Mm. Finkelstein, CLINICAL MEASURES, SMOKING, RADON EXPOSURE, AND RISK OF LUNG-CANCER IN URANIUM MINERS, Occupational and environmental medicine, 53(10), 1996, pp. 697-702
Objectives-Exposure to the radioactive daughters of radon is associate
d with increased risk of lung cancer in mining populations. An investi
gation of incidence of lung cancer following a clinical survey of Onta
rio uranium miners was undertaken to explore whether risk associated w
ith radon is modified by factors including smoking, radiographic silic
osis, clinical symptoms, the results of lung function testing, and the
temporal pattern of radon exposure. Methods-Miners were examined in 1
974 by a respiratory questionnaire, tests of lung function, and chest
radiography. A random selection of 733 (75%) of the original 973 parti
cipants was followed up by linkage to the Ontario Mortality and Cancer
Registries. Results-Incidence of lung cancer was increased threefold.
Risk of lung cancer among miners who had stopped smoking was half tha
t of men who continued to smoke. There was no interaction between smok
ing and radon exposure. Men with lung function test results consistent
with airways obstruction had an increased risk of lung cancer, even a
fter adjustment for cigarette smoking. There was no association betwee
n radiographic silicosis and risk of lung cancer. Lung cancer was asso
ciated with exposures to radon daughters accumulated in a time window
four to 14 years before diagnosis, but there was little association wi
th exposures incurred earlier than 14 years before diagnosis. Among th
e men diagnosed with lung cancer, the mean and median dose rates were
2.6 working level months (WLM) a year and 1.8 WLM/year in the four to
14 year exposure window. Conclusions-Risk of lung cancer associated wi
th radon is modified by dose and time from exposure. Risk can be subst
antially decreased by stopping smoking.