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The use of polybrominated diphenyl ethers (PBDEs) as flame retardants in Singapore is not strictly regulated; therefore these compounds can be readily found in furniture, electronic devices, and building materials. This study was the first of its kind to be conducted in Singapore to measure concentrations of PBDEs in house dust. Samples were collected from 31 homes in various locations across the island-state of Singapore, and a total eight PBDEs congeners were measured. PBDEs were detected in all 31 dust samples and the number of BDE congener detected per home ranged between 3 and 8. The most abundant BDE congeners found were BDE 47, 99 and 209, with a median value of 20 ng g−1 dust, 24 ng g−1 dust and 1000 ng g−1 dust, respectively. BDE 209 contributed 88% to the median of all the congeners, and BDE 47 and 99 contributed 1.8% and 3.5%, respectively. Different congener profiles were observed between this and studies conducted elsewhere, which is consistent with the use of different commercial PBDE around the world. No significant correlations between PBDE dust levels and residential characteristics (number of TVs and computers, floor area or flooring material) were observed. The daily intake of PBDEs via the inhalation pathway was estimated. House dust may be regarded as the most important exposure route of PBDEs for children.

Although the use of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) has been prohibited in Singapore since 1980, OCPs and PCBs still can be detected in the environment and represent a potential threat to public health. In this study, OCPs and PCBs were measured in house dust samples collected from 31 homes across the island-state of Singapore. Organochlorine pesticides, such as hexachlorocyclohexanes (HCHs), chlordanes and dichlorodiphenyltrichloroethanes (DDTs) were tested, with a range ofLOD to 240ngg(-1) dust,LOD to 110ngg(-1) dust andLOD to 770ngg(-1) dust, respectively. Of 41 target PCB congeners measured, 28 were detected, and the median level of SigmaPCBs was 5.6ngg(-1) dust. The prevalence of these pesticides and industrial chemicals which have been banned many years ago suggests limited indoor degradation and on-going environmental accumulation. Weak negative correlations between an increased elevation of the residence and the concentration of DDTs and some low-chlorinated PCB congeners were noted, most likely due to increased ventilation and distance from ground-based sources at higher floors. Levels detected in several studies conducted in the USA were several orders of magnitude higher than concentrations observed in Singapore. Heavier use of chlorinated products in the USA, as well as different sampling methods, sampling time and site characteristics are likely explanations for the observed differences. Daily human intake of OCPs and PCBs via house dust was calculated, but values were low compared with dietary data from overseas. Ingestion of dust is indeed an exposure passway for these organochlorines, but may not be the predominant one.