Trimethoprim and Sulfamethoxazole Residues in Untreated Wastewater used for Irrigation in Peri-urban Farms in Nairobi County, Kenya

摘要

Untreated wastewater is often recycled in peri-urban subsistence farming. This water may containresidues of pharmaceutically active compounds discharged into the wastewater. Of concern are theresidues of trimethoprim and sulfamethoxazole which are administered synergistically under thebrand name septrin or cotrimoxazole. These two antibiotics are administered to both humans andlivestock and belong to the group of medicines called ‘anti-infectives’. This being the case, they areadministered routinely to HIV-AIDS patients and to poultry and livestock as growth promoters, prophylaxisand to control microbial infections. Application of irrigation water with pharmaceutically active compoundsmay predispose microbial life to significant doses of the antibiotics for a non-limited span of time. Thishas been known to induce microbial resistance and thus minimize the drug sensitivity upon administration,an outcome that is harmful to human health and the environment. This study was carried out todetermine if there are pharmaceutically active residues of these antibiotics by the use of highperformance liquid chromatography coupled to spectroscopy. Untreated wastewater used for irrigationwas collected during the dry season from various peri-urban farms in Ruai and Njiru from small scalefarms along Ngong River. In the untreated wastewater, sulfamethoxazole levels ranged from 62.09 to88.66 ng/L while trimethoprim levels ranged from 24.71 to 27.52 ng/L. In all cases the results in thefarms upstream were higher than in those downstream. From these findings, it is recommended thatwastewater should be treated prior to recycling in farms.