Method for determining toxicologically relevant cadmium residues in the earthworm Eisenia fetida.
We investigated a method to isolate toxicologically relevant Cd in earthworms (Eisenia fetida) exposed in a 14-d 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-state 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.
Conder
Jason M
JM
Department of Zoology, Oklahoma State University, Stillwater 74078, USA. jasonmconder@yahoo.com
Seals
Lisa D
LD
Lanno
Roman P
RP
D000818:Animals; D002104:Cadmium / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D005591:Chemical Fractionation; D002623:Chemistry Techniques, Analytical / Q000379:methods; D004784:Environmental Monitoring / Q000379:methods*; D008658:Inactivation, Metabolic; D009835:Oligochaeta / Q000737:chemistry* / Q000378:metabolism; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D014116:Toxicology / Q000379:methods
D012989:Soil Pollutants; D002104:Cadmium