Health Risks of Ionizing Radiation: - Clark University

Figure 8-3. Many uranium mines were located on Native
American reservations. Navajo miners are pictured here
(www.ancestral.com/.../ _north_america/navajo.html).
model included several additional terms to account
for the effects of age, time, and arsenic exposure.
Morrison et al. (1998) assessed the lung cancer
risk in Newfoundland miners of fluorspar, a mineral
composed of calcium and fluorine. Risks appeared
to be higher at younger exposure ages and again an
inverse dose-rate effect was noted. The estimated
ERR was 0.0076/WLM for exposure durations over
20 years.
China. Xiang-Zhen et al. (1993) examined a
cohort of 17,143 underground tin miners in Yunnan
Province, Southern China. At the time of the study it
was the largest study of radon-exposed underground
miners. Lung cancer mortality risk was related to
exposure, although the slope of the dose-response
relationship was shallower after adjustment for
arsenic exposure (ERR 0.0016/WLM, 0.001-0.002).
Risk also declined with attained age, with years
since exposure, and with increasing exposure rate.
Czechoslovakia. A report by Sevc et al. (1976)
documented a significant association between radon
exposure and lung cancer in Czech miners. Tomasek
and Placek (1999) updated this assessment with a
cohort of 2,552 miners who had worked underground
between 1952 and 1959. The overall ERR estimate
in this cohort was 0.023/WLM (0.009-0.038); risk
was apparently higher at younger exposure ages and
decreased with time since exposure.
France. Uranium mining in France began in
1946 and has been carried out at mines in Vendee,
11 Based on interquartile ranges depicted in Tirmarche et al. (1992).
Uranium Miners 107
Herault, and the Massif Central. Exposures in the
first ten years of mining were relatively high (~5-50
WLM/yr) and in 1956 radiation protection protocols
were implemented throughout the industry resulting
in lower exposures thereafter (~1-4 WLM/yr) 11 .
Tirmarche et al. (1992) conducted a cohort study
of French uranium miners who worked for at least
2 years in underground mines between 1946 and
1972. Rogel et al. (2002) expanded the cohort and
derived an overall ERR of 0.008/WLM. An inverse
dose-rate effect was found, and the estimated ERR
was much higher for exposure after 1956, when the
dose rate was reduced (ERR 0.024/WLM).
Germany. Underground uranium mining was
a major industry in East Germany in the years after
World War II as East Germany, through the former
Wismut Company, was the main supplier of uranium
for the Soviet Union. According to Enderle and
Friedrich (1995), working conditions were initially
very poor although compliance with international
radiation protection standards was attained by 1970.
Uranium production generally stopped in the region
in 1990. Although the Wismut Company workers
represent the largest epidemiologic cohort study
of miners in the world with over 60,000 subjects,
risk estimates have not yet been published (Kreuzer
et al. 1999). A preliminary analysis of a subcohort
(Bruske-Hohlfeld et al. 1997) indicated that risks
were compatible with the joint analysis of 11 miner
cohorts discussed below.
Sweden. Radford and Renard (1984) studied
iron miners from the Luossovaara-Kiirunavaara
Aktiebolaget mine in Arctic Sweden. Among 1,415
miners there were 50 lung cancer deaths through
1976 where 13 were expected based on national
rates. The ERR was estimated to be 0.036/WLM
(90% CI 0.025-0.048).
8.4 Combined estimates of risk
The National Institute for Occupational Safety and
Health (NIOSH) reviewed epidemiological studies
of uranium miners in 1985. All studies showed
associations with lung cancer, and five primary
studies with exceptionally good background data