Abstract: Since the 1950s, per- and poly-fluoroalkyl substances (PFAS) have been widely used in numerous industrial and commercial applications such as lubricants, adhesives, stain and soil repellents, and paper coatings, as well as pharmaceuticals, insecticides, and fire-fighting foams. A number of PFAS have been identified and measured in the environment and as contaminants in different media. Numerous PFAS are classified as perfluoroalkyl acids (PFAAs) including perfluorinated sulfonic acids (PFSAs) and carboxylic acids (PFCAs) and include the well-known perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), and more recently emerging PFAAs such as perfluorinated phosphonic acids (PFPAs). The PFAS that are being produced have been in a state of flux over the last years as a result of phase-outs and regulations targeting PFAA chemistries with C8 chain lengths. PFAS replacements include new PFAAs such as shorter-chain analogues (e.g. perfluorobutane sulfonate (PFBS) and carboxylic acid (PFBA)), perfluorooctane-1-ethylcyclohexyl sulfonate (PFEtCHxS; a cyclic analog of PFOS) and numerous other substances such as various fluoropolymers.
PFAAs are often referred to as the “forever chemicals” as a consequence of their environmental stability. PFAAs are generally considered to be terminal products with respect to degradation and as a consequence have been shown to be bioaccumulative contaminants in exposed biota and wildlife and their ecosystems. For example, PFSAs and PFCAs, and a variety of their precursors have been reported in tissues or eggs of various (global) populations of wildlife, including birds and mammals. Over the last decades, time trend studies have shown the changing concentrations of mainly PFAAs in the tissues and eggs of higher trophic level wildlife and fish species. These wildlife exposures can be influenced by changes in sources and transport and due to a variety of physical (e.g. climate change) and ecological (changes in food we structure) factors depending on the species and population is question.
This presentation will 1) provide an overview of PFAS including newer replacement compounds, and wildlife exposure and bioaccumulation, 2) detail wildlife exposure case studies on the presence and trends of new and established PFAS in e.g. fish-eating birds from the Laurentian Great Lakes and Arctic mammals such as seals, beluga and polar bears, 3) detail how such PFAS data can feed into ecological risk assessments, which optimally requires a range of information for exposure and hazard assessments. Also discussed will be how PFAS information has fed into programs that have led to the global regulation of PFOS and PFOA and more recently perfluorohexane sulfonic acid (PFHxS).
Biography: Dr. Robert Letcher is a senior research scientist with Environment and Climate Change Canada (ECCC) and Adjunct Professor in the Departments of Biology and Chemistry, Carleton University. Dr. Letcher is a Fellow (Academy of Science) of the Royal Society of Canada. He is also Co-Editor-in-Chief and Co-Editor of the high impact scientific journals Environmental Research and Critical Reviews in Environmental Science and Technology, respectively. As reported in >400 research papers and >35 review papers in peer-reviewed scientific journals, as well as in other publications such as book chapters, books and reports, his research has advanced the understanding of the environmental persistence, exposure, bioaccumulation, fate, metabolism and effects of chemical contaminants, including per- and poly-fluoroalkyl substances (PFAS), in biota and their ecosystems throughout Canada and internationally.
Over the last 20 years, Dr. Letcher has supervised and mentored the projects of >26 graduate students and Post-Doctoral Fellows, which are part of collaborative projects with colleagues at numerous Canadian and International universities and institutions. A large part of Dr. Letcher’s work is devoted to top wildlife predators (e.g. birds and mammals) and fish in marine and freshwater ecosystems and their food webs. For example the Laurentian Great Lakes of North America and the circumpolar Arctic region, and supported by programs such as Northern Contaminants Program (NCP; Crown Indigenous Relations and Northern Affairs Canada (CIRNAC)), Chemicals Management Program (ECCC and Health Canada), the Natural Scientific Engineering and Research Council of Canada (NSERC), and the Arctic Council’s international Arctic Monitoring and Assessment Program (AMAP). This work has focused on circumpolar polar bears and their food webs, and the exposure and impacts of chemical contaminants, and by extension in Northerners and Inuit Peoples that consume them. His innovative research has highly influenced risk assessment and management of chemicals (including PFAS) in Canada and worldwide, for example, data and reviews for several chemicals now listed (e,g. PFOS and PFOA) on UNEP’s Stockholm Convention of Persistent Organic Pollutants.