Toxicity measurements in concentrated water samples - Rivm

Abstract
Toxicity measurements in concentrated water samples
Evaluation and validation
The National Institute for Public Health and the Environment, together with the Centre of Water
Management (formerly called Institute for Inland Water Management and Waste Water Treatment),
developed a method to measure the effects of toxic substances in surface water. This method can be
used to find out if, when ecological targets following from the European Water Framework Directive
are not met, this is caused by toxic substances. The method can also be used to identify sources of toxic
substances. Traditionally, mainly chemical techniques are applied for these purposes, but the
disadvantage is that they do not cover the large amounts of chemicals potentially present in surface
waters.
The method uses bioassays. For this purpose, the response of five species in the water under
investigation is studied. If a response is found, the substances causing this can be identified (if desired).
The method enables to investigate the combined effects of substances (synergistic or antagonistic).
Another advantage can be achieved by sample pre-treatment with a resin, allowing to concentrate the
toxic substances. This way acute tests can be used instead of chronic test (which are more expensive)
even if no acute effects can be found in the original (not concentrated) sample. In addition, natural
factors that influence the toxicity of surface water do not disturb the method after this pre-treatment.
Unfortunately, the toxicity of metals can not be investigated with this method.
Key words:
bioassays, toxicity, extraction, sample treatment, validation, toxic pressure
RIVM Report 607013010 3