NEW YORK (Reuters Health) - Workers at one US nuclear facility have suffered higher-than-average rates of certain cancers, a study shows -- suggesting that on-the-job exposures are to blame.
     The study looked at nearly 19.000 employees of the Savannah River Site, a South Carolina facility that has processed nuclear materials since the 1950s.
     Researchers found that while death rates from many causes were lower than national rates, workers had higher-than-expected rates of death from certain cancers.
     Among men, leukemia and cancer of the pleura, the tissue covering the lungs and lining the chest cavity, caused an abnormally high number of deaths, while female workers had elevated rates of kidney and skin cancers.
     Pleural cancer is strongly related to long-term exposure to asbestos. Some workers at the Savannah River Site were apparently overexposed to asbestos, based on "industrial hygiene" reports from the early 1970s, according to the researchers.
     Dr. David B. Richardson and colleagues at the University of North Carolina at Chapel Hill report the findings in the American Journal of Industrial Medicine.
     The study included 18.883 employees of the Savannah River Site who were hired prior to 1987 and worked there for at least three months.
     When the researchers looked at deaths from all causes and deaths from all cancers as a whole, the workers had rates that were below the US norm. However, as mentioned, there was an excess of certain cancers.
     "It is plausible, Richardson and his colleagues write, that occupational hazards, including asbestos and ionizing radiation, contribute to these excesses."
     The findings highlight the importance of ongoing government research into former nuclear workers' health, according to the researchers. This, they write, will be key to understanding "the range of potential occupational health effects," especially diseases that typically take years to become apparent.

SOURCE: American Journal of Industrial Medicine, December 2007.

*Correspondence to David B. Richardson, Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.

Funded by:
     National Institute for Occupational Safety and Health of the Centers for Disease Control and Prevention; Grant Number: R01 OH007871
Keywords
     cohort studies • mortality study • Savannah River Site • occupational diseases
Background
     Workers employed at the Savannah River Site (SRS) were potentially exposed to a range of chemical and physical hazards, many of which are poorly characterized. We therefore compared the observed deaths among workers to expectations based upon death rates for referent populations.
Methods
     The cohort included 18.883 SRS workers hired between 1950 and 1986. Vital status and cause of death information were ascertained through 2002. Sex-specific standardized mortality ratios (SMR) were computed using U.S. and South Carolina mortality rates. SMRs were tabulated separately for monthly-, weekly-, and hourly-paid men.
Results
     Males had fewer deaths from all causes [SMR = 0.80, 90% confidence interval (CI): 0.78, 0.82], all cancers (SMR = 0.85, 90% CI: 0.81, 0.89), and lung cancer (SMR = 0.88, 90% CI: 0.82, 0.95) than expected based upon US mortality rates. The SMR for cancer of the pleura was 4.25 (90% CI: 1.99, 7.97) for men. The SMR for leukemia was greater than unity for monthly-paid (SMR = 1.33, 90% CI: 0.88, 1.93) and hourly-paid (SMR=1.36, 90% CI: 1.02, 1.78) men. Female workers had fewer deaths from all causes (SMR = 0.75, 90% CI: 0.69, 0.82) than expected, but more deaths than expected from cancer of the kidney (SMR = 2.58, 90% CI: 1.21, 4.84) and skin (SMR = 3.90, 90% CI: 2.11, 6.61).
Conclusions
     While the observed numbers of deaths in most categories of cause of death were less than expected, there are greater than expected numbers of deaths due to cancer of the pleura and leukemia, particularly among hourly-paid male workers. It is plausible that occupational hazards, including asbestos and ionizing radiation, contribute to these excesses. Am. J. Ind. Med. 50:881-891, 2007. © 2007 Wiley-Liss, Inc.