PFAS released into the Tangipahoa River after a petrochemical plant explosion and fire in Louisiana, USA

Per- and polyfluoroalkyl substances (PFAS) are extensively reported in consumer products, industrial and municipal discharges, environmental matrices, and human tissues, and are increasingly associated with persistence and adverse health effects in wildlife and people. Despite thousands of accidental oil spills reported annually in the United States, PFAS emissions from petrochemical discharges and firefighting activities remain poorly characterized, limiting accurate assessment of environmental contamination and public-health risk. In August 2025, an explosion at Smitty's Supply in Roseland, Louisiana released 11.3 million gallons of residual oil, lubricants, and automotive fluids and thousands of gallons of firefighting foam, despite intensive recovery and cleanup efforts. Surface-water samples were collected along the Tangipahoa River (n = 56, 7 events over 8 spatial points), lower Tangipahoa River (n = 9, 2 events over 4-5 spatial points and in receiving estuary Lake Pontchartrain (n = 11, 2 events over 5-6 spatial points) over four months following the explosion and analyzed for 29 conventional and replacement PFAS using solid phase extraction and a state-of-the-art, validated HPLC-MS/MS method. Short-chain PFAS predominated, with PFPeA, PFHxA, and PFHpA detected in almost all river water samples at concentrations ranging from 0.16 to 398 ng/L. PFHxA accounted for the largest share (36-73%) of total quantified PFAS, followed by PFPeA (15-44%), PFBA, and PFHpA (4.7-16%). Flow-normalized mass discharges into the Tangipahoa River were estimated up to 111 g/day of PFPeA and 807 g/day of PFHxA. Second-order attenuation half-lives ranged from 7.48 to 15.3 days for PFPeA and 4.48-14.3 days for PFHxA. This study provides the first assessment of PFAS contamination associated with petroleum product releases into freshwater waterways, addressing a critical knowledge gap in Louisiana, a major hub for crude oil storage and distribution. Given the cultural importance of recreation and subsistence fishing in Louisiana, the observed PFAS profile has critical implications for long-term health impact assessments and for developing risk-management strategies for similar future incidents.