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Nonstick Taints: Fluorochemicals are in us all

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10:05pm, November 21, 2005
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A new federal study strongly suggests that all U.S. residents harbor measurable traces of fluorochemicals, compounds used to impart water- and oil-repelling features to a host of consumer products. Separately, Japanese researchers report that at least one of these pollutants reaches even fetuses.

According to the Environmental Protection Agency, human exposures are of concern. In laboratory animals, some of these long-lived compounds have caused developmental problems, liver toxicity, immune problems, and cancer.

The studies on people and fetuses, described last week in Baltimore at the Society of Environmental Toxicology and Chemistry (SETAC) annual meeting, were among roughly 2 dozen reports on the fate and potential consequences of fluorochemicals in people, wildlife, and the environment. Overall, the evidence suggests that these pollutants are ubiquitous.

Since the 1960s, manufacturers have used fluorine-based chemicals in a range of consumer goods, including nonstick cookware, oil-resistant food packaging, stain-resistant carpeting, and water-repelling fabrics. One frustration, noted scientists at the meeting, is that no one yet knows which sources—or uses—contribute most significantly to the residues showing up in people and the environment or at what dose such compounds might prove toxic.

Many of the more commonly used nonstick chemicals include as a basic building block either perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA). At the SETAC meeting, chemist Antonia Calafat of the Centers for Disease Control and Prevention (CDC) in Atlanta reported on 54 pooled samples of blood that had been collected 3 to 4 years ago as part of the National Health and Nutrition Examination Study. Each pool contained serum from 34 people, grouped by ethnicity and age.

PFOS values were 20 to 44 parts per billion (ppb) in non-Hispanic whites, between 10 and 30 ppb in blacks, and no more than 15 ppb in Mexican Americans, Calafat reported. PFOA values in all the pools were lower—between 2 to 8 ppb—but again, highest in non-Hispanic whites. Values differed little by age among the pools, which began at 12 to 19 years.

Although a few earlier studies had detected PFOS and PFOA in blood, CDC's analysis was the first designed to provide values representative of U.S. residents.

In a recent study of 15 new mothers, researchers at Hoshi University in Tokyo reported PFOS blood values of 4.9 to 17.6 ppb. The team also measured 1.6 to 4.7 ppb in the umbilical cord blood that had fed these women's babies in the womb. Blood from four moms—but not cord blood—had PFOA values ranging from 0.5 to 2.3 ppb.

Widespread fluorochemical contamination of fish, birds, and other animals turned up in a survey by Kurunthachalam Kannan and Ewan F. Sinclair of the New York State Department of Health in Albany. Such data suggest that game might be one source of these pollutants in the human diet.

Nonstick cookware has been investigated as another likely candidate, but in recent tests, the Food and Drug Administration found fry pans to be a negligible source. However, those tests showed that during microwaving, the grease-resistant paper used in popcorn bags releases traces of PFOA to the oil that coats the kernels.

Indeed, microwave popcorn is an extreme case. Paper temperatures that can exceed 200°C "significantly increase the potential for [PFOA] migration," say the FDA's Timothy H. Begley and his coworkers in College Park, Md. In the October Food Additives and Contaminants, they conclude that in their study of food-contact materials, treated paper is the greatest potential source of fluorochemicals.

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