Review on Heavy Metal Contamination in Vegetables Grown in Ethiopia and Its Economic Welfare Implications

Abstract

Urbanization is occurring rapidly throughout Ethiopia, as populations are increasingly migrating from rural areas to major cities. Vegetables constitute an important part of the human diet since they contain carbohydrates, proteins, vitamins, minerals and fibers required for human health. However, these plants contain both essential and toxic metals over a wide range of concentrations. Heavy metal contamination of the food items is one of the most important aspects of food quality assurance. The most common heavy metal contaminants are Cd, Cr, Cu, Hg, Pb, and Zn. Metals are natural components in soil. Some of these metals are micronutrients necessary for plant growth, such as Zn, Cu, Mn, Ni, and Co, while others have unknown biological function, such as Cd, Pb, and Hg. There is a strong link between micronutrient nutrition of plants, animals and humans and the uptake and impact of contaminants in these organisms. The content of essential elements in plants is conditional, the content being affected by the characteristics of the soil and the ability of plants to selectively accumulate some metals. They are also known to have effect on plant growth, ground cover and have a negative impact on soil. The uptake and bioaccumulation of heavy metals in vegetables is influenced by many factors such as climate, atmospheric depositions, the concentrations of heavy metals in soils, the nature of soil and the degree of maturity of the plants at the time of the harvest. Water pollution by heavy metals is mainly caused by point source emissions from mining activities and a wide variety of industries. The studies undertake to determine the concentration of heavy metals in soils, as well as on the vegetable grown in the vicinity of industrial areas and contaminated irrigation water in Ethiopia indicated that Vegetables grown in such lands, contaminated with heavy metals and unsafe for consumption. Prolonged human consumption of unsafe concentrations of heavy metals in food stuffs may lead to the disruption of numerous biological and biochemical processes in the human body, the chronic accumulation of heavy metals in the kidney and liver of humans causing disruption of numerous biochemical processes, leading to cardiovascular, nervous, and kidney and bone diseases. Heavy metals have greatest health risk to both adult and children consumers of vegetables grown in contaminated soil and water.

Keywords: Heavy metals, Waste water, Vegetables, Health risk