(31) A.A. Podowski, S. L. Sclove, A. Pilipowicz, and M.A.Q. Khan. Biotransformation and disposition of hexachlorocyclopentadiene in fish. Archives of Environmental Contamination and Toxicology 20 (1991), 488-496.
The fate of hexachlorocyclopentadiene (Hex) has been studied in fresh-water fish using in vivo and in vitro systems and applying statistical models to interpret the data. Hex injected into goldfish is readily distributed, stored and metabolized to numerous products (at least 11 organsoluble and various hydrophilic metabolites). The body residues of radioactivity decline in tissues with high levels in bile which increase with time, indicating this to be the major route of excretion of Hex and its metabolites. Elimination of total radioactivity in water indicated three phases of elimination with a calculated half-life of 7 days and predicted 90 and 95% clearance of 162 and 211 days, respectively. Out of 9 regression models, the 3-segment straight line model gave the best fit of the elimination data. A compartmental model indicated two elimination and one reabsorption phase. For a static system, with limited data, 2 phases of elimination were detected with a calculated half-life of 9 days and predicted 90 and 95% clearance of 77 and 107 days, respectively. Out of 6 regression models, the 2-segment exponential decay model gave the best fit. A compartmental model indicated that one elimination and one reabsorption phase were involved. In vivo metabolism of Hex by goldfish indicated that dechlorination, both reductive and oxidative, may produce a number of organosoluble and water-soluble products. Several of the organosolubles may be volatile, and at least 11 were characterized by thin-layer chromatography. The primary metabolites may react with endogenous molecules which render the more hydrophilic. In vitro studies using liver enzymes of bluegills indicated that both microsomal P-450 oxygenases and cytosolic GSH-transferases may be involved in Hex abolism. GSH can also alter Hex nonenzymically. The two hexane-extractable (in vitro) metabolites of Hex appear to be more polar than Hex. The inhibitors of the microsomal P-450 oxygenases (piperonlyl butoxide) and UDPGA-transferase (salicylamide) do not affect the toxicity of Hex to goldfish fingerlings, indicating that its toxicity may not be related with its metabolism--at least by these two liver microsomal enzymes.