Biomonitoring and Biomathematical Modeling of Health Risks Associated with Dumpsite Grown Vegetables in Lagos State

Abstract

Abstract Conversion of dumpsites to farm lands in several communities is a usual practice in Nigeria. Wastes accumulate heavy metals in a variety of forms. This study assessed the concentration, degrees of contamination and attendant health risk of heavy metals (HMs); using two major indigenous vegetables (Amaranthus viridis and Talinum triangulare) grown on five major dumpsites in Lagos state. After wet digestion, the mean concentrations of the HMs in the vegetable samples were evaluated using Atomic Absorption Spectrophotometer (AAS). Daily intake of Metals (DIM), tangent hazard quotient (THQ) and hazard index (HI) biomathematics were employed in the assessment of non-carcinogenic health risk. Incremental Lifetime Cancer Risk (ILCR) assessment was used to assess Carcinogenicity. HM concentrations detected fell within the following ranges: (0.59 to 0.37), (0.07 to 1.36), (0.30 to 2.21), (0.00 to 0.03) and (0.00 to 0.04) mg/kg; for zinc (Zn), Lead (Pb), Iron (Fe), cadmium (Cd), and chromium (Cr), respectively. Low to moderate variability and statistically significant differences were seen in the concentration of HMs in vegetables, (p<0.05). At Ikorodu, Pb concentration was above the world Health Organization (WHO) permissible range and has the highest contamination factor. DIM and THQ for Fe and Pb were above threshold values (>1); HI values for the vegetables exceeded WHO normal range (>1), except Abule-Egba samples. These values reveal great health risk from consumption of vegetables from four major sites. ILCR values for 43.3% of the samples were above the WHO (10-6) limits, indicating high risk of carcinogenicity over a life time of exposure.