Lung Cancer in French and Czech Uranium Miners: Radon-Associated Risk at Low Exposure Rates and Modifying Effects of Time since Exposure and Age at Exposure

Abstract

Radon is recognized as a public health concern for indoor exposure. Precise quantification derived from occupational exposure in miners is still needed for estimating the risk and the factors that modify the dependence on cumulated exposure. The present paper reports on relationship between radon exposure and lung cancer risk in French and Czech cohorts of uranium miners (n = 10,100). Miners from these two cohorts are characterized by low levels of exposure (average cumulated exposure of less than 60 WLM) protracted over a long period (mean duration of exposure of 10 years) and by a good quality of individual exposure estimates (95% of annual exposures based on radon measurements). The modifying effect of the quality of exposure on the risk is analyzed. A total of 574 lung cancer deaths were observed, which is 187% higher than expected from the national statistics. This significantly elevated risk is strongly associated with cumulated radon exposure. The estimated overall excess relative risk per WLM is 0.027 (95% CI: 0.017-0.043, related to measured exposures). For age at exposure of 30 and 20 years since exposure, the ERR/WLM is 0.042, and this value decreases by approximately 50% for each 10-year increase in age at exposure and time since exposure. The present study emphasizes that the quality of exposure estimates is an important factor that may substantially influence results. Time since exposure and simultaneously age at exposure were the most important effect modifiers. No inverse exposure-rate effect below 4 WL was observed. The results are consistent with estimates of the BEIR VI report using the concentration model at an exposure rate below 0.5 WL.

Mutation induction by inhaled radon progeny modeled at the tissue level

“…Local hyperplasia due to chronic exposure to radon progeny that occurs only beyond a threshold dose rate can provide an explanation for the inverse dose-rate effect and its disappearance at low cumulative doses as observed in several epidemiological studies of lung cancer among uranium miners (Lubin et al 1995;Tomasek et al 2008;Walsh et al 2010). Tomasek et al (2008) reported a threshold of 4 WL, which is in good agreement with the threshold based on the present simulations.…”

DoReMi workshop on multidisciplinary approaches to evaluating cancer risks associated with low-dose internal contamination

“…There are three cohorts of uranium miners, the Czech (n = 10,000), the French (n = 5,000) and German (n = 60,000) cohorts. The cohorts are characterised by a large size, early start dates (between the 1940s and 1950s), a long follow-up period (more than 30 years on average), a small percentage of participants lost to follow-up, and a large number of cancer and non-cancer deaths (Tomasek et al, 2008;Vacquier et al, 2008;Kreuzer et al, 2010). Individual information on radiation exposure (radon progeny, long-lived radionuclides, and external gamma radiation) is available for all cohort members and organ doses have already been calculated for several target organs.…”

“…In Europe, a tight collaboration between Czech, French, and German investigators already exists, based on several former common EC projects on uranium miners (Tirmarche et al, 2003;Tomasek et al, 2008;Tirmarche et al, 2010). Presently, the pooling of data from the three European and three Canadian miner studies is in preparation.…”

“…An excess of thyroid cancers has been observed after intake of radioactive iodine among those who were children living in the contaminated territories around Chernobyl (Zablotska et al, 2010;Cardis and Hatch, 2011; UNSCEAR, 2011). A linear exposure-risk relationship has been demonstrated from miner studies and also from large studies in the general population between radon inhalation and lung cancer risk, even at low levels of exposure (BEIR-VI, 1999;Darby et al, 2006;Tomasek et al, 2008). Nevertheless, except for these few exceptions, studies have not yet been able to quantify the dose-risk relationship between internal contamination and cancer risk at low doses.…”

Influence of radon protecting measures in children educational institutions on the radiation risk exposure to radon (an example of one of the schools in St. Petersburg)

“…были опубликованы результаты нескольких объ-единенных эпидемиологических исследова-ний связи облучения людей радоном в жи-лищах с раком легкого методом «случай-контроль», начатых еще в конце 1980-х гг. [10,[19][20][21][22], а также нескольких объединен-ных эпидемиологических исследований среди шахтеров с относительно низкими уровнями суммарной экспозиции [15,16,23,25]. Эти результаты были тщательно про-анализированы специально созданной в 2005 г. Рабочей группой МКРЗ, и в ноябре 2009 г. Комиссия одобрила «Заявление по радону», а в 2010 г. была выпущена Пуб-ликация 115 [7,12], в которой подтвер-ждается, что дополнительный абсолют-ный риск возникновения рака легкого, обусловленный радоном и его ДПР, рас-считанный для облучения в жилищах, со-поставим с оценками, полученными для шахтеров при низких уровнях экспози-ции.…”