Perfluorooctane Sulfonate (PFOS) and related chemical products
In 2000 several member countries agreed to informally work together to collect information on the environmental and human health hazards of perfluorooctane sulfonate (PFOS) to produce a hazard assessment. The decision followed the announcement by a major US manufacturer (3M) to globally phase out the manufacture and use of these chemicals beginning in 2001. The US and the UK agreed to lead the activity with the Secretariat assisting by requesting readily available exposure information from member countries as well as from non-member countries through IFCS and UNEP.
At the 31st Joint Meeting of the Chemicals Committee and the Working Party on Chemicals, Pesticides and Biotechnology (7-10 November 2000), it was agreed that, since this was a matter of sufficient interest to all member countries, this activity should be undertaken under the Existing Chemicals Programme, overseen by the Task Force on Existing Chemicals. A special meeting on PFOS and its salts was held on 25 January 2001 in Orlando, USA, where the draft hazard assessment was discussed. The draft hazard assessment was revised twice since December 2000 to incorporate comments and input from member countries, as well as to incorporate newly completed studies.
At the 34th Joint Meeting of the Chemicals Committee and the Working Party on Chemicals, Pesticides and Biotechnology (5-8 November 2002), the final draft of the assessment was endorsed. The Joint Meeting recommended that this document be derestricted and published under the authority of the Secretary General.
Recommendations of the hazard assessment
Perfluorooctane sulfonate (PFOS) is a candidate for further work.
Sufficient information exists to address hazard classification for all SIDS human health endpoints. PFOS is persistent, bioaccumulative and toxic to mammalian species. There are species differences in the elimination half-life of PFOS; the half-life is 100 days in rats, 200 days in monkeys, and years in humans. The toxicity profile of PFOS is similar among rats and monkeys. Repeated exposure results in hepatotoxicity and mortality; the dose-response curve is very steep for mortality. This occurs in animals of all ages, although the neonate may be more sensitive. In addition, a 2-year bioassay in rats has shown that exposure to PFOS results in hepatocellular adenomas and thyroid follicular cell adenomas; the hepatocellular adenomas do not appear to be related to peroxisome proliferation. Further work to elucidate the species differences in toxicokinetics and in the mode of action of PFOS will increase our ability to predict risk to humans. Epidemiologic studies have shown an association of PFOS exposure and the incidence of bladder cancer; further work is needed to understand this association.
Sufficient information exists to address hazard classification for all SIDS environmental endpoints. PFOS is persistent in the environment and has been shown to bioconcentrate in fish. It has been detected in a number of species of wildlife, including marine mammals. Its persistence, presence in the environment and bioaccumulation potential indicate cause for concern. It appears to be of low to moderate toxicity to aquatic organisms but there is evidence of high acute toxicity to honey bees. No information is available on effects on soil- and sediment-dwelling organisms and the equilibrium partitioning method may not be suitable for predicting PNECs for these compartments. PFOS has been detected in sediment downstream of a production site and in effluents and sludge from sewage treatment plants.Given the apparent widespread occurrence of PFOS, national or regional exposure information gathering and risk assessment may need to be considered. In addition, data on its toxicity to soil and sediment-dwelling organisms could be generated as a post-SIDS activity. There is currently no information on effects on soil- or sediment-dwelling organsisms and PFOS has been detected in sediment and its presence in sewage sludge could lead to soil exposure if spread on agricultural land.