Oral Presentation Society of Environmental Toxicology and Chemistry Australasia 2023

Identifying and prioritising human health risk pathways for PFAS in biosolids (#37)

Kate Langdon 1 , Janina Beyer 1 , Jennifer Braeunig 1 , Shaun Thomas 2
  1. NSW Department of Planning and Environment, Lidcombe, NSW, Australia
  2. Compliance and Regulatory Practice Branch, South Australian Environment Protection Authority, Adelaide, South Australia, Australia

Biosolids, which are the treated solid by-product from wastewater treatment plants, contain high concentrations of nutrients and organic matter. Therefore, land application of biosolids in an agricultural setting can be beneficial to the growth/yield of plants. However, due to the wide range of potential input sources into wastewater treatment plants (domestic and industrial), biosolids can contain a range of contaminants. To ensure that land application of biosolids does not pose a risk to human health or the environment, the key contaminants of concern and potential risk pathways need to be understood. Per- and poly-fluoroalkyl substances (PFAS) are a group of anthropogenic compounds that are regularly found in biosolids. There has been a considerable amount of interest recently in relation to PFAS in biosolids and if land application of biosolids results in a potential risk from PFAS to human health and the environment. This is also demonstrated in Australia by the inclusion of biosolids criteria for PFAS in the latest draft of the PFAS National Environmental Management Plan (NEMP version 3). The potential pathways of exposure to PFAS following land application of biosolids in agriculture can be complex as these compounds are persistent, toxic, bioaccumulative and mobile in the environment. We will present an approach for identifying and prioritising the key human health exposure pathways for PFAS in biosolids land applied in agriculture. The approach will focus on the three compounds with current toxicity reference values in Australia (perfluorooctane sulfonate [PFOS], perfluorohexane sulfonate [PFHxS] and perfluorooctanoic acid [PFOA]). The large variation in risk profiles from different exposure pathways will be demonstrated, highlighting that the human health exposure from meat and milk consumption are key exposure pathways. Case studies will also be used to demonstrate the importance of a robust conceptual site model that considers all potential pathways and receptors for exposure.