Investigation of perfluoroalkyl acid contamination hotspots in South Africa: a case study of fire outbreak sites

Abstract

This study investigated PFAS contamination at selected fire outbreak sites, focusing on PFOA and PFOS detection in soil and surface water samples in South Africa. The findings revealed varying contamination levels across samples. All soil samples contained PFOA and PFOS, at average concentrations of 10.97 ng·g⁻¹ dw and 18.58 ng·g⁻¹ dw, respectively. Similarly, PFOA and PFOS were found in all surface-water samples, with average levels of 5.16 ng·L⁻¹ and 11.48 ng·L⁻¹, respectively. PFOA and PFOS remained detectable in soil at multiple sites up to 2–5 years after documented incidents, indicating persistence at fire-impacted locations. An exploratory Welch’s t-test did not indicate statistically detectable differences between soil and surface-water concentrations; however, inference is limited because surface-water sampling was limited (n = 2). A screening-level ingestion scenario was used to contextualize surface-water concentrations (HQ/HI), indicating potential concern only if these surface waters were used as drinking sources. Overall, the findings motivate expanded PFAS profiling (including precursors), improved hydrologic pathway characterization (upstream/downstream designs), and broader spatial sampling to strengthen source attribution and exposure assessment in the African context.