The Presence of Heavy Metals in soil is a major threat to the human food-chain.
According to the World Health Organization, almost 200,000 people die every year from chemical poisoning, including heavy metals. Most of these could be prevented with protective measures and effective regulation.

Human cadmium toxicity was first reported in Japan during the 1950s. It became known as Itai-Itai disease, resulting from the consumption of rice grown in a contaminated floodplain downstream of mining activities.
Dietary intake of cadmium and other heavy metals remains an area of concern, which is why regulation has been proposed in Europe to limit contamination of soils.

How Heavy Metals enter and move around soils

Heavy metals contamination of soils may come from a number of different sources, including high naturally-occurring background levels, atmospheric deposition, sewage sludge or phosphate-base mineral fertilizers.