Oral Presentation SETAC Asia-Pacific Virtual Conference 2022

Derivation of PFAS Water Quality Objectives – Food Web Modelling Techniques (#87)

Cindy Cheung 1 , Belinda Goldsworthy 1 , Vicky Wiraatmadja 1 , Bryant Gagliardi 1 , Ken Gilbert 1
  1. AECOM, Fortitude Valley, QUEENSLAND, Australia

INTRODUCTION

Significant challenges arise when identifying and agreeing on scientifically robust yet realistically achievable ecological water quality objectives (WQO) for PFAS to guide remediation management goals. In Australia, when considering perfluorooctane sulfonate (PFOS), adoption of the HEPA (2020) 99% species protection (spp.) WQO of 0.00023 μg/L for sites is often an unrealistic goal and is subject to some inherent limitations and uncertainty relating to its derivation method and underlying ecotoxicity data. With recognition of these uncertainties and limitations, AECOM has derived site-specific PFOS and perfluorohexane sulfonate (PFHxS) WQOs via food web modelling that are protective of bioaccumulation and direct ecotoxicity to surface water marine ecology.

METHODS

AECOM’s validated in-house food web model was used to back calculate a surface water concentration that will not result in an unacceptable bioaccumulation exposure risk for aquatic receptors of interest (ROI) which included turtles, dugongs, aquatic birds, dolphins and a water rat. The following exposure pathways were considered in the food web model:

a) ingestion of aquatic plants

b) ingestion of pelagic and benthic invertebrates

c) ingestion of finfish

d) ingestion of surface water

e) incidental ingestion of sediment.

Inputs to the food web model included a range of field-derived bioaccumulation factors (BAF) and biota-sediment accumulation factors (BSAF). The toxicity reference values (TRVs) adopted in the model were selected for avian and mammalian receptors.

RESULTS AND DISCUSSION

The resultant WQOs for PFOS (0.03 μg/L) and PFHxS (0.04 μg/L) were considered to be protective of indirect (bioaccumulation) and direct ecotoxicity to surface water ecology (ANZG, 2018), marine benthic communities (Simpson et al, 2021) and human receptors via exposure from seafood consumption (FSANZ, 2017) and recreational activities (HEPA, 2020). These WQOs were subjected to independent review by two expert Australian risk assessors and a contaminated land auditor with no errors or objections received

  1. ANZG (2018) Australian and New Zealand Guidelines for Fresh and Marine Water Quality. Australian and New Zealand Governments and Australian state and territory governments, Canberra ACT, Australia.
  2. Burkard, L. (2021) Published Bioconcentration Factor (BCF) and Bioaccumulation Factor (BAF) Data for Per‐ and Polyfluoroalkyl Substances Across Aquatic Species. Environmental Toxicology and Chemistry, 40(6): 530–1543.
  3. Heads of EPA Australian and New Zealand (HEPA). (2020) PFAS National Environmental Management Plan 2.0, February 2020.
  4. Food Standards Australia New Zealand (FSANZ). (2017) Supporting Document 2: Assessment of potential dietary exposure to perfluoroctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS) occurring in foods sampled from contaminated sites.
  5. Simpson SL, Liu Y, Spadaro DA, Wang X, Kookana RS, GE Batley. 2021. Chronic effects and thresholds for estuarine and marine benthic organism exposure to perfluorooctane sulfonic acid (PFOS)-contaminated sediments: Influence of organic carbon and exposure routes, Science of The Total Environment, Vol. 776, 146008, ISSN 0048-9697