Sedimentary PBDEs in urban areas of tropical Asian countries

- Urban areas of tropical Asian countries had high sedimentary PBDE concentrations.
- BDE209 was the most predominant PBDE in the sediments, followed by nona-BDEs.
- Anaerobic debromination of BDE209 had possibly occurred in some sediment samples.
- PBDEs from inland sources (e.g., canals or rivers) may impact coastal areas.
- Tropical Asia may contribute significantly to the global distribution of PBDEs.

Polybrominated diphenyl ethers (PBDEs) were measured in surface sediment samples collected from urban canals or rivers in Lao PDR, Cambodia, Vietnam, India, Indonesia, Thailand, the Philippines, Malaysia and Japan. The total PBDE concentrations in the sediments ranged from 0.83 to 3140 ng/g dry wt. BDE-209 was predominant, ranging from 43% to 97% of total PBDEs, followed by nona-BDEs and some detectable concentrations of BDEs 47, 49, 99, 100, 153, 154 and 183. Sedimentary PBDE levels in Malaysia, Cambodia, the Philippines and Thailand were generally higher than those reported for highly industrialized countries. Spatial distribution of PBDEs indicated that inland sources may impact coastal areas. The presence of BDE congeners which are not contained in technical mixtures and the higher proportions of nona-BDEs relative to BDE-209 in the sediments were identified as indicators of debromination. BDE-209 was possibly debrominated under anaerobic conditions in some of the sediment samples.