State of the Science for Risk Assessment of PFAS at Contaminated Sites

The current state of human health and ecological risk assessment at contaminated sites impacted by per- and polyfluoroalkyl substances is constantly evolving as our understanding of exposure and toxicity of per- and polyfluoroalkyl substances continues to develop. Site-specific risk assessments primarily aim to understand the potential for human health and ecological risks that may occur at the point of releases, as well as potential human health and ecological risks that may occur off-site as a result of per- and polyfluoroalkyl substances transport away from the initial point of release. This chapter provides an overview of human health and wildlife exposure pathways at per- and polyfluoroalkyl substances contaminated sites, and for each pathway discusses the state of knowledge of drivers for risk-based management of contaminated sites, the screening levels available for site media, as well as site investigation and risk assessment tools for the exposure pathways. The chapter concludes with a discussion of data gaps resulting in uncertainty in per- and polyfluoroalkyl substances risk assessment to provide insight into possible prioritization of data analyses needed to support to risk assessment for per- and polyfluoroalkyl substances.