A worldwide evaluation of trophic magnification of per‐ and polyfluoroalkyl substances in aquatic ecosystems

A review of the published literature on the trophic magnification factor (TMF) for per‐ and polyfluoroalkyl substances (PFAS) was conducted to assess how biomagnification varies across aquatic systems worldwide. Although the TMF has been recognized as the most reliable tool for assessing the biomagnification of organic contaminants, peer‐reviewed studies reporting TMFs for PFAS are few and with limited geographical distribution. We found 25 published studies of the biomagnification of 35 specific PFAS, for which the TMF was generated through linear regression of individual log‐PFAS concentration and the δ15N‐based trophic position of each organism in the food webs. Studies were concentrated mainly in China, North America, and Europe, and the most investigated compound was perfluorooctane sulfonate (PFOS), which was frequently shown to be biomagnified in the food web (TMFs ranging from 0.8 to 20). Other long‐chain carboxylates displayed substantial variation in trophic magnification. Observed differences in the TMF were associated with length of the food web, geographic location, sampling methodologies, tissue analyzed, and distance from known direct PFAS inputs. In addition to biomagnification of legacy PFAS, precursor substances were observed to bioaccumulate in the food web, which suggests they may biotransform to more persistent PFAS compounds in upper trophic levels. This review discusses the variability of environmental characteristics driving PFAS biomagnification in natural ecosystems and highlights the different approaches used by each study, which can make comparisons among studies challenging. Suggestions on how to standardize TMFs for PFAS are also provided in this review. Integr Environ Assess Manag 2022;18:1500–1512. © 2022 SETAC KEY POINTS Polyfluoroalkyl substances (PFAS) studies using the trophic magnification factor (TMF) were concentrated mainly in China, North America, and Europe. Perfluorooctane sulfonate (PFOS) was the main compound analyzed over the 20 years of international concern regarding its potential to accumulate in biota. Long‐chain PFAS compounds showed considerable variation in their bioaccumulation through the food web, which was associated with differences not only in biological characteristics of the sampled organisms but also in methodologies among studies. The presence of PFAS precursors in the studied environments was highlighted as a potentially important factor in amplifying TMF values for legacy compounds.