Open landfill dumping areas for municipal wastes in Asian developing countries have recently
received particular attention with regard to environmental pollution problems. Because of the uncontrolled
burning of solid wastes, elevated contamination by various toxic chemicals including dioxins and related
compounds in these dumping sites has been anticipated. In this study, concentrations of polychlorinated
dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated
biphenyls (PCBs) were determined in soils from dumping sites in the Philippines, Cambodia, India, and
Vietnam. Residue concentrations of PCDD/Fs and coplanar PCBs in dumping site soils were apparently
greater than those in soils collected in agricultural or urban areas far from dumping sites, suggesting that
dumping sites are potential sources of PCDD/Fs and related compounds. Observed PCDD/F concentrations
in soils from dumping sites in the Philippines and Cambodia were comparable or higher than those reported
for dioxin-contaminated locations in the world (e.g., near the municipal waste incinerators and open landfill
dumping sites). Homologue profiles of PCDD/Fs in dumping site soils from the Philippines and, to a lesser
extent, from Cambodia and India reflected patterns of samples representing typical emissions, while profiles
of agricultural or urban soils were similar to those of typical environmental sinks. This result suggests recent
formation of PCDD/Fs in dumping site areas and that open dumping sites are a potential source of dioxins in
Asian developing countries. Uncontrolled combustions of solid wastes by waste pickers, generation of
methane gas, and low-temperature burning can be major factors for the formation of dioxins in dumping
sites. Elevated fluxes of PCDD/Fs to soils in dumping sites were encountered in the Philippines, Cambodia,
India, and Vietnam-Hanoi, and these levels were higher than those reported for other countries.
Considerable loading rates of PCDD/Fs in the dumping sites of these countries were observed, ranging from
20 to 3900 mg/yr (0.12-35 mg TEQ/yr). PCDD/F concentrations in some soil samples from the Philippines,
Cambodia, India, and Vietnam-Hanoi exceeded environmental guideline values, suggesting potential health
effects on humans and wildlife living near these dumping sites. The estimated intakes of dioxins via soil
ingestion and dermal exposure for children were higher than those for adults, suggesting greater risk of
dioxin exposure for children in dumping sites. To our knowledge, this is the first comprehensive study on
PCDD/Fs contamination in open dumping sites of Asian developing countries. On the basis of the result of
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this study, we have addressed a new environmental issue that open dumping sites are potential sources of
PCDD/Fs and related compounds, and dioxin contamination in dumping sites may become a key
environmental problem in developing countries.
