TOXICOKINETICS OF SELECTED POLYCYCLIC AROMATIC-HYDROCARBONS IN RAINBOW-TROUT FOLLOWING DIFFERENT ROUTES OF EXPOSURE

The toxicokinetics and bioavailabilities of 2‐methylnaphthalene (2‐MN), fluorene and pyrene were studied in rainbow trout (Salmo gairdners) implanted with an indwelling cannula in the dorsal aorta. After intraarterial injection of one of the polycyclic aromatic hydrocarbons (PAHs) (10 mg/kg) to trout, chemical concentration in the blood was found to decline triphasically with time. The terminal half‐lives of elimination from the blood for 2‐MN, fluorene and pyrene were 9.6, 10.5 and 12.8 h, respectively. The toxicokinetics of the PAHs in trout were best described by a three‐compartment open model with the central compartment and the deep peripheral compartment representing the blood and fatty tissues of trout, respectively. The PAHs were metabolized by trout mainly to water‐soluble metabolites which were excreted into the urine and bile. When trout were exposed to water containing 2‐MN, fluorene or pyrene (0.5 mg/L), the chemical was detected almost immediately in the blood. The apparent bioavailabilities of 2‐MN, fluorene and pyrene in trout were 20, 36 and 35%, respectively. In contrast, little or no unchanged chemical was detected in the blood of trout following intragastric administration of 2‐MN, fluorene or pyrene (50 mg/kg). These results indicate that the PAHs are absorbed systemically by trout via the branchial route at rates much faster than that of the oral route. Copyright © 1990 SETAC