**1. Introduction**

The term metallic trace elements or heavy metals denote the elements of the periodic table having densities greater than 5.0 g.cm−3. They contain metals and metalloids [1]. They are naturally present in the environment, but the various industrial revolutions and the exponential progress of heavy industries have led to an increasingly massive release of these pollutants into the environment.

The environment is made up of several compartments, which are the final recipients of these heavy metal discharges. One of these compartments is the soil. Soils are the precursors of food for the majority of the world's inhabitants; their pollution by these metals therefore presents a threat to human health. Indeed, metallic trace elements can, under certain conditions, pass from soils to crops grown on them.

Among the metallic trace elements most in contact with human food, we can cite lead, cadmium, manganese, chromium, copper, nickel and zinc. Manganese, copper, zinc and nickel are considered as trace elements. However, depending on their concentrations, studies have shown that these trace elements can have different toxicities on human health. Lead, chromium and cadmium are considered strict pollutants because of the harmful effects they can have on human health. Faced with this increasingly growing threat, several questions may arise: What are the soil parameters that influence the penetration of metals into the plants we or animals eat? Once contaminated food is consumed, what health problems are we exposed to?

To provide some answers to these concerns, the main objective of this work is to document the toxicity of the metallic trace elements mentioned above on human health through food. Specifically, it will be a question of recalling the main sources of contamination of these metallic trace elements, showing their behaviour in soils and drawing up their toxicological profiles.
