(ABD) is a pneumonitis resulting from high exposure to soluble beryllium compounds or low-fired beryllium oxide that has not been seen for decades and low-fired beryllium oxide has not been commercially available since 1950. The onset of symptoms was usually immediate, but could be delayed from several hours up to 3 days. Symptoms included dypsnea, fatigue, fever, night sweats and cough. Pulmonary function tests revealed obstructive lung disease with impaired gas exchange. Most of the cases of ABD usually resolved completely, however, there were incidents of fatal outcomes or subsequent development of chronic beryllium disease. Airborne exposures to beryllium metal, beryllium oxide or beryllium alloy fumes or dust are not associated with acute or short-term respiratory reactions.
Clinical cCBD was diagnosed, before the late 1980’s, when clinical symptoms were observed along with changes in chest x-rays or lung function tests. In 1951, it was suggested that CBD was an immune-mediated disease and subsequently the term beryllium sensitization was initially defined by the beryllium skin patch test (BeBLPT). Patch tests results were 100% positive in beryllium workers who had previously been diagnosed with clinical cCBD. The use of the BeBLPT was curtailed because simultaneous experimental application of multiple tests sensitized members (positive patch test) of control populations and because it was suggested that the test might exacerbate existing cCBD.
The clinical course of cCBD is considered highly variable since the symptomatic disease may not develop or it may develop slowly over time. The earliest manifestations of clinical chronic beryllium disease (cCBD) are the symptoms of shortness of breath, dry cough, or wheeze, and in some, night sweats or fatigue. Chest radiographs can be normal, but often range from small nodular opacities, with an upper level predominance, to formation of conglomerate masses. Also, a chest x ray may demonstrate abnormalities with the person being asymptomatic relative to pulmonary functions. Progression may lead to weight loss, acrocyanosis (blueness or pallor of the extremities usually associated with pain and numbness), heart failure, and possible death. In addition to cCBD, these symptoms may be found in persons with other lung diseases and in persons with no diagnosable disease.
Pulmonary responses to cCBD also vary. Some have normal lung volume, but abnormal gas exchange in either diffusing capacity for carbon monoxide or by arterial blood gas analysis. Some have air flow limitations and later followed by restrictions in lung volumes. In the early stages of the disease, alterations in lung function include airflow obstruction, later developing a mixed pattern of obstruction and restriction. Pure restriction develops toward the end stage of the disease. The most common abnormalities seen early in the course of the disease are a post exercise increase in the alveolar-arterial oxygen gradient and diffusing capacity and a reduction in lung capacity.
Subclinical CBD was a term that originated in the late 1980s and the criterion for diagnosis of CBD was changed. The diagnosis of Subclinical CBD is based on abnormal lymphocyte proliferation tests for beryllium sensitization and the presence, upon lung biopsy, of non-caseating granulomas. Granuloma formation can exist with no symptomology or physical impairment of health or proliferation of granulomas may lead to symptoms of cCBD. The link between the presence of granulomas and the development of clinical disease symptoms can be elusive because the latency from time of first beryllium exposure to the development of clinical disease ranges from a few years to several decades. With Subclinical CBD, there are no clinical symptoms and there is no measurable impairment.
The term beryllium sensitization, as it is used today, refers to the accepted theoretical recognition of beryllium by the immune system which may be detected only via an in-vivo patch test, an in-vitro blood test, or in-vitro bronchial lavage testing using soluble salts of beryllium such as beryllium sulfate or beryllium fluoride.
Beryllium sensitization is only definable as a test result. Beryllium sensitization is not a health effect, illness or disability nor does it predict clinical chronic beryllium disease.
Only workers who have immune sensitization to beryllium are believed to develop CBD (clinical and subclinical), however, persons have been diagnosed with cCBD who have not been found positive using the blood lymphocyte proliferation test (BeLPT) or bronchial lavage lymphocyte proliferation test (BALLPT) for sensitization.
Studies of beryllium-exposed workers demonstrate that the positive predictive value of a positive blood lymphocyte proliferation test to detect sub clinical CBD (sensitization and granuloma in lung parenchyma) ranges from 11 to 100%. However, absent a gold standard and the knowledge of prevalence, the PPV of the BeBLPT will continue to be a range of estimates.
Sensitization to beryllium is a measurement of lymphocyte proliferation in a laboratory test tube when lymphocytes are challenged with a soluble beryllium salt. Laboratory lymphocyte proliferation has also been identified with many other metals including nickel, hexavalent chromium, titanium, cadmium, gold, palladium, mercury, barium, aluminium, cobalt, copper, and zirconium. It is not yet known if all beryllium sensitized individuals will eventually develop CBD (cCBD or subclinical CBD).
Medical screenings of beryllium-exposed workers consistently demonstrate that a larger percentage of individuals will have a positive blood lymphocyte proliferation test to beryllium (become sensitized) than will be diagnosed with sub clinical CBD (sensitization and granuloma in lung parenchyma).
Studies have indicated that there are factors that may influence whether a worker may develop CBD. Genetic susceptibility, particle size, particle numbers, particle surface area, chemical form, peak exposure profiles have been suggested as possible contributors to the risk of clinical disease.
While many aspects of the etiology of CBD are still unclear, researchers have identified a genetic marker that appears to significantly increase the probability that a worker will develop CBD. CBD has been associated with the allelic substitution of glutamic acid for lysine at position 69 in the HLA-DPB1 protein.The results of this study indicated that CBD cases were more likely to have HLA-DPB1 alleles coding for aspartic acid (D) and glutamic acid (E) in positions 55 and 56 compared to the controls who where more likely to code for an alanine (A) in those positions 79% vs. 41%. Alleles, characterized by a codon for glutamic acid residue at position 69 (E69) in the amino acid sequence, also occurred more often in individuals with CBD than in those without (97% vs 27%. Allele specific analysis implicated an association between CBD and the inheritance of the common HLA-DPB1*0201, glutamic acid 69 containing allele.
Wang investigated the presence and absence of both HLA-DPB1 and HLA-DPA1 alleles in beryllium exposed individuals with and without CBD. This study verified the association between HLA-DPB1E69 and CBD; and it evaluated allele specific relations including the effect of homozygosity versus heterozygosity and disease status. The study found that 95% of participants having CBD were found to carry at least one HLA-DPB1E69 variant (or putative disease allele) compared to (45%) without disease. The data suggested that individuals homozygous for HLA-DPB1E69 were at an increased risk of disease compared to heterozygous individuals.
There is no epidemiological investigation on carcinogenicity of beryllium metal as an individual substance.
The past beryllium studies were conducted on beryllium production workers in the United States and deal with basically the same cohorts who were exposed to very high levels of beryllium and – very importantly – to multiple compounds and forms of beryllium as well as other known carcinogens (asbestos, silica, coal tar etc).
Many shortcomings of the early studies (like for example missing correction for smoking habits, comparison to inadequate controls etc) have been intensively discussed in the scientific literature; a summary of the discussions can be found in this dossier (under point 5.8.6).
Data from European disease registries and leading medical practitioners does not identify a link between beryllium exposure and lung cancer.
The Industrial Injuries Advisory Council Position Paper 27 on Beryllium and Lung Cancer (December 2009) states:
“The main epidemiological evidence on occupational risks of lung cancer in beryllium‐exposed workers derives from large US studies of beryllium process workers and of a US national register of beryllium workers. Although there have been several research reports, the evidence base is restricted to only a few cohorts with relevant data. The Council found no UK‐relevant studies to inform its inquiries.”
It can be concluded that the evidence for beryllium’s carcinogenic potential in humans is not as clear as suggested, and epidemiological data should be considered to be inadequate for beryllium metal as a substance, as data has been generated in groups exposed to various beryllium salts and compounds.
New studies, generated in accordance with OECD standards and GLP requirements and conforming with all the requirements of REACH, provide the scientific evidence that demonstrates that the current cancer classification for beryllium metal is inaccurate.
In addition, these studies have provided the needed scientific basis to differentiate toxicity differences between beryllium metal (which is used commercially) and soluble beryllium compounds (not used commercially).
A detailed scientific analysis of all of the available literature, using a globally accepted protocol, clearly demonstrated that the existing animal data on carcinogenic properties is conclusive only for rats and not for any other species. Scientific evidence has well established that the rat has a propensity to develop cancers and is not an adequate model for predicting carcinogenicity in humans.
It is also evident based on a number of assessments, that the epidemiology delivers only controversial evidence for a carcinogenic potential of beryllium and its soluble compounds.
This conclusion is supported by the fact that all of the epidemiology is derived from the same cohort (of highly exposed beryllium production workers), and depending on the reviewer and the statistical methodologies, a very small excess cancer risk may be found or not found.
When the cancer risk is adjusted for smoking and/or local population cancer rates the overall cancer risk becomes statistically insignificant.
No initiatives to collect data to build up a new cohort reflecting current exposures with detailed investigation of smoking habits have been taken even though exposure to beryllium exists in other worker populations and in the general population due to its occurrence as a natural element.
The following studies, by Harlan Laboratories Ltd, using beryllium metal, were conducted pursuant to OECD methodologies and Good Laboratory Practice requirements (GLP).
1) Acute oral toxicity (OECD 423, GLP)
Beryllium powder was suspended in polyethylene glycol 300 (PEG 300) and administered to total of 6 female rats. The animals were then observed for the next 14 days for viability, clinical signs, and bodyweight development. At the conclusion of the study, the animals were also subjected to a macroscopic necropsy. No mortality or clinical signs indicative of toxicity of toxicity were observed. Bodyweight development was also normal. The only observation noted was feces stained grey on first day of observation. This was due to staining by beryllium powder. It is concluded that the LD50 following oral administration of beryllium powder was above 2000 mg/kg bw. Accordingly, no classification for acute oral toxicity is considered required for beryllium metal.
2) Skin irritation (OECD 404, GLP)
Beryllium powder (0.5 g) was moistened with water (0.5 ml) and applied to the skin of three New Zealand white rabbits for 4 hours. The test item was then removed by flushing with lukewarm water. The skin reaction was assessed 1, 24, 48, and 72 hours after exposure. There were no indications of skin irritation at any of the timepoints. Accordingly, no classification for skin irritation is considered required for beryllium metal.
3) Eye irritation (OECD 405, GLP)
Beryllium powder (0.1 g) was instilled into the conjunctival sac of the left eye of three New Zealand white rabbits. The right eye was left untreated and served as control. The eye reaction was evaluated after 1, 24, 48, and 72 hours, and 7 days after exposure. There were no reactions in the cornea or iris. There was however a mild and transient redness of the conjunctiva (mean 24-72 hour value of 1 on the Draize scale). This redness was completely gone after 7 days. No classification for eye irritation is considered required as the reactions seen did not fulfill the criteria of EU Directive 2001/59/EC and EU Regulation 1272/2008.
4) Skin sensitization (OECD 406, GLP)
Beryllium powder was suspended in PEG 300 to a 15% concentration and injected intradermally together with Freund’s adjuvant in the dorsal skin of the scapular region. One week later the same area was clipped free of hair and a 50% solution (0.3 ml) of beryllium powder in PEG 300 was applied. The test item was held in contact with the skin for 48 hours. Control animals were treated the same way but with vehicle only. The animals were challenged two weeks by applying 0.2 ml of a 10% solution of beryllium powder to the left flank while the vehicle only was applied to the right flank. The test substance was held in contact with the skin for the next 24 hours. The skin reaction was then assessed 24 and 48 hours after removal of the substance. No skin reactions were observed in the control group or in the treated group. Accordingly, no classification for skin sensitization is considered required for beryllium metal.
5) Bacterial reverse mutation test (OECD 471, GLP)
Beryllium metal was extracted by shaking with physiological saline for 3 days at 37°C. The following concentrations were achieved in two separate experiments: 733.7 µg/ml and 124.0 µg/ml. Dilutions of 2.5, 5, 10, 20, 40, 60, 80 and 100% of the beryllium solutions were used in the main experiment. The main experiment was performed in the following strains: TA 1535, TA 1537, TA 98, and TA 100. In the plate incorporation assay the bacterial strains were incubated with the test item extract, metabolic activation system (rat liver S9 mix) or not, and overlay agar. The mixture was poured on selective agar plates, allowed to solidify and incubated for at least 48 h in the dark. The preincubation assay was performed in a similar manner however with a 60 minute preincubation period before plating. The performance of the system was verified by using known mutagens (with and without metabolic activation). No cytotoxicity was observed at any of the concentrations tested. There was no increase in revertant colonies following exposure to beryllium metal extracts with and without metabolic activation.
6) Mammalian chromosome aberration (OECD 473, GLP)
As beryllium metal is relatively insoluble, it was extracted at 37°C for 3 days at a loading rate of 100 mg/l in the cell culture medium used in the assay under non-abrasive shaking. Extract concentration of 3.258/20.27 μg Be/ml culture medium with FCS and 20.83/4.434 μg Be/ml culture medium without FCS were analytically found in the extracts prepared for the first/second experiment. The extracts were used to expose the cells at 100% (pure extract), 75% and 50%. Human whole blood cultures were set up. After 72 h, the cells were incubated with the test item extracts for 4 or 22 hours in presence or absence of a metabolic activation system (rat liver S9 mix), respectively (cell culture medium of cultures with 4 hours exposure was replaced by fresh test item-free culture medium after that period). 19 hours after start of exposure, colcemid was added to the cultures to arrest cells in metaphase. Three hours later, cells were washed, fixed, metaphases stained and microscopically evaluated. All experimental conditions were tested in two independent cell cultures. The experiment was repeated for confirmation. Statistically significant increase in the number of structural chromosome aberrations was observed only at one incidence (22 h of 75% extract). As this increase was not dose-dependent (no increase at 100% extract), within the historical control data of the laboratory and was not reproducible in the repeat experiment, it was considered incidental. Beryllium metal powder, extracted at worst-case conditions in culture medium for cell exposure, was not clastogenic in human lymphocytes.
7) Mammalian mutation (OECD 476, GLP)
Due to insolubility of the test item in cell culture media, the test item was extracted at 37°C for 3 days at a loading rate of 100 mg/l in the culture medium used in the assay under non-abrasive shaking. The extracts were used to expose the cells. The following concentrations were achieved: 3.12 µg Be/ml culture medium were analytically found in the extract prepared for the first experiment; 4.477 µg Be/ml culture medium were analytically found in the extract prepared for the second experiment without FCS, and 14.02 µg Be/ml in the extract prepared with FCS. The assay was performed in two independent experiments. V79 cells were exposed to the test item extracts for 4 h with and without metabolic activation (rat liver S9 mix), or for 24 h in absence of metabolic activation. The highest concentration of the test item extract was 100%, and the lowest concentration investigated was 12.5%. Three days after treatment, cells were subcultivated. After an expression time of 7 days, cells were again subcultivated and 6-thioguanine was added to the culture medium to kill all cells that were not mutated in the HPRT-locus. Surviving cells were allowed to form colonies within 8 days. Colonies were stained, their size evaluated, and counted. Cell survival was determined after treatment (parallel cultures) and after subcultivation. The performance of the test system was proven by parallel experiments with know mutagens. Beryllium metal powder extracts did not induce mutations in the HPRT locus of V79 cells.
8) Unscheduled DNA synthesis
Due to insolubility of the test item in cell culture media, the test item was extracted at 37°C for 3 days at a loading rate of 100 mg/l in the culture medium used in the assay under non-abrasive shaking. The extracts were used to expose the cells.
The UDS study contains the results from many different experiments. Freshly isolated rat hepatocytes were exposed to 0, 50% or 100% of beryllium metal extract with 0, 0.67, 1.19, 1.71, or 2.23 µg/ml 2-AAF for 18 hours in the presence of 3HTdR (methyl-3H-thymidine). The uptake of radioactivity was determined by autoradiography. Vehicle control groups and cultures treated only with the beryllium metal powder extract were tested in parallel. For each concentration, including the controls, 100 cells were evaluated. In the DNA repair assay the mutagen (2-AAF) alone was always able to induce relevant DNA repair synthesis (distinct increase in the number of nuclear and net grain counts as well as % cells in repair). No increase in DNA repair was observed for cells treated with the test item extract alone. When cells were treated in parallel with the mutagen 2-AAF a distinct decrease of the of the mean net grain counts and of the amount of cells in repair was found after treatment with 100 % of the test item extract. However, a clear dose dependence was not observed. It is concluded that beryllium metal extract did not cause DNA damage in this study but at the highest dose exerted an effect on the repair of pre-existing DNA damage.
9) Cell transformation assay (OECD Draft Proposal: In vitro Syrian hamster embryo (SHE) cell transformation assay, GLP)
As beryllium is relatively insoluble in cell culture media, the test item was extracted at 37°C for 3 days at a loading rate of 100 mg/l in the culture medium used in the assay under non-abrasive shaking. The extracts were used to expose the cells. A concentration of 22.95 µg Be/ml culture medium was analytically found in the extract prepared for the experiment. Female and male hamsters were mated, and the pregnant females sacrificed in day 13 of gestation. Embryos were isolated from the uteri, decapitated, eviscerated and delimbed and the remaining parts minced in washing solution. Cells were obtained by stirring the pieces in trypsin/pancreatin solution for 10 min., and recovery of the isolated cells from the supernatant by centrifugation. Cells were plated, dead cells removed after 3-4 hours by washing, and cells were allowed to expand for 20 hours. Thereafter, cells were trypsinized and stored frozen in liquid nitrogen until use. For the experiments, a first layer of cells was seeded on culture dishes and lethally irradiated (feeder cells). The next day, the target cells were seeded on top of the feeder cells. The cells were incubated with the test item extracts (25-100%) for 7 days continuously to allow colony formation. Thereafter, cells were fixed with methanol, stained with Giemsa and microscopically evaluated for colony morphology. No metabolic activation system was used, as the primary SHE cells have enough metabolic capacity. Performance of the test system was proven by parallel experiments with benzo[a]pyrene. No cytotoxicity was observed at any of the concentrations tested. Beryllium metal powder extracts induced a criss-cross growth of cells within the colonies, which is different compared to the normal waive-like growth of SHE cell colonies.
Beryllium metal is not acutely toxic and does not cause eye and skin irritation, or skin sensitization. The studies also clearly demonstrate that beryllium metal does not induce DNA damage (mutagenic or larger structural re-arrangements). Extract of beryllium metal did also not induce unscheduled DNA synthesis, indicative of DNA damage, in the UDS study. The same experiment also investigated the effects of co-incubating with beryllium and the positive control, 2-acetylaminofluorene. It was observed that beryllium had an effect on DNA repair synthesis (suppressed) at the highest concentration of 2-aminofluorene (96% of cells in repair synthesis). The cell transformation assay indicated that beryllium metal extracts can induce changes in colony morphology of Syrian hamster embryo cells. However, the mechanism behind this effect, and the relevance to human exposure, can not be determined. As the genotoxicity tests were all negative, it is excluded that the morphological change observed is due to mutation or chromosome structural changes. The results of the REACH studies have been presented in peer reviewed papers, Strupp C. (2011) Beryllium Metal I. Experimental Results on Acute Oral Toxicity, Local Skin and Eye Effects, and Genotoxicity. Ann Occup Hyg; 55: 30–42 and Strupp C. (2011) Beryllium Metal II. A Review of the Available Toxicity Data Ann Occup Hyg; 55: 43–56. These new and important studies have been summarized in English, German and French.
The primary potential health risk associated with the processing of beryllium metal and beryllium-containing materials is chronic beryllium disease (CBD). Throughout the history of beryllium usage, prevention of CBD has dictated the level of risk management measures employed to protect workers and the public. Inhalation of beryllium particulate is the primary toxicologically relevant route of exposure for CBD. Controlling worker occupational exposures to beryllium can include process ventilation, defined work practices and personal protective equipment.
Beryllium metal, copper-beryllium alloys (CuBe), aluminium-beryllium alloys (AlBe) and nickel-beryllium alloys (NiBe), in solid form and as contained in finished products, present no special health risks. Most manufacturing operations conducted properly on well-maintained equipment are capable of safely processing beryllium-containing alloys. However, like many industrial materials, beryllium does present a health risk if handled improperly. The inhalation of beryllium dust, mist or fume can cause a serious lung condition in some individuals. The degree of hazard varies depending on the form of the product, and how the material is processed and handled. All metal removal operations performed on beryllium products must be performed with appropriate work practices and engineering controls designed to control the release or generation of airborne beryllium-containing dust, mist or fume. The highest potential for exposure exists in foundries that normally melt and cast a variety of alloys. Very few of the alloys cast contain beryllium, and none contain more than 2 % Be. The more common alloys in foundries that occasionally cast beryllium containing alloys produce other bronzes like CuCrZr, CuNiSi, CuP, CuAl, CuAlNi. Be containing master alloys are added to the molten copper in the furnace to introduce beryllium into the alloy, before it is cast in moulds. Further processing may occur to meet customer specifications. This processing is usually performed at other locations having the capabilities for further processing.
Potential for exposure to beryllium-containing particulate should be determined by conducting a workplace exposure characterization which includes air sampling in the worker’s breathing zone, work area and throughout the department. Facilities handling beryllium-containing materials in ways which generate particulate are encouraged to use engineering and work practice controls, including personal protective equipment, to control potential worker exposure.
A model was developed that focuses on keeping beryllium work areas clean and keeping particles and solutions containing beryllium out of the lungs, off the skin, off of clothing, in the work process, in the work area and on the plant site. Worker and management education and motivation are important components. A combination of engineering, work practice and personal protection approaches are used, as needed, to attain the reduction in potential occupational exposure. The model prevents sensitization to beryllium (BeS), subclinical chronic beryllium disease (CBD) and clinical CBD. The model is based on the knowledge, experience and understanding gained from the most recent studies which includes the potential exposure risks posed by the various chemical forms of beryllium and disease prevention methods tailored to specific material processing operations, engineering, work practice control, and personal protective measures that have been demonstrated to be effective in preventing sensitization and CBD.
Research findings suggest that consistently keeping airborne exposure in beryllium production operations to beryllium below of 2.0 µg/m3 can prevent clinical CBD. Recent research findings have also indicated that individuals at operations with exposures that rarely exceed 0.2 µg/m3 did not experience sensitization or subclinical CBD.
The studies by Madl (2007) and United States National Institute for Occupational Safety and Health (2005) provide the best evidence to demonstrate that CBD (predominantly subclinical CBD) can occur in workers exposed at levels below 2.0 µg/m3. The Madl study, using over 3,000 personal air samples, is the first study to actually perform a complete dose reconstruction of persons defined as beryllium sensitized or diagnosed with subclinical CBD or clinical CBD. The Madl study concluded:
“Results showed that exposure metrics based on shorter averaging times (i.e., year versus complete work history) better identified the upper bound worker exposures which could have contributed to the development of BeS or CBD. It was observed that all beryllium sensitized and CBD workers were likely exposed to beryllium concentrations greater than 0.2 µg/m3 (95th percentile) and 90% were exposed to concentrations greater than 0.4 µg/m3 (95th percentile) within a given year of their work history. Based on this analysis, it would appear that BeS and CBD generally occurred as a result of exposures greater than 0.4 µg/m3 and that maintaining exposures below 0.2 µg/m3 95% of the time may prevent BeS and CBD in the workplace.”
The NIOSH study performed a cross-sectional survey to examine prevalence of BeS and CBD, and relationships between BeS and CBD and work areas/processes at a copper beryllium alloy strip and wire finishing facility. The study concluded:
“Sensitization and CBD were associated with an area in which beryllium air levels exceeded 0.2 µg/m3, and not with areas where this level was rarely exceeded.”
In another study by the National Institute for Occupational Safety and Health an epidemiological surveillance study was completed to detect sub-clinical (asymptomatic) chronic beryllium disease (CBD) among a population of 264 workers at the world’s largest primary beryllium production facility over a six year period. The strengths of this study lie in its design and in the detailed data that were available, both from workers (e.g., specific work histories) and from existing historical sampling data where 4022 full-shift personal cassette samples representing 269 different jobs was available for analysis (averaging over 14 samples per job title). The personal exposure data was adjusted for changes in worker exposure over time by estimating the overall annualized changes in exposure using 76,349 area samples collected over the study period. The exposure estimates for each job were applied to each worker’s work history to generate worker-specific historical exposure profiles, which were then summarized for use in epidemiologic analyses. This analysis, creating job exposure matrices for all categories of production, production support and administrative personnel, is unsurpassed by any previous study. The study observed that 6 of the 264 workers exposed above 0.38 µg-yrs/m3 were determined to have asymptomatic sub-clinical CBD. The study also showed that persons having cumulative exposures below 0.38 µg-yrs/m3 did not have subclinical or clinical chronic beryllium disease.
