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(278) Perfluoroalkyl Acids and Amides: Preliminary Risk Characterization and Estimation. Purdy, Rich1, Walker, John2, 1 2 ABSTRACT- The U.S. TSCA Interagency Agency Testing Committee (ITC), using tools for screening large chemical inventories, identified 50 perfluorinated chemicals with persistence and bioconcentration potential. No data were available for most of the 50 perfluorinated chemicals. However, recent data submissions for one of these chemicals were of sufficient interest to stimulate the development of crude risk estimations. These estimations are being used to evaluate the veracity of the screening tools and to initiate development of QSARs for predicting physical properties, toxicity, persistence and bioconcentration potential of other perfluorinated chemicals. Almost all recently available data are for perfluorooctane sulfonate (PFOS), which is found in blood of humans and animals throughout the northern hemisphere. PFOS is an uncoupler of oxidative phosphorylation. The amide of PFOS (PFOSA) is the most potent uncoupler ever tested. It is found sporadically in wildlife and humans. In some species PFOSA is found at levels equal to those species' PFOS levels. PFOS and PFOSA are unusual biomagnifiers in that they are powerful surfactants and relatively soluble in water. PFOS was benchmarked against DDT and PCBs and found to be similar in some ways but different in others that raise concerns. Example: the food-to-liver biomagnification factor is 20 times greater than PCBs. The calculated cumulative dose in seals and dolphins is greater than the LOEL in rats. The aggregate toxic level of PFOS and PFOSA in bottle-nosed dolphin livers was found to be up to 7.5 ppm PFOS toxic equivalents. This is close to rat liver NOEL of 15 ppm. PFOS has been found in eagle plasma up to 2.6 ppm. The NOEL in rat plasma is 5.3 ppm. The very close proximity of levels found in tissues and the calculated cumulative dose to NOELs and LOELs suggest that humans and ecosystems could be at risk when exposed to these chemicals. Key words: risk, Perfluorochemical, Perfluorooctanesulfonate, uncoupler |
