Abstract
High heavy metal pollution of the environment has been tied to civilization, urbanization, and industrialization, leading to the overwhelming of natural cleansing and cycling processes in many ecosystems. This study investigates the sources, the extent of pollution and possible health effects of heavy metals via edible vegetables grown in the urban areas of Lagos metropolis. Plants, soil and irrigation water samples were randomly collected in triplicates from vegetable farms in four most industrialized/commercialized Local Government Areas of Lagos State (Ojo, Amuwo-Odofin, Yaba and Kosofe). Dusts and particulate matter deposits on the abaxial leaf surfaces were analyzed for atmospheric deposition. Dried plants were crushed into fine powder before extraction. The physico-chemical, phytochemical and anti-oxidant composition of the plant parts were determined using standard methods. Atomic absorption spectrometer was used to determine heavy metal composition. Plant samples were authenticated as Allium Schoneoprasum (LUH 9803), Lactuva Sativa L. (LUH 9084) and Amaranthus spp. (LUH 9085). The highest concentration of chromium (7.6±0.00), cadmium (5.1±0.04) and zinc (9.7±0.01) were observed at Kosofe while that for copper (5.2±0.04) and lead (15.7±0.03) was found at Ojo and Amuwo-Odofin soil samples respectively. Estimation of the chronic daily intake (CDI), target hazard quotient (THQ), and health risk index (HRI) showed no carcinogenic threat to the food chain, with values under the permissible daily intake limit.