An evaluation of selected organochlorine pesticide residues [p,p'- dichlorodiphenyltrichloroethane (DDT), p,p'- dichlorodiphenyldichloroethylene (DDE), p,p'- dichlorodiphenyldichloroethane (DDD), alpha, beta, gamma and delta- hexachlorocyclohexane (HCH)] in the surface soils of Hanoi, Vietnam was carried out. Sixty representative soil samples were collected from the centre of Hanoi and five surrounding districts. In agricultural areas, SigmaDDT concentrations ranged from < 0.02 to 171.83 ng g(-1) (mean 89.86 ng g(-1)) dry weight, whereas SigmaHCH concentrations ranged from < 0.05 to 20.57 ng g(-1) (mean 8.03 ng g(-1)) dry weight. Investigation of the ratio of different isomers in the soil samples indicates that there has been no recent input of DDT and HCH in the study area.

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Selected organochlorine pesticides (p,p'-DDT, p,p'-DDE, p,p'-DDD, alpha,beta,gamma,delta-HCH) were analyzed in the surface soils of Bacninh, Viet Nam. Forty representative soil samples were collected from Bacninh town and three surrounding districts. SigmaDDT concentrations ranged from <0.02 to 160.86 ng g(-1) dry weight, whereas SigmaHCH concentrations ranged from <0.05 to 9.54 ng g(-1) dry weight. The half-life times of SigmaDDT and SigmaHCH are 6.7 and 4.9 years, respectively. The decreasing trends of SigmaDDT and SigmaHCH levels during the period from 1992 to 2006 are observed. There is no recent input of DDT and HCH in the study area.