Bioassays with Earthworms Eisenia foetida

According to OECD Method 207 [40] bioassays with earthworms could be applied as acute or chronic tests. In both cases 10 or more animals of known weight are exposed to 500 g of sample. For acute toxicity, the test duration is limited to 2 weeks and the number of survivors and their weight are determined and compared with the results obtained from reference samples. For the chronic test, the animals are left in the vessels for up to 2 months (and are fed, of course), in addition to the number of adult survivors the number of cocoons (reproduction) is evaluated. 

The acute test does not seem to be suitable for the analysis of biodegradable materials, especially when the polymers are digestible by the earthworms. Compost is an optimal nutrition source for these animals and should never be tested to determine earthworm toxicity. The weight gain from the feed effect may cover possible smaller inhibition 

It may be an interesting task for future research to look at the digestion residues of biodegradable polymers obtained from long-term biotests with earthworms. The animal s conversion pathway differs significantly from those of microorganisms and may lead to other metabolites and residues. 

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