Residential radon exposure and lung cancer risk in Misasa, Japan: a case-control study

In order to investigate an association between residential radon exposure a nd risk of lung cancer, a case-control study was conducted in Misasa Town, Tottori Prefecture, Japan. The case series consisted of 28 people who had d ied of lung cancer in the years 1976-96 and 36 controls chosen randomly fro m the residents in 1976, matched by sex and year of birth. Individual resid ential radon concentrations were measured for 1 year with alpha track detec tors. The average radon concentration was 46 Bq/m(3) for cases and 51 Bq/m( 3) for controls. Compared to the level of 24 or less Bq/m(3), the adjusted odds ratios of lung cancer associated with radon levels of 25-49, 50-99 and 100 or more Bq/m(3), were 1.13 (95% confidence interval; 0.29-4.40), 1.23 (0.16-9.39) and 0.25 (0.03-2.33), respectively. None of the estimates showe d statistical significance, due to small sample size. When the subjects wer e limited to only include residents of more than 30 years, the estimates di d not change substantially. This study did not find that the risk pattern o f lung cancer, possibly associated with residential radon exposure, in Misa sa Town differed from patterns observed in other countries.