Bioaccumulation of DDT pesticide in cultured Asian seabass following dietary exposure.

Bioaccumulation and metabolism of p,p'-DDT was studied in the marine carnivorous fish Lates calcarifer, Asian seabass, in a controlled aquaculture experiment. Over a 42-d period, seabass were fed pellets dosed with p,p'-DDT at environmentally realistic levels. Virtually all p,p'-DDT in pellets bioaccumulated in the fish with an uptake efficiency of 98%. The levels of p,p'-DDT and the metabolites p,p'-DDD and p,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 of p,p'-DDT, which occurs mainly in the liver, resulted in the degradation of 2.5% of p,p'-DDT into p,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 (microg/g), highlighting the need to revise models on the transfer of persistent organic pollutants in the marine environment and aquaculture systems.