PARKERSBURG - The C8 Science Panel released three additional reports this week, which include findings of a possible association between C8 exposure and preeclampsia; a possible association between C8 exposure and a marker of liver cell damage and exposure studies in DuPont workers showing higher rates of death due to kidney cancer, non-malignant kidney disease and mesothelioma possibly linked to higher C8 exposure rates.
The three-member C8 Science Panel is conducting 11 studies to determine whether there is a probable link between C8 and disease; C8 is the common name given to perfluorooctanoic acid, (sometimes called PFOA), a manmade chemical used in manufacturing products including non-stick cookware, protective finishes on carpets, and water-resistant clothing. A class action lawsuit was brought against DuPont Washington Works by six affected communities regarding the release of C8 from the plant. As part of a settlement, an independent health project was undertaken in which nearly 70,000 individuals who lived, worked or attended school in the six affected districts during a certain period of time were tested and interviewed. In addition studies of DuPont workers were also undertaken.
As part of the most recent reports, the panel analyzed pregnancies of women who participated in a health study in 2005-2006. There were 11,737 pregnancies reported between 1990-2005. The relationship between C8 exposure during pregnancy and the risk of miscarriage, stillbirth and preeclampsia (a condition involving high blood pressure and leakage of protein into the urine during pregnancy), preterm delivery, term low birthweight and birth defects was studied.
According to the report, the panel found "there was no association between the estimated serum level of C8 at the time of pregnancy and risk of miscarriage, stillbirths were reported for 106 pregnancies and no assoiciation was found with C8 exposure. Based on our results, it does not appear that the survival of the pregnancy was affected by serum PFOA level," according to the report.
No association between C8 and preterm birth, low birth weight or birth defects was reported.
"Preeclampsia was noted for 730 pregnancies, and there was evidence for an association compared to the pregnancies with the lowest levels of C8, women with the highest levels of PFOA had a relative risk of 1.4 percent. There are no other studies to support or challenge our findings of an association for preeclampsia. The association with preeclampsia is small but clearly present based on a variety of ways of examining exposure," according to the study.
In DuPont's response to the report, the company noted "no associations observed between PFOA exposure and any birth outcomes that were evaluated. A small statistical association was observed between estimated PFOA exposure and self-reported preelcampsia."
Another report found "serum levels of ALT (an enzyme released after liver injury) increased with increasing concentrations of PFOA and that the risk of having an abnormal level of ALT also increased with increasing levels of C8. Neither of the other two markers (GGT or bilirubin) showed a clear relationship with PFOA," according to the science panel's report. "This association with ALT is unlikely to be due to chance, as it is highly statistically significant. It is not explained by the other detailed information included in the statistical models - age, physical activity, body mass index, average househoeld income, educational level, race, alcohol consumption and cigarette smoking," according to the study.
"These results show a positive association between PFOA and PFOS concentrations and ALT serum levels, a marker of liver cell damage," according to the panel.
The science panel's report noted "the main limitation of the present study is the cross-sectional design; both PFOA and the liver markers were measured at the same time, so we do not know whether the PFOA exposure came before any changes in markers of liver function. This makes it impossible to know whether PFOA can cause changes in liver markers." The report also noted "having high levels of ALT does not necessarily imply a liver disease, although many liver conditions manifest themselves with increases in these markers before clinical signs are evident."
According to DuPont's statement regarding these findings: "As indicated by the science panel, higher ALT may occur with a liver condition but does not necessarily imply one. The design of this study does not allow for any cause and effect determination."
The mortality rate of DuPont workers in relation to their C8 exposure was the subject of a third report that notes the science panel "found significantly increased rates of death among the more highly exposed workers, for three causes: kidney cancer; non-malignant kidney disease (chronic kidney disease) and mesothelioma. While the trends of increased rates with more exposure were statistically significant for kidney disease, they were based on small numbers, 12 kidney cancers; 13 chronic kidney disease cases; and there was no overall excess risk of these diseases for all workers combined," according to the report.
That same report also notes the panel believes the increased risk with higher PFOA exposure for mesothelioma was not due to PFOA but "more likely to asbestos, because individuals with higher PFOA also happened to have had higher past exposure to asbestos, such as maintenance workers."
"However, the increased risk for the more highly exposed in relation to malignant kidney and non-malignant kidney disease could possibly be due to PFOA; the kidney is the site in a body where PFOA is found," according to the report.
Commenting on this study DuPont said: "The report observed that overall mortality was low, which is common when comparing worker populations to the U.S. population. The DuPont workers had 30 percent lower mortality and 26 percent lower cancer mortality, than the general population."
Relating to the statistical association between higher C8 exposure and higher mortality due to kidney cancer and chronic kidney disease, the science panel pointed out "there was no overall excess risk of theses diseases for all workers combined."
DuPont spokesmen also noted an occupational study among PFOA-exposed workers conducted by the University of Minnesota did not report any increase in kidney diseases, including cancer.
Regarding the findings on Mesothelioma mortality, DuPont's statement noted: "The science panel stated it does not believe this was related to PFOA, but rather, due to the connection between asbestos and mesothelioma. All DuPont sites adhere to strict federal and state health and safety standards regarding asbestos. DuPont officials also pointed out the science panel did not report any associations between estimated PFOA exposure and any of the other causes of mortality that were examined.
Members of the C8 Science Panel are Dr. Tony Fletcher, London School of Hygiene and Tropical Medicine, Dr. David Savitz, Mount Sinai School of Medicine, and Dr. Kyle Steenland, Rollins School of Public Health, Emory University.
More information on the panel and its work can be found at www.c8sciencepanel.org.