Residential radon gas exposure and lung cancer - The Iowa radon lung cancer study

Exposure to high concentrations of radon progeny (radon) produces lung canc er in both underground miners and experimentally exposed laboratory animals . To determine the risk posed by residential radon exposure, the authors pe rformed a population-based, case-control epidemiologic study in Iowa from 1 993 to 1997. Subjects were female Iowa residents who had occupied their cur rent home for at least 20 years. A total of 413 lung cancer cases and 614 a ge-frequency-matched controls were included in the final analysis. Excess o dds were calculated per 11 working-level months for exposures that occurred 5-19 years (WLM5-19) prior to diagnosis for cases or prior to time of inte rview for controls, Eleven WLM5-19 is approximately equal to an average res idential radon exposure of 4 pCl/liter (148 Bq/m(3)) during this period, Af ter adjustment for age, smoking, and education, the authors found excess od ds of 0.50 (95% confidence interval: 0.004, 1.81) and 0.83 (95% percent con fidence interval: 0.11, 3.34) using categorical radon exposure estimates fo r all cases and for live cases, respectively. Slightly lower excess odds of 0.24 (95 percent confidence interval: -0.05, 0.92) and 0.49 (95 percent co nfidence interval: 0.03, 1.84) per 11 WLM5-19 were noted for continuous rad on exposure estimates for all subjects and live subjects only. The observed risk estimates suggest that cumulative ambient radon exposure presents an important environmental health hazard.