An approach to assess the regulatory relevance of microevolutionary effects in ecological risk assessment of chemicals: a case study with cadmium.

The authors suggest an approach to assess the regulatory relevance of microevolutionary effects of chemicals based on a comparison of concentrations at which microevolutionary effects have been reported in the literature and conventionally derived ecotoxicological threshold concentrations. The authors found reports of microevolutionary effects of cadmium in freshwater organisms at hardness-normalized concentrations between 0.5 µg Cd L(-1) and 6290 µg Cd L(-1) (normalized to a hardness of 50 mg CaCO3 L(-1)). These concentrations were at least 1.5 times higher than the hardness-normalized hazardous concentration for 5% of the organisms of 0.34 µg Cd L(-1). This suggests that there is no immediate need to consider microevolutionary effects of Cd in environmental risk assessments of freshwater environments. However, some other aspects should be kept in mind as well. First, microevolutionary effects have so far only been investigated at few, relatively high concentrations of Cd and not encompassing the 5% hazardous concentration. Second, different types of microevolutionary effects or investigated ecotoxicological end points may influence the conclusions of the suggested comparative approach. Finally, factors influencing the bioavailability of Cd were not commonly reported in the literature, which made normalization of concentrations at which evolutionary effects occurred impossible and affected the number of studies that could be evaluated in the suggested approach.