International demand for food and services drives environmental footprints of pesticide use

Modern agriculture's high yields, achieved through the Green Revolution's intensive practices (irrigation, fertilizers, pesticides), are unsustainable due to ecosystem damage, resource depletion, and climate change contributions. While studies have quantified environmental footprints concerning greenhouse gas emissions, water scarcity, biodiversity loss, and land use, the environmental pressures from pesticide use have been largely overlooked. Pesticides cause biodiversity loss and disrupt ecosystem functions, making their environmental risk reduction a key goal of global agricultural and environmental policies. The European Union's Farm to Fork Strategy, aiming for a sustainable food system, necessitates quantifying pesticide footprints across the supply chain and understanding how international trade drives pesticide use among nations. Previous environmental impact assessments have used pressure-oriented (elementary flows) and impact-oriented (midpoint and endpoint impacts) indicators stemming from Life Cycle Assessments (LCAs). Pesticides have been incorporated into chemical footprints assessed via bottom-up LCAs using impact-oriented indicators. However, bottom-up LCAs are limited in accounting for consumption-driven hotspots and global supply chain impacts. This study uses a top-down approach based on multi-region input-output (MRIO) analysis to quantify the global environmental footprint of pesticide use, considering international supply chain linkages and trade relationships.

The literature highlights the unsustainable nature of modern agricultural practices, emphasizing the need for a more holistic approach to environmental impact assessments. While considerable research exists on the environmental footprint of various aspects of food production and consumption, the contribution of pesticides has been relatively understudied. The authors review existing methodologies, such as bottom-up LCAs and pressure-oriented and impact-oriented indicators, noting their limitations in capturing the complexities of global supply chains and international trade. The existing literature lays the groundwork for the study's application of the MRIO analysis, which offers a more comprehensive approach to quantifying the global footprint of pesticide use.

The study defines pesticide footprints as hazard loads (HL), measuring the total body weight (bw) of non-target organisms needed to absorb pesticide residues accumulated annually without adverse effects. The HL is calculated as HL = [M_i/(NOAEL_i × 365)], where M_i is the total mass of active ingredient i and NOAEL_i is its no-observed adverse effect level. This approach considers both pesticide accumulation and toxicity. The analysis uses a top-down approach, employing MRIO analysis to link pesticide applications (PEST-CHEMGRIDSv1.0 database), a global environmental model, and a global supply-chain model. The study includes 82 countries and territories, either top agricultural producers, pesticide users, or high-income economies. Pesticide residues were estimated using a mechanistic, spatially-explicit model, considering soil properties, agricultural practices, and hydrometeorological variables. The model was run for 48 years to reach a near steady-state and included 80 active ingredients used in crop production. The hazard loads were then traced along international trade routes using the MRIO model, quantifying pesticide footprints from the primary producer to the final consumer perspectives. Footprints were assessed for different sectors (plant-based foods, animal-based foods, services, etc.) and for per-capita analysis. Net trade balances were calculated to identify net importers and exporters of pesticide footprints. Robustness checks and Monte Carlo simulations were used to assess uncertainty in the estimates.

The study accounts for 3.24 Mt of pesticides (79% of global pesticide use in 2015). Globally, 1.99 Gt-bw of hazard loads resulted, with 34% attributed to consumption in developed countries and 66% to developing countries. Insecticides were the largest contributors (80% of global footprints). Plant-based foods bore the largest portion (59%), with orchards, fruits, and grapes being the main contributors (17%). Developed countries had a higher fraction of footprints linked to empty-calorie foods (17%) compared to developing countries (9%). Globally, 32% of pesticide footprints were traded internationally. Developed countries had 49% of their pesticide footprints embodied in international trade, while developing countries had only 23%. High-income countries had the highest per-capita pesticide footprints, with Spain having the highest. China is the largest net importer of pesticide hazard loads, followed by Germany and the UK. The USA is the largest net exporter. Many European countries imported substantial hazard loads from active substances banned within their own countries. The largest international flow of embodied pesticide footprints was from the USA to China (0.029 Gt-bw), primarily due to soybean trade. Analysis of pesticide footprints per unit mass, calories, and protein in various food products showed significant variations. Orchard fruits and grapes had the highest footprints per unit mass and calories.

The findings highlight the significant role of international trade in the distribution of pesticide-related environmental burdens. Developed countries' consumption significantly contributes to pesticide contamination in other nations, particularly through the import of products containing banned substances. This emphasizes the need for international cooperation and reciprocal pesticide regulations to prevent the transfer of environmental burdens. The study's findings challenge the common assumption that animal-based foods always have higher environmental footprints than plant-based foods, showing that some plant-based foods (orchards, fruits, grapes) have higher pesticide footprints than certain animal-based foods. The results suggest that dietary shifts toward plant-based foods must be accompanied by strategies to minimize food waste and loss and reduce overconsumption of empty-calorie products. The significant uncertainty in global pesticide use data, especially in developing countries, underscores the importance of improving data collection and sharing internationally.

This study demonstrates the significant global environmental footprint of pesticide use, highlighting the role of international trade in shifting these impacts across nations. The findings call for international policy actions to address the disproportionate burden on developing countries, advocating for fairer trade practices and promoting sustainable pest management. Future research should focus on detailed analyses of pesticide use in non-cropland settings and investigate the specific drivers of increasing pesticide footprints, using techniques like structural decomposition analysis. Improved data collection and open access to global pesticide use data are crucial for effective policy development and a more sustainable agricultural future.

The study acknowledges limitations in the PEST-CHEMGRIDSv1.0 database, which does not include all active ingredients and assumes similar relationships between pesticide application rates and covariates across countries. Uncertainties in FAOSTAT data, particularly in Africa and Oceania, affect the accuracy of estimates. The use of crop maps from circa 2000 may lead to a slight underestimation of global pesticide footprints. The analysis excludes pesticide use in non-cropland settings. The assumption of equal pesticide application rates for local consumption and export crops may affect the estimates of internationally traded footprints. The pesticide hazard loads do not fully reflect human health effects or acute toxicities to all non-target organisms.