Cancer and occupational exposure to arsenic: A study of pesticide workers

Mortality and morbidity experience was studied in 1,393 persons exposed to considerably high air concentrations of inorganic arsenicals for varying lengths of time during the manufacture and packaging of various pesticides in a plant in Baltimore, Maryland. Study subjects were traced for the period 1946–1977, and vital status was determined for 86.9% of 1,050 men and 66.8% of 343 women. The observed numbers of deaths from all and selected causes were compared with the expected numbers of deaths derived from population mortality rates. Among men, 23 deaths from lung cancer and 2 deaths from anemias represented statistically significant excesses over the expected numbers (P < 0.05). Lung cancer mortality was especially high in male production workers with presumed high exposure to arsenicals for a prolonged period of time. A dose-response effect was suggested for lung cancer mortality which increased with length of arsenical exposure, but no such relationship appeared for nonarsenical exposure. Workers with high arsenical exposure also had increased frequencies of such forms of arsenism as keratoses and perforation of the nasal septum. Analysis of the 23 male lung cancer deaths and 23 matched controls suggested a relationship, though not statistically significant, between lung cancer and antecedent keratoses. These findings provide strong evidence for a causal relationship between occupational exposure to inorganic arsenicals and lung cancer.