What is it about?
Soil pollution research in Africa has focused mostly on heavy metals and mining contamination, leaving pesticides comparatively under studied. This study set out to close that gap by testing for actual pesticide residues in the ground. Between 2022 and 2024, researchers collected 272 topsoil samples from farms across 13 African countries, covering a range of farming systems, and screened each sample for 153 different pesticide compounds and their breakdown products. Pesticides turned up in 216 of the 272 samples, 63 different compounds in total, and notably, several of these weren't even registered for use in the countries where they were found, and some are outright banned in the European Union. The most commonly detected substances included dinoterb, a DDT breakdown product, chlorpyrifos, and several herbicides like atrazine and glyphosate's main metabolite, all compounds with known environmental or toxicological red flags. Concentrations varied widely, but at roughly a quarter of the sampled locations, pesticide levels were high enough to pose a real ecological risk, with chlorpyrifos responsible for the most instances of exceeding safety thresholds
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Why is it important?
Pesticide pollution in soil is a genuine blind spot in African soil health monitoring, most existing pollution mapping efforts, as other recent reviews have noted, skew heavily toward heavy metals and mining related contamination, leaving a limited picture of chemical pesticide exposure across the continent. This study is one of the first to put real numbers behind that gap at a multi-country scale, and the findings are concerning on two fronts: not just that pesticides are present, but that some of the most frequently detected compounds are unregistered or banned substances, meaning they're likely entering these soils through unregulated channels, counterfeit products, or cross border trade. For regulators, that's a direct signal that enforcement and registration systems have real gaps. For food safety and ecological health more broadly, the finding that a quarter of sites cross a recognized risk threshold is a concrete basis for prioritizing which compounds and regions need monitoring attention first.
Perspectives
This study lands squarely in territory I think our field has been slow to address. We talk a great deal about nutrient depletion and physical degradation in African soils, and comparatively little about the chemical residues we're actively adding to them. What strikes me most is the presence of unregistered and banned compounds in the samples, that's not simply a monitoring gap, it's a signal of weak regulatory enforcement and an active market for chemicals that shouldn't be reaching farmers in the first place. I'd want to see this data cross-referenced against local pesticide import and distribution records, since if certain unregistered compounds are clustering in particular countries or regions, that points to specific supply chains worth investigating. It's also worth noting how this complements the soil pollution mapping work coming out of the continent recently: that review found African pollution monitoring is overwhelmingly focused on metals, and this pesticide dataset is a clear, concrete example of exactly the kind of gap that leaves unaddressed
Dr Samuel Ayodele Mesele
International Institute of Tropical Agriculture
Read the Original
This page is a summary of: African Soils Are Also under Threat: Occurrence of Pesticides in Agricultural Soils and Implications, Environmental Science & Technology, June 2026, American Chemical Society (ACS),
DOI: 10.1021/acs.est.5c15564.
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