Environmental and public health risks of urban agriculture in Kisumu city, Kenya

Kenya's blueprint on national development (Vision 2030) is based on the principles of sustainable development and it has prioritized agriculture to drive economic development. The current Kenya’s Constitution (2010) provides for the right to a clean and healthy environment as well as to food of good quality. The aim of this study was to determine the environmental and public health risks of crops grown in the privately- owned land within Kisumu City, Kenya. This study was premised on the assumption that farm produce from privately – owned land is relatively safe as they are less predisposed to municipal wastes, waste water and exhaust fumes. Therefore, the study was carried out in privately-owned land away from road reserves and storm water from rivers, roads and built up urban areas. This study assessed concentrations of Lead, Zinc, Copper, Cadmium, Iron, and Chromium in 5 leafy vegetables; 2 root crops; and 1 fruit crop. The study involved a sample of 24 edible tissues of crops (5 leafy vegetables - vigna sinensis, chlorophytum comosum, crotolariabrevidens, amaranthus and kales; 2 root crops (dioscorea and Manihot esculenta), and 1 fruit crop (Carica papaya) and 24 soil samples. The results of this study show that there are low traces of heavy metals in the crops and those found in the soils, vegetables and fruits are within the WHO/FAO permissible standards. The highest concentrations of Pb, Zn, Cu, and Fe were found in carica papaya (0.303ppm) crotolariabrevidens (8.167ppm), crotolariabrevidens (13.6ppm), and amarantus (6.637ppm) respectively. The concentrations of Pb, Zn, CU, Fe, and Cr in the soils were, respectively, 0.313ppm, 0.359ppm, 0.054ppm, 123.093ppm and 0.049ppm, while the WHO/FAO standards for Pb, Zn, Cu, Fe, and Cr in soil are 100ppm, 300ppm, 100ppm, 50,000ppm, and 100ppm respectively. WHO/FAO limits for Pb, Cd, Cr, Zn, and Cu in vegetables and fruits are 0.5, 0.2, 1.2, 1.5, and 2.0 respectively. No traces of cadmium and chromium were found in the sampled crops. So, farm produce from such parcels of land are safe for human consumption. The results of the study indicate that it is possible to undertake safe urban farming on privately – owned land in the City for the benefit of the residents. So, necessary measures should be taken by the City authority to promote urban farming, including land use zoning and control of waste disposal into the farms. Other measures include regular monitoring of urban farming for quality and safety concerns.