A ten-year surveillance of PCDD/Fs and PCBs in raw milk from bovine, ovine, and caprine farms in a peri-industrial area of southern Italy

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) remain among the most persistent threats to food safety in peri-industrial agropastoral systems, yet long-term, multi-species surveillance data capable of disentangling environmental, biological, and regulatory determinants of contamination remain relatively scarce in the European literature. This study presents results from a ten-year monitoring program (2016–2025) of PCDD/Fs and PCBs in raw milk from bovine, ovine, and caprine farms reared within the industrially impacted territory of Taranto, southern Italy. A total of 671 samples were analysed by high-resolution gas chromatography–mass spectrometry, and contamination dynamics were modeled using linear mixed-effects regression accounting for farm distance from the industrial perimeter, animal species, and sampling year. PCBs exhibited a significant inverse relationship with distance, whereas pure PCDD/Fs showed no measurable spatial gradient, a pattern consistent with their greater soil persistence and likely reflecting decades-long environmental homogenization. Caprine and ovine milk consistently and substantially exceeded bovine concentrations across all contaminant classes, confirming small ruminants as the most sensitive sentinel species. A significant increasing temporal trend was attributable to sustained soil contamination and to the progressive, deliberate concentration of monitoring on sentinel high-risk holdings. These findings provide a transferable evidentiary basis for species-differentiated, soil-informed surveillance design in European territories affected by legacy industrial contamination.