Airborne and dust-bound PBDEs indoors and outdoors in İzmir, Türkiye: A multi-route exposure - risk assessment

Phased-out flame retardants, e.g., polybrominated diphenyl ethers (PBDEs), persist in environmental media due to their resistance to degradation and ongoing emissions from PBDE containing materials and industrial activities. This study addresses a notable data gap in a unique setting, i.e., İzmir, Türkiye, by investigating PBDE levels at homes, schools, and café/bar/restaurants, and assessing exposure and associated health risks. Indoor and outdoor air and dust samples were collected from rural, suburban, and urban areas. Exposure through ingestion, dermal absorption, and inhalation routes, and associated chronic-toxic and carcinogenic risks were estimated with Monte Carlo Simulation. Despite having been phase-out, house-dust ƩBDE concentrations remained prevalent with average levels of >2000 ng/g in schools and homes, while outdoors they were <500 ng/g. BDE-209 was the predominant congener with an indoor air concentration of 486 pg/m³ in schools and 56.7 pg/m³ in homes. BDE-209 contributed 83.5-90.4 % of the indoor air ƩBDE concentration in schools, while in homes this contribution ranged from 70.8 to 75.8 %. Aggregate exposure estimates show the predominant PBDE congener, BDE-209, was primarily exposed by accidental ingestion (58.6 %) followed by dermal absorption (21.9 %) and inhalation (19.5 %). Chronic-toxic risk (CTR, for BDE-47, BDE-99, BDE-153, and BDE-209) and carcinogenic risk (CR, for BDE-209) for the ingestion and dermal absorption routes indicated that house-dust and indoor-air PBDE exposures are not found to be considerable for human health. However, the contribution of inhalation route to the aggregate exposure of BDE-28, BDE-47, BDE-100, BDE-99 (87.0 %, 60.5 %, 54.3 %, and 57.3 %, respectively) may indicate the evermore PBDE exposure by inhalation for lower brominated congeners as they become more significant through environmental debromination of the predominant BDE-209.