Considerations for toxicity experiments and risk assessments with PFAS mixtures

Area of Science:

• Environmental Chemistry
• Toxicology
• Risk Assessment

Background:

• Per- and polyfluoroalkyl substances (PFAS) are widely studied, yet significant knowledge gaps persist regarding their toxicity and interactions in mixtures.
• Research on PFAS toxicity, bioaccumulation, biomagnification, and mixture interactions is increasing.
• Understanding PFAS mixture dynamics is critical due to their prevalence and the variability of their concentrations.

Purpose of the Study:

• To discuss available approaches for mixture risk assessment, specifically for PFAS mixtures.
• To highlight lessons learned from studying chemical mixtures and apply them to PFAS.
• To explore challenges in designing and interpreting aquatic toxicity experiments for PFAS binary mixtures.

Main Methods:

• Review of existing mixture risk assessment approaches.
• Analysis of challenges in single-chemical and binary-mixture toxicity studies for PFAS.
• Exploration of experimental design for aquatic concentration-response experiments with PFOS and PFHxS mixtures.

Main Results:

• Limited toxicological data for most PFAS complicates mixture risk assessment.
• Designing and interpreting aquatic toxicity experiments for PFAS binary mixtures presents challenges.
• PFAS mixture concentrations vary significantly across different sites and over time.

Conclusions:

• Addressing PFAS mixture risk requires a combination of traditional toxicity studies and novel methods (in vitro assays, read-across, QSAR).
• Site-specific empirical data, including toxicity sampling and community structure studies, are essential for a comprehensive understanding of PFAS mixture impacts.
• Future research should integrate diverse methodologies to effectively assess and manage risks posed by PFAS mixtures.