Pesticiden in terrestrische Natura 2000-gebieden: Verkennende beoordeling op aanwezigheid, blootstellingsroutes en potentiële ecologische risico’s voor bodemorganismen en niet-doelwit geleedpotigen

The ruling of the Dutch Council of State on 2 April 2025 regarding the use of plant protection products in lily cultivation near the Natura 2000 site Holtingerveld provides the impetus for a closer examination of the knowledge base on pesticides in nature areas. The ruling highlights that, for permitting purposes, insight is required into both the presence of pesticides and their potential effects on protected nature, while such insights are currently only limited. This study aims, based on an initial inventory of existing monitoring studies, to provide insight into the presence and distribution of pesticides in terrestrial Natura 2000 sites, to identify the main knowledge gaps, and to make a first step towards estimating ecological risks and formulating management and policy options. The analysis is based on available measurement data from 12 Natura 2000 sites, comprising a total of 13 soil samples and 63 plant samples. In these samples, 84 different active substances and metabolites were detected. Most substances were found in plants, indicating that atmospheric deposition is an important exposure pathway: pesticides can be transported through the air over long distances and deposited on vegetation, even hundreds of metres from agricultural fields. Spray drift appears to be mainly relevant at short distances from farmland. No exceedances of conservatively derived ecological threshold values were found in soil samples. In plant samples, however, exceedances were identified for nine substances, meaning that negative effects on sensitive species cannot be ruled out with certainty in these cases. When mixtures of multiple pesticides are taken into account, around 22% of the plant samples show combined exposure levels that may exceed a preliminary risk threshold. An important outcome of this exploration is that the available ecotoxicological knowledge is limited, particularly with regard to long-term (chronic) and cumulative effects. As a result, population- and ecosystem-level effects can currently only be assessed in a very general way. In addition, there is a lack of a systematic and standardised monitoring programme, making it difficult to trace exposure pathways and leaving spatial and seasonal patterns largely unknown. The study concludes that an area-based approach is necessary. The origin of pesticides cannot be unambiguously attributed to individual farms, meaning that assessment is primarily meaningful at the landscape level. From a policy perspective, the main options lie in combining improved monitoring with dispersion models, strengthening buffer zones, and stimulating emission-reducing and precision application techniques. This exploration therefore provides a first basis for developing a more robust assessment framework for pesticides in and around Natura 2000 sites.