This study of shipyard workers shows the opposite:
http://www.ecolo.org/documents/documents_in_english/low-dose-NSWS-shipyard.pdfABSTRACT:
This paper is a summary of the 1991 Final Report of the Nuclear
Shipyard Worker Study (NSWS), a very comprehensive study of occupational
radiation exposure in the US. The NSWS compared three cohorts: a high-dose
cohort of 27,872 nuclear workers, a low dose cohort of 10,348 workers, and a
control cohort of 32,510 unexposed shipyard workers. The cohorts were
matched by ages and job categories. Although the NSWS was designed to
search for adverse effects of occupational low dose-rate gamma radiation, few
risks were found. The high-dose workers demonstrated significantly lower
circulatory, respiratory, and all-cause mortality than did unexposed workers.
Mortality from all cancers combined was also lower in the exposed cohort. The
NSWS results are compared to a study of British radiologists. We recommend
extension of NSWS data from 1981 to 2001 to get a more complete picture of
the health effects of 60Co radiation to the high-dose cohort compared to the
controls.