Polychlorobenzenes and polychlorinated biphenyls in ash and soil from several industrial areas in North Vietnam: residue concentrations, profiles and risk assessment

Polychlorinated benzenes (PCBzs) including penta- and hexachlorobenzene can be unintentionally formed from thermal processes in different industrial activities, and very little information is available on the contamination and emission characteristics of these new persistent organic pollutants from industries in Vietnam. In this study, contamination of PCBzs (including penta- and hexachlorobenzene, named PeCBz and HCB, respectively) and PCBs (including CB-28, 52, 101, 153, 138, 180) in fly ash, bottom ash and soil from combustion processes of waste incineration, metallurgy (steel making and zinc production) and cement production from several provinces in the Northern Vietnam, including Hai Duong, Hanoi, Bac Ninh, Hai Phong and Thai Nguyen, was preliminary investigated. The PCBzs concentrations in fly ash, bottom ash and soil ranged from 2.7 to 100 ng g(-1), from 2.7 to 159 ng g(-1) and from 0.28 to 33.9 ng g(-1), respectively. Relatively high residues of PeCBz in fly ash and bottom ash from municipal waste incinerators in some provinces from the Northern Vietnam were encountered. Total PCBs concentrations ranged from 18.0 to 8260 ng g(-1), from 1.0 to 10600 ng g(-1) and from 14.5 to 130 ng g(-1) for the fly ash, bottom ash and soil, respectively. Daily intakes of PeCBz, HCB and PCBs through soil ingestion and dermal exposure estimated for children ranged 0.33-9.93 (mean 3.14), 0.39-21.1 (mean 4.9) and 6.09-1530 ng/kg bw/day (mean 346), respectively; and these intakes were about 4.7-5.4 times higher than those estimated for adult. The intakes of PeCBz and HCB were relatively low, while those for PCBs exceeded WHO TDI for some samples.