Chemical accumulation and biotransformation enzyme activities of rainbow trout embryos in waterborne exposure to PCB-77

The penetration potential of a lipophilic pollutant, 3,3′,4,4′-tetrachlorobiphenyl (PCB-77), and the exposure time needed to activate the monooxygenase system of fish at the advanced embryonal stage were studied. Rainbow trout (Oncorhynchus mykiss) embryos were exposed to different doses (0, 1, 10, and 100 μg l−1) of PCB-77. Results indicated rapid and high accumulation of PCB-77 into the eggs. At the lowest test concentrations (1 and 10 μg l−1), all of the free PCB-77 was absorbed by embryos in three days. At the highest concentration (100 μg l−1), the accumulation limit (˜144 ng embryo−1) of the chemical was already reached after first exposure day. The microsomal CYP1A mono-oxygenase system (EROD) was shown to be a sensitive indicator of embryonic exposure, being induced at the low (1 μgl−1, 10 ng embryo−1) PCB-77 concentrations and after a short (three day) exposure time.