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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 6827

Jason M. Conder, Lisa D. Seals, and Roman P. Lanno; Method for determining toxicologically relevant cadmium residues in the earthworm Eisenia fetida. Chemosphere 49:1-7, 2002

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We investigated a method to isolate toxicologically relevant Cd in earthworms (Eisenia fetida) exposed in a 14-day Cd bioaccumulation study. A procedure involving acid insoluble ash (AIA) content was combined with homogenization and centrifugation techniques to divide total earthworm Cd burdens into supernatant (metallothionein-bound), pellet (toxicologically active), and soil-associated Cd fractions. Whereas the supernatant fraction of the earthworm digests increased linearly throughout the exposure period (from approximately 0 to 3.59 mmol/kg), the pellet fraction reached a steady-sate concentration (95% CI) of 1.2(0.9-1.4) mmol/kg, suggesting the ability of the metallothionein detoxification system to sequester incoming Cd. The AIA method was useful for correcting earthworm Cd concentrations for ingested soil-associated Cd and observing soil ingestion, which was suppressed in Cd-spiked artificial soil (1.06(0.57-1.55)%) compared to controls (17.25(14.36-20.15)%). These methods may be useful in investigating soil ingestion and Cd uptake and detoxification in earthworms.