Environmental quality standards: endpoints or triggers for a tiered ecological effect assessment approach?

The recently derived Dutch Environmental Quality Standards (EQS) for water, soil, and sediment for approximately 170 substances have been evaluated. Three methods have been used to derive the Dutch EQS. Independent of how the EQS were derived, they are given equal weight in Dutch environmental policy. Scientifically, the three methods may deserve different weights. For example, for soil and sediment, the least reliable method had to be applied to derive most of the EQS. Ecological effects in these compartments may be either overestimated or underestimated. A multitiered approach is proposed, which is relevant for all parties involved, including other countries, and which may help improve ecological effect assessment.