Evaluation of Site-specific Human Health Risks and Calculation of Risk-based Threshold Concentrations of PFOS and PFOA Using Bioaccumulation Modeled Fish Tissue Concentrations
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The United States Environmental Protection Agency recently finalized toxicity reference doses (RfD) and drinking water quality criteria for the perfluoroalkyl and polyfluoroalkyl substances (PFASs) perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA).

Along with drinking water and indoor dust, diet items including fish and shellfish may be a significant contribution to human intake of PFASs. To evaluate the potential risks to human health from consumption of fish tissue by recreational fishermen, a Fish Tissue Criteria (FTC) was derived from the RfD for the sum of the PFOS and PFOA. A RSC of 20% and 100% were both assumed for evaluation of human health risks from sites with historical PFAS contamination. The FTC for the sum of PFOS and PFOA ranged from 15 ng/g to 73 ng/g, wet weight for a 20% and 100% RSC, respectively. The FTC was compared to empirical concentrations of PFASs in fish from four sites with historic PFAS contamination, and concentrations in fish exceeded the FTCs at 75% of sites using an RSC of 100% and all four sites when using an RSC of 20%. PFOS represented 99% of the sum of the PFOS and PFOA exposure in fish where measured concentrations of both were available. Additionally, a food web model was used to calculate risk-based concentrations of PFOA and PFOS in sediment and water that would be associated with the FTC. The model showed good agreement between modeled and empirical concentrations in fish (when available for a site) with a mean model bias of 0.9 for PFOS and 2.9 for PFOA. Assuming a 20% RSC, absence of model-predicted risk is expected if concentrations of PFOS sediment and surface water are both less than 0.75 ng/g, dw (assuming 1% OC) for sediment and 12.4 ng/L respectively. Assuming a 100% RSC, absence of model-predicted risk is expected if concentrations of PFOS sediment and surface water are both less than 3.7 ng/g, dw and 62 ng/L, respectively.

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Publication Summary

  • Geosyntec Authors: Jennifer A. Arblaster
  • All Authors: Jennifer A. Arblaster
  • Title: 37th SETAC North America Annual Meeting
  • Event or Publication: Event
  • Practice Areas: Environmental Management, Water and Natural Resources, Water Management
  • Citation: November 6-10, 2016
  • Date: 2016
  • Location: Orlando, Florida
  • Type: Presentation