Overview
- The peer-reviewed study published Oct. 23, 2026, analyzed about 1.86 million records from the EPA’s January 2026 UCMR5 dataset and found roughly 98 percent of individual PFAS results were reported as below laboratory minimum reporting levels.
- Using censoring-aware statistical models that generated 500 imputed values for each below-limit result, the authors estimate conventional summaries capture only about 44 percent of the modeled average for 25 PFAS, implying average concentrations could be roughly double reported figures.
- For the six PFAS covered by EPA’s national regulation, the team found an average of about 2.6 ng/L when non-detects are counted as zero versus a modeled estimate near 5.2 ng/L, with results varying by model assumptions.
- The authors released an open-source tool called PFAS-CAST and urged agencies to publish lab reporting limits, disclose how often results are below those limits, present uncertainty-aware estimates alongside standard summaries, and improve lab sensitivity.
- The paper stresses these outputs are model-based estimates not new measurements and says further testing, stronger lab methods, and clearer reporting are needed before changing public-health conclusions or regulatory limits.