Dangerous pesticides found in Nyandarua potatoes.
Some pesticides used by potato farmers in Nyandarua County are banned, the Pest Control Products Board (PCPB) has revealed.
In an exclusive interview, the board’s Chief Executive Officer Frederick Muchiri disclosed that Chlorpyrifos and Fenitrothion—two insecticides detected at levels exceeding the European Market and Codex Maximum Residue Limits (MRL) in potatoes, according to a recent study by Egerton University—are not approved for agricultural use.
“The board wishes to state that it has not approved the use of these two insecticides on potatoes and any use of these products by farmers is illegal,” said Mr Muchiri.
A farm worker sprays a potato farm with pesticides and herbicides in Elburgon, Nakuru County in this photo taken on November 17, 2022.
According to him, Chlorpyrifos is only registered for use in building, construction and wood treatment and has not been approved for agricultural use.
Fenitrothion, on the other hand, is highly toxic to humans and can cause significant damage to the brain, lungs, liver and kidneys, leading to organ dysfunction.
“I call for adherence to label instructions and good agricultural practices to avoid feeding Kenyans with poisonous food,” he added.
Mr Muchiri was responding to a report by researchers from Nakuru’s Egerton University, which revealed that some insecticides harmful to human health were found in potatoes collected from various farmers in Nyandarua County.
Despite widespread pesticide use in Nyandarua involving many active ingredients, the study found that most pesticide residues were below the European Union (EU) and Codex Maximum Residue Limits.
The Codex limits, developed jointly by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), represent the highest legally tolerated pesticide residue levels in food or feed when pesticides are applied correctly.
The regulatory body also noted that the majority of other pesticides analysed were within regulatory thresholds.
However, the study highlights that farmers’ reliance on non-expert guidance is linked to a lack of technical knowledge and limited access to agricultural experts.
The study was done by researchers from Egerton University.
“In this regard, the board and other partner organisations have been training Spray Service Providers (SSPs) in various counties to bridge this gap. Promoting the use of SSPs who possess the necessary training, tools and equipment has great potential to foster more responsible pesticide use,” Mr Muchiri said.
While the study evaluated the effect of common household processing methods such as frying and cooking on reducing pesticide residues in potatoes, the board does not recommend relying on these methods.
Dr Githaiga Wagate, from the Registration Department’s toxicology division at the board advises farmers to use only registered pesticides approved by the board to ensure MRLs are not exceeded.
Seek expert advice
He also urged farmers to follow label instructions carefully, observe post-harvest intervals, avoid improper mixing of chemicals, and seek expert advice.
The Egerton University researchers established that some potato tubers contained residues of banned pesticides that even boiling could not eliminate.
Millicent Kanario and her two senior colleagues Prof Joseph Wafula and Dr John Masani from the university’s Department of Dairy and Food Science and Technology traced the problem back to farms.
They visited 275 randomly selected potato farmers in Nyandarua County finding that nearly all (98.8 percent) used synthetic pesticides.
The study revealed that most farmers applied synthetic pesticides regularly, sometimes weekly, and many mixed different pesticide types together.
“Only 12 percent of the farmers actually followed the instructions on the pesticide labels,” the report stated.
“We found that the majority of farmers rely on advice from agrochemical retailers or fellow farmers rather than the official manufacturer’s guidelines,” Ms Kanario and her colleagues reported.
Their research—titled Influence of On-farm Pesticide Practices and Processing Methods on Pesticide Residue Levels in Potato Tubers (Solanum tuberosum L.) in Nyandarua County, Kenya—has been accepted for publication by The Journal of Food Protection but has not yet been published.
Some of the chemicals widely used by farmers and which find their way onto Kenyan dinner tables are banned in Europe and other parts of the world.
These two pesticides are linked to serious health issues such as brain damage and hormone disruption. They were detected in potato samples at levels above international safety limits.
Ms Kanario and her team tested raw and cooked samples of the Shangi potato variety from sampled farmers for commonly used pesticide residues.
The board has been phasing out chlorpyrifos-based pesticides for agricultural use scheduled for completion by December 31, 2024, due to concerns about the pesticide's potential negative impact on human health, especially children, and the environment.
