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Nuclear workers
Many
studies have been carried out of cancer among nuclear industry
workers. Most of the exposures to these workers were in line
with international standards. In contrast, many workers at
the Mayak plant in Russia received high doses over a protracted
period, and raised (but poorly quantified) risks have been
seen for several types of cancer in this group. Some of the
worker studies have been limited by relatively small population
sizes and/or short follow-up periods. The larger studies include
a combined analysis of abaut 95.000 workers in Canada, the
US and the UK, and cohorts of over 100.000 nuclear workers
in Japan (although with a short follow-up) and the UK. Most
of the analyses have looked only at mortality. There has been
some variation in the findings, which may be due in part to
low statistical precision. However, mortality has often been
lower than in the general population, due probably to factors
associated with selection into and continuation of employment.
The larger studies have tended to indicate an increasing trend
in leukaemia risk with increasing dose, whereas the evidence
for a dose-related increase in solid tumour risks has generally
been less. However, the confidence limits for these trend
estimates have been relatively wide, and encompass risks extrapolated
from the Japanese atomic-bomb survivors as well as a range
of values, both higher and lower. More precise information
will be obtained from an ongoing international collaborative
study of cancer risk in nuclear industry workers.
At
present, the findings from these studies do not indicate the
need to modify current radiation protection measures for workers.
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