Environmental and Health Risk Assessment of Perfluoroalkylated and Polyfluoroalkylated Substances (PFASs) in Sweden

This report summarizes the outcome of a project to present new information and knowledge about possible environmental- and health risks of perfluoroalkylated and polyfluoroalkylated substances (PFASs) in the Swedish population and in Swedish biota. The project was carried out as a risk assessment, consisting of an exposure assessment with Swedish biomonitoring data for 23 PFASs measured in humans, mammals, birds and fish, a hazard assessment with toxicological data from studies on mammals, birds and fish for the selected compounds and a risk characterization for humans, mammals, birds and fish. This is the first environmental and health risk assessment investigating a large number of PFASs, individually and in combination.In the human exposure assessment, two populations were identified and selected – individuals exposed indirectly via the environment (i.e. the general population) and an occupationally exposed subpopulation – professional ski waxers. The exposure data used consisted of PFASs levels in blood and serum. The result showed that PFAS congeners were found at low ppb (ng/ml) concentrations in serum in the general population. In a small subpopulation eating contaminated fish, PFOS was found at higher ppb concentrations.In the occupationally exposed, the levels of some congeners were significantly higher than in the average population, i.e. PFNA and PFOA reaching high ppb and low ppm (μg/ml) levels in serum, being approximately 125 and 200 times higher than in the general population. Temporal trend studies in the general population showed that the levels of PFOS, PFDS, PFOSA and PFOA seem to decrease, whereas, the levels of PFBS, PFHxS, PFNA, PFDA and PFUnDA in serum seem to increase.In the human hazard assessment, toxicity data and conclusions were primarily based on already existing hazard- and/or risk assessments and supplemented with additional published toxicological data of relevance. Two toxicological endpoints common for PFASs were identified and selected: 1) hepatotoxicity and 2) reproductive toxicity. For congeners lacking toxicological data or internal dose measurements a read-across was performed to the closest most potent congener for the respective endpoint. In addition, other endpoints showing lower effect levels were also considered. The result showed that the PFAS congeners were relatively similar with regard to their hepatotoxic and reproductive toxic properties, with points of departure (PODs) ranging from 4–89 μg/ml serum and 4–> 60 μg/ml, respectively. However, relevant toxicological data with internal doses were available for 4 of 15 congeners in the general population and for 5 of 17 in the occupationally exposed. For some congeners, other endpoints were identified at very low doses (e.g. immunotoxicity, impaired mammary gland development, obesity), similar to or below current human exposure levels. Epidemiological studies on PFASs showed inconsistent results.The risk characterization did not indicated any cause for concern 2 for hepatotoxicity or reproductive toxicity in the general population, neither for congeners assessed individually nor in combination. PFOS levels in the subpopulation that consumed contaminated fish were, or were close to, being of concern. For the occupationally exposed ski waxers a cause for concern was identified for hepatotoxicity based on single and combined PFAS exposure, as well as for reproductive toxicity based on combined PFAS exposure. It should be noted, that this group comprises a very limited number of people in Sweden.In the environmental exposure assessment, five species/subgroups with corresponding tissues were identified and selected: 1) seals (liver), 2) otters (liver), 3) birds (eggs), 4) marine fish (liver), and 5) highly exposed freshwater fish (muscle) based on the presence of PFASs in these species. All of these are present in or connected to the aquatic environment, demonstrating how PFASs enter the food chain via this route. In contrast, PFASs-levels were significantly lower in the terrestrial species examined. PFOS was the dominant congener in all species, often present at levels one to three orders of magnitude higher than the other congeners, and found at low ppm (μg/g) or high ppb (ng/g) levels in seals and otters, bird’s eggs and highly exposed freshwater fish, and at low ppb levels in marine fish. In seals and otters, there was a tendency for levels of sulfonates to decrease and carboxylates to increase. In peregrine falcon eggs, all PFASs detected were long chain congeners and temporal trends showed that the levels of sulfonates were either unchanged or decreasing. For carboxylates, the levels of congeners with 11–15 carbons were decreasing, but increasing for PFNA and PFDA. In marine fish, all congeners detected contained six or more carbons for sulfonates and nine or more for carboxylates, likely reflecting the higher bioconcentration factor (BCF) for the long chain congeners. In highly exposed freshwater fish, PFASs levels were significantly higher than in marine fish. In the environmental hazard assessment, hepatotoxicity and reproductive toxicity were assessed for seals and otters, and the PODs were derived from the same toxicological database as for the human hazard assessment but with hepatic concentrations used as internal dose. Toxicological data with hepatic PFASs-levels were available for 4 of 17 congeners assessed; thus data for the other congeners had to be extrapolated. For birds, only data from reproductive toxicity studies with PFASs-levels in eggs were considered, which was available for 5 of 15 congeners, and data for the other congeners had to be extrapolated. Few relevant studies on the reproductive toxicity of PFASs in birds were available, with effects being shown only for PFOS, hence the data can be considered uncertain with regard to effects and effect levels, and consequently, the extrapolations were uncertain. For fish, toxicological data were available for 5 of 17 congeners but are highly uncertain due to different species, study durations and endpoints used in the different studies.The result of the environmental risk characterization indicated a cause for concern for seals and otters for hepatotoxicity and reproductive toxicity, for either individual congeners and/or all congeners combined. It should be noted that the conclusions regarding seals and otters are based on the average PFASslevels at the latest time-point in temporal studies, and that the levels can be higher on an individual basis, which would result in lower safety margins than presented herein. For reproductive toxicity in birds, a cause for concern was indicated for PFOS where the highest level in peregrine falcons eggs (sampled in 2006) exceeded the toxic effect level identified in one study and where the average PFOS level is close to the toxic effect level. Thus, it cannot be excluded that these levels of PFOS in the eggs could give rise to adverse effects. For marine as well as freshwater fish, the available data do not indicate any cause for concern, even in waters contaminated by PFOS. However, it should be noted that the data for fish, monitoring as well as toxicity data, were subject to highly uncertain extrapolations.