TOXICOKINETICS OF WATERBORNE PYRENE IN RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) FOLLOWING BRANCHIAL OR DERMAL EXPOSURE

The uptake and depuration of waterborne pyrene were studied in rainbow trout (Oncorhynchus mykiss) implanted with a dorsal aortic cannula. T he trout were placed individually either in an exposure chamber (chamb er-restrained mode) or in a 30-1 glass aquarium (free-swimming mode) a nd exposed to water containing 8 mg l(-1) pyrene for 4 h at 12+/-2 deg rees C. The exposure chamber could be divided by a latex diaphragm int o the front and the rear subcompartments and used to study either the branchial or the dermal uptake of waterborne pyrene by trout. After py rene exposure, the trout were provided with uncontaminated water to st udy the depuration of pyrene. Blood samples were withdrawn through the cannula at specific time intervals during and after pyrene exposure. The blood samples were extracted by hexane and analyzed for pyrene by HPLC. Pyrene concentrations in the blood of trout after branchial expo sure were significantly higher than those of the dermally exposed trou t indicating the gills as the most important route of waterborne pyren e absorption. Our results also showed that the chamber-restrained trou t had a significantly larger area under the blood concentration-time c urve than the free-swimming trout although both groups of fish had bee n exposed to 8 mg l(-1) of waterborne pyrene. Since an exposure chambe r may enhance the systemic absorption of waterborne pyrene by the trou t, care must be exercised in extrapolating results from the chamber-re strained trout to the free-swimming trout.