A Review of Heavy Metal Contamination of Food Crops in Nigeria

Abstract

Heavy metal contamination of food crops is an issue of global concern that ultimately results in toxicity and diseases in humans and animals through consumption of contaminated soils and food crops. With a population of 182 million people, Nigeria is regarded as the most populous country in Africa. The people suffer environmental pollution from high levels of heavy metal accumulation in the environment and in food crops. Heavy metals have atomic densities higher than 4 g/cm3, and these include lead (Pb), cadmium (Cd), zinc (Zn), mercury (Hg), arsenic (As), silver (Ag), chromium (Cr), copper (Cu), iron (Fe), and platinum (Pt). The high level of environmental contamination by these metals is dangerous because their uptake by plants and subsequent accumulation in food crops consumed by humans and animals is deleterious to health. There are many known sources of harmful metals, including the earth, which releases them into food, air, and water, and anthropogenic activities, such as the application of fertilizer in agriculture, the use of pesticides and herbicides, and irrigation. Other sources are automobile emissions, paints, cigarette smoking, industries, and sewage and waste disposal. Evidence shows that vegetables and other food crops consumed in Nigeria are contaminated by heavy metals, and this is associated with adverse health issues, such as cancer, which is currently on the rise in Nigeria. It is therefore vital that communities with high levels of heavy metal pollution avoid eating large quantities of these food items. There is also the need for the monitoring of levels of these injurious elements in food crops.

The role of Serendipita indica and Lactobacilli mixtures on mitigating mycotoxins and heavy metals’ risks of contaminated sewage sludge and its composts

“…This indicates that this treatment of Mss was not enough to mitigate the HM risks for human health and air pollution. Our recorded data matched those of 60 who mentioned that air pollution is caused by the high levels of heavy metals in the atmosphere. Also, the values matched with those of the permissible levels of the European Commission.…”

A Review of the Health Implications of Heavy Metals in Food Chain in Nigeria

“…With the early industrialisation stage in Nigeria and poor implementation of environmental protection policies and regulations, its environmental pollution and contamination have been a great concern. According to Onakpa et al [28], both natural and anthropogenic sources are pathways by which heavy metals and metalloids contaminate many Nigeria food crops and vegetables. Previous studies on the health implications of heavy metals are fragmented and mostly focused on individual states and localities within Nigeria [29][30][31].…”

Effects of food processing methods on migration of heavy metals to food

“…Different kinds of seeds contain different levels of heavy metals. This is because different plants have different proper to uptake heavy metals [2]. However, the effect of soil contamination could not be estimated without information about the area where the plants grew up.…”

“…Noodles including glass noodles were made from grains or vegetables. Grains and vegetables also uptake heavy metals from environment and accumulate them [2]. Heavy metals would be transferred to noodles from raw materials.…”

“…Heavy metals are one of the main contaminants and they are ubiquitous in environment [1]. Heavy metals naturally exist on the earth's crust and they are significantly contaminated to environment by mining and processing metal ore. Human activity such as pesticide and herbicide applications also occur heavy metals in environment [2]. Heavy metals are accumulated in plants from environment such as soils and air, and they are transferred to animals through the food chains.…”