Objectives Lung cancer caused by radon in miners is a well-known risk. However, the risk estimates vary between studies and between mines. We have studied the dose response–relationship in a Swedish iron ore mine where two other studies have previously reached different risk estimates. As this mine has relatively low radon levels, the results are highly relevant for risk estimation in non-uranium underground mines.
Methods A new cohort of 5486 male workers employed from 1923 to 1996 was established. Cumulative radon exposures were assessed based on a large number of measurements, including reconstructions of historical conditions. 122 lung cancer cases occurred during the follow-up period of 1958–2000.
Results The average cumulative exposure in underground workers was 32 kBq year/m3 (65 working level months (WLM)), experienced over 14.6 years. The excess RR (ERR) per kBq year/m3 was 0.046 (95% CI 0.015 to 0.077; 0.022 ERR/WLM). Confounding by quartz may affect these results but appears to account only for 10–20% of the risk. The results for squamous cell and small cell lung cancer were 0.049 and 0.072, respectively. However, no increased risk was observed for adenocarcinoma (0.000 ERR per kBq year/m3, 95% CI −0.017 to 0.017).
Conclusion Our overall risk estimate is about half of that found in the first Malmberget study but twice that found in the same cohort in the previously published pooled analysis. Radon did not increase the risk for adenocarcinoma in the lung.
- Lung cancer
- non-ionizing radiation
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Funding This study was financially supported by the Swedish Council for Working Life and Social Research, the Swedish Radiation Protection Authority and the Cancer Research Foundation in Northern Sweden.
The study has been carried out with the permission of the mining company, LKAB.
Competing interests One of the authors was previously employed and one is still employed by the company.
Ethics approval This study has been approved by the Ethics Committee at Umeå University (ref. 03-040).
Provenance and peer review Not commissioned; externally peer reviewed.
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