Formatted Title:

Evaluating Human Health Risk of PFAS in Sediments and Shellfish towards Recreational Harvesters

Background/Objectives:

Per- and polyfluoroalkyl substances (PFAS) are a class of chemical contaminants that have raised concern due to their presence in a variety of environmental media and the evolving understanding of health risks. In New Hampshire’s Great Bay, they are of particular concern because this urbanized estuary contains multiple PFAS sources including, but not limited to, wastewater discharges and historical AFFF use. Like may coastal communities, it is also used for recreational and commercial harvesting of bivalve shellfish by residents. The objective of this study was to evaluate the human health risk for recreational harvesters by combining 1) locally collected data for the presence of PFAS in sediments and shellfish with 2) an exposure model that considers shellfish ingestion, sediment contact and incidental sediment ingestion.

Approach/Activities:

Seven sites within Great Bay were chosen to cover different PFAS sources (i.e., wastewater versus AFFF) and areas representative of the Bay. At each site, surface water, sediment and, based on availability, bivalve shellfish were sampled including American oysters, European oysters, razor clams, blue mussels and softshell clams. Samples were analyzed for 26 PFAS via ultra-high-performance liquid chromatography-tandem mass spectrometry at Clarkson University. To evaluate risk for human health, exposure pathways were modeled in combination with current USEPA toxicity factors (i.e., RfDs) for detected PFAS with available toxicological information to derive hazard quotients from potential exposure scenarios.

Results/Lessons Learned:

Based on USEPA assumptions of toxicity, PFOS and PFOA in select shellfish samples, combined with sediment exposure, present the most risk to recreational harvesters due to their recently lowered factors as well as the limited physicochemical information to characterize their exposure from sediments. Additional data on certain exposure factors (e.g., dermal absorption coefficients, bioavailability, film-forming behaviors and occurrence variability) are necessary to refine estimates of risks from multimedia exposures involving PFAS. This creates uncertainty for the evaluation of sediments thereby complicating risk communication with various stakeholders, including regulators and the regulated community. Finally, site-specific information on community behaviors or local regulatory actions is critical for risk assessments when evaluating unique recreational scenarios.

Kathryn Crawford

Affiliation

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(Group 1, Poster Board #31) Evaluating Human Health Risk of PFAS in Sediments and Shellfish towards Recreational Harvesters