Uptake, elimination, and biotransformation of aqueous and dietary DDT in marine fish

Abstract

To understand the biokinetics and potential risks of p,p'-dichlorodiphenyltrichloroethane (DDT) and its metabolites, p,p'-dichlorodiphenyldichloroethylene (DDE) and p,p'-dichlorodiphenyldichloroethane (DDD), in fish, we exposed the black sea breams (Acanthopagrus schlegeli) to aqueous and dietary DDTs and then evaluated the bioaccumulation, distribution, biotransformation, and elimination of DDTs under controlled laboratory conditions. The fish rapidly accumulated DDTs from both routes of exposure, particularly the gills and viscera. Elimination of DDTs following aqueous or dietary uptake was slow, and biotranslocation of DDTs was significant during the exposure period but negligible during the depuration period. The biotransformation process was more significant following dietary exposure. During depuration, DDE was the major biotransformed product in the sea breams' carcasses while DDD was the major product in the gills and viscera. However, DDD had a significantly higher elimination rate than DDE and, subsequently, the fish retained more DDE in the body. Intraspecies variability in the elimination and biotransformation processes in fish was observed. We demonstrated that the route of exposure significantly affected the fate and biokinetics of DDTs in fish. The application of a dynamic model provided a tool for quantifying the elimination and biotransformation of DDT in fish. The present study provided insights into the bioaccumulation and biotransformation pathways of DDT in fish that could have important ecotoxicological implications.