UPDATED MORTALITY ANALYSES OF PERNIS EPIDEMIOLOGIC DATA ON HUMAN EXPOSURES TO ALDRIN AND DIELDRIN

An extensive clinical and epidemiological study of workers engaged in the manufacturing and formulation of aldrin and dieldrin, the Pernis s tudy, provides occupational hygiene and biological monitoring data on individual exposures over the years of employment and provides the opp ortunity to investigate dose-response relationships for these chemical s. The human epidemiological mortality data on these workers, who were exposed to fairly substantial lifetime average daily doses of aldrin and dieldrin, suggest that low-dose exposures do not significantly inc rease human mortality and may even decrease the human mortality hazard rate. While hormesis from low-dose exposure to aldrin and dieldrin is not statistically significant, it is observed in the raw data and in the best fitting dose-response models. The decrease in risk suggests i ncreased survival time at low doses of aldrin and dieldrin. Using an u pper bound on cancer potency based on mouse liver tumors, the U.S. Env ironmental Protection Agency (EPA) estimated that lifetime average dai ly doses (LADDs) of 0.0000625 and 0.00625 mu g/kg body weight/day woul d correspond to increased cancer risks of 0.000001 and 0.0001, respect ively. However, the best estimate from the Pernis epidemiological data is that LADDs of 0.0000625 and 0.00625 mu g/kg body weight/day corres pond to no increase in cancer risk and a decrease in the probability o f mortality from all causes by the age of 70 years. At low doses of al drin and dieldrin, the estimated decrease in mortality in a reference period of 70 years is more than 1000 times larger than the U.S. EPA's upper bound on the increase in the lifetime probability of cancer.