ORIGINAL ABSTRACT

Pollution is recognized as a major threat to soil health; however, significant gaps persist regarding the distribution and risks of chemicals in developing regions. This study investigated the occurrence of pesticide residues in African agricultural soils. Between 2022 and 2024, we collected 272 topsoil samples from 13 countries representing diverse farming systems and analyzed them for 153 pesticide residues, including active ingredients and their metabolites. Pesticides were detected in 216 samples, with 63 different residues identified, several of which were unregistered in the countries where they were found and some banned in the European Union. The most frequently detected compounds were dinoterb, DDE-p,p', chlorpyrifos, metolachlor, atrazine-hydroxy-2, AMPA, and imidacloprid, all of which are substances of environmental, ecotoxicological, or toxicological concern. Individual pesticide concentrations ranged from <0.001 to 4.896 mg kg-1, and the total pesticide load reached 6.998 mg kg-1. At least 25% of the sampling locations are expected to present a high ecological risk (RQ ≥ 1), although data gaps for some substances limit assessment accuracy. Eleven pesticides exceeded the risk thresholds in at least one sample, with chlorpyrifos driving the most exceedances. A monitoring- and hazard-based prioritization approach highlighted additional high-concern compounds, notably dinoterb and glyphosate/AMPA. Overall, the findings reveal the significant environmental impacts of agricultural intensification and highlight regulatory challenges related to pesticide use across Africa.