conversely, all six of the workers with CBD had first been exposed to
beryllium at least five years prior to the screening (Schuler et al.,
Table 2).
    As has been seen in other studies, beryllium sensitization and CBD
were found among workers who were typically exposed to low time-
weighted average airborne concentrations of beryllium. While jobs in
the rod and wire area had the highest exposure levels in the plant, the
median personal sample value was only 0.12 [mu]g/m\3\. However, workers
may have occasionally been exposed to higher beryllium levels for short
periods during specific tasks. A small fraction of personal samples
recorded in rod and wire were above the OSHA PEL of 2.0 [mu]g/m\3\, and
half of workers with sensitization or CBD reported that they had
experienced a ``high-exposure incident'' at some point in their work
history (Schuler et al., 2005). The only group of workers with no cases
of sensitization or CBD, a group of 26 office administration workers,
was the group with the lowest recorded exposures (median personal
sample 0.01 [mu]g/m\3\, range <0.01-0.06 [mu]g/m\3\).
    After the BeLPT screening was conducted in 2000, the company began
implementing new measures to further reduce workers' exposure to
beryllium (Thomas et al., 2009). Requirements designed to minimize
dermal contact with beryllium, including long-sleeve facility uniforms
and polymer gloves, were instituted in production areas in 2000. In
2001 the company installed LEV in die grinding and polishing. LP
samples collected between June 2000 and December 2001 show reduced
exposures plant-wide. Of 2,211 exposure samples collected, 98 percent
were below 0.2 [mu]g/m\3\, and 59 percent below the limit of detection
(LOD), which was either 0.02 [micro]g/m\3\ or 0.2 [micro]g/m\3\
depending on the method of sample analysis (Thomas et al., 2009).
Median values below 0.03 [mu]g/m\3\ were reported for all processes
except the wire annealing and pickling process. Samples for this
process remained somewhat elevated, with a median of 0.1 [mu]g/m\3\. In
January 2002, the plant enclosed the wire annealing and pickling
process in a restricted access zone (RAZ), requiring respiratory PPE in
the RAZ and implementing stringent measures to minimize the potential
for skin contact and beryllium transfer out of the zone. While exposure
samples collected by the facility were sparse following the enclosure,
they suggest exposure levels comparable to the 2000-01 samples in areas
other than the RAZ. Within the RAZ, required use of powered air-
purifying respirators indicates that respiratory exposure was
negligible.
    To test the efficacy of the new measures in preventing
sensitization and CBD, in June 2000 the facility began an intensive
BeLPT screening program for all new workers. The company screened
workers at the time of hire; at intervals of 3, 6, 12, 24, and 48
months; and at 3-year intervals thereafter. Among 82 workers hired
after 1999, three (3.7 percent) cases of sensitization were found. Two
(5.4 percent) of 37 workers hired prior to enclosure of the wire
annealing and pickling process were found to be sensitized within 3 and
6 months of beginning work at the plant. One (2.2 percent) of 45
workers hired after the enclosure was confirmed as sensitized.
    Thomas et al. calculated a sensitization IR of 1.9 per 1,000
person-months for the workers hired after the exposure control program
was initiated in 2000 (``program workers''), using the sum of
sensitization-free months of employment among all 82 workers as the
denominator (Thomas et al., 2009). They calculated an estimated IR of
3.8 per 1,000 person-months for 43 workers hired between 1993 and 2000
who had participated in the 2000 BeLPT screening (``legacy workers'').
This estimated IR was based on one BeLPT screening, rather than BeLPTs
conducted throughout the legacy workers' employment. The denominator in
this case is the total months of employment until the 2000 screening.
Because sensitized workers may have been sensitized prior to the
screening, the denominator may overestimate sensitization-free time in
the legacy group, and the actual sensitization IR for legacy workers
may be somewhat higher than 3.8 per 1,000 person-months. Based on
comparison of the IRs and the prevalence rates discussed previously,
the authors concluded that the combination of dermal protection,
respiratory protection, housekeeping improvements and engineering
controls implemented beginning in 2000 appeared to have reduced the
risk of sensitization among workers at the plant. However, they noted
that the small size of the study population and the short follow-up
time for the program workers suggested that further research is needed
to confirm the program's efficacy (Thomas et al., 2009).
    Stanton et al. (2006) conducted a study of workers in three
different copper-beryllium alloy distribution centers in the United
States. The distribution centers, including one bulk products center
established in 1963 and strip metal centers established in 1968 and
1972, sell products received from beryllium production and finishing
facilities and small quantities of copper-beryllium, aluminum-
beryllium, and nickel-beryllium alloy materials. Work at distribution
centers does not require large-scale heat treatment or manipulation of
material typical of beryllium processing and machining plants, but
involves final processing steps that can generate airborne beryllium.
Slitting, the main production activity at the two strip product
distribution centers, generates low levels of airborne beryllium
particles, while operations such as tensioning and welding used more
frequently at the bulk products center can generate somewhat higher
levels. Non-production jobs at all three centers included shipping and
receiving, palletizing and wrapping, production-area administrative
work, and office-area administrative work.
    The authors estimated workers' beryllium exposures using IH data
from company records and job history information collected through
interviews conducted by a company occupational health nurse. Stanton et
al. evaluated airborne beryllium levels in various jobs based on 393
full-shift LP samples collected from 1996 to 2004. Airborne beryllium
levels at the plant were generally very low, with 54 percent of all
samples at or below the LOD, which ranged from 0.02 to 0.1 [mu]g/m\3\.
The authors reported a median of 0.03 [mu]g/m\3\ and an arithmetic mean
of 0.05 [mu]g/m\3\ for the 393 full-shift LP samples, where samples
below the LOD were assigned a value of half the applicable LOD. Median
and geometric mean values for specific jobs ranged from 0.01-0.07 and
0.02-0.07 [micro]g/m\3\, respectively. All measurements were

below the OSHA PEL of 2.0 [mu]g/m\3\ and 97 percent were below the DOE
action level of 0.2 [mu]g/m\3\. The paper does not report use of
respiratory or skin protection. Exposure conditions may have changed
somewhat over the history of the plant due to changes in exposure
control measures, including improvements to product and container
cleaning practices instituted during the 1990s.
    Eighty-eight of the 100 workers (88 percent) employed at the three
centers at the time of the study participated in screening for
beryllium sensitization. Blood samples were collected between November
2000 and March 2001 by the company's medical staff. Samples collected
from employees of the strip metal centers were split and evaluated at
two laboratories, while samples from the bulk product center workers
were evaluated at a single laboratory. Participants were considered to
be ``sensitized'' to beryllium if two or more BeLPT results, from two
laboratories or from repeat testing at the same laboratory, were found
to be abnormal. One individual was found to be sensitized and was
offered clinical evaluation, including BAL and fiberoptic bronchoscopy.
He was found to have lung granulomas and was diagnosed with CBD.
    The worker diagnosed with CBD had been employed at a strip metal
distribution center from 1978 to 2000 as a shipper and receiver,
loading and unloading trucks delivering materials from a beryllium
production facility and to the distribution center's customers.
Although the LP samples collected for his job between 1996 and 2000
were generally low (n = 35, median 0.01, range < 0.02-0.13 [micro]g/
m\3\), it is not clear whether these samples adequately characterize
his exposure conditions over the course of his work history. He
reported that early in his work history, containers of beryllium oxide
powder were transported on the trucks he entered. While he did not
recall seeing any breaks or leaks in the beryllium oxide containers,
some containers were known to have been punctured by forklifts on
trailers used by the company during the period of his employment, and
could have contaminated trucks he entered. With 22 years of employment
at the facility, this worker had begun beryllium-related work earlier
and performed it longer than about 90 percent of the study population
(Stanton et al., 2006).
h. Nuclear Weapons Production Facilities & Cleanup of Former Facilities
    Primary exposure from nuclear weapons production facilities comes
from beryllium metal and beryllium alloys. A study conducted by Kreiss
et al. (1989) documented sensitization and CBD among beryllium-exposed
workers in the nuclear industry. A company medical department
identified 58 workers with beryllium exposure among a work force of
500, of whom 51 (88 percent) participated in the study. Twenty-four
workers were involved in research and development (R&D), while the
remaining 27 were production workers. The R&D workers had a longer
tenure with a mean time from first exposure of 21.2 years, compared to
a mean time since first exposure of 5 years among the production
workers. The number of workers with abnormal BeLPT readings was 6, with
4 being diagnosed with CBD. This resulted in an estimated 11.8 percent
prevalence of sensitization.
    Kreiss et al. (1993) expanded the work of Kreiss et al. (1989) by
performing a cross-sectional study of 895 (current and former)
beryllium workers in the same nuclear weapons plant. Participants were
placed in qualitative exposure groups (``no exposure,'' ``minimal
exposure,'' ``intermittent exposure,'' and ``consistent exposure'')
based on questionnaire responses. The number of workers with abnormal
BeLPT totaled 18 with 12 being diagnosed with CBD. Three additional
workers with sensitization developed CBD over the next 2 years.
Sensitization occurred in all of the qualitatively defined exposure
groups. Individuals who had worked as machinists were statistically
overrepresented among beryllium-sensitized cases, compared with non-
cases. Cases were more likely than non-cases to report having had a
measured overexposure to beryllium (p = 0.009), a factor which proved
to be a significant predictor of sensitization in logistic regression
analyses, as was exposure to beryllium prior to 1970. Beryllium
sensitized cases were also significantly more likely to report having
had cuts that were delayed in healing (p = 0.02). The authors concluded
that individual variability and susceptibility along with exposure
circumstances are important factors in developing beryllium
sensitization and CBD.
    In 1991, the Beryllium Health Surveillance Program (BHSP) was
established at the Rocky Flats Nuclear Weapons Facility to offer BLPT
screening to current and former employees who may have been exposed to
beryllium (Stange et al., 1996). Participants received an initial BeLPT
and follow-ups at one and three years. Based on histologic evidence of
pulmonary granulomas and a positive BAL-BeLPT, Stange et al. published
a study of 4,397 BHSP participants tested from June 1991 to March 1995,
including current employees (42.8 percent) and former employees (57.2
percent). Twenty-nine cases of CBD and 76 cases of sensitization were
identified. The sensitization rate for the population was 2.43 percent.
Available exposure data included fixed airhead (FAH) exposure samples
collected between 1970 and 1988 (mean concentration 0.016 [micro]g/
m\3\) and personal samples collected between 1984 and 1987 (mean
concentration 1.04 [micro]g/m\3\). Cases of CBD and sensitization were
noted in individuals in all jobs classifications, including those
believed to involve minimal exposure to beryllium. The authors
recommended ongoing surveillance for workers in all jobs with potential
for beryllium exposure.
    Stange et al. (2001) extended the previous study, evaluating 5,173
participants in the Rocky Flats BHSP who were tested between June 1991
and December 1997. Three-year serial testing was offered to employees
who had not been tested for three years or more and did not show
beryllium sensitization during the previous study. This resulted in
2,891 employees being tested. Of the 5,173 workers participating in the
study, 172 were found to have abnormal BeLPT. Ninety-eight (3.33
percent) of the workers were found to be sensitized (confirmed abnormal
BeLPT results) in the initial screening, conducted in 1991. Of these
workers 74 were diagnosed with CBD (history of beryllium exposure,
evidence of non-caseating granulomas or mononuclear cell infiltrates on
lung biopsy, and a positive BeLPT or BAL-BeLPT). A follow-up survey of
2,891 workers three years later identified an additional 56 sensitized
workers and an additional seven cases of CBD. Sensitization and CBD
rates were analyzed with respect to gender, building work locations,
and length of employment. Historical employee data included hire date,
termination date, leave of absences, and job title changes. Exposure to
beryllium was determined by job categories and building or work area
codes. Personal beryllium air monitoring results were used, when
available, from employees with the same job title or similar job.
However, no quantitative information was presented in the study. The
authors conclude that for some individuals, exposure to beryllium at
levels less that the OSHA PEL could cause sensitization and CBD.
    Viet et al. (2001) conducted a case-control study of the Rocky
Flats worker population studied by Stange et al. (1996 and 2001) to
examine the relationship between estimated

beryllium exposure level and risk of sensitization or CBD. The worker
population included 74 beryllium-sensitized workers and 50 workers
diagnosed with CBD. Beryllium exposure levels were estimated based on
FAH airhead samples from one building, the beryllium machine shop.
These were collected away from the BZ of the machine operator and
likely underestimated exposure. To estimate levels in other locations,
these air sample concentrations were used to construct a job exposure
matrix that included the determination of the Building 444 exposure
estimates for a 30-year period; each subject's work history by job
location, task, and time period; and assignment of exposure estimates
to each combination of job location, task, and time period as compared
to Building 444 machinists. The authors adjusted the levels observed in
the machine shop by factors based on interviews with former workers.
Workers' estimated mean exposure concentrations ranged from 0.083
[micro]g/m\3\ to 0.622 [micro]g/m\3\. Estimated maximum air
concentrations ranged from 0.54 [micro]g/m\3\ to 36.8 [micro]g/m\3\.
Cases were matched to controls of the same age, race, gender, and
smoking status (Viet et al., 2001).
    Estimated mean and cumulative exposure levels and duration of
employment were found to be significantly higher for CBD cases than for
controls. Estimated mean exposure levels were significantly higher for
sensitization cases than for controls. No significant difference was
observed for estimated cumulative exposure or duration of exposure.
Similar results were found using logistic regression analysis, which
identified statistically significant relationships between CBD and both
cumulative and mean estimated exposure, but did not find significant
relationships between estimated exposure levels and sensitization
without CBD. Comparing CBD with sensitization cases, Viet et al. found
that workers with CBD had significantly higher estimated cumulative and
mean beryllium exposure levels than workers who were sensitized, but
did not have CBD.
    Johnson et al. (2001) conducted a review of personal sampling
records and medical surveillance reports at an atomic weapons
establishment in Cardiff, United Kingdom. The study evaluated airborne
samples collected over the 36-year period of operation for the plant.
Data included 367,757 area samples and 217,681 personal lapel samples
from 194 workers over the time period from 1981-1997. Data was
available prior to this time period but was not analyzed since this
data was not available electronically. The authors estimated that over
the 17 years of measurement data analyzed, airborne beryllium
concentrations did exceed 2.0 [micro]g/m\3\, however, due to the
limitations with regard to collection times it is difficult to assess
the full reliability of this estimate. The authors noted that in the
entire plant's history, only one case of CBD had been diagnosed. It was
also noted that BeLPT has not been routinely conducted among any of the
workers at this facility.
    Armojandi et al. (2010) conducted a cross-sectional study of
workers at a nuclear weapons research and development (R&D) facility to
determine the risk of developing CBD in sensitized workers at
facilities with exposures much lower than production plants. Of the
1875 current or former workers at the R&D facility, 59 were determined
to be sensitized based on at least two positive BeLPTs (i.e., samples
drawn on two separate occasions or on split samples tested in two
separate DOE-approved laboratories) for a sensitization rate of 3.1
percent. Workers found to have positive BeLPTs were further evaluated
in an Occupational Medicine Clinic between 1999 through 2005. Armojandi
et al. (2010) evaluated 50 of the sensitized workers who also had
medical and occupational histories, physical examination, chest imaging
with high-resolution computed tomography (HRCT) (N = 49), and pulmonary
function testing (nine of the 59 workers refused physical examinations
so were not included in this study). Forty of the 50 workers chosen for
this study underwent bronchoscopy for bronchoalveolar lavage and
transbronchial biopsies in additional to the other testing. Five of the
49 workers had CBD at the time of evaluation (based on histology or
high-resolution computed tomography); three others had evidence of
probable CBD; however, none of these cases were classified as severe at
the time of evaluation. The rate of CBD at the time of study among
sensitized individuals was 12.5 percent (5/40) for those using
pathologic review of lung tissue, and 10.2 percent (5/49) for those
using HRCT as a criteria for diagnosis. The rate of CBD among the
entire population (5/1875) was 0.3 percent.
    The mean duration of employment at the facility was 18 years, and
the mean latency period (from first possible exposure) to time of
evaluation and diagnosis was 32 years. There was no available exposure
monitoring in the breathing zone of workers at the facility but the
beryllium levels were believed to be relatively low (possibly less than
0.1 [mu]g/m\3\ for most jobs). There was not an apparent exposure-
response relationship for sensitization or CBD. The sensitization
prevalence was similar and the CBD prevalence higher among workers with
the lower-exposure jobs. The authors concluded that these sensitized
workers, who were subjected to an extended duration of low potential
beryllium exposures over a long latency period, had a low prevalence of
CBD (Armojandi et al., 2010).
i. Aluminum Smelting
    Bauxite ore, the primary source of aluminum, contains naturally
occurring beryllium. Worker exposure to beryllium can occur at aluminum
smelting facilities where aluminum extraction occurs via electrolytic
reduction of aluminum oxide into aluminum metal. Characterization of
beryllium exposures and sensitization prevalence rates were examined by
Taiwo et al. (2010) in a study of nine aluminum smelting facilities
from four different companies in the U.S., Canada, Italy and Norway.
    Of the 3,185 workers determined to be potentially exposed to
beryllium, 1,932 agreed to participate in a medical surveillance
program between 2000 and 2006 (60 percent participation rate). The
medical surveillance program included serum BeLPT analysis,
confirmation of an abnormal BeLPT with a second BeLPT, and follow-up of
all confirmed positive responses by a pulmonary physician to evaluate
for progression to CBD.
    Eight-hour TWAs were assessed utilizing 1,345 personal samples
collected from the 9 smelters. The personal beryllium samples obtained
showed a range of 0.01-13.00 [mu]g/m\3\ time-weighted average with an
arithmetic mean of 0.25 [mu]g/m\3\ and geometric mean of 0.06 [mu]g/
m\3\. Exposure levels to beryllium observed in aluminum smelters are
similar to those seen in other industries that utilize beryllium. Of
the 1,932 workers surveyed by BeLPT, nine workers were diagnosed with
sensitization (prevalence rate of 0.47 percent, 95% confidence interval
= 0.21-0.88 percent) with 2 of these workers diagnosed with probable
CBD after additional medical evaluations.
    The authors concluded that compared with beryllium-exposed workers
in other industries, the rate of sensitization among aluminum smelter
workers appears lower. The authors speculated that this lower observed
rate could be related to a more soluble form of beryllium found in the
aluminum smelting work environment as well as

the consistent use of respiratory protection. However, the authors also
speculated that the 60 percent participation rate may have
underestimated the sensitization rate in this worker population.
    A study by Nilsen et al. (2010) also found a low rate of
sensitization among aluminum workers in Norway. Three-hundred sixty-two
workers and thirty-one control individuals were tested for beryllium
sensitization based on the BeLPT. The results found that one (0.28%) of
the smelter workers had been sensitized. No borderline results were
reported. The exposure estimated in this plant was 0.1 [micro]g/m\3\ to
0.31 [micro]g/m\3\ (Nilsen et al., 2010).
6. Animal Models of CBD
    This section reviews the relevant animal studies supporting the
mechanisms outlined above. Researchers have attempted to identify
animal models with which to further investigate the mechanisms
underlying the development of CBD. A suitable animal model should
exhibit major characteristics of CBD, including the demonstration of a
beryllium-specific immune response, the formation of immune granulomas
following inhalation exposure to beryllium, and mimicking the
progressive nature of the human disease. While exposure to beryllium
has been shown to cause chronic granulomatous inflammation of the lung
in animal studies using a variety of species, most of the granulomatous
lesions were formed by foreign-body reactions, which result from
persistent irritation and consist predominantly of macrophages and
monocytes, and small numbers of lymphocytes. Foreign-body granulomas
are distinct from the immune granulomas of CBD, which are caused by
antigenic stimulation of the immune system and contain large numbers of
lymphocytes. Animal studies have been useful in providing biological
plausibility for the role of immunological alterations and lung
inflammation and in clarifying certain specific mechanistic aspects of
beryllium disease. However, the lack of a dependable animal model that
mimics all facets of the human response combined with study limitations
in terms of single dose experiments, few animals, or abbreviated
observation periods have limited the utility of the data. Currently, no
single model has completely mimicked the disease process as it
progresses in humans. The following is a discussion of the most
relevant animal studies regarding the mechanisms of sensitization and
CBD development in humans. Table A.2 in the Appendix summarizes
species, route, chemical form of beryllium, dose levels, and
pathological findings of the key studies.
    Harmsen et al. performed a study to assess whether the beagle dog
could provide an adequate model for the study of beryllium-induced lung
diseases (Harmsen et al., 1986). One group of dogs served as a control
group (air inhalation only) and four other groups received high
(approximately 50 [mu]g/kg) and low (approximately 20 [mu]g/kg) doses
of beryllium oxide calcined at 500 [deg]C or 1,000[deg] C, administered
as aerosols in a single exposure. As discussed above, calcining
temperature controls the solubility and SSA of beryllium particles.
Those particles calcined at higher temperatures (e.g., 1,000[deg] C)
are less soluble and have lower SSA than particles calcined at lower
temperatures (e.g., 500 [deg]C). Solubility and SSA are factors in
determining the toxic potential of beryllium compounds or materials.
    Cells were collected from the dogs by BAL at 30, 60, 90, 180, and
210 days after exposure, and the percentages of neutrophils and
lymphocytes were determined. In addition, the mitogenic responses of
blood lymphocytes and lavage cells collected at 210 days were
determined with either phytohemagglutinin or beryllium sulfate as
mitogen. The percentage of neutrophils in the lavage fluid was
significantly elevated only at 30 days with exposure to either dose of
500 [deg]C beryllium oxide. The percentage of lymphocytes in the fluid
was significantly elevated in samples across all times with exposure to
the high dose of this beryllium oxide form. Beryllium oxide calcined at
1,000[deg] C elevated lavage lymphocytes only in high dose at 30 days.
No significant effect of 1,000[deg] C beryllium oxide exposure on
mitogenic response of any lymphocytes was seen. In contrast, peripheral
blood lymphocytes from the 500 [deg]C beryllium oxide exposed groups
were significantly stimulated by beryllium sulfate compared with the
phytohemagglutinin exposed cells. The investigators in this study were
able to replicate some of the same findings as those observed in human
studies--specifically, that beryllium in soluble and insoluble forms
can be mitogenic to immune cells, an important finding for progression
of sensitization and proliferation of immune cells to developing full-
blown CBD.
    In another beagle study Haley et al. also found that the beagle dog
appears to model some aspects of human CBD (Haley et al., 1989). The
authors monitored lung pathologic effects, particle clearance, and
immune sensitization of peripheral blood leukocytes following a single
exposure to beryllium oxide aerosol generated from beryllium oxide
calcined at 500 [deg]C or 1,000[deg] C. The aerosol was administered to
the dogs perinasally to attain initial lung burdens of 6 or 18 [mu]g
beryllium/kg body weight. Granulomatous lesions and lung lymphocyte
responses consistent with those observed in humans with CBD were
observed, including perivascular and peribronchiolar infiltrates of
lymphocytes and macrophages, progressing to microgranulomas with areas
of granulomatous pneumonia and interstitial fibrosis. Beryllium
specificity of the immune response was demonstrated by positive results
in the BeLPT, although there was considerable inter-animal variation.
The lesions declined in severity after 64 days post-exposure. Thus,
while this model was able to mimic the formation of Be-specific immune
granulomas, it was not able to mimic the progressive nature of disease.
    This study also provided an opportunity to compare the effects of
beryllium oxide calcination temperature on granulomatous disease in the
beagle respiratory system. Haley et al. found an increase in the
percentage and numbers of lymphocytes in BAL fluid at 3 months post-
exposure in dogs exposed to either dose of beryllium oxide calcined at
500 [deg]C, but not in dogs exposed to the material calcined at the
higher temperature. Although there was considerable inter-animal
variation, lesions were generally more severe in the dogs exposed to
material calcined at 500 [deg]C. Positive BeLPT results were observed
with BAL lymphocytes only in the group with a high initial lung burden
of the material calcined at 500 [deg]C, but positive results with
peripheral blood lymphocytes were observed at both doses with material
calcined at both temperatures.
    The histologic and immunologic responses of canine lungs to
aerosolized beryllium oxide were investigated in another Haley et al.
(1989) study. Beagle-dogs were exposed in a single exposure to high
dose (50 [micro]g/kg of body weight) or low dose (l7 [micro]g/kg)
levels of beryllium oxide calcined at either 500[deg] or 1000[deg] C.
One group of dogs was examined up to 365 days after exposure for lung
histology and biochemical assay to determine the fate of inhaled
beryllium oxide. A second group underwent BAL for lung lymphocyte
analysis for up to 22 months after exposure. Histopathologic
examination revealed peribronchiolar and perivascular lymphocytic
histiocytic

inflammation, peaking at 64 days after beryllium oxide exposure.
Lymphocytes were initially well differentiated, but progressed to
lymphoblastic cells and aggregated in lymphofollicular nodules or
microgranulomas over time. Alveolar macrophages were large, and filled
with intracytoplasmic material. Cortical and paracortical lymphoid
hyperplasia of the tracheobronchial nodes was found. Lung lymphocyte
concentrations were increased at 3 months and returned to normal in
both dose groups given 500 [deg]C treated beryllium chloride. No
significant elevations in lymphocyte concentrations were found in dogs
given 1,000[deg] C treated beryllium oxide. Lung retention was higher
in the 500 [deg]C treated beryllium oxide group. The lesions found in
dog lungs closely resembled those found in humans with CBD: severe
granulomas, lymphoblast transformation, increased pulmonary lymphocyte
concentrations and variation in beryllium sensitivity. It was concluded
that the canine model for berylliosis may provide insight into this
disease.
    In a follow-up experiment, control dogs and those exposed to
beryllium oxide calcined at 500 [deg]C were allowed to rest for 2.5
years, and then re-exposed to filtered air (controls) or beryllium
oxide calcined at 500 [deg]C for an initial lung burden (ILB) target of
50 [mu]g beryllium oxide/kg body weight (Haley et al., 1992). Immune
responses of blood and BAL lymphocytes, and lung lesions in dogs
sacrificed 210 days post-exposure, were compared with results following
the initial exposure. The severity of lung lesions was comparable under
both conditions, suggesting that a 2.5-year interval was sufficient to
prevent cumulative pathologic effects. Conradi et al. (1971) found no
exposure-related histological alterations in the lungs of six beagle
dogs exposed to a range of 3,300-4,380 [mu]g Be/m\3\ as beryllium oxide
calcined at 1,400[deg] C for 30 min, once per month for 3 months.
Because the dogs were sacrificed 2 years post-exposure, the long time
period between exposure and response may have allowed for the reversal
of any beryllium-induced changes (EPA, 1998).
    A 1994 study by Haley et al. showed that intra-bronchiolar
instillation of beryllium induced immune granulomas and sensitization
in monkeys. Haley et al. (1994) exposed male cynomolgus monkeys to
either beryllium metal or beryllium oxide calcined at 500 [deg]C by
intrabronchiolar instillation as a saline suspension. Lymphocyte counts
in BAL fluid were observed, and were found to be significantly
increased in monkeys exposed to beryllium metal on post-exposure days
14 to 90, and on post-exposure day 60 in monkeys exposed to beryllium
oxide. The lungs of monkeys exposed to beryllium metal had lesions
characterized by interstitial fibrosis, Type II cell hyperplasia, and
lymphocyte infiltration. Some monkeys also exhibited immune granulomas.
Similar lesions were observed in monkeys exposed to beryllium oxide,
but the incidence and severity were much less. BAL lymphocytes from
monkeys exposed to beryllium metal, but not from monkeys exposed to
beryllium oxide, proliferated in response to beryllium sulfate in the
BeLPT (EPA, 1998).
    In an experiment similar to the one conducted with dogs, Conradi et
al. (1971) found no effect in monkeys (Macaca irus) exposed via whole-
body inhalation for three 30-minute monthly exposures to a range of
3,300-4,380 [mu]g Be/m\3\ as beryllium oxide calcined at 1,400[deg] C.
The lack of effect may have been related to the long period (2 years)
between exposure and sacrifice, or to low toxicity of beryllium oxide
calcined at such a high temperature.
    As discussed earlier in this Health Effects section, at the
cellular level, beryllium dissolution must occur for either a dendritic
cell or a macrophage to present beryllium as an antigen to induce the
cell-mediated CBD immune reactions (Stefaniak et al., 2006). Several
studies have shown that low-fired beryllium oxide, which is
predominantly made up of poorly crystallized small particles, is more
immunologically reactive than beryllium oxide calcined at higher firing
temperatures that result in less reactivity due to increasing crystal
size. As discussed previously, Haley et al. (1989a) found more severe
lung lesions and a stronger immune response in beagle dogs receiving a
single inhalation exposure to beryllium oxide calcined at 500 [deg]C
than in dogs receiving an equivalent initial lung burden of beryllium
oxide calcined at 1,000[deg] C. Haley et al. found that beryllium oxide
calcined at 1,000[deg] C elicited little local pulmonary immune
response, whereas the much more soluble beryllium oxide calcined at 500
[deg]C produced a beryllium-specific, cell-mediated immune response in
dogs (Haley et al., 1991).
    In a later study, beryllium metal appeared to induce a greater
toxic response than beryllium oxide following intrabronchiolar
instillation in cynomolgus monkeys, as evidenced by more severe lung
lesions, a larger effect on BAL lymphocyte counts, and a positive
response in the BeLPT with BAL lymphocytes only after exposure to
beryllium metal (Haley et al., 1994). Because an oxide layer may form
on beryllium-metal surfaces after exposure to air (Mueller and
Adolphson, 1979; Harmsen et al., 1986) dissolution of small amounts of
poorly soluble beryllium compounds in the lungs might be sufficient to
allow persistent low-level beryllium presentation to the immune system
(NAS, 2008).
    Genetic studies in humans led to the creation of an animal model
containing different human HLA-DP alleles inserted into FVB/N mice for
mechanistic studies of CBD. Three strains of genetically engineered
mice (transgenic mice) were created that conferred different risks for
developing CBD based on human studies (Weston et al., 2005; Snyder et
al., 2008): (1) the HLDPB1*401 transgenic strain, where the transgene
codes for lysine residue at the 69th position of the B-chain conferred
low risk of CBD; (2) the HLA-DPB1*201 mice, where the transgene codes
for glutamic acid residue at the 69th position of the B-chain and
glycine residues at positions 84 and 85 conferred medium risk of CBD;
and (3) the HLA-DPB1*1701 mice, where the transgene codes for glutamic
acid at the 69th position of the B-chain and aspartic acid and glutamic
acid residues at positions 84 and 85, respectively, conferred high risk
of CBD (Tarantino-Hutchinson et al., 2009).
    In order to validate the transgenic model, Tarantino-Hutchison et
al. challenged the transgenic mice along with seven different inbred
mouse strains to determine the susceptibility and sensitivity to
beryllium exposure. Mice were dermally exposed with either saline or
beryllium, then challenged with either saline or beryllium (as
beryllium sulfate) using the MEST protocol (mouse ear-swelling test).
The authors determined that the high risk HLA-DPB1*1701 transgenic
strain responded 4 times greater (as measured via ear swelling) than
control mice and at least 2 times greater than other strains of mice.
The findings correspond to epidemiological study results reporting an
enhanced CBD odds ratio for the HLA-DPB1*1701 in humans (Weston et al.,
2005; Snyder et al., 2008). Transgenic mice with the genes
corresponding to the low and medium odds ratio study did not respond
significantly over the control group. The authors concluded that while
HLA-DPB1*1701 is important to beryllium sensitization and progression
to CBD, other genetic and environmental factors contribute to the
disease process as well.

7. Preliminary Beryllium Sensitization and CBD Conclusions
    It is well-established that skin and inhalation exposure to
beryllium may lead to sensitization and that inhalation exposure, or
skin exposure coupled with inhalation exposure, may lead to the onset
and progression of CBD. This is supported by extensive human studies.
While all facets of the biological mechanism for this complex disease
have yet to be fully elucidated, many of the key events in the disease
sequence have been identified and described in the previous sections.
Sensitization is a necessary first step to the onset of CBD (NAS,
2008). Sensitization is the process by which the immune system
recognizes beryllium as a foreign substance and responds in a manner
that may lead to development of CBD. It has been documented that a
substantial proportion of sensitized workers exposed to airborne
beryllium progress to CBD (Rosenman et al., 2005; NAS, 2008; Mroz et
al., 2009). Animal studies, particularly in dogs and monkeys, have
provided supporting evidence for T-cell lymphocyte proliferation in the
development of granulomatous lung lesions after exposure to beryllium
(Harmsen et al., 1986; Haley et al., 1989, 1992, 1994). The animal
studies have also provided important insights into the roles of
chemical form, genetic susceptibility, and residual lung burden in the
development of beryllium lung disease (Harmsen et al., 1986; Haley et
al., 1992; Tarantino-Hutchison et al., 2009). OSHA has made a
preliminary determination to consider sensitization and CBD to be
adverse events along the pathological continuum in the disease process,
with sensitization being the necessary first step in the progression to
CBD.
    The epidemiological evidence presented in this section demonstrates
that sensitization and CBD are continuing to occur from present-day
exposures below OSHA's PEL (Rosenman, 2005 with erratum published
2006). The available literature discussed above shows that disease
prevalence can be reduced by reducing inhalation exposure (Thomas et
al., 2009). However, the available epidemiological studies also
indicate that it may be necessary to minimize skin exposure to further
reduce the incidence of sensitization (Bailey et al., 2010). The
preliminary risk assessment further discusses the effectiveness of
interventions to reduce beryllium exposures and the risk of
sensitization and CBD (see section VI, Preliminary Risk Assessment).
    Studies have demonstrated there remains a prevalence of
sensitization and CBD in facilities with exposure levels below the
current OSHA PEL (Rosenman et al., 2005; Thomas et al., 2009), that
risk of sensitization and CBD appears to vary across industries and
processes (Deubner et al., 2001; Kreiss et al., 1997; Newman et al.,
2001; Henneberger et al., 2001; Schuler et al., 2005; Stange et al.,
2001; Taiwo et al., 2010), and that efforts to reduce exposure have
succeeded in reducing the frequency of beryllium sensitization and CBD
(Bailey et al., 2010) (See Table A-1 in the Appendix).
    Of workers who were found to be sensitized and underwent clinical
evaluation, 20-49 percent were diagnosed with CBD (Kreiss et al., 1993;
Newman, 1996, 2005 and 2007; Stange et al., 2001). Overall prevalence
of CBD in cross-sectional screenings ranges from 0.6 to 8 percent
(Kreiss et al., 2007). A study by Newman (2005) estimated from ongoing
surveillance of sensitized individuals, with an average follow-up time
of 6 years, that 31 percent of beryllium-exposed employees progressed
to CBD (Newman, 2005). However, Newman (2005) went on to suggest that
if follow-up times were increased the rate of progression from
sensitization to CBD could be much higher. A study of nuclear weapons
facility employees enrolled in an ongoing medical surveillance program
found that only about 20 percent of sensitized individuals employed
less than five years eventually were diagnosed with CBD, while 40
percent of sensitized employees employed ten years or more developed
CBD (Stange et al., 2001) indicating length of exposure may play a role
in further development of the disease. In addition, Mroz et al. (2009)
conducted a longitudinal study of individuals clinically evaluated at
National Jewish Health (between 1982 and 2002) who were identified as
having sensitization and CBD through workforce medical surveillance.
The authors identified 171 cases of CBD and 229 cases of sensitization;
all individuals were identified through workplace screening using the
BeLPT (Mroz et al., 2009). Over the 20-year study period, 8.8 percent
(i.e., 22 cases out 251 sensitized) of individuals with sensitization
went on to develop CBD. The findings from this study indicated that on
the average span of time from initial beryllium exposure to CBD
diagnosis was 24 years (Mroz et al., 2009).

E. Beryllium Lung Cancer Section

    Beryllium exposure has been associated with a variety of adverse
health effects including lung cancer. The potential for beryllium and
its compounds to cause cancer has been previously assessed by various
other agencies (EPA, ATSDR, NAS, NIEHS, and NIOSH) with each agency
identifying beryllium as a potential carcinogen. In addition, the
International Agency for Research on Cancer (IARC) did an extensive
evaluation in 1993 and reevaluation in April 2009 (IARC, 2012). In
brief, IARC determined beryllium and its compounds to be carcinogenic
to humans (Group 1 category), while EPA considers beryllium to be a
probable human carcinogen (EPA, 1998), and the National Toxicology
Program (NTP) has determined beryllium and its compounds to be known
carcinogens (NTP, 2014). OSHA has conducted an independent evaluation
of the carcinogenic potential of beryllium and these compounds as well.
The following is a summary of the studies used to support the Agency
findings that beryllium and its compounds are human carcinogens.
1. Genotoxicity Studies
    Genotoxicity can be an important indicator for screening the
potential of a material to induce cancer and an important mechanism
leading to tumor formation and carcinogenesis. In a review conducted by
the National Academy of Science, beryllium and its compounds have
tested positively in nearly 50 percent of the genotoxicity studies
conducted without exogenous metabolic activity. However, they were
found to be non-genotoxic in most bacterial assays (NAS, 2008).
    Gene mutations have been observed in mammalian cells cultured with
beryllium chloride in a limited number of studies (EPA, 1998; ATSDR,
2002; Gordon and Bowser, 2003). Culturing mammalian cells with
beryllium chloride, beryllium sulfate, or beryllium nitrate has
resulted in clastogenic alterations. However, most studies have found
that beryllium chloride, beryllium nitrate, beryllium sulfate, and
beryllium oxide did not induce gene mutations in bacterial assays with
or without metabolic activation. In the case of beryllium sulfate, all
mutagenicity studies (Ames (Simmon, 1979; Dunkel et al., 1984;
Arlauskas et al., 1985; Ashby et al., 1990); E. coli pol A (Rosenkranz
and Poirer, 1979); E. coli WP2 uvr A (Dunkel et al., 1984) and
Saccharomyces cerevisiae (Simmon, 1979)) were negative with the
exception of results reported for Bacillus subtilis rec assay (Kada et
al., 1980; Kanematsu et al., 1980; EPA, 1998). Beryllium sulfate did
not induce unscheduled

DNA synthesis in primary rat hepatocytes and was not mutagenic when
injected intraperitoneally in adult mice in a host-mediated assay using
Salmonella typhimurium (Williams et al., 1982).
    Beryllium nitrate was negative in the Ames assay (Tso and Fung,
1981; Kuroda et al., 1991) but positive in a Bacillus subtilis rec
assay (Kuroda et al., 1991). Beryllium chloride was negative in a
variety of studies (Ames (Ogawa et al., 1987; Kuroda et al., 1991); E.
coli WP2 uvr A (Rossman and Molina, 1984); and Bacillus subtilis rec
assay (Nishioka, 1975)). In addition, beryllium chloride failed to
induce SOS DNA repair in E. coli (Rossman et al., 1984). However,
positive results were reported for Bacillus subtilis rec assay using
spores (Kuroda et al., 1991), E. coli KMBL 3835; lacI gene (Zakour and
Glickman, 1984), and hprt locus in Chinese hamster lung V79 cells
(Miyaki et al., 1979). Beryllium oxide was negative in the Ames assay
and Bacillus subtilis rec assays (Kuroda et al., 1991; EPA, 1998).
    Gene mutations have been observed in mammalian cells (V79 and CHO)
cultured with beryllium chloride (Miyaki et al., 1979; Hsie et al.,
1979a, b), and culturing of mammalian cells with beryllium chloride
(Vegni-Talluri and Guiggiani, 1967), and beryllium sulfate (Brooks et
al., 1989; Larramendy et al., 1981) has resulted in clastogenic
alterations--producing breakage or disrupting chromosomes (EPA, 1998).
Beryllium chloride evaluated in a mouse model indicated increased DNA
strand breaks and the formation of micronuclei in bone marrow (Attia et
al., 2013).
    Data on the in vivo genotoxicity of beryllium are limited to a
single study that found beryllium sulfate (1.4 and 2.3 g/kg, 50 percent
and 80 percent of median lethal dose) administered by gavage did not
induce micronuclei in the bone marrow of CBA mice. However, a marked
depression of erythropoiesis (red blood cell production) was suggestive
of bone marrow toxicity which was evident 24 hours after dosing. No
mutations were seen in p53 or c-raf-1 and only weak mutations were
detected in K-ras in lung carcinomas from F344/N rats given a single
nose-only exposure to beryllium metal (Nickell-Brady et al., 1994). The
authors concluded that the mechanisms for the development of lung
carcinomas from inhaled beryllium in the rat do not involve gene
dysfunctions commonly associated with human non-small-cell lung cancer
(EPA, 1998).
2. Human Epidemiological Studies
    This section reviews in greater detail the studies used to support
the mechanistic findings for beryllium-induced cancer. Table A.3 in the
Appendix summarizes the important features and characteristics of each
study.
    a. Beryllium Case Registry (BCR).
    Two studies evaluated participants in the BCR (Infante et al.,
1980; Steenland and Ward, 1991). Infante et al. (1980) evaluated the
mortality patterns of white male participants in the BCR diagnosed with
non-neoplastic respiratory symptoms of beryllium disease. Of the 421
cases evaluated, 7 of the participants had died of lung cancer. Six of
the deaths occurred more than 15 years after initial beryllium
exposure. The duration of exposure for 5 of the 7 participants with
lung cancer was less than 1 year, with the time since initial exposure
ranging from 12 to 29 years. One of the participants was exposed for 4
years with a 26-year interval since the initial exposure. Exposure
duration for one participant diagnosed with pulmonary fibrosis could
not be determined; however, it had been 32 years since the initial
exposure. Based on BCR records, the participants were classified as
being in the acute respiratory group (i.e., those diagnosed with acute
respiratory illness at the time of entry in the registry) or the
chronic respiratory group (i.e., those diagnosed with pulmonary
fibrosis or some other chronic lung condition at the time of entry into
the BCR). The 7 participants with lung cancer were in the BCR because
of diagnoses of acute respiratory illness. For only one of those
individuals was initial beryllium exposure less than 15 years prior.
Only 1 of the 6 (with greater than 15 years since initial exposure to
beryllium) had been diagnosed with chronic respiratory disease. The
study did not report exposure concentrations or smoking habits. The
authors concluded that the results of this cohort agreed with previous
animal studies and with epidemiological studies demonstrating an
increased risk of lung cancer in workers exposed to beryllium.
    Steenland and Ward (1991) extended the work of Infante et al.
(1980) to include females and to include 13 additional years of follow-
up. At the time of entry in the BCR, 93 percent of the women in the
study, but only 50 percent of the men, had been diagnosed with CBD. In
addition, 61 percent of the women had worked in the fluorescent tube
industry and 50 percent of the men had worked in the basic
manufacturing industry. A total of 22 males and 6 females died of lung
cancer. Of the 28 total deaths from lung cancer, 17 had been exposed to
beryllium for less than 4 years and 11 had been exposed for greater
than 4 years. The study did not report exposure concentrations. Survey
data collected in 1965 provided information on smoking habits for 223
cohort members (32 percent), on the basis of which the authors
suggested that the rate of smoking among workers in the cohort may have
been lower than U.S. rates. The authors concluded that there was
evidence of increased risk of lung cancer in workers exposed to
beryllium and diagnosed with beryllium disease.
b. Beryllium Manufacturing and/or Processing Plants (Extraction,
Fabrication, and Processing)
    Several epidemiological cohort studies have reported excess lung
cancer mortality among workers employed in U.S. beryllium production
and processing plants during the 1930s to 1960s. The largest and most
comprehensive study investigated the mortality experience of 9,225
workers employed in seven different beryllium processing plants over a
30-year period (Ward et al., 1992). The workers at the two oldest
facilities (i.e., Lorain, OH, and Reading, PA) were found to have
significant excess lung cancer mortality relative to the U.S.
population. Of the seven plants in the study, these two plants were
believed to have the highest exposure levels to beryllium. A different
analysis of the lung cancer mortality in this cohort using various
local reference populations and alternate adjustments for smoking
generally found smaller, non-significant rates of excess mortality
among the beryllium employees (Levy et al., 2002). Both cohort studies
are limited by a lack of job history and air monitoring data that would
allow investigation of mortality trends with beryllium exposure. The
majority of employees at the Lorain, OH, and Reading, PA, facilities
were employed for a relatively short period of less than one year.
    Bayliss et al. (1971) performed a nested cohort study of more than
7,000 former workers from the beryllium processing industry employed
from 1942-1967. Information for the workers was collected from the
personnel files of participating companies. Of the more than 7,000
employees, a cause of death was known for 753 male workers. The number
of observed lung cancer deaths was 36 compared to 34.06 expected for a
standardized mortality ratio (SMR) of 1.06. When evaluated by the
number of years of employment, 24 of the 36 men were employed for less
than 1 year in

the industry (SMR = 1.24), 8 were employed for 1 to 5 years (SMR 1.40),
and 4 were employed for more than 5 years (SMR = 0.54). Half of the
workers who died from lung cancer began employment in the beryllium
production industry prior to 1947. When grouped by job classification,
over two thirds of the workers with lung cancer were in production-
related jobs while the rest were classified as office workers. The
authors concluded that while the lung cancer mortality rates were the
highest of all other mortality rates, the SMR for lung cancer was still
within range of the expected based on death rates in the United States.
The limitations of this study included the lack of information
regarding exposure concentrations, smoking habits, and the age and race
of the participants.
    Mancuso (1970, 1979, 1980) and Mancuso and El-Attar (1969)
performed a series of occupational cohort studies on a group of over
3,685 workers (primarily white males) employed in the beryllium
manufacturing industry during 1937-1948.\3\ The beryllium production
facilities were located in Ohio and Pennsylvania and the records for
the employees, including periods of employment, were obtained from the
Social Security Administration. These studies did not include analyses
of mortality by job title or exposure category. In addition, there were
no exposure concentrations estimated or adjustments for smoking. The
estimated duration of employment ranged from less than 1 year to
greater than 5 years. In the most recent study (Mancuso, 1980),
employees from the viscose rayon industry served as a comparison
population. There was a significant excess of lung cancer deaths based
on the total number of 80 observed lung cancer mortalities at the end
of 1976 compared to an expected number of 57.06 based on the comparison
population resulting in an SMR of 1.40 (p < 0.01) (Mancuso, 1980).
There was a statistically significant excess in lung cancer deaths for
the shortest duration of employment (< 12 months, p < 0.05) and the
longest duration of employment (> 49 months, p < 0.01). Based on the
results of this study, the author concluded that the ability of
beryllium to induce cancer in workers does not require continuous
exposure and that it is reasonable to assume that the amount of
exposure required to produce lung cancer can occur within a few months
of exposure regardless of the length of employment.
---------------------------------------------------------------------------

    \3\ The third study (Mancuso et al., 1979) restricted the cohort
to workers employed between 1942 and 1948.
---------------------------------------------------------------------------

    Wagoner et al. (1980) expanded the work of Mancuso (1970; 1979;
1980) using a cohort of 3,055 white males from the beryllium
extraction, processing, and fabrication facility located in Reading,
Pennsylvania. The men included in the study worked at the facility
sometime between 1942 and 1968, and were followed through 1976. The
study accounted for length of employment. Other factors accounted for
included age, smoking history, and regional lung cancer mortality.
Forty-seven members of the cohort died of lung cancer compared to an
expected 34.29 based on U.S. white male lung cancer mortality rates (p
< .05). The results of this cohort showed an excess risk of lung cancer
in beryllium-exposed workers at each duration of employment (< 5 years
and >= 5 years), with a statistically significant excess noted at < 5
years durations of employment and a >= 25-year interval since the
beginning of employment (p < 0.05). The study was criticized by several
epidemiologists (MacMahon, 1978, 1979; Roth, 1983), by a CDC Review
Committee appointed to evaluate the study, and by one of the study's
coauthors (Bayliss, 1980) for inadequate discussion of possible
alternative explanations of excess lung cancer in the cohort. The
specific issues identified include the use of 1965-1967 U.S. white male
lung cancer mortality rates to generate expected numbers of lung
cancers in the period 1968-1975 and inadequate adjustment for smoking.
    Ward et al. (1992) performed a retrospective mortality cohort study
of 9,225 male workers employed at seven beryllium processing
facilities, including the Ohio and Pennsylvania facilities studied by
Mancuso and El-Attar (1969), Mancuso (1970; 1979; 1980), and Wagoner et
al. (1980). The men were employed for no less than 2 days between
January 1940 and December 1988. At the end of the study 61.1 percent of
the cohort was known to be living and 35.1 percent was known to be
deceased. The duration of employment ranged from 1 year or less to
greater than 10 years with the largest percentage of the cohort (49.7
percent) employed for less than one year, followed by 1 to 5 years of
employment (23.4 percent), greater than 10 years (19.1 percent), and 5
to 10 years (7.9 percent). Of the 3,240 deaths, 280 observed deaths
were caused by lung cancer compared to 221.5 expected deaths, yielding
a statistically significant SMR of 1.26 (p < 0.01). Information on the
smoking habits of 15.9 percent of the cohort members, obtained from a
1968 Public Health Service survey conducted at four of the plants, was
used to calculate a smoking-adjusted SMR of 1.12, which was not
statistically significant. The number of deaths from lung cancer was
also examined by decade of hire. The authors reported a relationship
between earlier decades of hire and increased lung cancer risk.
    The EPA Integrated Risk Information System (IRIS), IARC, and
California EPA Office of Environmental Health Hazard Assessment (OEHHA)
have all based their cancer assessment on the Ward et al. 1992 study,
with supporting data concerning exposure concentrations from Eisenbud
and Lisson (1983) and NIOSH (1972), who estimated that the lower-bound
estimate of the median exposure concentration exceeded 100 [micro]g/
m\3\ and found that concentrations in excess of 1,000 [micro]g/m\3\
were common. The IRIS cancer risk assessment recalculated expected lung
cancers based on U.S. white male lung cancer rates (including the
period 1968-1975) and used an alternative adjustment for smoking. In
addition, one individual with lung cancer, who had not worked at the
plant, was removed from the cohort. After these adjustments were made,
an elevated rate of lung cancer was still observed in the overall
cohort (46 cases vs. 41.9 expected cases). However, based on duration
of employment or interval since beginning of employment, neither the
total cohort nor any of the subgroups had a statistically significant
excess in lung cancer (EPA, 1987). Based on their evaluation of this
and other epidemiological studies, the EPA characterized the human
carcinogenicity data then available as ``limited'' but ``suggestive of
a causal relationship between beryllium exposure and an increased risk
of lung cancer'' (IRIS database). This report includes quantitative
estimates of risk that were derived using the information presented in
Wagoner et al. (1980), the expected lung cancers recalculated by the
EPA, and bounds on presumed exposure levels.
    Levy et al. (2002) questioned the results of Ward et al. (1992) and
performed a reanalysis of the Ward et al. data. The Levy et al.
reanalysis differed from the Ward et al. analysis in the following
significant ways. First, Levy et al. (2002) examined two alternative
adjustments for smoking, which were based on (1) a different analysis
of the American Cancer Society (ACS) data used by Ward et al. (1992)
for their smoking adjustment, or (2) results from a smoking/lung cancer
study of veterans (Levy and Marimont, 1998). Second, Levy et al. (2002)
also examined the

impact of computing different reference rates derived from information
about the lung cancer rates in the cities in which most of the workers
at two of the plants lived. Finally, Levy et al. (2002) considered a
meta-analytical approach to combining the results across beryllium
facilities. For all of the alternatives Levy et al. (2002) considered,
except the meta-analysis, the facility-specific and combined SMRs
derived were lower than those reported by Ward et al. (1992). Only the
SMR for the Lorain, OH, facility remained statistically significantly
elevated in some reanalyses. The SMR obtained when combining over the
plants was not statistically significant in eight of the nine
approaches they examined, leading Levy et al. (2002) to conclude that
there was little evidence of statistically significant elevated SMRs in
those plants.
    One occupational nested case-control study evaluated lung cancer
mortality in a cohort of 3,569 male workers employed at a beryllium
alloy production plant in Reading, PA, from 1940 to 1969 and followed
through 1992 (Sanderson et al., 2001). There were a total of 142 known
lung cancer cases and 710 controls. For each lung cancer death, 5 age-
and race-matched controls were selected by incidence density sampling.
Confounding effects of smoking were evaluated. Job history and
historical air measurements at the plant were used to estimate job-
specific beryllium exposures from the 1930s to 1990s. Calendar-time-
specific beryllium exposure estimates were made for every job and used
to estimate workers' cumulative, average, and maximum exposure. Because
of the long period of time required for the onset of lung cancer, an
``exposure lag'' was employed to discount recent exposures less likely
to contribute to the disease.
    The cumulative, average, and maximum beryllium exposure
concentration estimates for the 142 known lung cancer cases were 46.06
 9.3[micro]g/m\3\-days, 22.8  3.4 [micro]g/
m\3\, and 32.4  13.8 [micro]g/m\3\, respectively. The lung
cancer mortality rate was 1.22 (95 percent CI = 1.03 - 1.43). Exposure
estimates were lagged by 10 and 20 years in order to account for
exposures that did not contribute to lung cancer because they occurred
after the induction of cancer. In the 10- and 20-year lagged exposures
the geometric mean tenures and cumulative exposures of the lung cancer
mortality cases were higher than the controls. In addition, the
geometric mean and maximum exposures of the workers were significantly
higher than controls when the exposure estimates were lagged 10 and 20
years (p < 0.01).
    Results of a conditional logistic regression analysis indicated
that there was an increased risk of lung cancer in workers with higher
exposures when dose estimates were lagged by 10 and 20 years. There was
also a lack of evidence that confounding factors such as smoking
affected the results of the regression analysis. The authors noted that
there was considerable uncertainty in the estimation of exposure in the
1940's and 1950's and the shape of the dose-response curve for lung
cancer. Another analysis of the study data using a different
statistical method did not find a significantly greater relative risk
of lung cancer with increasing beryllium exposures (Levy et al., 2007).
The average beryllium air levels for the lung cancer cases were
estimated to be an order of magnitude above the current 8-hour OSHA TWA
PEL (2 [mu]g/m\3\) and roughly two orders of magnitude higher than the
typical air levels in workplaces where beryllium sensitization and
pathological evidence of CBD have been observed. IARC evaluated this
reanalysis in 2012 and found the study introduced a downward bias into
risk estimates (IARC, 2012).
    Schubauer-Berigan et al. reanalyzed data from the nested case-
control study of 142 lung cancer cases in the Reading, PA, beryllium
processing plant (Schubauer-Berigan et al., 2008). This dataset was
reanalyzed using conditional (stratified by case age) logistic
regression. Independent adjustments were made for potential confounders
of birth year and hire age. Average and cumulative exposures were
analyzed using the values reported in the original study. The objective
of the reanalysis was to correct for the known differences in smoking
rates by birth year. In addition, the authors evaluated the effects of
age at hire to determine differences observed by Sanderson et al. in
2001. The effect of birth cohort adjustment on lung cancer rates in
beryllium-exposed workers was evaluated by adjusting in a multivariable
model for indicator variables for the birth cohort quartiles.
    Unadjusted analyses showed little evidence of lung cancer risk
associated with beryllium occupational exposure using cumulative
exposure until a 20-year lag was used. Adjusting for either birth
cohort or hire age attenuated the risk for lung cancer associated with
cumulative exposure. Using a 10- or 20-year lag in workers born after
1900 also showed little evidence of lung cancer risk, while those born
prior to 1900 did show a slight elevation in risk. Unlagged and lagged
analysis for average exposure showed an increase in lung cancer risk
associated with occupational exposure to beryllium. The finding was
consistent for either workers adjusted or unadjusted for birth cohort
or hire age. Using a 10-year lag for average exposure showed a
significant effect by birth cohort.
    The authors stated that the reanalysis indicated that differences
in the hire ages among cases and controls, first noted by Deubner et
al. (2001) and Levy et al. (2007), were primarily due to the fact that
birth years were earlier among controls than among cases, resulting
from much lower baseline risk of lung cancer for men born prior to 1900
(Schubauer-Berigan et al., 2008). The authors went on to state that the
reanalysis of the previous NIOSH case-control study suggested the
relationship observed previously between cumulative beryllium exposure
and lung cancer was greatly attenuated by birth cohort adjustment.
    Hollins et al. (2009) re-examined the weight of evidence of
beryllium as a lung carcinogen in a recent publication (Hollins et al.,
2009). Citing more than 50 relevant papers, the authors noted the
methodological shortcomings examined above, including lack of well-
characterized historical occupational exposures and inadequacy of the
availability of smoking history for workers. They concluded that the
increase in potential risk of lung cancer was observed among those
exposed to very high levels of beryllium and that beryllium's
carcinogenic potential in humans at these very high exposure levels
were not relevant to today's industrial settings. IARC performed a
similar re-evaluation in 2009 (IARC, 2012) and found that the weight of
evidence for beryllium lung carcinogenicity, including the animal
studies described below, still warranted a Group I classification, and
that beryllium should be considered carcinogenic to humans.
    Schubauer-Berigan et al. (2010) extended their analysis from a
previous study estimating associations between mortality risk and
beryllium exposure to include workers at 7 beryllium processing plants.
The study (Schubauer-Berigan et al., 2010) followed the mortality
incidences of 9,199 workers from 1940 through 2005 at the 7 beryllium
plants. JEMs were developed for three plants in the cohort: The Reading
plant, the Hazleton plant, and the Elmore plant. The last is described
in Couch et al. 2010. Including these JEMs substantially improved the
evidence base for evaluating the carcinogenicity of beryllium and, and
this change

represents more than an update of the beryllium cohort. Standardized
mortality ratios (SMRs) were estimated based on US population
comparisons for lung, nervous system and urinary tract cancers, chronic
obstructive pulmonary disease (COPD), chronic kidney disease, and
categories containing chronic beryllium disease (CBD) and cor
pulmonale. Associations with maximum and cumulative exposure were
calculated for a subset of the workers.
    Overall mortality in the cohort compared with the US population was
elevated for lung cancer (SMR 1.17; 95% CI 1.08 to 1.28), COPD (SMR
1.23; 95% CI 1.13 to 1.32), and the categories containing CBD (SMR
7.80; 95% CI 6.26 to 9.60) and cor pulmonale (SMR 1.17; 95% CI 1.08 to
1.26). Mortality rates for most diseases of interest increased with
time-since-hire. For the category including CBD, rates were
substantially elevated compared to the US population across all
exposure groups. Workers whose maximum beryllium exposure was >= 10
[mu]g/m\3\ had higher rates of lung cancer, urinary tract cancer, COPD
and the category containing cor pulmonale than workers with lower
exposure. These studies showed strong associations for cumulative
exposure (when short-term workers were excluded), maximum exposure or
both. Significant positive trends with cumulative exposure were
observed for nervous system cancers (p = 0.0006) and, when short-term
workers were excluded, lung cancer (p = 0.01), urinary tract cancer (p
= 0.003) and COPD (p < 0.0001).
    The authors concluded the findings from this reanalysis reaffirmed
that lung cancer and CBD are related to beryllium exposure. The authors
went on to suggest that beryllium exposures may be associated with
nervous system and urinary tract cancers and that cigarette smoking and
other lung carcinogens were unlikely to explain the increased
incidences in these cancers. The study corrected an error that was
discovered in the indirect smoking adjustment initially conducted by
Ward et al., concluding that cigarette smoking rates did not differ
between the cohort and the general U.S. population. No association was
found between cigarette smoking and either cumulative or maximum
beryllium exposure, making it very unlikely that smoking was a
substantial confounder in this study (Schubauer-Berigan et al., 2010).
3. Animal Cancer Studies
    This section reviews the animal literature used to support the
findings for beryllium-induced lung cancer. Lung tumors have been
induced via inhalation and intratracheal administration of beryllium to
rats and monkeys, and osteosarcomas have been induced via intravenous
and intramedullary (inside the bone) injection of beryllium in rabbits
and possibly in mice. The chronic oral studies did not report increased
incidences of tumors in rodents, but these were conducted at doses
below the maximum tolerated dose (MTD) (EPA, 1998).
    Early animal studies revealed that some beryllium compounds are
carcinogenic when inhaled (ATSDR, 2002). Animal experiments have shown
consistent increases in lung cancers in rats, mice and rabbits
chronically exposed to beryllium and beryllium compounds by inhalation
or intratracheal instillation. In addition to lung cancer,
osteosarcomas have been produced in mice and rabbits exposed to various
beryllium salts by intravenous injection or implantation into the bone
(NTP, 1999).
    In an inhalation study assessing the potential tumorigenicity of
beryllium, Schepers et al. (1957) exposed 115 albino Sherman and Wistar
rats (male and female) via inhalation to 0.0357 mg beryllium/m\3\ (1
[gamma] beryllium/ft\3\) \4\ as an aqueous aerosol of beryllium sulfate
for 44 hours/week for 6 months, and observed the rats for 18 months
after exposure. Three to four control rats were killed every two months
for comparison purposes. Seventy-six lung neoplasms, \5\ including
adenomas, squamous-cell carcinomas, acinous adenocarcinomas, papillary
adenocarcinomas, and alveolar-cell adenocarcinomas, were observed in 52
rats exposed to beryllium sulfate aerosol. Adenocarcinomata were the
most numerous. Pulmonary metastases tended to localize in areas with
foam cell clustering and granulomatosis. No neoplasia was observed in
any of the control rats. The incidence of lung tumors in exposed rats
is presented in the following Table 2:
---------------------------------------------------------------------------

    \4\ Schepers et al. (1957) reported concentrations in [gamma]
Be/ft\3\; however, [gamma]/ft\3\ is no longer a common unit.
Therefore, the concentration was converted to mg/m\3\.
    \5\ While a total of 89 tumors were observed or palpated at the
time of autopsy in the BeSO4-exposed animals, only 76
tumors are listed as histologically neoplastic. Only the new growths
identified in single midcoronal sections of both lungs were
recorded.

                       Table 2--Neoplasm Analysis
------------------------------------------------------------------------
                     Neoplasm                       Number    Metastases
------------------------------------------------------------------------
Adenoma..........................................        18
Squamous carcinoma...............................         5            1
Acinous adenocarcinoma...........................        24            2
Papillary adenocarcinoma.........................        11            1
Alveolar-cell adenocarcinoma.....................         7
Mucigenous tumor.................................         7            1
Endothelioma.....................................         1
Retesarcoma......................................         3            3
                                                  ----------------------
  Total..........................................        76            8
------------------------------------------------------------------------

    Schepers (1962) reviewed 38 existing beryllium studies that
evaluated seven beryllium compounds and seven mammalian species.
Beryllium sulfate, beryllium fluoride, beryllium phosphate, beryllium
alloy (BeZnMnSiO4), and beryllium oxide were proven to be
carcinogenic and have remarkable pleomorphic neoplasiogenic
proclivities. Ten varieties of tumors were observed, with
adenocarcinoma being the most common variety.
    In another study, Vorwald and Reeves (1959) exposed Sherman albino
rats via the inhalation route to aerosols of 0.006 mg beryllium/m\3\ as
beryllium oxide and 0.0547 mg beryllium/m\3\ as beryllium sulfate for 6
hours/day, 5 days/week for an unspecified duration. Lung tumors (single
or multifocal) were observed in the animals sacrificed following 9
months of daily inhalation exposure. The histologic pattern of the
cancer was primarily adenomatous; however, epidermoid and squamous cell
cancers were also observed. Infiltrative, vascular, and lymphogenous
extensions often developed with secondary metastatic growth in the
tracheobronchial lymph nodes, the mediastinal connective tissue, the
parietal pleura, and the diaphragm.
    In the first of two articles, Reeves et al. (1967a) investigated
the carcinogenic process in lungs resulting from chronic (up to 72
weeks) beryllium sulfate inhalation. One hundred fifty male and female
Sprague Dawley C.D. strain rats were exposed to beryllium sulfate
aerosol at a mean atmospheric concentration of 34.25 [mu]g beryllium/
m\3\ (with an average particle diameter of 0.12 [micro]m). Prior to
initial exposure and again during the 67-68 and 75-76 weeks of life,
the animals received prophylactic treatments of tetracycline-HCl to
combat recurrent pulmonary infections.
    The animals entered the exposure chamber at 6 weeks of age and were

exposed 7 hours per day/5 days per week for up to 2,400 hours of total
exposure time. An equal number of unexposed controls were held in a
separate chamber. Three male and three female rats were sacrificed
monthly during the 72-week exposure period. Mortality due to
respiratory or other infections did not appear until 55 weeks of age,
and 87 percent of all animals survived until their scheduled
sacrifices.
    Average lung weight towards the end of exposure was 4.25 times
normal with progressively increasing differences between control and
exposed animals. The increase in lung weight was accompanied by notable
changes in tissue texture with two distinct pathological processes--
inflammatory and proliferative. The inflammatory response was
characterized by marked accumulation of histiocytic elements forming
clusters of macrophages in the alveolar spaces. The proliferative
response progressed from early epithelial hyperplasia of the alveolar
surfaces, through metaplasia (after 20-22 weeks of exposure), anaplasia
(cellular dedifferentiation) (after 32-40 weeks of exposure), and
finally to lung tumors.
    Although the initial proliferative response occurred early in the
exposure period, tumor development required considerable time. Tumors
were first identified after nine months of beryllium sulfate exposure,
with rapidly increasing rates of incidence until tumors were observed
in 100 percent of exposed animals by 13 months. The 9-to-13-month
interval is consistent with earlier studies. The tumors showed a high
degree of local invasiveness. No tumors were observed in control rats.
All 56 tumors studied appeared to be alveolar adenocarcinomas and 3
``fast-growing'' tumors that reached a very large size comparatively
early. About one-third of the tumors showed small foci where the
histologic pattern differed. Most of the early tumor foci appeared to
be alveolar rather than bronchiolar, which is consistent with the
expected pathogenesis, since permanent deposition of beryllium was more
likely on the alveolar epithelium rather than on the bronchiolar
epithelium. Female rats appeared to have an increased susceptibility to
beryllium exposure. Not only did they have a higher mortality (control
males [n = 8], exposed males [n = 9] versus control females [n = 4],
exposed females [n = 17]) and body weight loss than male rats, but the
three ``fast-growing'' tumors only occurred in females.
    In the second article, Reeves et al. (1967b) described the rate of
accumulation and clearance of beryllium sulfate aerosol from the same
experiment (Reeves et al., 1967a). At the time of the monthly
sacrifice, beryllium assays were performed on the lungs,
tracheobronchial lymph nodes, and blood of the exposed rats. The
pulmonary beryllium levels of rats showed a rate of accumulation which
decreased during continuing exposure and reached a plateau (defined as
equilibrium between deposition and clearance) of about 13.5 [mu]g
beryllium for males and 9 [mu]g beryllium for females in whole lungs
after approximately 36 weeks. Females were notably less efficient than
males in utilizing the lymphatic route as a method of clearance,
resulting in slower removal of pulmonary beryllium deposits, lower
accumulation of the inhaled material in the tracheobronchial lymph
nodes, and higher morbidity and mortality.
    There was no apparent correlation between the extent and severity
of pulmonary pathology and total lung load. However, when the beryllium
content of the excised tumors was compared with that of surrounding
nonmalignant pulmonary tissues, the former showed a notable decrease
(0.50  0.35 [mu]g beryllium/gram versus 1.50
0.55 [mu]g beryllium/gram). This was believed to be largely a result of
the dilution factor operating in the rapidly growing tumor tissue.
However, other factors, such as lack of continued local deposition due
to impaired respiratory function and enhanced clearance due to high
vascularity of the tumor, may also have played a role. The portion of
inhaled beryllium retained in the lungs for a longer duration, which is
in the range of one-half of the original pulmonary load, may have
significance for pulmonary carcinogenesis. This pulmonary beryllium
burden becomes localized in the cell nuclei and may be an important
factor in eliciting the carcinogenic response associated with beryllium
inhalation.
    Groth et al. (1980) conducted a series of experiments to assess the
carcinogenic effects of beryllium, beryllium hydroxide, and various
beryllium alloys. For the beryllium metal/alloys experiment, 12 groups
of 3-month-old female Wistar rats (35 rats/group) were used. All rats
in each group received a single intratracheal injection of either 2.5
or 0.5 mg of one of the beryllium metals or beryllium alloys as
described in Table 3 below. These materials were suspended in 0.4 cc of
isotonic saline followed by 0.2 cc of saline. Forty control rats were
injected with 0.6 cc of saline. The geometric mean particle sizes
varied from 1 to 2 [micro]m. Rats were sacrificed and autopsied at
various intervals ranging from 1 to 18 months post-injection.

                           Table 3--Summary of Beryllium Dose From Groth et al. (1980)
----------------------------------------------------------------------------------------------------------------
                                                  Percent other   Total No. rats   Compound dose
          Form of Be              Percent Be        compounds        autopsied         (mg)        Be dose  (mg)
----------------------------------------------------------------------------------------------------------------
Be metal.....................  100.............  None...........              16             2.5             2.5
                                                                              21             0.5             0.5
Passivated Be metal..........  99..............  0.26% Chromium.              26             2.5             2.5
                                                                              20             0.5             0.5
BeAl alloy...................  62..............  38% Aluminum...              24             2.5            1.55
                                                                              21             0.5             0.3
BeCu alloy...................  4...............  96% Copper.....              28             2.5             0.1
                                                                              24             0.5            0.02
BeCuCo alloy.................  2.4.............  0.4% Cobalt....              33             2.5            0.06
                                                 96% Copper.....              30             0.5           0.012
BeNi alloy...................  2.2.............  97.8% Nickel...              28             2.5           0.056
                                                                              27             0.5           0.011
----------------------------------------------------------------------------------------------------------------

    Lung tumors were observed only in rats exposed to beryllium metal,
passivated beryllium metal, and beryllium-aluminum alloy. Passivation
refers to the process of removing iron contamination from the surface
of

beryllium metal. As discussed, metal alloys may have a different
toxicity than beryllium alone. Rats exposed to 100 percent beryllium
exhibited relatively high mortality rates, especially in the groups
where lung tumors were observed. Nodules varying from 1 to 10 mm in
diameter were also observed in the lungs of rats exposed to beryllium
metal, passivated beryllium metal, and beryllium-aluminum alloy. These
nodules were suspected of being malignant.
    To test this hypothesis, transplantation experiments involving the
suspicious nodules were conducted in nine rats. Seven of the nine
suspected tumors grew upon transplantation. All transplanted tumor
types metastasized to the lungs of their hosts. Lung tumors were
observed in rats injected with both the high and low doses of beryllium
metal, passivated beryllium metal, and beryllium-aluminum alloy. No
lung tumors were observed in rats injected with the other compounds.
From a total of 32 lung tumors detected, most were adenocarcinomas and
adenomas; however, two epidermoid carcinomas and at least one poorly
differentiated carcinoma were observed. Bronchiolar alveolar cell
tumors were frequently observed in rats injected with beryllium metal,
passivated beryllium metal, and beryllium-aluminum alloy. All stages of
cuboidal, columnar, and squamous cell metaplasia were observed on the
alveolar walls in the lungs of rats injected with beryllium metal,
passivated beryllium metal, and beryllium-aluminum alloy. These lesions
were generally reduced in size and number or absent from the lungs of
animals injected with the other alloys (BeCu, BeCuCo, BeNi).
    The extent of alveolar metaplasia could be correlated with the
incidence of lung cancer. The incidences of lung tumors in the rats
that received 2.5 mg of beryllium metal, and 2.5 and 0.5 mg of
passivated beryllium metal, were significantly different (p <= 0.008)
from controls. When autopsies were performed at the 16-to-19-month
interval, the incidence (2/6) of lung tumors in rats exposed to 2.5 mg
of beryllium-aluminum alloy was statistically significant (p = 0.004)
when compared to the lung tumor incidence (0/84) in rats exposed to
BeCu, BeNi, and BeCuCo alloys, which contained much lower
concentrations of Be (Groth et al., 1980).
    Finch et al. (1998b) investigated the carcinogenic effects of
inhaled beryllium on heterozygous TSG-p53 knockout mice
(p53+/-) and wild-type (p53+/+) mice. Knockout mice can be
valuable tools in determining the role of specific genes on the
toxicity of a material of interest, in this case, beryllium. Equal
numbers of approximately 10-week-old male and female mice were used for
this study. Two exposure groups were used to provide dose-response
information on lung carcinogenicity. The maximum initial lung burden
(ILB) target of 60 [mu]g beryllium was based on previous acute
inhalation exposure studies in mice. The lower exposure target level of
15 [mu]g was selected to provide a lung burden significantly less than
the high-level group, but high enough to yield carcinogenic responses.
Mice were exposed in groups to beryllium metal or to filtered air
(controls) via nose-only inhalation. The specific exposure parameters
are presented in Table 4 below. Mice were sacrificed 7 days post
exposure for ILB analysis, and either at 6 months post exposure (n = 4-
5 mice per group per gender) or when 10 percent or less of the original
population remained (19 months post exposure for p53+/-
knockout and 22.5 months post exposure for p53+/+ wild-type mice). The
sacrifice time was extended in the study because a significant number
of lung tumors were not observed at 6 months post exposure.

                                                Table 4--Summary of Animal Data From Finch Et Al., 1998 b
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Number of mice
                                  Mean  exposure      Target be lung                        Mean daily  exposure                        with 1 or more
         Mouse strain              concentration      burden  ([mu]g)     Number of mice     duration  (minutes)   Mean ILB  ([mu]g)   lung tumors/total
                                   ([mu]g Be/L)                                                                                number  examined
--------------------------------------------------------------------------------------------------------------------------------------------------------
Knockout (p53+/-).............  34                  15                  30                  112 (single)          NA                  0/29
                                36                  60                  30                  139[Dagger]           NA                  4/28
Wild-type (p53\+/+\)            34                  15                  6*                  112 (single)          12  4   NA
                                36                  60                  36[dagger]          139[Dagger]           54  6   0/28
Knockout (p53+/-).............  NA (air)            Control             30                  60-180 (single)       NA                  0/30
--------------------------------------------------------------------------------------------------------------------------------------------------------
ILB = initial lung burden; NA = not applicable
Median aerodynamic diameter of Be aerosol = 1.4 [mu]m ([sigma]g = 1.8)
* Wild-type mice in the low exposure group were not evaluated for carcinogenic effects; however ILB was analyzed in six wild-type mice.
[dagger] Thirty wild-type mice were analyzed for carcinogenic effects; six wild-type mice were analyzed for ILB.
[Dagger] Mice were exposed for 2.3 hours/day for three consecutive days.

    Lung burdens of beryllium measured in wild-type mice at 7 days post
exposure were approximately 70-90 percent of target levels. No
exposure-related effects on body weight were observed in mice; however,
lung weights and lung-to-body-weight ratios were somewhat elevated in
60 [mu]g target ILB p53+/- knockout mice compared to
controls (0.05 < p < 0.10). In general, p53+/+ wild-type mice survived
longer than p53+/- knockout mice and beryllium exposure
tended to decrease survival time in both groups. The incidence of
beryllium-induced lung tumors was marginally higher in the 60 [mu]g
target ILB p53+/- knockout mice compared to 60 [mu]g target
ILB p53+/+ wild-type mice (p = 0.056). The incidence of lung tumors in
the 60 [mu]g target ILB p53+/- knockout mice was also
significantly higher than controls (p = 0.048). No tumors developed in
the control mice, 15 [mu]g target ILB p53+/- knockout mice,
or 60 [mu]g target ILB p53+/+ wild-type mice throughout the length of
the study. Most lung tumors in beryllium-exposed mice were squamous
cell carcinomas, three of four of which were poorly circumscribed and
all were associated with at least some degree of granulomatous
pneumonia. The study results suggest that having an inactivated p53
allele is associated with lung tumor progression in p53+/-
knockout mice. This is based on the significant difference seen in the
incidence of beryllium-induced lung neoplasms for the
p53+/-knockout mice compared with the p53\+/+\ wild-type
mice. The authors conclude that since there was a relatively late onset
of tumors in the beryllium-exposed p53+/- knockout mice, a
6-month bioassay in this mouse strain might not be an appropriate model
for lung carcinogenesis (Finch et al., 1998b).

    Nickell-Brady et al. (1994) investigated the development of lung
tumors in 12-week-old F344/N rats after a single nose-only inhalation
exposure to beryllium aerosol, and evaluated whether beryllium lung
tumor induction involves alterations in the K-ras, p53, and c-raf-1
genes. Four groups of rats (30 males and 30 females per group) were
exposed to different mass concentrations of beryllium (Group 1: 500 mg/
m\3\ for 8 min; Group 2: 410 mg/m\3\ for 30 min; Group 3: 830 mg/m\3\
for 48 min; Group 4: 980 mg/m\3\ for 39 min). The beryllium mass median
aerodynamic diameter was 1.4 [mu]m ([sigma]g = 1.9). The
mean beryllium lung burdens for each exposure group were 40, 110, 360,
and 430 [mu]g, respectively.
    To examine genetic alterations, DNA isolation and sequencing
techniques (PCR amplification and direct DNA sequence analysis) were
performed on wild-type rat lung tissue (i.e., control samples) along
with two mouse lung tumor cell lines containing known K-ras mutations,
12 carcinomas induced by beryllium (i.e., experimental samples), and 12
other formalin-fixed specimens. Tumors appeared in beryllium-exposed
rats by 14 months, and 64 percent of exposed rats developed lung tumors
during their lifetime. Lungs frequently contained multiple tumor sites,
with some of the tumors greater than 1 cm. A total of 24 tumors were
observed. Most of the tumors (n = 22) were adenocarcinomas exhibiting a
papillary pattern characterized by cuboidal or columnar cells, although
a few had a tubular or solid pattern. Fewer than 10 percent of the
tumors were adenosquamous (n = 1) or squamous cell (n = 1) carcinomas.
    No transforming mutations of the K-ras gene (codons 12, 13, or 61)
were detected by direct sequence analysis in any of the lung tumors
induced by beryllium. However, using a more sensitive sequencing
technique (PCR enrichment restriction fragment length polymorphism
(RFLP) analysis) resulted in the detection of K-ras codon 12 GGT to GTT
transversions in 2 of 12 beryllium-induced adenocarcinomas. No p53 and
c-raf-1 alterations were observed in any of the tumors induced by
beryllium exposure (i.e., no differences observed between beryllium-
exposed and control rat tissues). The authors note that the results
suggest that activation of the K-ras proto-oncogene is both a rare and
late event, possibly caused by genomic instability during the
progression of beryllium-induced rat pulmonary adenocarcinomas. It is
unlikely that the K-ras gene plays a role in the carcinogenicity of
beryllium. The results also indicate that p53 mutation is unlikely to
play a role in tumor development in rats exposed to beryllium.
    Belinsky et al. (1997) reviewed the findings by Nickell-Brady et
al. (1994) to further examine the role of the K-ras and p53 genes in
lung tumors induced in the F344 rat by non-mutagenic (non-genotoxic)
exposures to beryllium. Their findings are discussed along with the
results of other genomic studies that look at carcinogenic agents that
are either similarly non-mutagenic or, in other cases, mutagenic. The
authors conclude that the identification of non-ras transforming genes
in rat lung tumors induced by non-mutagenic exposures, such as
beryllium, as well as mutagenic exposures will help define some of the
mechanisms underlying cancer induction by different types of DNA
damage.
    The inactivation of the p16INK4a (p16) gene is a contributing
factor in disrupting control of the normal cell cycle and may be an
important mechanism of action in beryllium-induced lung tumors.
Swafford et al. (1997) investigated the aberrant methylation and
subsequent inactivation of the p16 gene in primary lung tumors induced
in F344/N rats exposed to known carcinogens via inhalation. The
research involved a total of 18 primary lung tumors that developed
after exposing rats to five agents, one of which was beryllium. In this
study, only one of the 18 lung tumors was induced by beryllium
exposure; the majority of the other tumors were induced by radiation
(x-rays or plutonium-239 oxide). The authors hypothesized that if p16
inactivation plays a central role in development of non-small-cell lung
cancer, then the frequency of gene inactivation in primary tumors
should parallel that observed in the corresponding cell lines. To test
the hypothesis, a rat model for lung cancer was used to determine the
frequency and mechanism for inactivation of p16 in matched primary lung
tumors and derived cell lines. The methylation-specific PCR (MSP)
method was used to detect methylation of p16 alleles. The results
showed that the presence of aberrant p16 methylation in cell lines was
strongly correlated with absent or low expression of the gene. The
findings also demonstrated that aberrant p16 CpG island methylation, an
important mechanism in gene silencing leading to the loss of p16
expression, originates in primary tumors.
    Building on the rat model for lung cancer and associated findings
from Swafford et al. (1997), Belinsky et al. (2002) conducted
experiments in 12-week-old F344/N rats (male and female) to determine
whether beryllium-induced lung tumors involve inactivation of the p16
gene and estrogen receptor [alpha] (ER) gene. Rats received a single
nose-only inhalation exposure to beryllium aerosol at four different
exposure levels. The mean lung burdens measured in each exposure group
were 40, 110, 360, and 430 [mu]g. The methylation status of the p16 and
ER genes was determined by MSP. A total of 20 tumors detected in
beryllium-exposed rats were available for analysis of gene-specific
promoter methylation. Three tumors were classified as squamous cell
carcinomas and the others were determined to be adenocarcinomas.
Methylated p16 was present in 80 percent (16/20), and methylated ER was
present in one-half (10/20), of the lung tumors induced by exposure to
beryllium. Additionally, both genes were methylated in 40 percent of
the tumors. The authors noted that four tumors from beryllium-exposed
rats appeared to be partially methylated at the p16 locus. Bisulfite
sequencing of exon 1 of the ER gene was conducted on normal lung DNA
and DNA from three methylated, beryllium-induced tumors to determine
the density of methylation within amplified regions of exon 1 (referred
to as CpG sites). Two of the three methylated, beryllium-induced lung
tumors showed extensive methylation, with more than 80 percent of all
CpG sites methylated.
    The overall findings of this study suggest that inactivation of the
p16 and ER genes by promoter hypermethylation are likely to contribute
to the development of lung tumors in beryllium-exposed rats. The
results showed a correlation between changes in p16 methylation and
loss of gene transcription. The authors hypothesize that the mechanism
of action for beryllium-induced p16 gene inactivation in lung tumors
may be inflammatory mediators that result in oxidative stress. The
oxidative stress damages DNA directly through free radicals or
indirectly through the formation of 8-hydroxyguanosine DNA adducts,
resulting primarily in a single-strand DNA break.
    Wagner et al. (1969) studied the development of pulmonary tumors
after intermittent daily chronic inhalation exposure to beryllium ores
in three groups of male squirrel monkeys. One group was exposed to
bertrandite ore, a second to beryl ore, and the third served as
unexposed controls. Each of these three exposure groups contained 12
monkeys. Monkeys from each group were sacrificed after 6, 12, or 23
months of exposure. The 12-month sacrificed

monkeys (n = 4 for bertrandite and control groups; n = 2 for beryl
group) were replaced by a separate replacement group to maintain a
total animal population approximating the original numbers and to
provide a source of confirming data for biologic responses that might
arise following the ore exposures. Animals were exposed to bertrandite
and beryl ore concentrations of 15 mg/m\3\, corresponding to 210 [mu]g
beryllium/m\3\ and 620 [mu]g beryllium/m\3\ in each exposure chamber,
respectively. The parent ores were reduced to particles with geometric
mean diameters of 0.27 [mu]m ( 2.4) for bertrandite and
0.64 [mu]m ( 2.5) for beryl. Animals were exposed for
approximately 6 hours/day, 5 days/week. The histological changes in the
lungs of monkeys exposed to bertrandite and beryl ore exhibited a
similar pattern. The changes generally consisted of aggregates of dust-
laden macrophages, lymphocytes, and plasma cells near respiratory
bronchioles and small blood vessels. There were, however, no consistent
or significant pulmonary lesions or tumors observed in monkeys exposed
to either of the beryllium ores. This is in contrast to the findings in
rats exposed to beryl ore and to a lesser extent bertrandite, where
atypical cell proliferation and tumors were frequently observed in the
lungs. The authors hypothesized that the rats' greater susceptibility
may be attributed to the spontaneous lung disease characteristic of
rats, which might have interfered with lung clearance.
    As previously described, Conradi et al. (1971) investigated changes
in the lungs of monkeys and dogs two years after intermittent
inhalation exposure to beryllium oxide calcined at 1,400 [deg]C. Five
adult male and female monkeys (Macaca irus) weighing between 3 and 5.75
kg were used in the study. The study included two control monkeys.
Beryllium concentrations in the atmosphere of whole-body exposed
monkeys varied between 3.30 and 4.38 mg/m\3\. Thirty-minute exposures
occurred once a month for three months, with beryllium oxide
concentrations increasing at each exposure interval. Lung tissue was
investigated using electron microscopy and morphometric methods.
Beryllium content in portions of the lungs of five monkeys was measured
two years following exposure by emission spectrography. The reported
concentrations in monkeys (82.5, 143.0, and 112.7 [mu]g beryllium per
100 gm of wet tissue in the upper lobe, lower lobe, and combined lobes,
respectively) were higher than those in dogs. No neoplastic or
granulomatous lesions were observed in the lungs of any exposed animals
and there was no evidence of chronic proliferative lung changes after
two years.
4. In vitro Studies
    The exact mechanism by which beryllium induces pulmonary neoplasms
in animals remains unknown (NAS 2008). Keshava et al. (2001) performed
studies to determine the carcinogenic potential of beryllium sulfate in
cultured mammalian cells. Joseph et al. (2001) investigated
differential gene expression to understand the possible mechanisms of
beryllium-induced cell transformation and tumorigenesis. Both
investigations used cell transformation assays to study the cellular/
molecular mechanisms of beryllium carcinogenesis and assess
carcinogenicity. Cell lines were derived from tumors developed in nude
mice injected subcutaneously with non-transformed BALB/c-3T3 cells that
were morphologically transformed in vitro with 50-200 [mu]g beryllium
sulfate/ml for 72 hours. The non-transformed cells were used as
controls.
    Keshava et al. (2001) found that beryllium sulfate is capable of
inducing morphological cell transformation in mammalian cells and that
transformed cells are potentially tumorigenic. A dose-dependent
increase (9-41 fold) in transformation frequency was noted. Using
differential polymerase chain reaction (PCR), gene amplification was
investigated in six proto-oncogenes (K-ras, c-myc, c-fos, c-jun, c-sis,
erb-B2) and one tumor suppressor gene (p53). Gene amplification was
found in c-jun and K-ras. None of the other genes tested showed
amplification. Additionally, Western blot analysis showed no change in
gene expression or protein level in any of the genes examined. Genomic
instability in both the non-transformed and transformed cell lines was
evaluated using random amplified polymorphic DNA fingerprinting (RAPD
analysis). Using different primers, 5 of the 10 transformed cell lines
showed genomic instability when compared to the non-transformed BALB/c-
3T3 cells. The results indicate that beryllium sulfate-induced cell
transformation might, in part, involve gene amplification of K-ras and
c-jun and that some transformed cells possess neoplastic potential
resulting from genomic instability.
    Using the Atlas mouse 1.2 cDNA expression microarrays, Joseph et
al. (2001) studied the expression profiles of 1,176 genes belonging to
several different functional categories. Compared to the control cells,
expression of 18 genes belonging to two functional groups (nine cancer-
related genes and nine DNA synthesis, repair, and recombination genes)
was found to be consistently and reproducibly different (at least 2-
fold) in the tumor cells. Differential gene expression profile was
confirmed using reverse transcription-PCR with primers specific to the
differentially expressed genes. Two of the differentially expressed
genes (c-fos and c-jun) were used as model genes to demonstrate that
the beryllium-induced transcriptional activation of these genes was
dependent on pathways of protein kinase C and mitogen-activated protein
kinase and independent of reactive oxygen species in the control cells.
These results indicate that beryllium-induced cell transformation and
tumorigenesis are associated with up-regulated expression of the
cancer-related genes (such as c-fos, c-jun, c-myc, and R-ras) and down-
regulated expression of genes involved in DNA synthesis, repair, and
recombination (such as MCM4, MCM5, PMS2, Rad23, and DNA ligase I).
5. Preliminary Lung Cancer Conclusions
    OSHA has preliminarily determined that the weight of evidence
indicates that beryllium compounds should be regarded as potential
occupational lung carcinogens. Other scientific organizations,
including the International Agency for Research on Cancer (IARC), the
National Toxicology Program (NTP), the U.S. Environmental Protection
Agency (EPA), the National Institute for Occupational Safety and Health
(NIOSH), and the American Conference of Governmental Industrial
Hygienists (ACGIH) have reached similar conclusions with respect to the
carcinogenicity of beryllium.
    While some evidence exists for direct-acting genotoxicity as a
possible mechanism for beryllium carcinogenesis, the weight of evidence
suggests a possible indirect mechanism may be responsible for most
tumorigenic activity of beryllium in animal models and possibly humans
(EPA, 1998). Inflammation has been postulated to be a key contributor
to many different forms of cancer (Jackson et al., 2006; Pikarsky et
al., 2004; Greten et al., 2004; Leek, 2002). In fact, chronic
inflammation may be a primary factor in the development of up to one-
third of all cancers (Ames et al., 1990; NCI, 2010).
    In addition to a T-cell mediated response beryllium has been
demonstrated to produce an inflammatory response in animal models
similar to other particles (Reeves et al., 1967; Swafford et al., 1997;
Wagner et al., 1969) possibly

contributing to its carcinogenic potential. Animal studies, as
summarized above, have demonstrated a consistent scenario of beryllium
exposure resulting in chronic pulmonary inflammation. Studies conducted
in rats have demonstrated that chronic inhalation of materials similar
in solubility to beryllium result in increased pulmonary inflammation,
fibrosis, epithelial hyperplasia, and, in some cases, pulmonary
adenomas and carcinomas (Heinrich et al., 1995; Nikula et al., 1995;
NTP, 1993; Lee et al., 1985; Warheit et al., 1996). This response is
generally referred to as an ``overload'' response or threshold effect.
Substantial data indicate that tumor formation in the rat after
exposure to some sparingly soluble particles at doses causing marked,
chronic inflammation is due to a secondary mechanism unrelated to the
genotoxicity (or lack thereof) of the particle itself.
    It has been hypothesized that the recruitment of neutrophils during
the inflammatory response and subsequent release of oxidants from these
cells have been demonstrated to play an important role in the
pathogenesis of rat lung tumors (Borm et al., 2004; Carter and
Driscoll, 2001; Carter et al., 2006; Johnston et al., 2000; Knaapen et
al., 2004; Mossman, 2000). Inflammatory mediators, as characterized in
many of the studies summarized above, have been shown to play a
significant role in the recruitment of cells responsible for the
release of reactive oxygen and hydrogen species. These species have
been determined to be highly mutagenic themselves as well as mitogenic,
inducing a proliferative response (Feriola and Nettesheim, 1994; Jetten
et al., 1990; Moss et al., 1994; Coussens and Werb, 2002). The
resultant effect is an environment rich for neoplastic transformations
and the progression of fibrosis and tumor formation. This finding does
not imply no risk at levels below an inflammatory response; rather, the
overall weight of evidence is suggestive of a mechanism of an indirect
carcinogen at levels where inflammation is seen. While tumorigenesis
secondary to inflammation is one reasonable mode of action, other
plausible modes of action independent of inflammation (e.g.,
epigenetic, mitogenic, reactive oxygen mediated, indirect genotoxicity,
etc.) may also contribute to the lung cancer associated with beryllium
exposure.
    Epidemiological studies indicate excess risk of lung cancer
mortality from occupational beryllium exposure levels at or below the
current OSHA PEL (Schubauer-Berigan et al., 2010; Table 4).

F. Other Health Effects

    Past studies on other health effects have been thoroughly reviewed
by several scientific organizations (NTP, 1999; EPA, 1998; ATSDR, 2002;
WHO, 2001; HSDB, 2010). These studies include summaries of animal
studies, in vitro studies, and human epidemiological studies associated
with cardiovascular, hematological, hepatic, renal, endocrine,
reproductive, ocular and mucosal, and developmental effects. High-dose
exposures to beryllium have been shown to have an adverse effect upon a
variety of organs and tissues in the body, particularly the liver. The
adverse systemic effects from human exposures mostly occurred prior to
the introduction of occupational and environmental standards set in
1970-1972 (OSHA, 1971; ACGIH, 1971; ANSI, 1970) and 1974 (EPA, 1974)
and therefore are less relevant today than in the past. The available
data is fairly limited. The hepatic, cardiovascular, renal, and ocular
and mucosal effects are briefly summarized below. Health effects in
other organ systems listed above were only observed in animal studies
at very high exposure levels and are, therefore, not discussed here.
 1. Hepatic Effects
    Beryllium has been shown to accumulate in the liver and a
correlation has been demonstrated between beryllium content and hepatic
damage. Different compounds have been shown to distribute differently
within the hepatic tissues. For example, beryllium phosphate had
accumulated almost exclusively within sinusoidal (Kupffer) cells of the
liver, while the beryllium derived from beryllium sulfate was found
mainly in parenchymal cells. Conversely, beryllium sulphosalicylic acid
complexes were rapidly excreted (Skillteter and Paine, 1979).
    According to a few autopsies, beryllium-laden liver had central
necrosis, mild focal necrosis as well as congestion, and occasionally
beryllium granuloma.
    Residents near a beryllium plant may have been exposed by inhaling
trace amounts of beryllium powder, and different beryllium compounds
may have induced different toxicant reactions (Yian and Yin, 1982).
2. Cardiovascular Effects
    There is very limited evidence of cardiovascular effects of
beryllium and its compounds in humans. Severe cases of chronic
beryllium disease can result in cor pulmonale, which is hypertrophy of
the right heart ventricle. In a case history study of 17 individuals
exposed to beryllium in a plant that manufactured fluorescent lamps,
autopsies revealed right atrial and ventricular hypertrophy (Hardy and
Tabershaw, 1946). It is not likely that these cardiac effects were due
to direct toxicity to the heart, but rather were a response to impaired
lung function. However, an increase in deaths due to heart disease or
ischemic heart disease was found in workers at a beryllium
manufacturing facility (Ward et al., 1992).
    Animal studies performed in monkeys indicate heart enlargement
after acute inhalation exposure to 13 mg beryllium/m\3\ as beryllium
hydrogen phosphate, 0.184 mg beryllium/m\3\ as beryllium fluoride, or
0.198 mg beryllium/m\3\ as beryllium sulfate (Schepers 1964). Decreased
arterial oxygen tension was observed in dogs exposed to 30 mg
beryllium/m\3\ as beryllium oxide for 15 days (HSDB, 2010), 3.6 mg
beryllium/m\3\ as beryllium oxide for 40 days (Hall et al., 1950), or
0.04 mg beryllium/m\3\ as beryllium sulfate for 100 days (Stokinger et
al., 1950). These are expected to be indirect effects on the heart due
to pulmonary fibrosis and toxicity which can increase arterial pressure
and restrict blood flow.
3. Renal Effects
    Renal calculi (stones) were unusually prevalent in severe cases
that resulted from high levels of beryllium exposure. Renal stones
containing beryllium occurred in about 10 percent of patients affected
by high exposures (Barnett, et al., 1961). Kidney stones were observed
in 10 percent of the CBD cases collected by the BCR up to 1959 (Hall et
al., 1959). In addition, an excess of calcium in the blood and urine
has been seen frequently in patients with chronic beryllium disease
(ATSDR, 2002).
4. Ocular and Mucosal Effects
    Both the soluble, sparingly soluble, and insoluble beryllium
compounds have been shown to cause ocular irritation in humans (Van
Orstrand et al., 1945; De Nardi et al., 1953; Nishimura, 1966; Epstein,
1990; NIOSH, 1994). In addition, beryllium compounds (soluble,
sparingly soluble, or insoluble) have been demonstrated to induce acute
conjunctivitis with corneal maculae and diffuse erythema (HSDB, 2010).
    The mucosa (mucosal membrane) is the moist lining of certain
tissues/organs including the eyes, nose, mouth, lungs, and the urinary
and digestive tracts. Soluble beryllium salts have been

shown to be directly irritating to mucous membranes (HSDB, 2010).

G. Summary of Preliminary Conclusions Regarding Health Effects

    Through careful analysis of the current best available scientific
information outlined in this Health Effects Section V, OSHA has
preliminarily determined that beryllium and beryllium-containing
compounds are able to cause sensitization, chronic beryllium disease
(CBD) and lung cancer below the current OSHA PEL of 2 [mu]g/m\3\. The
Agency has preliminarily determined through the studies outlined in
section V.A.2 of this health effects section that skin and inhalation
exposure to beryllium can lead to sensitization; and inhalation
exposure, or skin exposure coupled with inhalation, can cause onset and
progression of CBD. In addition, the Agency has preliminarily
determined through studies outlined in section V.E. of this health
effects section that inhalation exposure to beryllium and beryllium
containing materials causes lung cancer.
1. Beryllium Causes Sensitization Below the Current PEL and
Sensitization is a Precursor to CBD
    Through the biological and immunological processes outlined in
section V.B. of the Health Effects, the Agency believes that the
scientific evidence supports the following mechanism for the
development of sensitization and CBD.
     Inhaled beryllium and beryllium-containing materials able
to be retained and solubilized in the lungs initiate sensitization and
facilitate CBD development (Section V.B.5).
     Beryllium compounds that dissolve in biological fluids,
such as sweat, can penetrate intact skin and initiate sensitization
(section V.A.2; V.B). Phagosomal fluid and lung fluid have been
demonstrated to dissolve beryllium compounds in the lung (section
V.A.2a).
     Sensitization occurs through a CD4+ T-cell mediated
process with both soluble and insoluble beryllium and beryllium-
containing compounds through direct antigen presentation or through
further antigen processing (section V.D.1) in the skin or lung. T-cell
mediated responses, such as sensitization, are generally regarded as
long-lasting (e.g., not transient or readily reversible) immune
conditions.
     Beryllium sensitization and CBD are adverse events along a
pathological continuum in the disease process with sensitization being
the necessary first step in the progression to CBD (section V.D).
    [cir] Animal studies have provided supporting evidence for T-cell
proliferation in the development of granulomatous lung lesions after
beryllium exposure (section V.D.2; V.D.6).
    [cir] Since the pathogenesis of CBD involves a beryllium-specific,
cell-mediated immune response, CBD cannot occur in the absence of
beryllium sensitization (V.D.1). While no clinical symptoms are
associated with sensitization, a sensitized worker is at risk of
developing CBD upon subsequent inhalation exposure to beryllium.
    [cir] Epidemiological evidence that covers a wide variety of
different beryllium compounds and industrial processes demonstrates
that sensitization and CBD are continuing to occur at present-day
exposures below OSHA's PEL (section V.D.4; V.D.5).
     OSHA considers CBD to be a progressive illness with a
continuous spectrum of symptoms ranging from its earliest asymptomatic
stage following sensitization through to full-blown CBD and death
(section V.D.7).
     Genetic variabilities may enhance risk for developing
sensitization and CBD in some groups (section V.D.3).
    In addition, epidemiological studies outlined in section V.D.5 have
demonstrated that efforts to reduce exposures have succeeded in
reducing the frequency of sensitization and CBD.
2. Evidence Indicates Beryllium is a Human Carcinogen
    OSHA has conducted an evaluation of the current available
scientific information of the carcinogenic potential of beryllium and
beryllium-containing compounds (section V.E). Based on weight of
evidence and plausible mechanistic information obtained from in vitro
and in vivo animal studies as well as clinical and epidemiological
investigations, the Agency has preliminarily determined that beryllium
and beryllium-containing materials should be regarded as human
carcinogens. This information is in accordance with findings from IARC,
NTP, EPA, NIOSH, and ACGIH (section V.E).
     Lung cancer is an irreversible and frequently fatal
disease with an extremely poor 5-year survival rate (NCI, 2009).
     Epidemiological cohort studies have reported statistically
significant excess lung cancer mortality among workers employed in U.S.
beryllium production and processing plants during the 1930s to 1970s
(Section V.E.2).
     Significant positive associations were found between lung
cancer mortality and both average and cumulative beryllium exposures
when appropriately adjusted for birth cohort and short-term work status
(Section V.E.2).
     Studies in which large amounts of different beryllium
compounds were inhaled or instilled in the respiratory tracts of
experimental animals resulted in an increased incidence of lung tumors
(Section V.E.3).
     Authoritative scientific organizations, such as the IARC,
NTP, and EPA, have classified beryllium as a known or probable human
carcinogen.
    While OSHA has preliminarily determined there is sufficient
evidence of beryllium carcinogenicity, the exact tumorigenic mechanism
for beryllium is unclear and a number of mechanisms are plausibly
involved, including chronic inflammation, genotoxicity, mitogenicity
oxidative stress, and epigenetic changes (section V.E.3).
     Studies of beryllium exposed animals have consistently
demonstrated chronic pulmonary inflammation after exposure (section
V.E.3).
    [cir] Substantial data indicate that tumor formation in certain
animal models after inhalation exposure to sparingly soluble particles
at doses causing marked, chronic inflammation is due to a secondary
mechanism unrelated to the genotoxicty of the particle (section V.E.5).
     A review conducted by the NAS (2008) found that beryllium
and beryllium-containing compounds tested positive for genotoxicity in
nearly 50 percent of studies without exogenous metabolic activity,
suggesting a possible direct-acting mechanism may exist (section V.E.1)
as well as the potential for epigenetic changes (section V.E.4).
    Other health effects have been summarized in sections F of the
Health Effects Section and include hepatic, cardiovascular, renal,
ocular, and mucosal effects. The adverse systemic effects from human
exposures mostly occurred prior to the introduction of occupational and
environmental standards set in 1970-1972 (OSHA, 1971; ACGIH, 1971;
ANSI, 1970) and 1974 (EPA, 1974) and therefore are less relevant today
than in the past.

APPENDIX

                           Table A.1--Summary of Beryllium Sensitization and Chronic Beryllium Disease Epidemiological Studies
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           (%) Prevalence                Range of         Exposure-
          Reference               Study type    ------------------------------------     exposure          response          Study          Additional
                                                   Sensitization          CBD          measurements      relationship     limitations        comments
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Studies Conducted Prior to BeLPT
--------------------------------------------------------------------------------------------------------------------------------------------------------
Hardy and Tabershaw, 1946....  Case-series.....  N/A.............  N/A.............  N/A.............  N/A............  Selection bias.  Small sample
                                                                                size.
Hardy, 1980..................  Case-series.....  N/A.............  N/A.............  N/A.............  N/A............  Selection bias.  Small sample
                                                                                size.
Machle et al., 1948..........  Case-series.....  N/A.............  N/A.............  Semi-             Yes............  Selection bias.  Small sample
                                                                                quantitative.                                       size;
                                                                                unreliable
                                                                                exposure data.
Eisenbud et al., 1949........  Case-series.....  N/A.............  N/A.............  Average           ...............  ...............  Non-
                                                                                concentration:                                      occupational;
                                                                                350-750 ft from                                     ambient air
                                                                                plant--0.05-0.1                                     sampling.
                                                                                5 [mu]g/m\3\;.
                                                                                <350 ft from
                                                                                plant--2.1
                                                                                [mu]g/m\3\.
Lieben and Metzner, 1959.....  ................  N/A.............  ................  N/A.............  ...............  No quantitative  Family member
                                                                                exposure data.   contact with
                                                                                contaminated
                                                                                clothes.
Hardy et al., 1967...........  Case Registry     N/A.............  N/A.............  N/A.............  N/A............  Incomplete       ...............
                                Review.                                                                                exposure
                                                                                concentration
                                                                                data.
Hasan and Kazemi, 1974.......  ................  N/A.............  ................  ................  ...............  ...............  ...............
Eisenbud and Lisson, 1983....  ................  N/A.............  1-10............  ................  ...............  ...............  ...............
Stoeckle et al., 1969........  Case-series (60   N/A.............  ................  ................  No.............  Selection bias.  Provided
                                cases).                                                                                information
                                                                                regarding
                                                                                progression
                                                                                and
                                                                                identifying
                                                                                sarcoidosis
                                                                                from CBD.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Studies Conducted Following the Development of the BeLPT
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                                             Beryllium Mining and Extraction
--------------------------------------------------------------------------------------------------------------------------------------------------------
Deubner et al., 2001b........  Cross-sectional   4.0 (3 cases)...  1.3 (1 case)....  Mining, milling-- No.............  Small sample     Personal
                                (75 workers).                                         range 0.05-0.8                     size.            sampling.
                                                                                [mu]g/m\3\;
                                                                                Annual maximum
                                                                                0.04-165.7
                                                                                [mu]g/m\3\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     Beryllium Metal Processing and Alloy Production
--------------------------------------------------------------------------------------------------------------------------------------------------------
Kreiss et al., 1997..........  Cross-sectional   6.9 (43 cases)..  4.6 (29 cases)..  Median--1.4       No.............  Inconsistent     Short-term
                                study of 627                                          [mu]g/m\3\.                        BeLPT results    Breathing Zone
                                workers.                                                                                between labs.    sampling.