Prevention, Pesticides and Toxic Substances

OPPT has been assessing perfluor,inated compounds since 1999. This interest was prompted by reports submitted to the agency describing the toxic properties and widespread presence in the environment, including in human populations, of some of these chemicals. Initial efforts focused on perfluorooctane sulfonate (PFOS), and the assessment of ecological and human health hazards was recently published under the auspices of the Organization for Economic Cooperation and Development (OECD, 2002). In general, PFOS is persistent and does not biodegrade in the environment. It bioaccumulates in fish, and the half-life in humans is estimated to be on the order ofyears. Biomonitoring studies have shown that PFOS is present in humans and wildlife around the world. The toxicity profile ofPFOS is consistent in mice, rats and monkeys, and includes liver toxicity, hypolipidemia, liver tumors, and developmental toxicity. In all species and life stages, there is a very steep dose-response curve for mortality which appears to be related to the cumulative internal dose. The U.S. EPA Office of Research and Development has been investigating the mode ofaction of the neonatal mortality associated with prenatal exposure to PFOS for several years.