Urbanization and industrialization has led to accumulation of potentially toxic metals in the environment. Toxic metal pollutants threatens life and ecosystems and results in problems to plants, animals and human as well as soil, water and air. Human exposure to these toxic metals has been a major concern since they effect human health. There is urgent need for researcher to unravel the potentially toxic metal levels in the environment, which can aid in developing ways of controlling the metals. This study investigated the levels of potentially toxic metals in selected staple vegetable crops grown in western Kenya as an indicator of the extent of toxic metal pollution. Copper (Cu), Lead (Pb), Cadmium (Cd), Chromium (Cr) and Zinc (Zn) were determined during the months of November (2010) (wet season) and February(2011) (dry season). Twenty five (25) sites were investigated in this study. An atomic absorption spectrophotometer was used for the analysis of the samples. All cowpea (Vigna unguiculata) and Kales (Brassica oleracea) 95% of sweet potato (Ipomoea batatas) samples had Pb levelsof 22.22±21.16 – 23.35±27.77 mg/kg, which exceeded the World Health Organization (WHO) recommended safe limit of 0.3 mg/kg. The maximum CDI values ranged from 0.00572 to 0.65201 mg/kg-day and the maximum HQ values ranged from 0.31084 to 65.60966 mg/kg-day. Higher concentrations of Pb pollution may be attributed to continous use of inorganic fertilizers on farms and the use of leaded petrol in urban arean. For all seasons, the HQs of Pb were way above unity implying that non-cancer risk exposure to lead was highly likely among the residents of the studied areas. This study further recommends health caution for residents who consume vegetables produced within the study area due to associated health risks.
Keywords: Chronic daily intake; Food crops; Hazard quotient; Potentially toxic metals