Inorganic arsenic--ambient level approach to the control of occupational cancerigenic exposures.

In 1820 the first malignancies ascribed as due to occupational arsenic exposure were reported as scrotal cancers among smelters. A century later the causal relationship between chronic occupational, environmental or medical arsenical exposure and skin carcinogenesis was firmly established. From 1948 to 1975, nine out of eleven epidemiological studies have shown, initially or upon review, significant excess mortality from respiratory cancer among diverse occupations exposed to various inorganic arsenicals. Two of the nine studies have shown concommitant, significant excess mortality from lymphatic cancer, and another, from skin cancer. Additionally, two such studies have revealed a dose-response relationship between arsenical exposure and lung carcinogenesis. In the first, reported in 1969, the relationship was semi-quantitative, with a possible interactive role by sulfur dioxide or other contaminants. The other demonstrated a dose-response which was quantitative for arsenic per se. Upon our reinterpretation, this dose-response also demonstrated an increased lung cancer mortality risk apparently at arsenic concentrations above 1 mug/M3, calculated as the 8-hour TWA daily exposure over a 40-year working life. However, these and related data do not reveal a definite no-effect exposure level. Thus, in the absence of data documenting a cancerigenically safe level of occupational exposure and because of the environmental ubiquity of arsenic, the conclusion is drawn that the arsenic body burden of workers should not be occupationally increased above that produced by the ambient level.