Ref ID : 7031
Janeck J. Scott-Fordsmand, Janson M. Weeks, and Stephen P. Hopkin; Importance of Contamination History for Understanding Toxicity of Copper to Earthworm Eisenia fetida (Oligochaeta: Annelida), Using Neutral-red Retention Assay. Environmental Toxicology & Chemistry 19(7):1774-1780, 2000
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Eisenia fetida was exposed in the laboratory to a range of elevated soil copper (Cu) concentrations under two different contamination histories. An EC10 for reproduction was observed at 34 mgCu/kg for soil spiked with Cu 1 day prior to running the experiment (newly spiked soil). Soil contaminated with Cu in the field more than 70 years previously (field-contaminated soil) caused a 10% decrease in reproduction at 248 mgCu/kg. Survival and cocoon wet weights were not affected by soil concentrations up to 1,400 mgCu/kg under either contamination history. Adult growth was reduced at 428 mgCu/kg (EC10) in newly spiked soil but not in field-contaminated soil at concentrations up to 1,400 mgCu/kg. The contamination history, as well as the toxicological parameter, was important in the interpretation of the outcome of a standard laboratory toxicity test. The lysosomal membrane stability of coelomocytes, measured as neutral-red retention time (NRR-time), was reduced at soil Cu concentrations lower than those affecting reproduction and demonstrated a dose-response relationship. The NRR-time was some severely reduced in worms exposed to newly Cu-spiked soil (EC10=8 mgCu/kg) than worms exposed to field-contaminated soil (EC10=69 mgCu/kg). The NRR-time reflected the bioactive Cu fraction, showing a good correlation with reproduction under both contamination histories.