]
                                for 465 minutes
                                 0.07 ug/m[3]
Two
                                 2.1 ug/m[3]
                                for 30 minutes
                                  0 ug/m[3]
                                for 450 minutes
                                 0.13 ug/m[3]
                              Exceeds Proposed AL
Three
                                 2.1 ug/m[3]
                                for 45 minutes
                                  0 ug/m[3]
                                for 435 minutes
                                 0.2 ug/m[3]
                              Exceeds Proposed AL
Four
                                 2.1 ug/m[3]
                                for 60 minutes
                                  0 ug/m[3]
                                for 420 minutes
                                 0.26 ug/m[3]
                             Exceeds Proposed PEL
Short-Term Exposure and Constant Background Exposure at the Action Level (AL) of 0.1 ug/m[3]
One
                                 2.1 ug/m[3]
                                for 15 minutes
                                 0.1 ug/m[3]
                                for 465 minutes
                                 0.16 ug/m[3]
                              Exceeds Proposed AL
Two
                                 2.1 ug/m[3]
                                for 30 minutes
                                 0.1 ug/m[3]
                                for 450 minutes
                                 0.23 ug/m[3]
                             Exceeds Proposed PEL
Three
                                 2.1 ug/m[3]
                                for 45 minutes
                                 0.1 ug/m[3]
                                for 435 minutes
                                 0.29ug/m[3]
                             Exceeds Proposed PEL
Increasing Short-Term Exposure Level, With No Other Exposure
One
4 ug/m[3]
 for 15 minutes
0 ug/m[3]
for 465 minutes
0.13 ug/m[3]
Exceeds Proposed AL
One
8 ug/m[3]
for 15 minutes
0 ug/m[3]
for 465 minutes
0.25 ug/m[3]
Exceeds Proposed PEL
One
12 ug/m[3]
for 15 minutes
0 ug/m[3]
for 465 minutes
0.38 ug/m[3]
Exceeds Proposed PEL
Increasing Short-Term Exposure Level and Constant Background Exposure of 0.1 ug/m[3]
One
                                  4 ug/m[3]
                                for 15 minutes
                                 0.1 ug/m[3]
                                for 465 minutes
                                 0.22 ug/m[3]
                             Exceeds Proposed PEL
Notes:
8 hours = 480 minutes.
8-hour TWAs calculated using OSHA's equation from 29 CFR 1910.1000(d)(1)(i) for determining an 8-hour TWA exposure:
(Concentration1 X Time1 + Concentration2 X Time2 + Concentrationn X Timen)/480 minutes).
In the absence of any other beryllium exposures, the short-term threshold above which the proposed PEL of 0.2 ug/m[3] cannot be achieved is 48 minutes at 2.1 ug/m[3], or 15 minutes at 6.4 ug/m[3].

Table IV-83 also indicates the relatively narrow range of short-term and background exposure conditions under which the STEL could be exceeded without also exceeding the PEL.
Evidence That STEL Exposures Can Occur
OSHA considered the available information for samples designated as short-term with results exceeding 2.0 ug/m[3] (OSHA, 2009; NEHC, 2003).  OSHA also examined results exceeding 6.4 ug/m[3], the short-term (15-minute) threshold above which the PEL cannot be achieved. Among a total of 651 short-term samples, 117 (18 percent) exceeded the proposed STEL of 2.0 ug/m[3], and 39 (6 percent) exceeded 6.4 ug/m[3].  These details provide evidence that short-term exposures do occur and can exceed the proposed STEL.
In reviewing the short-term exposure data by decade, OSHA observed a trend toward a lower percentage of sample results exceeding 2.0 ug/m[3] in more recent decades.  However, as shown in Table IV-84, excessive short-term exposures continue to occur.  During the most recent time period analyzed (2000 to 2008), only 5 of 82 positive short-term samples (6 percent) exceeded 2.0 ug/m[3], while the other 94 percent were all less than or equal to 1.0 ug/m[3].  In total, only 6% of the 623 positive short term measurements were greater than 1.0 ug/m[3] and less than or equal to 2.0 ug/m[3].
Table IV-84 -- Distribution of Short-term Beryllium Exposure Levels, Over Three Decades
                                  Time Period
          Number of Positive Short-Term Sample Results[a]
(ug/m[3])

                                  0 to <= 1
                               > 1 to <= 1.5
                               > 1.5 to <= 2
                               > 2 to <= 6.4
                                   > 6.4
                                     Total
                                Total 1980-2008
                                      468
                                    (75.1%)
                                      21
                                    (3.4%)
                                      17
                                    (2.7%)
                                      78
                                    (12.5%)
                                      39
                                    (6.3%)
                                      623
                                    (100%)
Decade
                               1980 through 1989
                                      74
                                    (50.7%)
                                       7
                                    (4.8%)
                                      14
                                    (9.6%)
                                      38
                                    (26.0%)
                                      13
                                    (8.9%)
                                      146
                                    (100%)
                               1990 through 1999
                                      317
                                    (80.3%)
                                      14
                                    (3.5%)
                                       3
                                    (0.8%)
                                      38
                                    (9.6%)
                                      23
                                    (5.8%)
                                      395
                                    (100%)
                             2000 and later [2008]
                                      77
                                    (93.9%)
                                       0
                                     (0%)
                                       0
                                     (0%)
                                       2
                                    (2.4%)
                                       3
                                    (3.7%)
                                      82
                                    (100%)
a 	Short-term sample results associated with industries addressed in Methodology through Dental Laboratories, Sections 2 through 11 of this PEA (593 positive short-term sample results reported in IMIS and 30 short-term results reported by the U.S. Navy, a total of 623 samples). OSHA removed 28 non-detectable U.S. Navy samples that had reporting limits between 1.0 ug/m[3] and 2.0 ug/m[3] (i.e., greater than 1.0 ug/m[3] and less than 2.0 ug/m[3]). Before those 28 U.S. Navy samples were removed, the data set included 593 IMIS and 58 U.S. Navy samples (a total of 651 STEL samples).

Source: OSHA, 2009; NEHC, 2003

Affected Industries and Job Categories
OSHA analyzed the short-term IMIS data by industry. As for all analysis in Section 12 -- Short-Term Exposures, OSHA restricted the data to only those samples associated with the application groups described earlier in Beryllium Production through Dental Laboratories, Sections 3 through 11 of this PEA.  The analysis shows that short-term tasks or jobs involving elevated exposures are most often associated with beryllium production and the secondary smelting, refining, and alloying industries, although elevated short-term exposures do occasionally occur in other major beryllium industries as well.
Overall, 82 percent (494 samples) of the 606 short-term IMIS sample results for all beryllium industries analyzed in this section (12 -- Short-Term Exposures) were 2.0 ug/m[3] or less (range 0.005 ug/m[3] to 7.1 ug/m[3]).  The individual industry sectors analyzed by median short-term exposure levels, presented in Table IV-85 (details by job category in Table IV-88 in Short-Term Exposures Appendix 2), include beryllium production (0.7 ug/m[3]); beryllium oxide (0.4 ug/m[3]); aluminum and copper foundries (0.17 ug/m[3]); secondary smelting, refining, and alloying, including handling of scrap and recycled materials (0.6 ug/m[3]); copper rolling, drawing, and extruding (0.08 ug/m[3]); welding and cutting (0.07 ug/m[3]); and dental laboratories (0.1 ug/m[3]).  The data for each of these sectors are well supported, with at least 10 short-term samples for each industry, except for the beryllium oxide industry, with seven samples.,   OSHA observes that the median short-term sample result for each of these industries is less than one-half the proposed STEL (medians range from 20 to 35 percent of the proposed STEL for beryllium production; beryllium oxide; and secondary smelting, refining, and alloying (including handling of scrap and recycled materials) and just 4 percent to 9 percent of the proposed STEL for the remaining industries).  These findings suggest that elevated short-term exposures are infrequent in the industries covered by the proposed standard.
Table IV-87 in Short-Term Exposures Appendix 1 confirms this observation, using 149 PBZ exposure results from the Navy to demonstrate that task-based short-term samples typically are less than or equal to 2.0 ug/m[3]. In this dataset, 87 percent (130 samples) of the 149 short-term sample results were 2.0 ug/m[3] or less (conversely only 13 percent, or 19 samples exceed 2.0 ug/m[3]).

Table IV-85 -- Summary of OSHA IMIS PBZ Short-Term Air Sampling Results Positive for Total Beryllium by
Industry Sector
                           Beryllium Industry Sector
                                IMIS Job Titles
                          Short-Term Exposure Sources
                                  No. Samples
                      Beryllium Concentration (ug/m[3])
                              Sample Distribution

                                     Mean
                                    Median
                                    Minimum
                                    Maximum
                                    <= 2.0
                                   ug/m[3]
                                   (Percent)
                               > 2.0 ug/m[3]
                                   (Percent)
Beryllium Production (Section 3)
Foundry (mold and core preparation, shakeout, melting and casting); machining; pebble plant operator; pelletizing; powdering; sheet operator; welding and cutting
                     Transition activities (transferring)
                                      96
                                      4.4
                                      0.7
                                     0.01
                                      99
                                      63
                                     (65%)
                                      33
                                     (35%)
Beryllium Oxide
(Section 4)
Welding and cutting; engine manufacturing
      Transition activities (transferring), breaching enclosed processes
                                       7
                                      0.7
                                      0.4
                                      0.1
                                      2.0
                                       7
                                    (100%)
                                       0
                                     (0%)
Nonferrous Foundries (Section 5)
Furnace - melting and casting; shakeout; mold and core preparation; machining; welding and cutting
  Hot processes that generate fumes; dross handling; tasks that disturb dust
                                      80
                                      1.0
                                     0.17
                                     0.01
                                      8.8
                                      65
                                     (81%)
                                      15
                                     (19%)
Secondary Smelting, Refining, Alloying
(Section 6)
Electrical - engineering; foundry; mold and core; pressing; calcining; furnace charging; incinerator; kiln; laboratory technician; material handling; heavy equipment operations; mechanical processing; scrap operations; sweeping; tool-making; laundry operator; repair and maintenance
Hot processes that generate fumes; high-energy activities; tasks that disturb dust (including housekeeping and maintenance)
                                      194
                      (substantial legacy exposure data)
                                      2.1
                                      0.6
                                     0.02
                                      18
                                      135
                                     (70%)
                                      59
                                     (30%)
Precision Turned Products (Section 7)
No short-term exposure data
  Potential for breaching enclosed processes; uncontrolled cutting fluid mist
                                       0
                                      n/a
                                      n/a
                                      n/a
                                      n/a
                                       0
                                     (0%)
                                       0
                                     (0%)
Copper Rolling, Drawing, Extruding (Section 8)
Furnace - melting and casting; mechanical processing; forging; powdering
               Friable beryllium oxide on surfaces being worked
                                      10
                                     0.28
                                     0.08
                                     0.01
                                      0.9
                                      10
                                    (100%)
                                       0
                                     (0%)
Fabrication of Beryllium Alloy Products (Section 9)
No short-term exposure data
                                     none
                                       0
                                      n/a
                                      n/a
                                      n/a
                                      n/a
                                       0
                                     (0%)
                                       0
                                     (0%)
Welding
(Section 10)
Welding and cutting
               Friable beryllium oxide on surfaces being worked
                                      209
                                     0.21
                                     0.07
                                     0.005
                                      7.1
                                      204
                                     (98%)
                                       5
                                     (2%)
Dental Laboratories
(Section 11)
Dental laboratory
        Grinding and polishing; abrasive blasting (on beryllium alloy)
                                      10
                                     0.11
                                      0.1
                                      0.1
                                      0.2
                                      10
                                    (100%)
                                       0
                                     (0%)
                                                                          TOTAL

                                      606

                                     0.005
                                      99
                                      494
                                     (82%)
                                      112
                                     (18%)
Note:
n/a: not applicable

Source: OSHA Integrated Management Information System (IMIS) Database, 1978 -2008 (OSHA, 2009)

Relationship of Control Methods for STEL and PEL Exposures
As discussed earlier, only a relatively narrow range of short-term and background exposure conditions exists under which the proposed STEL (2.0 ug/m[3]) could be exceeded without also exceeding the proposed PEL of 0.2 ug/m[3].  Additionally, with a background exposure at the proposed action level (0.1 ug/m[3]), the proposed PEL will be exceeded with two or more short term exposures of at least 2.0 ug/m[3].  There are a larger number of scenarios in which an alternative STEL of 1.0 ug/m[3] could be exceeded and still comply with the proposed PEL of 0.2 ug/m[3].  Using the same methodology from Table IV-83, OSHA estimates that with a background exposure of 0.1 ug/m[3], it would take four or more short-term exposures of 1.1 ug/m[3] to exceed the proposed PEL.
Effective controls for reducing short-term exposure levels are required to maintain exposure levels at the proposed PEL or lower.  To achieve the proposed PEL, employers should be aware of the impact that short-term exposures have on the 8-hour TWA and thus make efforts to reduce short-term exposures as part of their overall exposure-reduction strategy.  However, as discussed below the controls that OSHA has recommended to reduce the workers' 8-hr TWA would also be applicable to reduce short term exposures.
Information  presented in Table IV-84 (623 short-term beryllium samples from IMIS and the U.S. Navy) suggests that 81 percent of workers' short-term exposures are already at or below 2.0 ug/m[3]. However,  OSHA  does not have sufficient detail in the activities of the workers to know if these samples were in operations that are most likely to produce exposures above the STEL. Therefore the estimate could underestimate the percentage of workers in activities that are most likely be affected by high short term exposures that are already below the proposed STEL.  However, based on relationship between the STEL to the 8 hour TWA as described in Table IV-84 and the controls OSHA has recommended to reduce worker's exposure to below the 8 hr TWA, OSHA preliminarily concludes that the proposed STEL of 2.0 ug/m[3] is achievable in most operations most of the time.  OSHA believes that the control measures identified in the technological feasibility analysis to reduce exposures to the proposed PEL will similarly reduce exposures to the proposed STEL or below.  In many situations, these controls will have reduced short-term exposures as a necessary condition of reducing the full-shift exposure. For example, in material handling operations, modifying the process by ensuring enclosure of drums and preventing leakage reduces the highest short-term exposures and the 8-hour TWA, which is influenced by the short-term exposures.  Refer to Beryllium Production through Dental Laboratories, Sections 3 through 11 of this PEA, for details on how these additional controls affect exposures above the proposed PEL.
Many of  the engineering control measures described in this technological feasibility analysis and listed in Appendix B of the proposed rule are recommended for operations with the potential for highest short term exposures.  In most cases, reducing peak exposures during short term tasks will be necessary to reduce the TWA exposures to workers who are currently exposed above the proposed PEL.
OSHA has been able to obtain only limited information regarding work shifts where both a short-term exposure and an 8-hour TWA exposure were obtained.  Table IV-86 presents the limited dataset containing eight samples with both short-term and 8-hour TWA values.  OSHA is unable to use this information to characterize the nature of STEL and PEL exposures for all the affected job categories, as these data represent only a few operations.  As previously discussed, however, these data show how it is possible to have instances where the short-term exposures are above the proposed STEL when the 8-hour TWA exposures are below the proposed PEL.
These data indicate that high mechanical energy operations, such as grinding, can produce peak exposures that exceed the proposed STEL and PEL, as is the case with the 10 ug/m[3] short-term exposure associated with the 1.0 ug/m[3] 8-hour TWA (NEHC, 2003). This phenomenon is common to all operations with elevated peak exposures.  OSHA assumes that the engineering controls listed in Appendix B can be implemented to reduce elevated short-term exposures, as well as background exposure levels.  For example, partial enclosures, automation, and improved material handling systems all address potential peak exposures in those problematic operations such as furnace operations and mechanical processing operations identified in Beryllium Production through Secondary Smelting, Refining, and Alloying, Including Handling of Scrap and Recycled Materials, Sections 3 through 6 of this PEA.  Lacking the comparative data of short-term and 8-hour TWA exposures for the vast majority of operations, OSHA cannot determine to what extent the remaining 18 percent of the population exposed over the proposed STEL will shift toward maintaining short-term exposures at or below 2.0 ug/m[3].  OSHA requests additional information that may help in identifying the conditions under which the proposed STEL can and cannot be achieved, including correlated short-term and 8-hour TWA exposures.
The data in Table IV-86 help to demonstrate the importance of reducing peak exposures for operations in which peak exposures contribute to both elevated short-term and full-shift TWA exposures.  The engineering controls identified in Secondary Smelting, Refining, and Alloying, Including Handling of Scrap and Recycled Materials, Sections 3 through 11 of this PEA that reduce the highest full-shift exposures also reduce peak exposures.  Reduction of peak exposures will in turn result in lower short-term exposures in these operations. In these situations, if after implementing all feasible control options, short term exposures continue to exceed the proposed STEL, the employer will have to employ respiratory protection to reduce short-term exposures, while also characterizing the associated 8-hour TWA exposures in order to develop a comprehensive exposure-control program that satisfies the provisions of the proposed standard.  In some cases, respiratory protection might only be necessary for short-term exposures if the background exposure is minimal, or respiratory protection might be needed to control both short-term and 8-hour TWA exposures.  The type of respiratory protection should be determined in accordance with the Respiratory Protection standard (29 CFR 1910.134).
Additional Control Measures
As mentioned previously in this section of the PEA (12 -- Short-Term Exposures), control measures are similar (often identical) for short-term activities and longer processes.  Additionally, to be effective, the controls that manage daily exposures must reduce short-term exposures as part of the effort. The following controls represent examples that reduce both short-term and full-shift exposures.  The controls are described in Beryllium Production through Dental Laboratories, Sections 3 through 11 of this PEA, and many of them are listed in Appendix B of OSHA's proposed rule.  These measures are mentioned here as examples of how controls are applicable to short-term exposure, both as part of a general exposure control strategy and in the event that efforts need to be targeted at short-term exposures.
Control Measures for Transition Activities Involving Material Handling and Transfers
Material handlers may experience elevated exposures when entering production areas. For example, workers in foundries and smelters that deliver furnace charge materials (i.e., materials to be put in the furnace for melting) may be exposed from ongoing furnace operations. To reduce exposures, this material delivery might be timed so that workers making the deliveries approach the furnace between periods of degassing, sparging, and dross skimming, thus avoiding periods when airborne contaminant levels in that area are highest. In another example, material handlers may be exposed from shakeout operations in foundries, as they are present in this operation when they deliver the cast to the shakeout area.  Workers who usually work in the area but are not specifically involved in the shakeout process should move out of the area before vibrating equipment is activated.  Until such time as all beryllium operations are reduced to the proposed PEL and STEL, workers should not linger in areas where exposure is not adequately controlled.
Control Measures for Machining Activities
Emissions from short- and long-term machining activities can expose workers to beryllium if these activities are not properly controlled. Many machining operations use metalworking fluid to regulate the temperature at the point of operation. Free beryllium particles in air and beryllium particles suspended in metalworking fluid mist are potential sources of exposure, and both can be controlled using enclosures and ventilation.
Hands et al. (1996) concluded that machining equipment with LEV and total enclosures designed by the original equipment manufacturer provides the most effective control of metalworking fluid mist exposure.  Additionally, NIOSH investigators determined that entry, or even partial entry, into a machine tool enclosure led to higher operator exposures.  The investigators used an aerosol photometer and video exposure monitoring to identify the peak metalworking fluid exposures of machine operators in the course of their work.  One worker had his highest metalworking fluid exposure (0.93 mg/m[3]) when he was inside a machining center cleaning; another worker had his highest exposures (0.45 mg/m[3] and 0.63 mg/m[3]) when he was at the open doors of partially enclosed machining centers, sometimes with his arm inside (NIOSH ECTB 218-12a, 1997).
OSHA compared exposures at a facility that had fully enclosed and ventilated operations to another facility that did not have these control measures fully implemented.  At ERG Beryllium Site 1, all machining operations were fully enclosed and ventilated, and full-shift PBZ exposure results were characterized by a median of 0.02 g/m[3] and a mean of 0.035 g/m[3] (range of 0.02 g/m[3] to 0.11 g/m[3]).  In contrast, control measures were not as fully implemented at ERG Beryllium Site 4 (also referred to as Site 9), some machining operations were not enclosed (i.e., open machining), and some enclosures and/or LEV systems were in need of upgrades to ensure that sufficient exhaust flow and containment were always available. The beryllium samples were collected over two shifts and are characterized by a mean of 1.48 ug/m[3], a median of 0.29 ug/m[3], and a range from 0.03 ug/m[3] to 41.48 ug/m[3].  During the site surveys, ERG investigators noted that workers improperly positioned several exhaust ducts by a few centimeters, resulting in less than optimal exhaust flow around the parts being machined, or positioned themselves too close to the point of operation (ERG Beryllium Site 4, 2003; ERG Beryllium Site 9, 2004).  Local exhaust ventilation (LEV) was applied to open machining operations through the use of moveable exhaust ducts manually positioned close to the point of operation.  These operations relying on worker-positioned LEV and/or partial enclosure resulted in sample levels notably higher than those found at Site 1, where all operations were fully enclosed and ventilated.
Work practices can also play an important role in worker exposures.  Opening or entering an enclosed process can lead to increased short-term exposures.  If an operator opens the enclosure while particles remain suspended or if he reaches into the enclosure, the operator's breathing zone exposure is influenced by the enclosure contents.  At ERG Beryllium Site 4, the highest total beryllium exposure level of 6.6 ug/m[3] was obtained on a machinist operating a fully enclosed and ventilated double-sided lapper.  During the lapping cycle, it was noted that the worker opened the machine enclosure four to five times to check on the progress of the parts.  It is likely that this work practice increased the machinist's exposure to beryllium (ERG Beryllium Site 4, 2003).  Eliminating or minimizing this work practice will help significantly reduce machinists' exposures.  Alternatively, the doors of the fully enclosed and ventilated machine enclosure could be interlocked with the machining cycle such that the enclosure cannot be opened during the machining cycle and the operator has to wait a designated period of time at the completion of the cycle (e.g., 1 to 2 minutes) before the door can be opened to retrieve the machined part.  Materion Corporation advocates a similar approach and recommends that enclosure doors and ventilation systems be interlocked to the machine controls in a manner that requires the ventilation to be operating before startup, and stops the machine automatically if the doors are opened (Materion SF 201, 2011).
Another work practice that can help reduce exposures is the adjustment of equipment and materials so they are close to the door (which remains sealed during operation) to reduce the extent to which the worker must reach inside.  Handles, trays, and tongs extend the reach without causing the worker to lean toward the open door.
As discussed in the opening paragraphs of the Additional Control Measures subsection of this Short-Term Exposure section, exposure reductions demonstrated for 8-hour TWA sample results likely translate into exposure reductions for short-term samples too.  For additional information, see the discussion on additional controls for machinists (those turning both pure beryllium and beryllium alloy products in Section 7 -- Precision Turned Products of this PEA).
Control Measures for Hot Processes That Generate Fumes
Furnaces typically generate beryllium fumes over an extended period of time (depending on the amount of metal being melted), but worker exposures can be intermittent if workers approach the furnace only occasionally to check the melt or make additions.  Pouring molten beryllium alloys also constitutes an intermittent activity that is sometimes associated with elevated short-term exposures.
Foundries will also need to upgrade LEV on furnaces to improve fume and dust capture and reduce the influence of cross-drafts (CCMA, 2000).  A foundry casting copper-based alloy (CCMA Case History Foundry C) used a horseshoe-shaped slotted hood at the top of the furnace (CCMA, 2000).  This design allows ready access to the molten metal for treatment and dross skimming.  An auxiliary ventilation system would be required to ensure that skimmed dross and the associated scoop would be continually held under exhaust ventilation as they passed between the furnace mouth, the dross receptacle, and the scoop storage area.  At a beryllium alloy foundry where NIOSH found beryllium exposures for nearly all foundry workers to be below 0.5 ug/m[3] (NIOSH EPHB 326-16a), the employer had installed a slotted hood above the furnace in the green sand foundry and a slotted hood with flexible hoses connected to a Hawley Trav-L-Vent system over the crucible to remove fumes during pouring and transport.  In the ingot foundry, the furnace was equipped with both a slotted hood over the furnace pot and a canopy hood with canvas side extensions.  Visual observations indicated that dust and smoke from the melting and casting operations were effectively captured at the LEV openings.  Controls for foundry furnaces are discussed in this PEA at Section 5 -- Nonferrous Foundries.
Control Measures for Dross Handling
Dross handling is a short-term intermittent activity performed routinely in facilities that melt beryllium alloys.  Dross skimming takes several minutes, during which workers are exposed to beryllium fume (from the furnace and hot tools coated with molten metal) and flaking beryllium oxide (develops as the molten dross cools).  Dross receptacles can be fitted with LEV. A beryllium producer designed and installed a ventilated dross collection tray that integrates fume control with furnace-mounted slot hood exhaust ventilation.  The tray extends down to the edge of the furnace slot hood opening; using a skimming tool, the operator places several scoops of dross from the furnace onto the tray.  Dross fumes are collected by both the furnace slot hood and the dross hood.  When the tray is full, the operator activates a control that retracts the dross tray into a ventilated enclosure and dumps the tray contents into a barrel (also under exhaust ventilation) (Corbett, 2005).
A related source of exposure is furnace tools that have come into contact with the molten metal.  Dross skimming rakes, furnace lining rub bars, thermal couples, and degassing wands, used as part of dross handling operations, release fumes as they are removed from the furnace after tasks that bring them in contact with molten metal.  At Materion Corporation's beryllium production facility, furnace operators place the furnace tools in ventilated tool holders after use to capture residual beryllium fumes.  This control method should work equally well for capturing beryllium fumes from furnace tools at beryllium alloy foundries.  Since dross handling and work with the associated tools are short-term tasks, these controls are specifically intended to reduce exposures during these brief activities and prevent an increase in background exposure levels due to beryllium release.  These controls benefit 8-hour TWA exposures and short-term exposures equally when the majority of the worker's daily exposure occurs during short-term activities. These and other controls for dross handling are discussed in this PEA at Section 5 -- Nonferrous Foundries.
Control Measures for Dust-Disturbing Tasks
Dry sweeping and use of compressed air to clean surfaces can contribute to higher beryllium exposures.  The Materion Worker Protection Model calls for rigorous housekeeping (see Methodology Appendix 1 in Section 2 of this PEA for a detailed discussion of the Materion Worker Protection Model).  In facilities with airborne beryllium exposures, housekeeping should be performed routinely and thoroughly to prevent the accumulation of dust that can be spread to other work areas or become airborne if disturbed.  Cleaning should be performed with HEPA vacuums instead of traditional vacuums, and the use of compressed air and dry sweeping should be avoided, as these intermittent activities can all result in high short-term exposures. Eliminating these sources of elevated short-term exposures by switching to HEPA vacuums will reduce workers' short-term exposures.  Wet methods may also be used to clean beryllium contamination instead of dry methods or compressed air.
Control Measures for Friable Beryllium Oxide on Surfaces Being Worked
Loosely adhered oxides of beryllium have also been implicated in overexposures during tasks, such as welding, that otherwise are rarely associated with excessive exposure.  Workers who move materials into position and then work on them can experience short-term exposures during direct handling of these oxide-coated materials.  According to representatives of Materion Corporation, welding fumes could account for just 10 percent of welders' beryllium exposure when welding on beryllium coated with surface oxide.  Flaking oxide may account for 90 percent of the beryllium exposure experienced by a welder and has been implicated in the exposure levels recorded at the Materion Elmore facility (Corbett, 2006; Kent, 2005).  Employers might be able to eliminate the release of loosely adhered oxide by chemically stripping and pickling the beryllium alloy work piece prior to welding on it.  These procedures remove the loose surface oxides and stabilize the surface to prevent additional loosely adhered beryllium oxides from forming (Materion Information Meeting, 2012).  Eliminating the loosely adhered oxides would eliminate this source of exposure for tasks such as handling or transporting materials. For additional information, see Section 10 of this PEA -- Welding.
Control Measures for Grinding and Polishing
While some workers might grind and polish beryllium-containing materials for a substantial portion of their shift, for many others (including dental technicians), grinding and polishing are intermittent short-term activities, interspersed with other activities.  For manual grinding tasks, regardless of the nature of the industry, the primary beryllium producer suggests a booth designed with both backdraft and downdraft exhaust ventilation inside the enclosure (Materion Information Meeting, 2012).  For example, such a booth would include a front opening and rear exhaust, as is available for abrasive cut-off saws (Figure VS-80-17 in ACGIH, 2010), and the downdraft table ventilation of a hand-grinding bench (Figure VS-80-18 in ACGIH, 2010).  An adaptation to provide a rear-slot exhaust (rather than plain rear takeoff) is preferable for hand grinding, which might not occur at a single fixed spot inside the booth.  The booth exhaust should be fitted with a HEPA filter, and special precautions must be used when servicing the booth or blower and changing the filter (e.g., respiratory protection is needed for these tasks). The booth should also be equipped with alarms to indicate when filter performance falls outside an effective range.  These controls are equally effective for short-term intermittent activity and steady-state activity conducted over most of the shift.  Controls for grinding and polishing are discussed in this PEA at Section 5 -- Nonferrous Foundries and Section 11 -- Dental Laboratories.
Feasibility Conclusion