Linking exposure pathways to internal concentrations of brominated flame retardants in Swedish mothers and their toddlers

Abstract: Brominated flame retardants (BFRs) have been used in a variety of consumer products to enhance their fire safety. This has resulted in exposure of the environment, wildlife and humans causing risks of endocrine disruption. The use restrictions of many BFRs have resulted in the introduction of other brominated chemicals (emerging BFRs) on the market. Humans are exposed to BFRs primarily via diet and dust ingestion, but the importance of the different exposure pathways has scarcely been studied. Children in particular have not been studied well due to lack of biomonitoring data.In this thesis, a mother-toddler cohort (n=24) from Uppsala was studied for their exposure to tri-decabrominated diphenyl ethers (tri-decaBDEs), isomer-specific hexabromocyclododecanes (HBCDs) and emerging BFRs (EBFRs). A clean-up and fractionation method was developed for determination of the above-mentioned BFRs in the same sample without dividing the sample. Measures of external exposure from dietary intake and dust ingestion were estimated. These were compared to internal concentrations (serum, feces) to determine which exposure pathways were most important for explaining the different BFR concentrations and patterns found in mothers and toddlers.Taking all the results into account, the toddlers’ higher serum levels of tetra-pentaBDEs seem to be the result of previous breastfeeding and those of octa-decaBDEs from exposure to house dust. For mothers, diet was estimated to be the main exposure route of tri-hexaBDEs and HBCDs. Dust ingestion was estimated to be the main route for BDE-209 exposure in mothers.Significant correlations were found between the tetra-decaBDE concentrations in matched serum and feces samples indicating that feces could be used as a non-invasive sample matrix for biomonitoring of PBDEs in toddlers. EBFRs were detected in the feces of toddlers and in a few serum samples from both mothers and toddlers indicating that exposure to these replacement chemicals occurs.