Breastfeeding during infancy and consumption of fish and dairy products are associated with chlorinated persistent organic pollutants in serum from Swedish adolescents

Background: Food is considered the predominant source of human exposure to chlorinated and brominated persistent organic pollutants (POPs). Exposure and potential sources of these compounds are less studied in adolescents. We aimed to investigate blood serum levels of chlorinated and brominated POPs in Swedish adolescents and to investigate associations with breastfeeding and food consumption. Methods: A national representative sample of adolescents (three age groups with mean age of 12, 15 and 18 years) (N=1096) were recruited between September 2016 and May 2017 in the study Riksmaten adolescents 2016-17. Diet was assessed using a web-based 24-h dietary recall method and frequency questions. Chlorinated POPs (including ten polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), dichlorodiphenyldichloroethylene (p,p'-DDE)) and three polybrominated diphenylethers (PBDEs) were analysed in blood serum using gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) analysis. Associations between breastfeeding duration during infancy and consumption of five food groups (i.e. fish and shellfish, dairy products, eggs, meat, fats and oils) and serum POP concentrations were investigated. Results: HCB, p,p'-DDE, and CB118, 138, 153, 170, 180 and 187 were detected in most samples while the other analysed POPs were below limit of quantification in ≥60% of the samples. Longer breastfeeding time was associated with higher concentrations of p,p'-DDE, CB118, and CB138-187 (i.e. sum of CB138, 153, 170, 180, 187). Consumption of fish and shellfish was positively associated with concentrations of HCB and CB118. Consumption of dairy products was positively associated with concentrations of HCB and CB138-187. Egg consumption was positively associated with p,p'-DDE. Conclusion: Serum concentrations of HCB, p,p'-DDE and PCBs in Swedish adolescents are comparable to concentrations in other European adolescent populations. Breastfeeding, fish, dairy products, and eggs are probable sources of chlorinated POP exposure in Swedish adolescents.