open access

Abstract

Contamination of food crops by heavy metals (HMs) is a public health concern that is gradually becoming a global challenge. There is rising concern about food safety and human health due to the unceasing release of HMs into the environment by various forms of anthropogenic activities and natural processes. HMs are highly persistent and when they contaminate the food chain a sustainable circle is created in the food web, the metals will be revolving between the environment, food crops and the human body. This article intended to provide an overview of the sources of HMs and their consumption through food crops. The study reviewed relevant literature published online between January 2018 and December 2020. The leading sources of food crop contamination are sewage and industrial effluents, mining, smelting, illicit dumping of solid waste, abuse of agrochemicals, atmospheric deposit and chemical processing. Leafy vegetables in general and wheat grains are the most contaminated food crops. Pb, Cr and Cd were the most reported HMs in food crops in the last three years. The rate of food crops HMs contamination in the last three years was found to be in the following order: Pb>Cd>Cr>As>Zn>Ni>Cu>Mn>Fe>Hg>Co>Al.