Use of earthworms in toxicity tests for naturally occurring glycoalkaloids found in white potatoes and for pentachlorophenol: Modifications of a soil toxicity test

A standard soil toxicity test using the earthworm Eisenia fetida was modified to test the toxicity of naturally occurring glycoalkaloids found in the white potato Solanum tuberosum to earthworms and to evaluate the uptake of radiolabeled pentachlorophenol by the earthworms from soil. Chicken broth-saturated cellulose was found to be an acceptable foodstuff substitute for fermented alfalfa feed when mortality due to pentachlorophenol (PCP) toxication was the measured endpoint for 21-day tests using a natural silt loam and an artificial soil. The LC50 values for PCP were 104 mg PCP/kg artificial soil and 72 mg PCP/kg Millville silt loam when chicken broth-saturated cellulose was the foodstuff. When alfalfa was the foodstuff, the LC50 values were 72 mg PCP/kg artificial soil and 54 mg PCP/kg Millville silt loam. High pressure liquid chromatography was used to verify concentrations of PCP in the soils. To test glycoalkaloid toxicity, earthworms were fed boluses of ground Iyophilized white potato sprouts hydrated with chicken broth and ground Iyophilized white potato sprouts mixed with chicken broth-saturated cellulose. The earthworms avoided the food boluses which contained approximately 100 mg total glycoalkaloid/g dry mass (lyophilized potato sprouts and broth) and consumed portions of bolus containing approximately 16 mg total glycoalkaloid/g dry mass (lyophilized potato sprouts mixed with chicken broth-saturated cellulose). In a separate test, radiolabeled pentachlorophenol ([14C]PCP) was used to determine earthworms' uptake of PCP from soil. Uptake of [ 14C]PCP by earthworms was measurable in soils containing lower concentrations of PCP, but not in those containing higher concentrations of PCP owing to the deaths of the earthworms as a result of PCP toxicity at higher concentrations. Analysis of soil and earthworm samples was conducted by oxidizing the samples and counting disintegrations per minute of radiolabled carbon dioxide with a scintillation counter. The ratio of microcuries per gram dry mass of worm to microcuries per gram dry mass of soil was maximum at 25 mg PCP/kg soil dry mass. The modifications of the soil toxicity test were successful for both the natural toxin and the radiolabeled xenobiotic.