Proximate Compositions and Health Risk Evaluation of Heavy Metal Uptake by Vegetables Grown at a Waste –Water Irrigated Site in Fct, Abuja, Nigeria

Abstract

The purpose of the study was to evaluate some proximate compositions and health risk of heavy metal uptake by vegetables grown at a waste-water irrigated sites in FCT, Abuja. The study was carried in dry seasons between 2015 and 2017. Two different types of vegetable samples (Lagos Spinach- Celosia argentea and African Egg-plant- Solanum macrocarpon) were collected simultaneously from three irrigated farm sites. Heavy metal levels were quantified using Atomic Absorption Spectrophotometer (AAS). Other parameters were determined using standard methods. The levels of heavy metals in vegetables varied according to sites. Proximate composition in both vegetable leaves recorded higher mean values for total ash (8.65-8.97), crude fibre (10.83-11.25), protein (4.96-5.08), Fat (3.05-3.29) and dry matter (65.58-68.85) indicating that they were rich in nutrients that  promote healthy living. The mean levels of Zn (3.36±0.50) and Ni (0.03±0.01) in Lagos Spinach ; and Zn (2.80±0.36) and Ni  (0.04±0.02) in African Egg-plant were generally lower than the FAO/WHO permissible limits except for Fe (14.96±0.86),(15.81±0.89) and Pb (1.12±0.11), (1.31±0.11) in both vegetables that were significantly higher (P<0.05) . Lagos Spinach recorded lower Metal Pollution Index (10.35) while African Egg-plant had the highest value (12.18) suggesting that these vegetables may present more health risk to the consumers of these vegetable. Daily Intake values of Fe (0.089), Zn (0.020), Ni (0.001) and Pb (0.006) in Lagos Spinach and Fe (0.094), Zn (0.017), Ni (0.001) and Pb (0.008) in African Egg-plant were below the WHO/FAO and USEPA permissible limits. However, Health risk index of heavy metals in vegetable samples were less than 1 indicating no significant health risk associated with the consumption of vegetables by the consumers.