Applying the Pesticide Load Index to characterize ecotoxicological impact from pesticide use in the EU

Improving the sustainability of agriculture requires an advanced assessment of the ecological impacts of pesticides at both policy and scientific levels. This can be achieved by integrating ecological considerations into the assessments of plant protection products beyond plot or experimental sites. Among plant protection products, pesticides are often the most harmful and toxic due to the chemical properties of their active substances (AS), which can range from non- to extremely toxic depending on the organism affected. Our study applies the Pesticide Load Index (PLI), as applied in Denmark and in the United Kingdom , to quantify pesticide risks to environmental health and biodiversity across the European Union. The PLI is defined as the sum of the application rate (AR) for each applied AS (k) divided by the toxicity (TOX) for a number of non-target taxa such as birds, mammals, fish, algae and agricultural beneficial insects like bees and natural enemies of pests, using the formula: PLI = Σ (ARk / TOXk,i).

Our methodology bridges the gap between ecological health and pesticide risk assessment using three extensive data sets (Figure 1). The first includes EU-wide estimations of AS emissions, as geospatial layers at 1km resolution, representing the most extensive data collection available for the entire European Union. The second dataset provides unparalleled granularity in AS use, capturing field-level information across France for the year 2018, including details on crop type distribution. The third dataset, sourced from the Pesticide Properties DataBase, assesses the ecological impacts of pesticide use by linking usage to ecotoxicological endpoints.

Figure 1: Overview of the methodology for the Pesticide Load Index (PLI) Study. 

By integrating acute toxicity, chronic toxicity, and environmental fate, our approach moves towards a thorough understanding of pesticide impacts. Acute toxicity, indicative of short-term exposure, highlights immediate and potentially severe effects, while chronic toxicity addresses the long-term consequences of prolonged and continuous exposure. The environmental fate sheds light on the pesticides' behaviour and transformation in the environment, considering their distribution, degradation, accumulation, and transport across air, water, and soil.

The outcomes of this study provide a new perspective on pesticide use within the EU. The highly granular nature of the PLI maps makes them key tools for identifying areas with high ecotoxic levels, and therefore informing where additional risk mitigation measures are necessary. Detailed analyses are done by i) identifying predicted hotspots of pesticide use across the EU, ii) analysing variations in bio-climatic regions, and iii) breaking down the results by crop type and region. The role of this approach in monitoring the progress towards the European Union Farm to Fork and Biodiversity strategies targets is therefore clear, particularly in relation to the ambitious target of reducing pesticide use and toxicity by 50% by 2030. 

Our framework provides essential ecological insights for biodiversity conservation and ecosystem preservation, providing policy-makers with spatially explicit data for better-tailored strategies. Additionally, by enabling comparisons between crops, regions, and EU Member States it can contribute as to developing protective, realistic, and scientifically sound regulatory frameworks.