Worms as a Substitute for Rodents in Toxicology: Acute Toxicity of Three Nickel Compounds

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Abstract
In a continuing investigation of the use of the common earthworm (Lumbricus terrestris) as test subjects for metal toxicity, three nickel salts were evaluated. Saline solutions of either the chloride, the sulfate, or the acetate were injected into the coelom of the worm. Care was taken not to enter the gastrointestinal tract. The acute toxicities were determined by graphical methods using probit paper. The most consistent results were found when lethality was measured at 48 h rather than 24 h. The 48-h LD50 values for the different salts of nickel are as follows: chloride, 52 mg/kg; sulfate, 54 mg/kg; and acetate, 69 mg/kg. The ratios of toxicity of nickel acetate to the chloride and sulfate salts in the worms are similar to those ratios noted in mice. The European Economic Commission (EEC) now suggests using earthworms for toxicity testing for legislation purposes.