| Abstract
| - Open landfill dumping areas for municipal wastes inAsian developing countries have recently receivedparticular attention with regard to environmental pollutionproblems. Because of the uncontrolled burning of solidwastes, elevated contamination by various toxic chemicalsincluding dioxins and related compounds in these dumpingsites has been anticipated. In this study, concentrationsof polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinateddibenzofurans (PCDFs), and coplanar polychlorinatedbiphenyls (PCBs) were determined in soils from dumpingsites in the Philippines, Cambodia, India, and Vietnam. Residueconcentrations of PCDD/Fs and coplanar PCBs in dumpingsite soils were apparently greater than those in soilscollected in agricultural or urban areas far from dumpingsites, suggesting that dumping sites are potential sourcesof PCDD/Fs and related compounds. Observed PCDD/Fconcentrations in soils from dumping sites in the Philippinesand Cambodia were comparable or higher than thosereported for dioxin-contaminated locations in the world(e.g., near the municipal waste incinerators and open landfilldumping sites). Homologue profiles of PCDD/Fs in dumpingsite soils from the Philippines and, to a lesser extent,from Cambodia and India reflected patterns of samplesrepresenting typical emissions, while profiles of agriculturalor urban soils were similar to those of typical environmentalsinks. This result suggests recent formation of PCDD/Fsin dumping site areas and that open dumping sites are apotential source of dioxins in Asian developing countries.Uncontrolled combustions of solid wastes by wastepickers, generation of methane gas, and low-temperatureburning can be major factors for the formation of dioxinsin dumping sites. Elevated fluxes of PCDD/Fs to soils in dumpingsites were encountered in the Philippines, Cambodia,India, and Vietnam−Hanoi, and these levels were higherthan those reported for other countries. Considerable loadingrates of PCDD/Fs in the dumping sites of these countrieswere observed, ranging from 20 to 3900 mg/yr (0.12−35 mgTEQ/yr). PCDD/F concentrations in some soil samplesfrom the Philippines, Cambodia, India, and Vietnam−Hanoiexceeded environmental guideline values, suggestingpotential health effects on humans and wildlife living nearthese dumping sites. The estimated intakes of dioxinsvia soil ingestion and dermal exposure for children werehigher than those for adults, suggesting greater risk of dioxinexposure for children in dumping sites. To our knowledge,this is the first comprehensive study on PCDD/Fscontamination in open dumping sites of Asian developingcountries. On the basis of the result of this study, wehave addressed a new environmental issue that opendumping sites are potential sources of PCDD/Fs and relatedcompounds, and dioxin contamination in dumping sitesmay become a key environmental problem in developingcountries.
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