Perfluoroalkyl Contaminants in a Food Web from Lake Ontario

Abstract

Perfluorooctane sulfonate (PFOS) is a persistent and bioaccumulative perfluorinated acid detectable in humans and wildlife worldwide that has alerted scientists to examine the environmental fate of other fluorinated organic contaminants. Recently a homologous series of perfluoroalkyl carboxylates (PFCAs) was detected in the Arctic, yet little is known about their sources, breadth of contamination, or environmental distribution. In this study we analyzed for PFOS, the homologous series of PFCAs ranging from 8 to 15 carbons in chain length, and the PFOS-precursor heptadecafluorooctane sulfonamide (FOSA) in various organisms from a food web of Lake Ontario. The sampled organisms included a top predator fish, lake trout (Salvelinus namaycush), three forage fish species including rainbow smelt (Osmerus mordax), slimy sculpin (Cottus cognatus), and alewife (Alosa pseudoharengus), and two invertebrates Diporeia (Diporeia hoyi) and Mysis (Mysis relicta). A striking finding was that the highest mean concentration for each fluorinated contaminantwas detected in the benthic macroinvertebrate Diporeia, which occupies the lowest trophic level of all organisms analyzed. Perfluorinated acid concentrations in Diporeia were often 10-fold higher than in Mysis, a predominantly pelagic feeder, suggesting that a major source of perfluoroalkyl contaminants to this food web was the sediment, not the water. PFOS was the dominant acid in all samples, but long-chain PFCAs, ranging in length from 8 to 15 carbons, were also detected in most samples between <0.5 and 90 ng/ g. Among Mysis and the more pelagic fish species (e.g. excluding Diporeia and sculpin) there was evidence for biomagnification, but the influence of foraging on highly contaminated Diporeia and sculpin by these fish may have overestimated trophic magnification factors (TMFs), which ranged from 0.51 for FOSA to 5.88 for PFOS. By accounting for the known diet composition of lake trout, it was shown that bioaccumulation was indeed occurring at the top of the food web for all perfluoroalkyl compounds except PFOA. Future monitoring at other locations in Lake Ontario, and in other aquatic environments, is necessary to determine if these food web dynamics are widespread. Archived lake trout samples collected between 1980 and 2001 showed that mean whole body PFOS concentrations increased from 43 to 180 ng/g over this period, but not linearly, and may have been indirectly influenced by the invasion and proliferation of zebra mussels (Dreissena polymorpha) through effects on the population and ecology of forage fishes.

Trends of polyfluoroalkyl compounds in marine biota and in humans

“…There were two trend publications about whole body PFOS concentration of archived lake trout samples (Salvelinus namaycush) from Lake Ontario. [122,123] According to Martin et al, the PFOS burden increased from 43 to 180 ng g À1 ww between 1980 and 2001. But the increase was not linear, decreasing concentrations in the mid-1990s were observed, followed by another increase until 2001.…”

“…But the increase was not linear, decreasing concentrations in the mid-1990s were observed, followed by another increase until 2001. [123] The authors supposed this might be caused by an indirect influence of the invasion of zebra mussels being a new, not contaminated diet for the trouts. Concerning PFOS their results were confirmed by Furdui et al, who analysed fish samples between 1979 and 2004.…”

“…PFUnDA was the most dominant PFCA which is probably caused by the high bioaccumulation and biomagnification potential. [123,[128][129][130][131] The high concentrations of PFUnDA in Asian skipjack tuna livers (Katsuwonus pelamis) indicate distinctive sources of PFCs arising from East Asian countries probably originating from the degradation of 10 : 2 FTOH. [130] In contrast, in Chinese sturgeon (Acipenser sinensis) PFTriDA was the most abundant PFCA in all tissues analysed except for muscle.…”

“…It was found in fish from the Baltic Sea and in American fish liver samples in a similar range as PFOS and in lower concentrations in skipjack tuna from Japan. [130] In general, PFOSA concentrations in marine fish were low, whereas high amounts in fish of Lake Ontario (up to 150 ng g À1 ww; whole fish) [123] or fish from the coast near Helsinki (up to 141 ng g À1 ww; liver) [135] probably indicate different sources of exposure. [77] PFOSAA was found in fish from China.…”

Associations between serum concentrations of perfluoroalkyl acids and serum lipid levels in a Chinese population

“…In recent years, PFAAs have attracted great attention internationally due to their global occurrences in environment and biota (Giesy and Kannan, 2001;Meesters and Schroder, 2004), as well as their toxicity (Lau et al, 2007) and bioaccumulation (Martin et al, 2004). PFAAs have also been found in potential human exposure pathways, such as food (Tittlemier et al, 2006), drinking water (Skutlarek et al, 2006), indoor air and dust (Shoeib et al, 2005), which hence raise great public-health concerns.…”