The study examined the temporal response of Hyalella azteca to pentachlorobenzene (PCBZ) in water-only exposures. Toxicity was evaluated by calculating the body residue of PCBZ associated with survival. The concentration of PCBZ in the tissues of H. azteca associated with 50% mortality decreased from 3 to 0.5 micromol/g over the temporal range of 1 to 28 d, respectively. No significant difference was observed in the body residue calculated for 50% mortality when the value was determined using live or dead organisms. Metabolism of PCBZ was not responsible for the temporal response because no detectable PCBZ biotransformation occurred over an exposure period of 10 d. A damage assessment model was used to evaluate the impact and repair of damage by PCBZ on H. azteca. The toxicokinetics were determined so that the temporal toxicity data could be fit to a damage assessment model. The half-life calculated for the elimination of PCBZ averaged approximately 49 h, while the value determined for the half-life of damage repair from the damage assessment model was 33 h.
Most of the polychlorinated biphenyl (PCB) body burden
accumulated by coho salmon (Oncorhynchus kisutch) from
the Laurentian Great Lakes is from their food. We used
diet information, PCB determinations in both coho salmon
and their prey, and bioenergetics modeling to estimate
the efficiency with which Lake Michigan coho salmon retain
PCBs from their food. Our estimate was the most
reliable estimate to date because (a) the coho salmon
and prey fish sampled during our study were sampled in
spring, summer, and fall from various locations throughout
the lake, (b) detailed measurements were made on the
PCB concentrations of both coho salmon and prey fish over
wide ranges in fish size, and (c) coho salmon diet was
analyzed in detail from April through November over a wide
range of salmon size from numerous locations throughout
the lake. We estimated that coho salmon from Lake
Michigan retain 50% of the PCBs that are contained within
their food.
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