DuPont epidemiologist studied the occupations of 6,027 employees between 1948 and 2002 and examined the causes of death for those who died during the 54-year period, according to DuPont. The epidemiologists then compared the mortality rates of the study participants to the rates found in three groups: other DuPont workers, West Virginia residents and members of the U.S. general population.
Results showed lower mortality rates than those found in West Virginia and the general population, according to DuPont. The results also were consistent with mortality rates in comparable workers from other DuPont plants, the company says.
DuPont: Study Will Be Shared with EPA
Dr. Sol Sax, chief medical officer for DuPont, said the study supports the company's position that there are no human health effects known to be caused by PFOA.
"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," he said.
Sax also argued that if PFOA had any health consequences, workers exposed to the compound regularly would show abnormal health effects. He also emphasized that the study's observations on worker mortality could be helpful in "understanding exposure effects on both industrial and lay populations."
Companies such as DuPont use PFOA - a man-made chemical that sometimes is called "C8" - to make fluoropolymers, which are used in the production of nonstick cookware and other products. EPA in 2000 began investigating PFOA because the chemical "is very persistent in the environment, was being found at very low levels both in the environment and in the blood of the general U.S. population and caused developmental and other adverse effects in laboratory animals," according to the agency.
Although DuPont has repeatedly said that PFOA does not pose a health risk to the general public, the company earlier this year agreed to "virtually eliminate the sources of exposure to PFOA from our manufacturing operations and products by 2015." The announcement was part of a global EPA campaign the agency launched in January to dramatically reduce PFOA releases and its presence in products.
USW: DuPont's Study "Flawed"
The United Steelworkers union (USW) scoffed at DuPont's study claims, accusing the company of misrepresenting information on the health effects of PFOA and withholding data on the high levels of PFOA found in the blood of its employees.
"DuPont is using this flawed study to justify the continued production of this controversial chemical and mislead the public into believing there is no evidence linking human health effects to PFOA exposure," said April Dreeke, USW strategic campaigns researcher. "We're demanding an immediate release of the complete study so the public does not have to rely on DuPont's word."
According to the union - which has criticized DuPont for its handling of PFOA at its plants - the study focuses on the causes of worker mortality rather than the occurrence of cancer and overall impact PFOA may have on the health of workers. The union said the study found that workers with high levels of PFOA had an increased incidence of heart disease in the most-exposed. Previous health studies conducted on workers also have established a relationship between PFOA exposure and increased levels of cholesterol.
"We wish there was an independent study proving that PFOA does not cause health effects or deaths in workers, but that is not the kind of study DuPont has conducted," said Jim Rowe, USW Local 943 president in Deepwater, N.J. "DuPont's study and their stated results appear designed to protect the company's image more so than its employees."
The DuPont study showed no increases in overall death rates from heart disease or cancer. There was a slight, but not statistically significant, increase in kidney cancer mortality, according to DuPont, but the company said most of those workers had little exposure to PFOA.
The study also showed a slight increase in diabetes death rates among Parkersburg workers compared with other DuPont employees, according to the company.
According to the union, blood samples taken by DuPont and USW show that employees often have much higher levels of PFOA in their blood than the average of 5 parts per billion found in the general population. The levels, according to USW, were up to 200 times higher in workers at DuPont's plant in Parkersburg, W.Va., and up to 160 times higher in workers at DuPont's plant on Richmond, Va., where the company says the chemical hasn't been used for years.
A call made to DuPont for comment on USW's statements was not returned.