Organochlorine pesticides and PCBs along the coast of north Vietnam.

Organochlorine pesticides and polychlorinated biphenyls (PCBs) were determined in sediments and clams collected from the coast of the north of Vietnam during the rainy season (August-September 1997). Results show that the organochlorine pesticides of major concern are HCHs (1.2-33.7 ng g-1 dry wt.), DDTs (6.2-10.4 ng g-1 dry wt.) and HCB (0.1-6.5 ng g-1 dry wt.). PCBs, in aroclor 1254 equivalents, were also generally present in concentrations ranging from 0.47 to 28.1 ng g-1 sediment dry wt. Concentrations measured in the soft tissues of clams (Meretrix meretrix) generally reflect the level of contamination at the sampling sites. In the clams, the concentrations of DDTs (12.0-23.3 ng g-1 dry wt.) and PCBs (5.1-25.3 ng g-1 dry wt.) were generally higher than those of other chlorinated hydrocarbons. These results underscore the need to improved environmental protection measures in order to reduce the exposure of the population to these persistent and bioaccumulative compounds through food ingestion.