Health Risks for a Rural Community in Bokkos, Plateau State, Nigeria, Exposed to Potentially Toxic Elements from an Abandoned Tin Mine

Abstract

The past mining activities in Bokkos Local Government Area (LGA) were performed in an uncontrolled way and gave rise to many abandoned ponds now serving as domestic and irrigation water sources. Past research focussed mainly on the environmental impact and we show for the first time what the human health risk through consumption of contaminated food crops is in these communities. This study was designed to determine the level of Potentially Toxic Elements (PTEs) contamination in pond water, soil, and food crops and assess the health risk of inhabitants in the abandoned tin mining community in Bokkos LGA. Samples of the mining pond water, soil, and selected food crops from farms irrigated with the pond water: bitter leaf (Vernonia amygdalina), pepper (Piper nigrum), okra (Albelmoschus esculentus), maize (Zea mays), sweet potato (Ipomoea batatas) and Irish potato (Solanum tuberosum) were analyzed for each of the eight PTEs (viz; Cu, Cr, Fe, Mn, Ni, Zn, Cd & Pb) using inductively coupled plasma optical emission spectrometry (ICP-OES). The results obtained showed that the levels of all the PTEs analysed in the soil, pond water, and selected food crops except for Fe and Mn in soil and Cd in sweet potato was greater than their corresponding background area values (p<0.05). Also, the mean concentrations of all the PTEs except for Cu in pond water were significantly (p< 0.05) higher than the WHO maximum permissible limit. With the exception of Fe, Ni, and Zn for pepper and okra, Cu and Fe for maize grains as well as Cu, Ni, and Zn for sweet and Irish potatoes and Fe and Cd for sweet potato, the mean concentrations of PTEs in the food crops were significantly higher than WHO maximum permissible limit. The EF values of Cd (0.39); Cu (3.59) and Ni (2.81); Cr (9.38) and Pb (17.84); and Mn (178.13) and Zn (83.22) classified the soil as minimally, moderately, significantly, and extremely highly enriched respectively. The PI values of all the PTEs in the soil studied were all greater than 5 indicating that the soils were severely contaminated. There was evidence that food crops significantly bioaccumulated PTEs either as a result of contaminated soil and/or irrigation water. The bioaccumulation was not uniform and was dominated by transfer from the polluted irrigation water. The bitter leaf, okra, and to some extent maize had the highest transfer of PTEs, and Mn, Cu, and Zn had the highest bioaccumulation in the food crops investigated. The Hazardous Index (HI) for the eight PTEs through the consumption of food crops was 107 for children and 33 for adults which greatly exceeded the recommended limit of 1, thus indicating that possible health risks exist for both local children and adults. For every PTE, the values of HI for children are many-fold higher than those for adults, which is of particular concern due to the high HI values for Pb found for maize consumption, a typical staple food. The cancer risk values for Cr and Ni for all the food crops were within 10 -3 to 10 -1 which is several fold higher than the permissible ...

Assessment of Heavy Metal Contamination and Risk Associated with Quarrying Activities in Marksino Concession Area, Akamkpa

“…The problem of agricultural land contamination with heavy metals in Nigeria and elsewhere around the globe has raised serious concerns for scientific community over the years (Chonokhuu et al, 2019;Mafulul et al, 2022). This is so because, potentially toxic elements such as arsenic causes skin infections, vascular diseases and visceral cancers, cadmium that is a human carcinogen causes renal disorder and can damage the kidney.…”