Mitigating PFAS contamination in the United States: assessing the impact of California’s legislation from 2018 to 2022 on drinking water quality

This study evaluates the impact of California's specific per- and polyfluoroalkyl substances (PFAS) legislation on perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) contamination levels in public drinking water. We conducted a comparative statistical analysis using data collected by the United States Environmental Protection Agency (US EPA) Unregulated Contaminant Monitoring Rules (UCMRs), specifically UCMR 3 and UCMR 5. To assess PFOA and PFOS levels in active public water systems during the pre-legislation period (2017) and the post-legislation period (2023) we applied Levene's test to assess differences in variances, followed by unpaired and Welch's t-tests to compare mean PFAS concentrations between the two time periods. We detected a significant decline in both PFOA and PFOS levels post-legislation, suggesting that robust state-level regulatory measures can effectively reduce PFAS contamination. Findings highlight the potential for California's comprehensive approach to serve as a model for national policy to mitigate PFAS exposure and protect public health.