Kales (Brassica oleracea) are a staple leafy vegetable in Kenya, consumed widely for their nutritional benefits. Nakuru County is a significant horticultural hub, with numerous small to large-scale farms cultivating kales. However, the increasing use of agrochemicals, coupled with industrial activities, raises concerns about the potential contamination of soil and crops by heavy metals. Therefore, this study determined the levels of selected heavy metals in samples of kales obtained from horticultural farms in Nakuru County, Kenya. A total of 120 kales (Sukuma wiki) leaves were randomly collected from Njoro, Molo, Naivasha, Nakuru East, Nakuru West, Subukia, Rongai and Gilgil sub-counties within the study area and transported to University of Eldoret Chemistry lab for sample preparation. There, the leaves samples were air dried, grinded and digested. Analysis was conducted using Shimadzu AAS model SpectrAA-200. Data generated was analysed descriptively and inferentially using SPSS. The study found that the concentrations of selected heavy metals (Cr, Fe, Cu, Mn, and Zn) in kales from various horticultural farms in Nakuru County were below the WHO/FAO permissible limits. These findings suggest that kales grown in this region are safe for consumption regarding these specific heavy metals. Further, there was a significant difference in Cu, Zn, Cr and Fe across 8 regions (P<0.05). The overall mean levels of heavy metals in the kales followed the order: Cr ˃ Fe ˃ Zn ˃ Mn ˃ Cu, with chromium being the most prevalent. Despite the current safety, continuous monitoring is important to ensure that heavy metal levels remain within safe limits, considering the ongoing use of agrochemicals and potential industrial pollution. Also, it is recommended that local authorities and agricultural stakeholders implement regular monitoring programs to track heavy metal concentrations in kales and other vegetables.
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