Accumulation and toxicokinetics of fluoranthene in water‐only exposures with freshwater amphipods

Two 10‐d water‐only toxicity tests with radiolabeled fluoranthene were conducted with two species of freshwater amphipods, Hyalella azteca and Diporeia sp. For H. azteca , 10‐d median lethal concentrations were 564 nmol/L and 481 nmol/L. Tentative median lethal doses, determined from the regressions of body burden of remaining live H. azteca versus survival, were 5.6 and 3.6 mmol fluoranthene/kg wet weight tissue. Diporeia appeared to be less sensitive, because survival in Diporeia was greater than 84% after 10‐d exposures. Elimination rates determined for Diporeia , ranging from 0.0011 to 0.0042/h (half‐lives of 7–26 d), were much slower than rates determined for H. azteca of 0.128 to 0.188/h (half‐lives of 4–6 h). Faster elimination in H. azteca may be related to its greater ability to metabolize fluoranthene. For H. azteca , an average of 17% of its body burden was present as metabolites after 24 h of exposure to radiolabeled fluoranthene, as compared to 5% for Diporeia . For Diporeia , exposure to various water concentrations of fluoranthene for various lengths of time resulted in declines in the conditional uptake clearance rates (ml water cleared/g wet weight tissue/h). A similar, although less dramatic trend was observed for conditional uptake clearance rates in H. azteca .