Occurrence and Risks of Per- and Polyfluoroalkyl Substances in Shellfish

Abstract

Purpose of review: Per- and polyfluoroalkyl substances (PFAS) are a diverse class of persistent, fluorinated surfactants used widely in industrial and commercial applications with known adverse health effects. Seafood consumption is thought to be an underappreciated source of PFAS exposure in the general population. This review synthesizes the current understanding of PFAS occurrence in shellfish, a term used to describe animals such as mollusk bivalves, certain gastropods (snails), cephalopods (e.g., octopuses and squid), and crustaceans, and highlights scientific gaps relative to bioaccumulation and the protection of shellfish consumers.

Recent findings: A range of sampling methodologies are used across studies, and the suite of PFAS surveyed across studies is highly variable. Concentrations of PFAS observed in shellfish vary by geographic location, shellfish species, habitat, and across PFAS compounds, and studies informing estimates of bioaccumulation of PFAS in shellfish are extremely limited at this time. This review identifies several important opportunities for researchers to standardize PFAS sampling techniques, sample preparation, and analytical methodologies to allow for better comparison of PFAS analytes both within and across future studies. Increasing the range of geographic locations where samples are collected is also a critical priority to support a greater knowledge of worldwide PFAS contamination. When put into the context of risk to consumer, concentrations of PFAS, especially PFOS, found in shellfish collected from sites containing aqueous film-forming foam (AFFF) and industrial contamination may present risks to frequent consumers. Further research is needed to protect shellfish consumers and to inform shellfish advisories and health protective policies.

Keywords: Bioaccumulation; Food safety; PFAS; Risk assessment; Shellfish.

Figure 1.

Conceptual model for PFAS exposure to humans via the consumption of shellfish. Boxes represent compartments where PFAS may accumulate. Arrows represent processes like bioaccumulation (A), bioconcentration (B), and biomagnification (C). Red text denotes taxa that meet the definition of shellfish in this review.

Figure 2.

Locations of PFAS occurrence studies described in this review (n = 23).

Figure 3.

Concentrations of perfluoroalkyl carboxylic acids (PFCAs) for bivalves (A), cephalopods (C), crustaceans (E) and gastropods (G) along with perfluoroalkyl sulfonic acids (PFSAs) bivalves (B), cephalopods (D), crustaceans (F) and gastropods (H). All concentrations are reported as mean ± standard error of the mean (SEM) of averages reported in occurrence studies

Figure 4:

Log transformed bioaccumulation factors (BAFs) for PFAS identified in this review. Y-axis represents log values for BAF while x-axis is studied PFCA and PFSA ordered by chain length.

Figure 5.

Hazard quotients for various consumers of bivalves based on concentrations reported from reviewed studies. The grey line at “1” indicates a consumed dosage equal to the threshold dose for risk described by either the Agency for Toxic Substances and Disease Registry (ATSDR) or U.S. EPA for respective PFAS. Each symbol represents the hazard quotient based on a calculation using the median observed PFAS concentration from the reviewed studies, with the bars extending to show the range of hazard quotients based on the minimum (left bar) and maximum (right bar) observed PFAS concentrations. Bars crossing the gray line indicate the potential for excessive exposure risk relative to threshold doses for respective PFAS.