* Animal studies have also reported effects on the lung, such as chronic pneumonitis, from chronic inhalation exposure. (1-3)

* The Reference Concentration (RfC) for beryllium is 0.00002 milligrams per cubic meter (mg/m3) based on respiratory effects in humans. The RfC is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. It is not a direct estimator of risk but rather a reference point to gauge the potential effects. At exposures increasingly greater than the RfC, the potential for adverse health effects increases. Lifetime exposure above the RfC does not imply that an adverse health effect would necessarily occur. (3)

* EPA has medium confidence in the RfC due to: (1) medium confidence in the study on which the RfC is based because no NOAEL was identified in the study, but a NOAEL slightly below the LOAEL was suggested in another study; and (2) medium confidence in the database due to lack of adequate exposure monitoring in the epidemiology studies and some uncertainty regarding the mechanism associated with progression to chronic beryllium disease in beryllium-sensitized individuals. (3)

* The Reference Dose (RfD) for beryllium is 0.002 milligrams per kilogram body weight per day (mg/kg/d) based on small intestinal lesions in dogs. (3)

* EPA has low to medium confidence in the RfD due to: (1) medium confidence in the study on which the RfD was based because there were small groups of animals, early mortality at the high dose level, no measure of immune response or function, and no control for potential litter effects, and (2) low to medium confidence in the database because there is only one chronic study in dogs showing adverse effect levels and other chronic studies in rodents demonstrated NOAELs at the highest doses tested. (3)

Reproductive/Developmental Effects:

* The potential for beryllium to induce developmental or reproductive effects has not been adequately assessed.

* Limited information is available on the reproductive or developmental effects of beryllium in humans following inhalation exposure. A case control study found no association between paternal occupational exposure and the risk of stillbirth, pre-term delivery, or small-for-gestational-age infants, although this study has limited sensitivity. (2,3)

* No data are available on reproductive or developmental effects in animals following inhalation. (2,3)

Cancer Risk:

* Several human epidemiological studies have investigated the relationship between beryllium exposure in workers and lung cancer deaths. Although there are shortcomings in all the studies, the results are suggestive of a causal relationship between beryllium exposure and an increased risk of lung cancer. (2,3)

* Beryllium compounds have been shown to cause lung cancer from inhalation exposure in rats and monkeys. (1,2,3)

* EPA has classified beryllium as a Group B1, probable human carcinogen. (3)

* EPA uses mathematical models, based on animal and human studies, to estimate the probability of a person developing cancer from breathing air containing a specified concentration of a chemical. EPA calculated an inhalation unit risk estimate of 2.4 × 10-3 (µg/m3)-1. EPA estimates that, if an individual were to continuously breathe air containing beryllium at an average of 0.0004 µg/m3 (4 x 10-7 mg/m3) over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical. Similarly, EPA estimates that continuously breathing air containing 0.004 µg/m3 (4 x 10-6 mg/m3) would result in not greater than a one-in-a-hundred thousand increased chance of developing cancer, and air containing 0.04 µg/m3 (4 x 10-5 mg/m3) would result in not greater than a one-in-ten thousand increased chance of developing cancer. For a detailed discussion of confidence in the potency estimates, please see IRIS. (3)

Physical Properties