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A simulation study of radon and thoron discrimination problem in case-control studies
Kazutaka Doi1, Shinji Tokonami, Hidenori Yonehara
1Regulatory Sciences Research Group, National Institute of Radiological Sciences, Chiba-shi, Chiba, Japan. kazutaka@nirs.go.jp
Journal of Radiation Research
|August 15, 2009
Summary
Thoron (Rn-220) interference in radon (Rn-222) measurements can cause significant downward bias in lung cancer risk studies. Using detectors with thoron discrimination is crucial for accurate epidemiological research.
Area of Science:
- Environmental Health
- Radiation Science
- Epidemiology
Background:
- Radon (Rn-222) is a major source of natural radiation exposure for the public.
- Previous studies on residential radon and lung cancer risk have yielded inconsistent results.
- Thoron (Rn-220) can interfere with passive radon detectors lacking thoron discrimination.
Purpose of the Study:
- To evaluate the impact of thoron interference on radon measurements.
- To assess the effect of thoron interference on lung cancer risk estimation in epidemiological studies.
Main Methods:
- A simulation study was conducted.
- Assumptions included varying numbers of cases, matching ratios, baseline risks, radon-related risks, radon and thoron concentrations, their correlation, and detector types.
- Evaluated bias in radon measurements due to thoron.
Main Results:
- Thoron interference can cause up to a 90% downward bias in estimated radon-related lung cancer risk under certain conditions.
- Bias magnitude increased with decreased radon concentration and increased thoron concentration.
- Bias was more pronounced with lower geometric means and higher geometric standard errors for radon, and vice versa for thoron.
Conclusions:
- Thoron interference significantly underestimates radon's contribution to lung cancer risk.
- Accurate epidemiological studies require passive radon detectors with thoron discrimination capabilities.
- Future research should utilize thoron-discriminating detectors to ensure reliable risk assessment.
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