Study Reveals Kenyan County Where Mangoes and Tomatoes Have Lowest Chemical Levels

A new study has identified Meru County as the location with the lowest overall chemical residue levels in fruit samples compared with three other Kenyan counties, raising fresh questions about the safety of fruits sold in local markets.

The research, published in the International Journal of Professional Practice in 2026, examined fruit samples collected from farms, open-air markets and supermarkets in Meru, Nairobi, Murang’a and Kirinyaga.

Researchers analysed 392 samples, including 130 mangoes, 131 tomatoes and 131 bananas collected between September 2024 and April 2025.

According to the findings, Meru recorded the lowest average total chemical concentration at 109.67 parts per million (ppm).

Kirinyaga followed with 146.1 ppm, while Nairobi recorded 153.21 ppm. Murang’a had the highest average concentration at 163.95 ppm.

The researchers, however, cautioned against interpreting the findings as proof that every mango or tomato purchased in Meru is safer, noting that separate county rankings for individual fruit varieties were not provided.

The study also raised concerns about chemical contamination in fruits sold across the country.

Overall, 26 per cent of the samples contained chemical contaminants above acceptable limits. Bananas recorded the highest proportion of samples exceeding the recommended thresholds at approximately 40 per cent.

Mangoes followed at 20 per cent, while tomatoes recorded 17 per cent.

Another worrying finding was the detection of arsenic residues in eight per cent of the mango samples. The researchers also established that fruits treated using calcium carbide had an average acetylene concentration of 1.38 mg/kg, exceeding the 0.7 mg/kg reference limit used in the study.

The research further revealed widespread use of chemicals among fruit traders and farmers.

Out of 180 respondents surveyed, 63 per cent admitted using chemicals to accelerate fruit ripening or delay maturity. Calcium carbide was the most commonly reported substance at 42 per cent, followed by ethephon at 27 per cent.

Nairobi recorded the highest reported chemical usage at 72 per cent, compared with 51 per cent in Meru.

The researchers recommended stronger market inspections, regular laboratory testing, vendor certification and improved storage facilities to address the problem.

They also urged authorities to promote safer fruit-ripening technologies and educate consumers about the potential dangers of improper chemical use.

https://peopledaily.digital/news/meru-is-the-safest-place-to-buy-mangoes-and-tomatoes-in-kenya-study

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