Unraveling Legacy and Emerging PFAS Characteristics in Milk across 15 Countries (2020–2024): Features, Temporal Trend,s and Risk Priority

Despite increasing concerns over the potential hazards of perfluoroalkyl and polyfluoroalkyl substances (PFAS), their characteristics, especially temporal trends, remain largely unexplored in milk. With milk sampled from 2020 to 2024, the temporal trends and cross-country variations of legacy and emerging PFAS were investigated across 15 countries for the first time. Among the 32 PFAS analyzed, 26 were detected in more than 40% of the samples and 18 were present in over 60%, indicating their widespread geographical occurrence. Over the five-year period, concentrations of legacy PFAS declined significantly (p < 0.05), with a reduction rate of 85.9%, whereas emerging PFAS─particularly hexafluoropropylene oxide dimer (HFPO-DA) and 6:2 fluorotelomer sulfonic acids (6:2 FTS)─increased sharply by 251% and 146%. Based on these observed trends, we further projected PFAS concentrations in milk through 2030 using three statistical models, revealing a potential dominance of emerging PFAS in the near future. Notably, spatial differences in PFAS distribution appear to be associated with intensive industrialization and socioeconomic activities. Furthermore, a risk prioritization analysis integrating eight exposure and toxicity domains identified HFPO-DA, perfluorooctanoic acid (PFOA), perfluoropentanoic acid (PFPeA), and perfluorohexanesulfonate (PFHxS) as priority contaminants. These findings provide critical insights into global PFAS regulations, their effectiveness, and the urgent need for continuous monitoring of novel PFAS in future food supply.