The mortality experience of a cohort of 3346 underground uranium miners evaluated in 1977 was updated through 1982. As of 1982, there were 1214 miners who were deceased; 255 had died of lung cancer. Variables considered in the development of the model included cumulative exposure, exposure rate, cumulative cigarette smoking, smoking rate, age at initial exposure, calendar year of initial exposure, birth year, height, duration of underground employment, and years of prior hardrock mining. Cumulative cigarette smoking and cumulative radon daughter exposure had a joint effect intermediate between additive and multiplicative, implying a synergistic relationship. Results indicated that modeling cumulative exposure alone may not adequately predict the relative risk of lung cancer from chronic exposure to radon daughters. Miners receiving a given amount of cumulative exposure at lower rates for longer periods of time were at greater risk relative to those with the same cumulative exposure received at higher rates for shorter time periods. Data suggested that radon daughters act at a late stage in the carcinogenic process. The epidemiologic model developed for this study was found to provide a very good fit to data from 60 to 6000 working level months.
NIOSH, Cincinnati, Ohio, 52 pages, 32 references