In Europe, for instance, “nonrelevant” metabolites are distinguished from metabolites that are “relevant for groundwater resources” or even “ecotoxicologically relevant”. The latter are those whose risk to soil or aquatic biota is comparable or higher than the parent and must meet the same standards as their parent. Groundwater-relevant metabolites are those likely to reach groundwater in concentrations above 0.1 μg/liter and to display the same toxicity as the parent compound.