Plant protection product residues in drinking water
Plant protection products are generally used in open fields and, as a result, also enter the environment. Under certain circumstances, some residues from these products can also make their way into the groundwater, surface water and drinking water.
In order to ensure that there is no risk to consumers, a general, substance-independent limit value of 0.1 micrograms per litre of drinking water applies in the EU for residues of active substances of plant protection products and their relevant metabolites in groundwater and drinking water (German Drinking Water Ordinance (TrinkwV), 2001).
In Germany, the responsibility for monitoring these limit levels lies with the federal states. If they detect exceeding levels of individual active substances or their degradation products, the state authorities determine whether this poses a health risk to consumers. For this purpose, the states use so-called drinking water guide values (microgram [μg] residue per litre of drinking water). Like the ADI value, the drinking water guide value specifies the maximum concentration of the residue in drinking water that can be consumed over the course of a life-time without any damage to health.
For plant protection products authorised in Germany, BfR determines the drinking water guide values based on the assumption of a daily drinking water consumption of 2 litres and a body weight of 70 kg. On precautionary grounds, the drinking water guide value should only constitute a maximum of 10% of the ADI. The absolute upper limit for a drinking water guide value is a concentration of 1,000 micrograms residue per litre of drinking water.
Based on the drinking water guide values determined by BfR, the German Federal Environment Agency (UBA) derives so-called action values for drinking water. From the perspective of health and drinking water hygiene, concentrations of plant protection product residues in drinking water are acceptable if they are below this action value.