Screening of halogenated flame retardants and microplastics in indoor air from various microenvironments in Barcelona, Spain

In this work, inhalation, dermal contact with dust, and dust ingestion will be investigated as key pathways of exposure to polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), dechloranes, short-chain chlorinated paraffins (SCCPs), and microplastics (MPs). To do it, airborne particulate matter below 2.5 µm aerodynamic diameter (PM₂.₅) and settled dust were sampled across common indoor micro-environments. PBDEs were only detected in 27% of airborne samples. In dust, concentrations reached 2907 ng/g, dominated by BDE-209. A similar trend was observed for NBFRs and SCCPs, with low detection in air except in certain workplaces and vehicles, while dust concentrations reached up to 17,584 and 37,744 ng/g, respectively. Dechloranes were detected exclusively in one dust sample at 10.1 ng/g. Regarding MPs, polyethylene terephthalate and polyvinyl chloride were quantified in 94 and 87% of the samples, with median concentrations of 360 and 451 ng/m3, respectively. Estimated daily intakes via inhalation, ingestion, and dermal contact were calculated from PM2.5 and dust concentrations. SCCPs were the dominant contributors across measured exposure pathways, typically exceeding 50%, followed by PBDEs and NBFRs. When comparing the three exposure pathways, the most relevant was the inhalation (52%), followed by dermal contact with dust and dust ingestion (33% and 15%, respectively). In all cases, estimated exposure levels remained below risk thresholds, indicating no immediate health concerns. However, unassessed pathways, such as dietary intake and gas-phase inhalation, may substantially increase total exposure, potentially elevating risk beyond current thresholds, highlighting the need for continued monitoring and regulatory action to mitigate potential future health risks.