Female Nuke Worker Mortality Analyzed

July 7, 2000
An occupational epidemiologist's study of female nuclear weapons workers illustrates an example of the "healthy-worker effect."

Employees should be skeptical of any report boasting that their health as a group is better than that of the general population, warned occupational epidemiologist at the University of Buffalo (UB).

Such a comparison will make the group and the company look good, said Gregg S. Wilkinson, Ph.D., a professor in the UB Department of Social and Preventative Medicine, because of an innate bias called the "healthy worker effect."

Wilkinson''s study of female nuclear weapons workers, presented recently at the annual meeting of the Society for Epidemiologic Research, illustrated an example of the healthy-worker effect, well-known among male workers but studied less frequently among female workers.

"The healthy-worker effect exerts its influence when fewer deaths are observed for workers in an industry, compared to the U.S. population," said Wilkinson. "The understanding is that people must have at least a minimum level of health to hold down a job, whereas the general population includes everyone -- healthy and sick."

Wilkinson compared death statistics for female workers at 12 nuclear weapons sites with the number of deaths expected to occur in the female population of the United States.

The study covered at total of 67,976 women who had worked at any of the sites before Jan. 1, 1980.

Results showed that at all of the sites, the number of deaths was either similar to or lower than that of the female population at large.

"Industries tend to sue such findings to show how well they''re doing," said Wilkinson. "But if you are going to get the right answers, you have to use appropriate comparisons. An appropriate comparison would be workers who are similar: either unexposed workers in the same plant, or workers who are similar but work in another plant where the exposure of interest does not exist."

However, the healthy-worker effect can also skew results of health studies involving workers in the same factory.

Wilkinson compared death statistics for female nuclear weapons workers who wore badges to monitor radiation exposure with deaths of women who did not wear badges because they weren''t exposed to radiation.

The results showed that there were 25 percent more deaths from all causes and 17 percent more deaths from all cancers among the unbadged workers.

Overall, Wilkinson said the study suggests that the healthy-worker effect also exists for female workers and must be taken into account in any studies of occupational health.

The study was funded by the National Institute for Occupational Safety and Health.

by Virginia Sutcliffe

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