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A RETROSPECTIVE LUNG CANCER MORTALITY STUDY OF PEOPLE EXPOSED TO INSOLUBLE ARSENIC SALTS AND RADON (SUMMARY) Liu, Yu Tang; Chui, Jin Institute of Occupational Medicine, Chinese of Preventive Medicine Beijing, China 100050 I. Although arsenic is an established carcinogen, nevertheless before 1983 there was no epidemiological evidence of carcinogenic activity for insoluble arsenic salts. The following results provide evidence that insoluble arsenic salts cause lung cancer. A. A retrospective cohort study of miners exposed to an insoluble arsenic salt (FeAsS) reported a mortality rate of 250/105. Another retrospective cohort study of miners exposed to another insoluble arsenic salt (AsZS2) reported a mortality rate of 290/105. B. The "arsenic dose" in lung tissues of miners with lung cancer who were exposed to insoluble arsenic salts was 17 times higher than that in "ordinary" populations (48.3:2.9 mg/g; n=100).

C. A significant dose-response relationship was found between arsenic concentrations in lung cancer tissues. D. Insoluble arsenic salts in many minerals exist in the form FeAsS. Their biological properties have not been studied. They are, however, recognized as non-soluble "insert" and "non-toxic. " In order to explore the etiology of lung cancer and to understand whether arsenopyrite (FeAsS) is "inert" in mammals, a metabolic study was carried out in rats using arsenopyrite. It was found that arsenopyrite through a biological catalytic reaction not only becomes soluble, but also produces a metabolite, which is a known carcinogen. This is arsenic trioxide, which in turn is metabolized to arsenous acid, arsenic acid, methyl arsenic and dimethyl arsenic. There is no doubt that arsenopyrite is a carcinogenic agent. - 2 -

E. Results of a multiple-factor (As, Cr, Ni, Be and Cd) logistic regression analysis showed that only As was significant. II. While radon is a well-known lung carcinogen, in the past, it has been recognized that a cumulative dose which when reaches 100 WLM may lead to risk of lung cancer. A 40-year retrospective cohort study showed that the average cumulative dose for each miner was 700 WLM, however, no extra lung cancer patients were observed. The cumulative dose limit thus increased from 100 WLM to 700 WLM. Therefore, the excess relative risk per WLM is calculated to be 0.214.