Geographic Variation in Serum Polychlorinated Dibenzo-p-dioxins, Polychlorinated Dibenzofurans and Polychlorinated Biphenyls: The Exposure Study on Susceptible People in Campania, Italy

The Exposure Study on Susceptible People (SPES) investigated environmental exposures in Campania, Southern Italy. This cross-sectional substudy examined geographic variation in 35 serum congeners of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in 600 adults sampled during 2016–2017. Participants lived in areas of high (n = 240), medium (n = 240) or low (n = 120) environmental pressure. Individual specimens were analysed at Université de Liège, Belgium (n = 400), or Istituto Zooprofilattico Sperimentale del Mezzogiorno (IZSM), Italy (n = 200). Overall, median middle-bound toxic equivalents (TEQs) were 2.10 pg WHO-2022-TEQ/g lipid for PCDD/Fs and 0.732 for dioxin-like PCBs; the six-indicator PCB median was 59.5 ng/g lipid. Laboratory-specific models were adjusted for age and sex. Geographic differences met the multiple-testing criterion for dioxin-like PCBs among Liège-tested participants and indicator PCBs among IZSM-tested participants. Adjusted dioxin-like PCB concentrations were highest at low pressure in the Liège-tested subset; indicator PCBs were higher at medium than high pressure in the IZSM-tested subset. Further lifestyle and dietary adjustments led to little change in these contrasts. The highest concentrations occurred in different environmental-pressure categories for different chemical classes.