Exposure of urban population to organophosphate esters and novel brominated flame retardants via indoor dust: Occurrence, sources and health risks in Uganda, East Africa

Abstract

Indoor environments are critical exposure pathways to flame retardants, yet data from Africa remain scarce. This study provides the first quantitative assessment of organophosphate esters (OPEs) and novel brominated flame retardants (NBFRs) in indoor dust from Ugandan households, establishing baseline data for East Africa. Dust samples collected from homes in Kampala were analyzed using gas chromatography–mass spectrometry (GC–MS). Concentrations of total OPEs (Σ5OPEs) and total NBFRs (Σ4NBFRs) ranged from 1,520–102,000 ng g-1 and 214–6,600 ng g-1, respectively. Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and 2,4,6-tribromophenyl allyl ether (TBP-AE) dominated OPE and NBFR profiles, respectively. Chlorinated OPEs contributed most to ΣOPEs, reflecting emissions from building materials and consumer products. Principal component analysis indicated household items, electrical equipment, and floor finishes as the major emission sources. Estimated human exposure doses showed that ingestion was the dominant route, with children more exposed than adults. Hazard index (HI) values were below 1 for all compounds, indicating negligible non-carcinogenic risk. Carcinogenic risk (CR) values ranged from 10-6–10-12, suggesting minimal lifetime cancer risks, though children exhibited relatively higher vulnerability. Compared with global datasets, OPE and NBFR levels in Kampala were within lower-to-median range but represent the inaugural dataset for sub-Saharan Africa. These findings provide a crucial regional reference for indoor flame-retardant exposure and highlight the need for extended studies across multiple indoor microenvironments to evaluate the long-term exposure pathways and inform safer chemical management.