The risk is no longer considered to be external to man, it is man who is at the origin of the risk.
Humans are exposed to heavy metals that are toxic to health, due to the increase in the use of these metals in recent years, which are being introduced into industrial processes and products.
Human exposure to heavy metals is generally in small but daily doses in various components such as food, materials around us, industrial activities... And in rare cases, through chemical accidents that have occurred in factories.
The transformation of heavy metals through human intervention makes it possible to modify the concentration of these heavy metals in industrial and agricultural activities. This transformation makes heavy metals more toxic and harmful to health and the environment.
Among the regulated pollutants are heavy metals, particularly arsenic, cadmium, mercury and lead. The other elements individually pose much less of a problem, either because they remain rare in the soil (this is the case for tin, selenium and metals that are sometimes very toxic but of specific use), or because in the forms in which they are found, they are only toxic to humans in exceptional concentrations and the ecosystems adapt to them (this is the case for copper, zinc, nickel, which are essential trace elements, and even chromium).
However, they can be harmful to agrosystems and by transfer to aquatic systems.