Fate of fenitrothion in eel gills

Abstract

Eels of species Anguilla anguilla were exposed to sublethal concentrations of fenitrothion in a flow-through test system. Bioaccumulation and elimination of the toxicant in the branchial tissue of the eels were studied. Steady-state was reached after 48 hr of exposure to 0.02 ppm of toxicant, and earlier (24 hr) exposed to 0.04 ppm. Steady-state was maintained until the end of the exposure in both experiments. The highest bioconcentration factor (BCF) value was calculated in animals exposed to 0.04 ppm of toxicant, showing the relationship between the bioconcencentration into gills and the water disponibility. When the animals were transferred to clean water (depuration phase) they showed a rapid tendency to eliminate the pesticide. Pharmaco-kinetics parameters for fenitrothion in eel gills (K1, K1 and T1/2) were calculated. They showed relatively low K2 (0.0014 and 0.029 hr-1) and higher half-lives. Paralelly, total protein content in the gills was monitored during exposure and depuration phases. A depletion of total proteins of a 70% was observed in gill tissue at the end of the pesticide exposure. Although a tendency to recover protein levels was observed during the depuration phases, the depletion was maintained until the end of the experiments. The results showed a stress situation as a consequence of fenitrothion exposure which indicates the use of proteins as response to the increased energy requirements in this tissue.