Daphnia magna wastewater toxicity assays:: an interlaboratory study

In order to protect aquatic life, many acute and short-term chronic whole effluent toxicity (WET) tests have been employed for assessment of the toxicity of wastewater. Toxicity tests using biological responses to measure effects provide valuable information about the significance of chemical contamination. The response of an organism to contaminated effluents provides an integrated measure of effects that reflects the combined actions of all. Acute toxicity tests with Daphnia magna are widely used. In order to verify the quality of such tests, the National Institute of Chemistry, organised an interlaboratory comparison. Seven interlaboratory trials named 'PT-Waste Water' were organised in the last four years. Toxicity with the Daphnia magna- mobility inhibition test (ISO 6341) was included in three rounds and about 20 laboratories, mostly from Slovenia, took part in each study. The purpose of the scheme was to enable participants to check their day-to day performance. The results of the toxicity tests were very good. The coefficient of variation of the results of participants decreased for sample T1 from 39.6% in the first inter-comparison to 14.5% in the third inter-comparison, and for sample T2 from 62.9% to 35.6%, respectively.