ASSESSMENT OF SELECTED ANTIBIOTICS IN UNTREATED WASTEWATER AND VEGETABLES IN URBAN AND PERI-URBAN FARMS IN EASTERN NAIROBI CITY, KENYA
Scholastica Gatwiri Mathenge*, Wachuka Gathigia Njoroge and Onesmus Muia Mutuku
Background: Most urban and peri-urban farmers in Kenya use untreated wastewater to irrigate crops. The vegetables irrigated with this water may accumulate unsafe levels of pharmaceutically active compounds. This poses a health concern to the consumers because of the known health problems such as antimicrobial resistance that may arise from gradual un-intended exposure of the body to antibiotics over prolonged spans of time. The presence of antibiotic residues in the vegetables may lead to initiation of bacterial resistance to the drugs due to the unintended long exposure from the environment. Unlike pesticides used on agricultural land, antibiotics have not aroused attention as potential pollutants until fairly recently. There are no reports on levels of antibiotic residues in untreated wastewater and vegetables in Kenya. This study aimed to determine the concentration of sulfamethoxazole (SMX) and trimethoprim (TMP) in untreated waste water and vegetables irrigated with the untreated waste water in Ruai and Njiru suburb farms. Methods: Untreated wastewater and vegetables were collected during the dry season from various sites in Ruai and Njiru from small scale farms along Ngong River. The samples underwent solvent extraction pre-analysis. The antibiotic residues were determined by high performance liquid chromatography. Results: In the untreated wastewater sulfamethoxazole (SMX) concentration ranged from 62.09 to 88.66 ng/kg while the levels of trimethoprim ranged from 24/71 to 24.99 ng/kg. The vegetables TMP concentration ranged from 2.16 to 15.45 ng/kg while the sulfamethoxazole levels ranged from 4.93-22.64 ng/kg. Conclusion: The wastewater used for irrigation was contaminated with the antibiotics sulfamethoxazole and trimethoprim. These antibiotics detected in the untreated wastewater were also present in the vegetable and therefore it can be concluded that it is not safe to consume vegetables contaminated with the antibiotic even though it is in small quantities because it will lead to undue exposure and tolerenca build-up by microbes resulting in resistance to the drugs that have residues in the environment.
Keywords: Antibiotics, Untreated waste water, Vegetables.
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