Understanding chemical mixtures in Swedish adolescents: an epidemiological investigation into exposure, sociodemographic determinants and immune-health effects

The world's human population is ubiquitously exposed to a complex mixture of chemicals. This thesis aims to analyse adolescent exposure in Sweden to a complex chemical mixture, including essential and non-essential elements, persistent organic pollutants (POPs), phthalates/phthalate alternatives, phosphorous flame retardants, and phenolic compounds. The research also investigated potential associations between this chemical mixture exposure and adolescent vaccination antibody titres of diphtheria, tetanus, pertussis, measles, and rubella. The study population (N=1082), Riksmaten Adolescents 2016-17 (RMA), were found to have similar chemical exposure levels as adolescents from Germany, Belgium, and the USA. Large population exceedances of biomonitoring guidance values were identified for lead, aluminium and per- and poly-fluoroalkyl substances. A conservative mixture risk assessment indicated that the effects of some of the investigated chemicals on the central nervous system may be a health concern. The level of mixture exposure varied based on factors such as age, gender, country of birth, parental education level, and longitude/latitude of the participant’s home address. Birth country was identified as the most influential determinant. Mixture exposure to elements and POPs was linked to decreased diphtheria, tetanus and pertussis antibody titres whilst the opposite was observed for measles and rubella antibody titres. However, the observed associations were weak and uncertain. This study revealed disparities in mixture exposure among Swedish adolescents born in different countries as well as gender and regional exposure differences. Addressing these disparities in mixture exposure is essential to achieve the United Nations sustainability goals of equality within and between countries and gender equality.