Parkersburg, WV, October 18, 2006--After following more than 6,000 employees for more than 50 years, DuPont epidemiologists today released a study that found no increased mortality risk in workers exposed to PFOA.
The results showed lower mortality rates than those found in both West Virginia and the U.S. general population. They also were consistent with mortality rates in comparable workers from other DuPont plants, a population generally more healthy than the population at large.
The study, which was reviewed by an external board of scientists, examined the occupations of 6,027 people who had worked at DuPont's Washington Works plant between 1948 until the end of 2002. It also examined the causes of death for those who had died over the 54-year period and compared the mortality rates to those found in three groups: Other DuPont workers, West Virginia residents, and members of the U.S. general population.
"The Washington Works II study supports a conclusion that there are no human health effects known to be caused by PFOA," said Sol Sax, M.D., chief medical officer for DuPont. "This study will add significantly to the existing body of research into the effects of exposure to PFOA and will be made available to the U.S. EPA and others.
"If health effects were associated with PFOA exposure, they almost certainly would be more prevalent among employees who are occupationally exposed to the compound or who handle it regularly," Sax said. "Consequently, the study's observations about worker mortality can be useful in understanding exposure effects on both industrial and lay populations."
Based on an observation in a 2005 study at the same plant that some lipids, such as cholesterol, were modestly increased in the most highly exposed group of workers, this study included a more detailed analysis of heart disease. This new study found no overall increase in heart disease deaths.
As is the case with epidemiology studies, mortality across various levels of exposure was analyzed. One specific analysis showed a slight increase in heart disease with increased exposure. It could be a random occurrence, or it could mean a small increase in workers most heavily exposed. DuPont intends to pursue additional analyses to understand this statistical observation fully.
The study found no increase in overall mortality from cancer.
Prostate cancer rates among the cases studied were found to be lower than rates in all three reference populations. This contrasts with a previous non- DuPont study where an increase in prostate cancer was reported.
Across the entire study population, there was a slight, but not statistically significant, increase in the rate of kidney cancer mortality. Most of the cases showed little exposure to PFOA, but the numbers were too small to draw any conclusions.
The entire study population showed diabetes death rates lower than those found in West Virginia or the United States. There was a slight, but statistically significant increase compared to rates found among other DuPont workers. Again, the numbers were too small to draw any conclusions.
Results from both phases of the study were reviewed by a board that advises DuPont on epidemiological issues. The board is composed of independent experts from Georgetown University, Harvard University, Johns Hopkins University, the University of Massachusetts - Lowell, the University of Washington and Yale University.
"This study is part of DuPont's ongoing PFOA research in cooperation with regulators, industry and academic communities to expand the understanding of the compound," said Robert Rickard, Ph.D., science director of the DuPont Haskell Laboratory for Health & Environmental Sciences.
