Fate of fenitrothion in eel gills

Eels of species Anguilla anguilla were exposed to sublethal concentrations of fenitrothion in a flow-through test system. Bioaccumulation and eliminat ion of the toxicant in the branchial tissue of the eels were studied. Stead y-state was reached after 48 hr of exposure to 0.02 ppm of toxicant, and ea rlier (24 hr) exposed to 0.04 ppm. Steady-state was maintained until the en d of the exposure in both experiments. The highest bioconcentration factor (BCF) value was calculated in animals exposed to 0.04 ppm of toxicant, show ing the relationship between the bioconcencentration into gills and the wat er disponibility. When the animals were transferred to clean water (depurat ion phase) they showed a rapid tendency to eliminate the pesticide. Pharmac o-kinetics parameters for fenitrothion in eel gills (K-1, K-1 and T-1/2) we re calculated. They showed relatively low K-2 (0.0014 and 0.029 hr(-1)) and higher half-lives. Paralelly, total protein content in the gills was monit ored during exposure and depuration phases. A depletion of total proteins o f a 70% was observed in gill tissue at the end of the pesticide exposure. A lthough a tendency to recover protein levels was observed during the depura tion phases, the depletion was maintained until the end of the experiments. The results showed a stress situation as a consequence of fenitrothion exp osure which indicates the use of proteins as response to the increased ener gy requirements in this tissue.