Per- and polyfluoroalkyl substances (PFAS) – unravelling exposure sources and demographical exposure patterns in a Swedish adolescent population

Abstract: Per- and polyfluoroalkyl acids (PFAS) is a group of anthropogenic substances, with some suspected to cause adverse health effects in humans. Little is known about adolescent exposure to PFAS, thus this thesis focuses on exposure sources and demographical exposure patterns of PFAS in a nationally representative Swedish adolescent (age 10-21 years) population (Riksmaten Adolescents 2016-17). Legacy PFAS, perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorohexane sulfonic acid (PFHxS) and perfluorooctane sulfonic acid (PFOS) were detected in serum from 70-100% of the participants (n=1098). Concentrations of PFOA, PFHxS and PFOS in serum increased with increased concentrations in drinking water (DW). Even though median PFAS concentrations in DW were as low as <1 ng/L, DW appeared as an important exposure source. Participants adhering to a diverse and healthy diet had higher PFNA, PFDA, PFUnDA and PFOS concentrations in serum than those that did not. This association was likely driven by a higher seafood consumption as a part of the healthy diet, supporting the notion that diet, apart from DW, is an important exposure source. Serum PFAS levels were on average highest among participants born in countries with high per capita income as compared to those born in low income countries. Conclusively, PFAS are chemicals of the industrialised world, with DW and seafood emerging as important exposure sources for adolescents. The findings of this thesis are important to consider in future risk assessments, as well as in studies of PFAS exposure and adolescent health.