Polychlorinated naphthalenes (PCNs): congener specific analysis, occurrence in food, and dietary exposure in the UK

Information on the occurrence of toxicologically significant polychlorinated naphthalenes (PCNs) in food, or on human exposure, is sparse. In this work, PCN congeners (PCNs 52, 53, 66/67, 68, 69, 71/72, 73, 74, and 75) were selected for analysis, based on the available literature on current occurrence and toxicology, and limited by the commercial availability of reference standards. The analytical methodology used cold solvent extraction of prehydrolyzed samples fortified with internal standards ((13)C(10) labeled PCNs), activated carbon and basic alumina purification, and measurement by HRGC-HRMS. The investigation showed PCN occurrence in all studied foods: meat, milk, fish, dairy and meat products, eggs, poultry, vegetables, fruits, etc. The most frequently detected congeners were PCN 52, PCNs 66/67, and PCN 73. The highest concentrations were observed in fish (maximum value of 37 ng/kg w.w. for the sum of the measured congeners). The dioxin-like toxicity (PCN TEQ) associated with these concentrations is 1-2 orders of magnitude lower than those reported for chlorinated dioxins or PCBs in food and, on the basis of dietary intakes estimated using very conservative assumptions regarding concentrations of these contaminants in the UK, the levels of PCNs alone in food do not suggest any toxicological concerns.