BIOACCUMULATION OF DDT PESTICIDE IN CULTURED ASIAN SEABASS FOLLOWING DIETARY EXPOSURE

Abstract

Bioaccumulation and metabolism ofp,p′-DDT was studied in the marine carnivorous fishLates calcarifer, Asian seabass, in a controlled aquaculture experiment. Over a 42-d period, seabass were fed pellets dosed withp,p′-DDT at environmentally realistic levels. Virtually allp,p′-DDT in pellets bioaccumulated in the fish with an uptake efficiency of 98%. The levels ofp,p′-DDT and the metabolitesp,p′-DDD andp,p′-DDE were analyzed in muscle, liver, visceral fat, brain, and remaining tissues. Partitioning of p,p′-DDT and its metabolites among the control, low-dose, and high-dose exposed seabass were 14.8% in muscle, 3.5% in liver, 37.1% in visceral fat, 0.11% in brain, and 45.5% in remaining tissues, where partitioning between tissues was a function of tissue lipid content.p,p′-DDT bioaccumulation increased linearly with exposure in visceral fat and muscle tissue. The metabolism ofp,p′-DDT, which occurs mainly in the liver, resulted in the degradation of 2.5% ofp,p′-DDT intop,p′-DDD,. These new findings show that bioaccumulation processes at environmentally realistic ingestion exposure levels (ng/g) differ from previous DDT ingestion studies conducted at unrealistically high DDT levels (μg/g), highlighting the need to revise models on the transfer of persistent organic pollutants in the marine environment and aquaculture systems.

This study is part of a scientific program entitled “Marine Environment Monitoring, Impact Assessment and Enhancement in Singapore,” funded by the Agency for Science, Technology, and Research, Singapore, and administered by the Tropical Marine Science Institute, Singapore. This study benefited from the valuable technical support of Ng Kay Leng and Edward Wild. Growth of fishes was supervised by Dr. Juan Walford and Dr. Balasubramaniam Sivaloganathan.