A significant proportion of potatoes consumed in Kenya contain alarmingly high levels of pesticide residues, posing a serious risk to consumer safety. Notably, banned insecticides such as chlorpyrifos and fenitrothion were detected in these potatoes at levels exceeding safety thresholds, a forthcoming study set to be published in the “Journal of Food Protection” in June reveals.
Long-term dietary exposure to pesticide residues—including metolachlor, chlorpyrifos, glyphosate, and atrazine—has been linked to a range of adverse health effects. These include birth defects, fetal toxicity, various forms of cancer, genetic disorders, neurotoxicity, and endocrine disruption.
The research conducted in Nyandarua County, the leading producer of potatoes in Kenya, revealed significant noncompliance among potato farmers regarding manufacturer guidelines for pesticide application rates, frequencies, and preharvest intervals. This noncompliance has resulted in elevated pesticide residue levels in the produce.
Other notable potato-growing counties in Kenya include Bomet, Meru, Nakuru, Uasin Gishu, Narok, Nyeri, Kiambu, Trans-Nzoia, West Pokot, and Elgeyo Marakwet.
The study uncovered several alarming trends and deviations from recommended pesticide usage practices among small-scale potato farmers. Notably, only 12% of farmers adhered to the manufacturer’s recommended application rates. The majority of farmers relied on advice from agrochemical retailers or peer farmers, rather than following established guidelines.
Additionally, the frequent mixing of pesticides and the practice of applying them on a weekly basis were common, further contributing to the elevated residue levels in the crops.
The study identified multiple pesticide residues in raw potato samples where the levels exceeded the maximum residue limits (MRLs) established by the European Union (EU) and Codex Alimentarius. Notably, residues of banned pesticides, such as chlorpyrifos and fenitrothion, were found to surpass the MRLs set by both regulatory bodies.
Analysis revealed that potato tubers from farmers who strictly followed manufacturer guidelines for pesticide application—including herbicides, fungicides, and insecticides—exhibited significantly lower residue levels. In contrast, those who relied on informal advice experienced markedly higher residue concentrations.
Additionally, the study indicated that certain cooking methods, particularly frying and boiling, were more effective in reducing pesticide residues in potatoes. Consequently, consumers concerned about pesticide exposure may wish to consider fried or boiled potatoes as safer alternatives to roasted varieties.
The study findings emphasize the critical importance of accurate information and adherence to recommended practices in effectively managing pesticide application and minimizing residue levels. Moreover, the results underscore the necessity for expanded educational initiatives aimed at promoting good agricultural practices within potato farming communities.
Full study report is available at: https://www.sciencedirect.com/science/article/pii/S0362028X25000730
