Federal researchers have asked a respected scientific journal to pull from its Web site a government-sponsored study that warned Americans could be exposed to C8 and similar chemicals when they eat chicken eggs.
The U.S. Environmental Protection Agency study, published in Environmental Science & Technology, was the first to find perfluorinated compounds, or PFCs, in U.S. chicken eggs.
Originally, EPA scientists cautioned that the study involved a small sample of eggs, but said the results indicated the need for a broader examination of the issue.
“A more comprehensive study should be carried out to have a better understanding of the distribution of the PFCs in chicken eggs and the potential for exposure to various PFCs through the diet,” said the study, published online July 23.
Then last week, the EPA scientist who led the study abruptly revealed that his team believes they made a major error. Eggs they tested probably didn’t really contain the chemical perfluorooctane sulfonate, or PFOS, the scientist said.
“It’s just a very, very big embarrassment for us,” said Andrew Lindstrom, the study’s lead EPA researcher. “As it turns out, we’re pretty sure that PFOS is not going to be an issue for the samples we had.”
Still, a similar study earlier this year found PFOS in chicken eggs in China, and other scientists have consistently found such chemicals in the eggs of wild birds.
EPA officials scrambled last week to explain problems with the study, and to insist there had been no political or industry involvement in the decision to withdraw the study.
“These things happen,” said Suzanne Ackerman, a spokeswoman with EPA’s Office of Public Affairs in Washington. “I don’t see anything nefarious about it. They made an error. They’re going to correct it. The end.”
In West Virginia, PFCs are a major issue because the water supplies for thousands of Parkersburg-area residents have been contaminated with the toxic chemical.
For decades, DuPont has used C8 to make Teflon and other products at its Washington Works plant along the Ohio River just south of Parkersburg.
C8 is another name for perfluorooctanoic acid, or PFOA. PFOA and PFOS are part of a family of PFCs that were widely used in nonstick coatings, stain-resistant fabrics, and food package coatings.
Around the world, researchers are finding that people have C8 and other PFCs in their blood. Evidence continues to mount about the dangers of these chemicals, but U.S. regulators have not set a federal standard for emissions or human exposure.
In January 2006, EPA and industry officials announced a voluntary plan to “phase out” the use of certain PFCs. But results of that program have been mixed, and new studies are raising concerns about the safety of alternative chemicals industry is using.
Scientists are still sorting out how humans are exposed to PFCs, and how long those chemicals may remain in consumer products and the environment. Previous studies have examined drinking water, Teflon pans, food and food packaging, and household dust as potential routes.
Studies have found PFCs in a variety of birds and bird eggs, including gull eggs from Lake Huron, guillemot eggs from the Baltic Sea, and egrets from Lake Shihwa in South Korea. Some studies linked the chemicals to nearby industrial areas, but others noted “widespread distribution” of the chemicals around the globe. Some studies also found an increase in concentrations of PFCs in bird eggs over the last four decades.
Recently, a small number of studies have examined PFC levels in store-bought food in Canada, Germany and the United Kingdom. Those studies have mostly examined chemical concentrations after various foods were mixed together, to try to estimate a typical diet.
The EPA chicken egg study was part of an effort by government researchers in the U.S. to refine methods of testing specific food items individually.
In their study, EPA scientists reported that they found PFOS in 31 of the 33 eggs they sampled from markets in North Carolina and Georgia. The median concentration was 133 parts per billion.
The study was published online July 23, and was slated to appear in Environmental Science & Technology, a peer-reviewed publication of the American Chemical Society.
On Aug. 13, Lindstrom and another EPA scientist, Mark Strynar, discussed their findings in an interview with the Sunday Gazette-Mail. As is now required by EPA, an agency public affairs officer, Robin Bailey, listened in on the interview.
A week later, Bailey called the Gazette-Mail back to say that EPA had asked ES&T to pull the paper from the Internet and not publish it in the journal’s print edition. Bailey emphasized that the decision was made “solely by the EPA scientists.”
“There was no outside influence from EPA management or anyone in the industry,” Bailey said.
In a follow-up interview, Lindstrom explained that, after the paper was published, he read in another scientist’s work that there is a material that looks like PFOS when analyzed with the equipment his team had used.
Lindstrom’s team tried to measure chemicals in the eggs with a mass spectrometer, a machine that identifies compounds based on a mass-to-charge ratio of charged particles from those compounds.
His team reviewed its samples again, and now believes they mistook this other material – called an “interfering compound” – for PFOS. The other substance has not been identified, Lindstrom said.
“It just turns out that there is this other material in these chicken eggs that is very difficult to distinguish from PFOS,” Lindstrom said. “Clearly, we made a mistake. It’s a complicated analysis, but we made a bad mistake.”
Several other scientists who have published peer-reviewed papers on PFCs in bird eggs spoke very highly of Lindstrom, saying his work in the field is well respected.
Nobuyoshi Yamashita of the National Institute of Advanced Industrial Science and Technology in Japan said he and his colleagues used a different method for their study that found PFOS in chicken eggs in China.
“We knew their mistake and all about [the] difficulty of egg analysis,” Yamashita said in an e-mail message. “It’s only a simple mistake and can be confirmed using [the] right methodology.”
Robert Letcher of the Canadian Wildlife Service said he suspected a problem with the EPA study when he saw that the PFOS levels were much higher than found in other studies of commercial chicken eggs.
The EPA results were far higher than PFOS levels of about 3 parts per billion cited by Letcher, and the range of 37 to 89 parts per billion in the Chinese study.
Letcher said he suspected the EPA study had a problem with instrumental PFOS contamination or perhaps PFOS contamination of the actual chicken egg samples.
Jerald Schnoor, a University of Iowa engineer and editor of ES&T, said that the journal would either pull the study from its Web site or post some sort of disclaimer.