Effects Based Methods for metals under the Water Framework Directive

Effects Based Methods are a promising new tool, and are considered for use under the Water Framework Directive. Effects Based Methods are a holistic approach which could assess the risks of chemical substances more accurately. Substances are grouped by their mode of action, and specific methods are subsequently developed based on this mode of action to establish a trigger value. This allows for regulating substances with the same mode of action.

This report evaluates the use of 13 Effects Based Methods that might be considered for regulating metals under the Water Framework Directive. Each Effects Based Method was evaluated with respect to three criteria that are critical when considering such methods for regulatory use. These criteria include specificity, sensitivity (to metals and to other classes of toxicants), and the link to higher levels of biological organisation.

The evaluation concludes that that each of the available methods has at least one significant limitation. Therefore, Effects Based Methods are today not well suited for regulating metals under the Water Framework Directive. Additionally, since metals are easily and routinely measured, the added benefit of developing Effects Based Methods for metals is unclear. Instead, it is recommended to further focus on developing bioavailability models for metals mixtures. Such models would be a more practical and cost-effective tool to assess metals under the Water Framework Directive in a holistic way.

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