Two perfluorinated compounds-- PFOA and PFOS-- were found in virtually all of 299 newborn babies studied in Baltimore, according to scientists from Johns Hopkins University. The results indicate that exposure in the womb to these two chemicals is virtually ubiquitous. Eight other PFCs were detected less frequently.

PFOS and PFOA concentrations were highly correlated with each other. The scientists also report that PFOS levels were higher in Asians and Blacks than in Whites, while PFOA levels were more evenly distributed among ethnic groups. Other demographic and socioeconomic did not emerge as important in predicting PFOS or PFOA levels.

What did they do? Apelberg et al. collected cord blood specimens from live births at Johns Hopkins Hospital in Baltimore, MD, obtaining sufficient quantities for analysis from a total of 299 babies. The samples were sent to the US Centers for Disease Control and Prevention for chemical analysis. They also collected demographic and health information about the mothers and babies who were sample. These data were taken from clinical databases maintained by the hospital. The data included information on when the mother was born, social class, past pregnancies, whether or not the mother was on public or private insurance for health care, gestational age, infant sex, etc. They used maternal cotinine levels (a blood indicator of exposure to nicotine) to gauge the mother's smoking activities.

What did they find?Apelberger et al. detected PFOS and PFOA in 99% and 100%, respectively, of cord blood samples analyzed. For PFOS, levels ran from undetected to 34.8 nanograms per milliliter, averaging (geometric mean) 4.9 ng/ml. For PFOA, the lowest measurement was 1.6 ng/ml while the highest was 7.1 ng/ml, with an average of 1.6 ng/ml. The other PFCs measured were found in fewer than half of samples examined.

Concentrations of PFOA and PFOS were highly correlated with one another: a baby with higher PFOA would have higher PFOS levels (p< 0.01).

Mean concentrations of PFOA and PFOS were higher in Asians (6 ng/ml) and Blacks (5.1 ng/ml) than in Whites (4.2 ng/ml). Males babies had higher PFOS and PFOA than female. Obese and underweight women had slightly higher concentrations than women of normal weight.

Context

Perfluorinated compounds like PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoate) are extremely persistent chemicals which at relatively high exposure levels cause cancer and tumors in rats, interfere with lipid metabolism and cause liver damage. They also cause developmental and reproductive harm.

Chemically, PFCs are formed by replacing hydrogen atoms in hydrocarbon chains with fluorine. The specific characteristics of the resulting compound will depend upon the number of fluorines in the new molecule and where they are located along the hydrocarbon chain.

Until recently, there were few public concerns about the health effects of PFCs because the levels to which humans are exposed seemed very low compared to the levels needed in animal experiments to cause harm. As a result, PFCs have been incorporated in a wide array of consumer products, from Teflon for creating nonstick pans to Scotchgard to Gore-Tex clothing. Medical scientists have even experimented with using PFCs in artificial blood.

This has changed. Recent revelations of old, undisclosed findings about human health impacts, new laboratory studies with animals and data showing that human exposure to PFCs is both ubiquitous and increasing together have catapulted the PFCs into intense scrutiny by health and environmental authorities. One public health advocacy organization, the Environmental Working Group, has been at the center of forcing this issue onto the public agenda.

What does it mean?These results confirm what earlier, small studies had indicated: Babies are exposed in the womb to PFCs, largely PFOS and PFOA. The levels observed in these Baltimore babies are somewhat lower than those observed in US adults and intermediate between levels seen in babies from Japan, Germany and northern Canada (graph to right).

adapted from Apelberg et al.

They all are several orders of magnitude lower than what most animal studies indicate are necessary to cause developmental harm. No data are available to evaluate whether, similar to several other contaminants like bisphenol A, some persistent organic pollutants, and some phthalates, high dose experiments do not accurately predict low dose effects. With these chemicals, low dose effects have been observed that are not anticipated by standard toxicological analysis.

The strong correlation between PFOS and PFOA suggests there may be a common source of exposure for the two compounds. According to the authors, "What was most surprising was a lack of association between PFOS and PFOA concentrations and maternal age, socioeconomic status, and inner city residence (urban vs suburban exposure).

Resources:

Environmental Working Group. 2003. PFCs: A Family of Chemicals That Contaminate The Planet.

Environmental Working Group. 2005. Former Dupont top expert: Company knew.

Kannan, K, S Corsolini, J Falandysz, G Fillmann, K Kumar, BG Loganathan, MA Mohd, J Olivero, WN Van, JH Yang, KM Aldoust. 2004. Perfluorooctanesulfonate and related fluorochemicals in human blood from several countries. Environmental Science and Technology 38: 4489-4495.

York, RG 2002. Oral (gavage) two-generation (one litter per generation) reproduction study of ammonium perfluorooctanoate (APFO) in rats. Report prepared for 3M, St. Paul, MN by Argus Research (Horsham, PA). Sponsor's Study No. T-6889.6., Reviewed in US EPA AR226-1092. This document is available for download from the Environmental Working Group; it is a 22MB file.