In October 2015, the NSW Government formed an expert panel to provide ongoing advice on contamination from the use of fire-fighting foams at the RAAF Williamtown Base. Preliminary investigations had identified that perfluoroalkyl substances from these foams were moving off the Base into the local community. A detailed site investigation and human health risk assessment (HHRA) were commissioned to inform management of the contamination in the areas around the Base. The role of the expert panel was to review the Site Investigation and HHRA to provide independent advice to the NSW government and the local community. The expert panel focused on developing an understanding the issues related to these unusual chemicals which are extremely persistent, bioaccumulative and water soluble.
These fire-fighting foams were historically made of per and poly fluorinated alkyl substances (PFAS) including chemicals like perfluorooctane sulfonate (PFOS). The unusual characteristics of these chemicals has required detailed consideration of significantly more exposure pathways than is common for contaminated land and groundwater investigations. The chemicals have moving widely in the environment. The rural fringe nature of this region has required a range of exposure pathways be evaluated including uptake into a variety of edible foods (e.g. fish, cattle meat, milk, honey, fruit and vegetables etc.). Issues such as large temporal and spatial variability, limits of reporting, interactions between surface water and groundwater (daylighting), biaoccumulation and availability of toxicological information have made development of a robust human health risk assessment a larger exercise than is common for contaminated sites.
The panel and its working groups have been discussing the best ways to address such issues. Discussion of the issues related to understanding fate and transport of these chemicals and how people and the environment might be exposed will be presented.