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Earthworms Indicate Soil Toxicity


Scientists can examine the tissue of earthworms and observe the effects of pollution.

By Jenny Bennett

Earthworms ingest soil contaminants and absorb them through the skin, making them an ideal indicator of soil toxicity.

The full text of this article can be purchased from Informit.

The contamination of soil with polycyclic aromatic hydrocarbons (PAHs) is of much concern due to the possible harmful effects these substances can have on human health. PAHs are lipophilic materials; this means they mix more easily with oil than water. Because of these properties, PAHs in the environment are found predominantly in soil, sediment and oily substances rather than in water or in air. In addition to their presence in fossil fuels they are also formed by incomplete combustion of carbon-containing fuels such as wood, coal, diesel, fat, tobacco and incense.

Earthworms are excellent model organisms in ecotoxicological studies of soil toxicity due to their exposure to soil contaminants via both ingestion and passive absorption through their skin. The recommended species of earthworm in such toxicity studies is Eisenia fetida, which is known under various common names such as redworm, brandling worm, tiger worm and red wiggler worm. These worms thrive in rotting vegetation, compost and manure. Scientists can examine the tissue of these worms and observe the effects of pollution, enabling them to identify the most efficient and effective action to prevent any detrimental outcome.

Many studies have examined the exposure of earthworms to lethal contaminants such as PAHs. The problem with these studies is that, because they kill the worm, they often do...

The full text of this article can be purchased from Informit.

Jenny Bennett is Publisher – Chemical Sciences at CSIRO Publishing.