Cancer incidence and mortality from exposure to radon progeny among Ontario uranium miners

Abstract of the article published in Occupational & Environmental Medicine, December 2016

Author(s):
Garthika Navaranjan1, Colin Berriault1, Minh Do1, Paul J. Villeneuve1,2,3 and Paul A. Demers1,3

1 Occupational Cancer Research Centre, Cancer Care Ontario, Toronto, ON
2 Department of Health Sciences, Carleton University, Ottawa, ON
3 Dalla Lana School of Public Health, University of Toronto, Toronto, ON

Abstract:

The study objectives were to extend the follow-up of the Ontario uranium miners cohort, one of the largest cohorts of uranium miners with low cumulative exposures, in order to examine the relationship between radon exposure and lung cancer mortality and incidence, and to address literature gaps, including the dose–response relationship between radon exposure and other cancer sites, and non-cancer mortality.

A cohort consisting of 28,546 male mine and mill workers with a mean cumulative radon exposure of 21.0 working level months (WLM) was created from the Canadian National Dose Registry and the Ontario Mining Master File. The follow-up for the cohort was recently extended for mortality (1954–2007) and cancer incidence (1969–2005). The Poisson regression method was used to estimate relative risks (RR) and excess relative risks (ERR) and their 95% confidence intervals (CI) with levels of cumulative radon exposure.

An increased risk of lung cancer and a dose–response relationship was observed with cumulative radon exposure. Miners exposed to >100 WLM demonstrated a twofold increase in the risk of lung cancer incidence (RR=1.89, 95% CI 1.54, 2.50) compared with the non-exposed group, and a linear ERR of 0.64/100 WLM (95% CI 0.43, 0.85), with similar results observed for mortality. No association was observed for other cancer sites (stomach, leukemia, kidney and extrathoracic airways) or non-cancer sites (cardiovascular diseases) with increasing cumulative exposure to radon.

In conclusion, these findings suggest no increased risk of cancer sites other than lung or non-cancer mortality from relatively low cumulative exposure to radon.

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