Uptake metabolism, and elimination of 14C-labeled 1,2,4-trichlorobenzene in rainbow trout and carp.

Fingerling rainbow trout (Salmo gairdneri) were exposed to 14C-labeled 1,2,4-trichlorobenzene (TCB) for 8 h in a static exposure (0.018 mg/l) or for 35 d in a continuous-flow exposure (0.020 mg/l) followed by a subsequent elimination period. For the 2 d after the 8-h exposure, the half-time (t 1/2) of elimination of 14C from muscle and liver was 0.4 d, while after the 35-d exposure an early rapid elimination of 14C from these tissues (t 1/2 = 0.4 d) was followed by a slower elimination (t 1/2 = 50 d) during d 4-36. The maximum bioconcentration factors for 14C in muscle and liver were 51 and 102 after the 8-h exposure and 89 and 389 during the 35-d exposure. The values for bile were much greater, reaching 240 after the 8-h exposure and 1400 during the 35-d exposure. When larger trout and carp (Cyprinus carpio) were exposed to [14C] TCB (0.2-0.4 mg/l) the bioconcentration factor for bile 14C to water 14C was less than 100. Pretreatment of trout with beta-naphthoflavone, an inducer of hepatic mixed-function oxidase, increased this bioconcentration factor for bile to several hundred. Solvent partitioning and thin-layer chromatography (TLC) indicated that about 60% of the 14C in bile of control trout or carp was present as highly polar biotransformation products, while for induced trout the value was more than 90%. TLC in two solvent systems suggested that at least two such products were present in bile from control fish and at least three in bile from induced fish. About half of the 14C in bile from induced trout was more polar than the 14C in bile from normal trout.