Current Levels of Heavy Metal Pollution in Africa

Abstract

ABSTRACT. Studies of environmental pollution in Africa indicate that toxic metal pollution has reached unprecedented levels over the past decade. Human exposure to toxic metals has become a major health risk on the continent and is the subject of increasing attention from national and international environmentalists. This paper reviews data from the past decade on environmental pollution in Africa and highlights countries where most heavy metal pollutions have been reported. Characteristics of heavy metal pollution in North, West, East and Southern regions of Africa have been described, as have major sources of pollution in the different regions. This review summarizes the sites where most of the heavy metal pollution has been reported in Africa and, where applicable, presents reported levels of pollution in different environmental compartments in the context of internationally acceptable limits. Contaminations in fish and food animals as well as impacts of heavy metal pollution on humans are also described.KEY WORDS: Africa, environment, heavy metals, pollution.J. Vet. Med. Sci. 72(10): 1257-1263, 2010 For many years, Africa was considered safe from heavy metal pollution [6]. However, rapid population growth and high urbanization rates have resulted in a recent expansion of cities in the absence of proper planning and without adequate waste disposal facilities [25]. Consequently, solid waste management has become a major challenge in many African countries, as waste production exceeds capacities for collection and disposal by local authorities [49]. As observed by the United Nations Centre for Human Settlements (UNCHS) [56], only one-third of the solid waste generated in urban areas across Africa is collected, and of that, only 2% is recovered and recycled. Furthermore, use of leaded gasoline [36], fugitive dusts [13], indiscriminate dumping and burning of toxic waste, including nickel/cadmium-based batteries, due to weak pollution legislation has worsened heavy metal pollution on the continent [22].Recently, the United Nations Environment Program (UNEP) Global Environment Outlook (GEO) 4 [58] noted that Africa continues to be at risk from hazardous and electronic waste dumping due to inadequate monitoring capabilities and institutional mechanisms for managing such waste. There are limited resources for environmental management in most African countries, as most developmental programs are focused on economic growth and industrialization [52]. As a result, industrial expansion and increased extraction of natural resources have resulted in widespread heavy metal pollution [3,59].According to a comprehensive study on the environmental burden of disease by the World Health Organization (WHO) [62], environmental risk factors account for a quarter of the total burden of disease and 2.97 million human deaths every year in Africa. Since toxic metals constitute serious health hazards, the extent of toxic metal contamination of the African environment has been the subject of considerable interest. Although improvements i...

Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: II. A focus on growth impairment in fish

“…In European rivers, Cd concentrations around 1 ppb or lower are typically reported (Pan et al, 2010), while higher values (up to 1 ppm) can occur in developing countries with rapidly growing industries (Yabe et al, 2010;Anetor, 2012). Cd is known to exert genotoxic and also carcinogenic activity (Waisberg et al, 2003;Bertin and Averbeck, 2006) and thus could possibly contribute to promotion of tumor formation in the aquatic organisms.…”

Occurrences and toxicological risk assessment of eight heavy metals in agricultural soils from Kenya, Eastern Africa

“…Elevated heavy metal levels of Cd (0.345-0.18 mg kg −1 ) and Cr (24.11-2.4 mg kg −1 ) in lettuce and Zn (130.1-6.4 mg kg −1 ) in spinach were reported in Ethiopia from Akaki River which was polluted with untreated sewage and industrial effluents (Prabu 2009). An international study in Dandora municipal waste site, East of Nairobi, was conducted by the UN Environmental Programme (UNEP), and the study revealed high levels of pollution of heavy metals in soils such as Pb (264.0 mg kg −1 ), Hg (18.6 mg kg −1 ), Cd (40.0 mg kg −1 ), and other heavy metals (Cr, Mn, Fe, Cu, Zn, and Co) ( (UNEP) 2007, Yabe et al 2010. In Ghana, a related study was carried out at Kumasi dumpsites and high levels of Pb (54.6 mg kg −1 ), Cd (2.87 mg kg −1 ), Cu (1631.67 mg kg −1 ), and Zn (2606.0 mg kg −1 ) were reported in soils used for vegetable cultivation (Odai et al 2008).…”

Uptake of lead, cadmium, and other metals in the liver and kidneys of cattle near a lead‐zinc mine in Kabwe, Zambia

“…In most African countries, the reliance on pollution-prone technologies and inadequate controls on the discharge of pollutants from mining activities have worsened metal pollution [3]. Yabe et al [4] recently noted that contamination of the environment and food animals with toxic metals has reached unprecedented levels over the past decade and that human exposure to toxic metals has become a major health risk on the continent. This was tragically demonstrated by the recent Pb poisoning disaster in Nigeria, where more than 160 people died, mostly children under the age of five ( [5]; http://www.worstpolluted.org/files/FileUpload/files/2010/ WWPP-Report-2010-Top-Six-Toxic-Threats-Web.pdf).…”