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An epidemiological analysis of the relationship between exposure to Rn progeny, smoking and bronchogenic carcinoma in the U-mining population of the Colorado Plateau--1960-1980.

This study investigates the relationship between exposure to radioactive Rn decay products during U mining and milling operations, cigarette smoking and age, on the incidence and mortality rates of lung cancer among U workers of the Colorado Plateau during the 20-yr period from 1960-1980. A case control sample was taken from an extensive data base of 9,817 men accumulated by one author (Saccomanno). A preliminary hypothesis had been made that a possible synergistic or at least additive effect might exist when the risk factors of exposure to Rn decay products and smoking were simultaneously present. This study would seem to indicate that a synergistic effect is not present. In this work, a total of 489 cases, defined as men having a cytological diagnosis of moderate or worse atypical squamous-cell metaplasia, and a random sample of 992 "non-cases" were selected retrospectively from the dynamic cohort of workers. These data analyzed from three different perspectives indicate significant effects due to Rn-decay-product exposure in excess of the expected incidence due to age and smoking history. The data also indicate that Rn-decay-product accumulations of less than 300 working level months (WLM) is not carcinogenic in non-cigarette smokers.