This blog is being shared under the SOT Secretary’s name as part of their official duties and should not be interpreted as their personal or professional opinions.
This blog was written by Talia Sager.
At the 2026 SOT Poster Session “Human Exposure Assessment/Biomonitoring,” I spoke with Kristin Isaacs, PhD, about her poster, “Identification and Risk-Based Prioritization of PFAS Source Signatures in US Drinking Water.” Her presentation highlights an important step forward in understanding how PFAS contamination patterns form and what they mean for public health. Her team’s work responds to the growing challenge of PFAS increasingly being detected in drinking water systems across the country, yet the sources of these chemicals and their potential biological relevance often remain unclear.
Using nationwide data from the US Environmental Protection Agency’s (US EPA) Fifth Unregulated Contaminant Monitoring Rule (UCMR5), the study analyzed concentrations of 29 PFAS measured at more than 45,000 locations. Through non-negative matrix factorization, the researchers identified five distinct PFAS source profiles, each pointing to different industrial uses, degradation pathways, or legacy contamination patterns. They then clustered drinking water systems based on these source signatures to better understand regional impact.
To determine potential health relevance, the team combined toxicokinetic modeling with new approach methodologies to estimate PFAS mixture bioactivity. By comparing predicted biological activity with modeled human exposure, they developed bioactivity-to-exposure ratios (BERs) that help prioritize which water systems may warrant closer scrutiny. Notably, the lowest BERs, which are indicative of elevated risk relevance, were found in samples influenced by multiple PFAS sources or historical contaminants like PFOA and PFOS.
This work demonstrates that existing monitoring data can be utilized to detect PFAS as well as uncover where they come from and their associated risk potential. This integrated framework offers a promising path for regulators and communities seeking clearer guidance on PFAS mitigation and cleanup.
This blog reports on the Poster Session titled “Human Exposure Assessment/Biomonitoring” that was held during the 2026 SOT Annual Meeting and ToxExpo.
This blog was prepared by an SOT Reporter and represents the views of the author. SOT Reporters are SOT members who volunteer to write about sessions and events in which they participate during the SOT Annual Meeting and ToxExpo. SOT does not propose or endorse any position by posting this article. If you are interested in participating in the SOT Reporter program in the future, please email SOT Headquarters.
#SOTReporter