Contact and Artificial Soil Tests Using Earthworms to Evaluate the Impact of Wastes in Soil

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Abstract
This study was designed to evaluate two methods using earthworms that can be used to estimate the biological impact of organic and inorganic compounds that may be in wastes applied to land for treatment and disposal. The two methods were the contact test and the artificial soil test. The contact test is a 48-h test using an adult worm, a small glass vial, and filter paper to which the test chemical or waste is applied. The test is designed to provide close contact between the worm and a chemical, similar to the situation in soils. The method provides a rapid estimate of the relative toxicity of chemicals and industrial wastes. The artificial soil test uses a mixture of sand, kaolin, peat, and calcium carbonate as a representative soil. Different concentrations of the test material are added to the artificial soil, adult worms are added, and worm survival is evaluated after two weeks.These studies have shown that (1) earthworms can be used to distinguish among a wide variety of chemicals with a high degree of accuracy, (2) earthworms are a suitable biomonitoring tool to measure the impact of chemicals in wastes added to soils, (3) the contact and artificial soil tests can measure the biological impact of chemicals applied to soils, (4) earthworms can be used to differentiate the impact of chemical groups and specific chemicals, and (5) the contact and artificial soil tests appear to identify the same relative toxicity of chemicals as rat toxicity data.