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(T/EH002) Influence of storing time and test container material on measured toxicity within Whole Effluent Assessment. De Maagd, Gert-Jan1, Kerkum, Lia1, Moraal, Harry1, 1 ABSTRACT- Within the Dutch Whole Effluent Assessment (WEA) procedure the quality of effluents is assessed based on acute and chronic toxicity, bioaccumulation, genotoxicity and persistence. For that purpose effluent samples are taken and transported to laboratories in which a series of tests is performed. One of the key-issues within the validation of test procedures within WEA is whether a stored effluent sample remains representative for the actual effluent it is taken from. Sorption, volatilisation and degradation in the sample can be expected to lead to a reduced toxicity with storage time. This is especially true for bioassays for no preservation compounds can be added to samples used in bioassays. In the present study the bacterial toxicity of six industrial effluent samples from various origins is studied as a function of storage time at 4 degrees C, and test container material, i.e. glass versus poly-ethene. In general, lower toxicities were measured in poly-ethene stored samples than in glass stored samples. The decrease in toxicity between 1 and 14 days of storage generally varied between a factor 1 and 1.5 for glass stored samples and a factor 1.5 and 3 for poly-ethene stored samples. From this it is concluded that glass test container should be used and that a storage time up to 14 days does not lead to significantly reduced bacterial toxicities. Key words: effluent, bioassay, microtox, storage |
