Consumer Risk Exposure to Chemical and Microbial Hazards Through Consumption of Fruits and Vegetables in Kenya

Abstract

Recently, there has been public outrage and media report on presence of heavy metal residues and pathogenic contamination in commonly consumed commodities including fruits and vegetables in Kenya. Chemical and microbial contaminants in food value chains pose serious health risk to the consumers hence the need for regular surveillance of these hazards to protect the public. This study provides insight into prevalence and levels of chemical and microbial pathogens in selected fruits and vegetables commonly consumed in urban and peri-urban areas in Kenya. Structured interviews, market observations and analytical determinations were used for data collection. Chemical and microbial analysis of randomly selected fruit and vegetable samples including kales, amaranth leaves, tomatoes and mangoes were analyzed using standard methods. Microbial analysis included total aerobic counts, anaerobic bacteria, yeast and moulds, coliforms, Enterobacteriaceae, Staphylococcus aureus, Listeria Monocytogenes, Escherisia coli and Clostridium botulinum while chemical analysis consisted of pesticides residues and heavy metals as well as nitrates. The results were evaluated against national and global standards for maximum residue limits (MRLs) for each commodity and pesticide. The findings demonstrated that fruit and vegetable samples were contaminated with pesticides residues some of which were beyond the allowed limits such as Dimethoate (>0.02mg/kg), Bifenthrin (>0.05mg/kg), Metribuzin (0.05mg/kg), Cyromazine (>0.05mg/kg), metalaxyl (>0.05mg/kg) and Pyrimethamil (>0.02 while mango had thiabendazole (0.031mg/kg) and contained heavy metals with Lead concentration ranging from < 0.01 mg/100g to >0.06 mg/100g compared to Cadmium levels of 0.01mg/100g. Nitrate content ranged from 100-200 mg/100g in vegetables and 120-210 mg/kg in fruit. Total aerobic counts ranged from 1.42x103 - 9.56x104 in the mango, 1.32x103 - 7.01x104 in tomato, 9.50x104 - 9.40x106 in kale and 2.46x106 - 7.60x107 in amaranth leaves. Anaerobic bacteria counts ranged from <1 - 7.74x104 in the mango, 1.83x103 - 5.65x103 in tomato, 9.50x102 - 1.18x106 in kale and 1.83x106 - 9.20x107 in amaranth leaves. Samples also showed presence of pathogenic microbes including Staphylococcus aureus and Escherishia coli. These findings show that compliance to food safety standards should be enforced so that the quality of Kenya's food supply meets the highest safety requirements to satisfy domestic and international demands. Control measures should emphasis on good agricultural practices, better postharvest handling practices, improved traceability and good hygienic practices in the markets.

Keywords: chemical residues, consumer risk, heavy metals, fruits and vegetables, microbial hazards, pesticide residues