Heavy metals in refuse dumpsites and their accumulations in edible tissues of vegetables in the Kumasi, Ghana

Abstract

Nana Attat Kufuor

Many dumpsites in the urban communities in Ghana are used for cultivation of crops, especially vegetables. However, these dumpsites may serve as potential sources of soil heavy metals that could enter the food chain mainly through cultivated food crops with serious consequences on human health. This study investigated the levels of two heavy metals, lead (Pb) and cadmium (Cd), in the soil and tissues of vegetables grown on such dumpsites. Soil and tissue (lettuce, cabbage, spring onion, tomato and the leaves of Xanthosoma sagitifolium) samples were collected from ten locations with two of these locations used as control. The samples were acid-digested and the metal concentrations determined using atomic absorption spectrometry. Pb and Cd contents of soils from all the eight dumpsites and one of the control locations were above the guidelines recommended by FAO and WHO. The highest Cd level in the soil (13.6 mgkg-1 of Cd) was found at Aketego dumpsite and the highest soil Pb (36.1 mgkg-1 Pb) was recorded at Meduma dumpsite. The leafy vegetables, cabbage, lettuce and X. sagitifolium (locally called ‘kontomire’) recorded relatively higher amounts of Pb and Cd in the edible parts. Further studies are required to determine how much of the daily diet these vegetables contribute to the total diets of the population and special attention to calculating the overall daily doses of Cd and Pb to pregnant mothers and children <5 years of age is thus warranted