Distribution and elimination of [14C] hexachlorobenzene after single oral exposure in the rainbow trout (Salmo gairdneri).

Distribution and elimination of hexachlorobenzene (HCB) after administration to rainbow trout (Salmo gairdneri) of a single oral dose of 5 microCi [14C] HCB/100 g body weight were studied by whole-body autoradiography and liquid scintillation counting. To obtain some information on the physicochemical properties of the radiolabelled compounds, whole-body autoradiography was performed exposing parallel sagittal sections, treated at -20 degrees C, evaporated at 50 degrees C, and extracted separately with polar and nonpolar solvents. At d 1, radioactivity was distributed throughout the body. The highest concentration of radioactivity was found in adipose tissue. In the abdominal fat, the peak level of radioactivity was measured at d 30. No part of the radioactivity in the bile was evaporable. Radioactivity in the intestinal content, the skin, and the uveal tract was partly evaporable, while only traces of radioactivity remained in adipose tissue after evaporation. Radioactivity in the bile was extractable with water only. No radioactivity remained in any tissue after extraction with polar and nonpolar solvents. The rate of elimination was slow, and substantial amounts of radioactivity remained in the body 120 d after administration. In addition to bile excretion of nonevaporable, water-soluble radiolabeled compounds, a possible excretion over the intestinal mucosa was suggested.