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| Science News - December , 2001 |
Foam spill study suggests perfluorinated surfactants’ fate
Bioconcentration factors for perfluorooctane sulfonate (PFOS) in fish in a contaminated stream have been found that range from 6300 to 125,000 indicating that in addition to being extremely persistent, PFOS is a contaminant with significant potential to bioaccumulate, scientist Cheryl Moody and colleagues report in an article just posted to ES&T's Research ASAP site. The field-determined values, which are based on analysis of PFOS concentrations in fish livers and surface water, are much higher than the scientists’ laboratory-determined bioconcentration factor of 5400, she says.
According to Moody, the discrepancy may be attributed to the creek fish having accumulated other compounds capable of breaking down to PFOS that were not measured in the water samples and therefore not accounted for.
In addition to determining bioconcentration factors, the scientists also identified, for the first time in environmental samples, long-chain (10-, 11- and 14-carbons in the backbone of the molecule) perfluorocarboxylates in fish livers. The presence of these compounds has implications for the toxicity of perfluorinated surfactants in the environment because perfluorinated carboxylic acids, particularly perfluorooctanoic acid (PFOA), and perfluorodecanoic acid (PFDA) are known peroxisome proliferators at relatively low concentrations; such compounds elevate rates of cell proliferation and cause liver cancer in rodents.
Perfluorinated surfactants have emerged as priority environmental contaminants recently as a result of recent reports about their detection in humans and wildlife, as well as concerns about their persistence and toxicity (Environ. Sci. Technol. 2001, 35 (7), 154A–160A). The analysis performed by Moody and co-workers at the University of Toronto and other Canadian institutions is based on sampling water and fish in Etobicoke Creek, near Toronto in Canada. On June 8, 2000, an accidental spill of fire-fighting foam containing perfluorinated surfactants occurred at the Toronto airport and dumped over 20,000 liters of fire-fighting foam into the stream.
Beginning the day after the spill, the researchers sampled water at the creek for 153 days. They also sampled small fish, first three weeks then seven months after the spill and used liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) to analyze the fish livers for perfluoroalkanesulfonates and perfluorocarboxylates, compounds of concern that are known to be, or thought to be present in the foam. Water samples were analyzed by using LC/MS/MS and 19F nuclear magnetic resonance (NMR). —REBECCA RENNER
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