A discussion on the potential impact of residential radon exposure on the quality of exposure and risk assessment for fo
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CONTROVERSIAL ISSUE
A discussion on the potential impact of residential radon exposure on the quality of exposure and risk assessment for former uranium miners Jing Chen1 Received: 14 August 2019 / Accepted: 25 September 2020 © The Author(s) 2020
Abstract Epidemiological evidence of lung cancer risk from radon is based mainly on studies of underground miners where occupational exposures were, historically, relatively high in comparison to residential indoor exposure. However, radiation protection measures have caused radon levels in uranium mines to decrease significantly in more recent periods. Miners’ occupational exposure is limited to their working years while they are exposed to environmental radon at home over their entire lifetime. Even during their limited working years, workers spend much more time at home than in workplaces. The biological effect of radon in mines cannot be distinguished from the biological effect of residential radon. Therefore, for an exposure–risk relationship study of former uranium miners, excess radon-induced lung cancer cases should be related to the combined radon exposure cumulated in workplaces and at homes in excess of the radon exposure of the reference population. This is especially important when residential radon levels differ or vary significantly between miners and the reference population over the course of extended follow-up years. This paper reviews some recent studies on former uranium miners, shares what seems controversial to the author and wonders whether lifetime exposure at home to widely varying radon concentrations can actually impact the quality of exposure assessment, and hence impact the results of the exposure–risk relationship. Keywords Radon-222 · Risk assessment · Uranium miners · Exposure assessment
Introduction Radon is present everywhere in the air in varying concentrations. Epidemiological evidence of lung cancer risk from radon is based mainly on studies of male underground miners where occupational exposures were, historically, relatively high in comparison to residential indoor exposure (NRC 1988, 1999; UNSCEAR 2009). However, over the past decades, radon levels in uranium mines have decreased significantly as the result of effective radiation protection measures in workplaces. For example, the average radon concentration in Canadian uranium mines over the past decade was 111 Bq/m3 (average annual exposure of 0.14 WLM, assuming F = 0.4 and 2000 working hours per year), comparable to the average radon concentration in Canadian homes, * Jing Chen [email protected] 1
Radiation Protection Bureau, Health Canada, 775 Brookfield Road, Ottawa, ON K1A 1C1, Canada
77 Bq/m3 (Chen 2017). In addition, miners’ occupational exposure to radon is limited to their working years, whereas their exposure to environmental radon everywhere occurs throughout their lifetime. Even during their limited working years, workers spend much more time at home than in workplaces. Time-activity data showed that Canadian adults spend 16 h (67% of daily time) at home, 5.
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