Beryllium, exposure

A new area of research concerns exposure assessment for beryllium in the production of nuclear weapons at nuclear defense industries. A safe level of exposure to beryllium is still unknown. Potential explanations include (1) the current exposure standard may not be protective enough to prevent sensitization, or (2) past exposure surveillance may have underestimated the actual exposure level because of a lack of understanding of the complexity of beryllium exposures. Task-based exposure assessment provides information not directly available through conventional sampling. It directly links exposure to specific activity associated with contaminant generation and provides in-depth evaluation of the worker s role in a specific task. In-depth task analysis is being used to examine physical, postural, and cognitive demands of various tasks. 

Program faculty members are developing an automated cascade impactor for collection of task-based size distribution data of beryllium-containing aerosols. Based on the size distribution, the fraction of beryllium-containing aerosol penetrating a respirator and the inhalation and deposition in different regions of the lungs can be estimated. 

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Further evidence that beryllium is a human lung carcinogen was the recent finding of increased risk among workers with higher beryllium exposures when dose estimates were lagged for 10 or 20 years. ... 

Environmental beryllium exposure is not generally thought to be a hazard to human health except in the vicinity of industrial sites where air, water and soil pollution have occurred. 

Beryllium, beryllium-containing alloys, and beryllium oxide ceramic in solid or massive form present no hazard whatsoever (31). Solid shapes maybe safely handled with bare hands (32) however, care must be taken in the fabrication and processing of beryllium products to avoid inhalation of airborne beryllium particulate matter such as dusts, mists, or fumes in excess of the prescribed workplace exposure limits. Inhalation of fine airborne beryllium may cause chronic beryllium disease, a serious lung disease in certain sensitive individuals. However, the vast majority of people, perhaps as many as 99%, do not react to beryllium exposure at any level (33). The biomedical and environmental aspects of beryllium have been summarized (34). 

The characteristics of long latency, miniscule insult levels, and nonspecific or low incidence pathology probably confounds trace element research as well. It is well established, for example, that the pulmonary syndrome associated with chronic beryllium exposure (24) and the skin cancer associated with chronic arsenic exposure (25) may have latency periods described in decades. Furthermore, berylliosis only affects a very small percentage of the population exposed. 

Beryllium compromises the immune system. Enzymes catalyzed by magnesium or calcium can be inhibited by beryllium succinic dehydrogenase is activated. Beryllium exposure leads to a deficiency in lung carbon monoxide diffusing capacity. Hypercalcemia (excess of calcium in the blood) can occur. 

Other effects of beryllium exposure include enlargement of the heart (which can lead to congestive heart failure), enlargement of the liver, and kidney stones. Finger clubbing is often seen with berylliosis. 

A sarcoidosis-like pulmonary disease has been clearly associated with beryllium exposure. 

Beryllium (atomic mass 9.01) is not truly a heavy metal, but this is one of the more hazardous toxic elements. Its most serious toxic effect is berylliosis, a condition manifested by lung fibrosis and pneumonitis, which may develop after a latency period of 5-20 years. Beryllium exposure also causes skin granulomas and ulcerated skin and is a hypersensitizing agent. 

In 1949, the Atomic Energy Commission adopted limits for beryllium exposure in the workplace of 25 pg m as a peak value and 2 pg m averaged over an 8-h day. These standards have essentially eliminated acute beryllium disease, and the last reported case occurred during the 1960s in the United States (Eisenbud and Lisson 1983). However, chronic beryllium disease has continued to occur, and recently the... 

Oral ingestion of beryllium has not been associated with any clinical diseases, and current studies do not suggest any risk from oral ingestions. While lung cancer is probably associated with increased beryllium exposures, the best data seems to indicate that the high exposures which occurred in the past were responsible, and suggest that cancer risk is not now a major problem. 

Beryllium exposure has been studied in 3185 workers from nine aluminium smelters owned by four different aluminium-producing companies, of whom 1932 workers participated in medical surveillance programs that included the serum beryllium lymphocyte proliferation test, confirmation of sensitization by at least two abnormal test results, and further evaluation for chronic beryllium disease in workers with beryllium sensitivity [41 ]. Nine workers had beryllium sensitivity (prevalence rate = 0.47%, 95% CI = 0.21, 0.88). The authors attributed the low rate of sensitization in aluminium smelters to the more soluble form of beryllium found in the aluminium smelting work environment and the consistent use of respiratory protection. 

Powers, M.B. Potential Beryllium Exposure While Processing Beryllia Ceramics for Electronics Applications. Brush Wellman, Cleveland, OH. 

The number of workers with potential beryllium exposure is not known, although estimates in the United States have ranged from 134,000 workers currently exposed to 800,000 individuals currently and previously exposed (17,39,40). It is likely that these numbers underestimate the actual number of exposed individuals, as it is difficult to estimate the number of downstream users of beryllium and former workers, and it does not include estimates outside the United States (1). The prevalence of CBD, from 20 epidemiologic studies, has been estimated at 1% to 5% of exposed workers, depending on the group of workers studied... 

Exposure to elevated concentrations of beryllium, usually in the 25 pg/m range or greater, (120) can result in inflammation of the upper and lower respiratory tract and airways, tracheitis, bronchiolitis, pulmonary edema, and a lymphocyte-predominant chemical pneumonitis (12,121-123). Although significantly less common than CBD, acute beryllium disease stiU occurs globally. In 2004, nine cases were reported from a South Korean liquid metal factory where measured beryllium exposures ranged from 3.13 to 112.3 pg/m (12). The manifestations... 

The primary therapeutic intervention is removal from exposure. Corticosteroids, oxygen, rest, and even ventilatory support, if needed, are part of an appropriate treatment regimen. The signs and symptoms of acute chemical pneumonitis may resolve within several weeks to several months. In its most severe form, this acute disease may be fatal. Approximately 17% of the acute cases in the Beryllium Case Registry progressed to CBD (122). It is unclear whether return to work and further beryllium exposure is safe for individuals who have experienced the acute pneumonitis. 

Infante PF, Newman LS. Beryllium exposure and chronic beryllium disease. Lancet 2004 363(9407) 415 16. 

Deubner DC, Lowney YW, Paustenbach DJ, et al. Contribution of incidental exposure pathways to total beryllium exposures. Appl Occup Environ Hyg 2001 16(5) 568-578. 

Beryllium exposure occurs in a wide variety of occupations. It may cause acute berylliosis (currently very rare), beryllium sensitization, chronic beryllium disease, or lung cancer. Imaging manifestations of chronic beryllium disease are generally similar to those of sarcoidosis, with nodules, ground glass abnormality, septal thickening, conglomerate masses, and mediastinal or hilar lymphadenopathy. 

In a retrospective study of the beryllium-processing industry, Seiler et al. (179,180) reviewed beryllium exposure measurements collected from 1950 through 1978 at five different facilities. More than 35 job titles were identified, with beryllium exposure concentration estimates based on job titles ranging from 0.12 pg/m for nurses at one facility to 22 pg/m for leach mill operators at another facility (compared with the 8-hr TWA exposure limit of 2 pg/m ). However, the authors noted that only 58% of the plant-specific job titles had at least two exposure measurements. In addition, sufficient information on individual plant processes was not available to fully characterize the potential reductions in exposure by engineering controls over time. In their analysis of 643 individual daily weighted average exposure values from 1972 to 1975, 67% of the mean breathing zone values exceeded 2 pg/m and 73% of the maximum exposures... 

Seiler DH, Rice C, Herrick RF, Hertzberg VS. A study of beryllium exposure measurements, part 1 estimation and categorization of average exposures from daily weighted average data in the beryllium industry. Appl Occup Environ Hyg 1996 11 89-97. 

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