Heavy metal toxicity

Heavy metals are chemical elements that are commonly found in our environment. Without realising it all people are exposed to heavy metals on a daily basis. However, the quantities that we inhale, ingest or come into contact with the skin are so small that they are usually harmless. In fact, small amounts of some heavy metals in our diet are essential to good health. These are referred to as trace elements and include iron, copper, manganese, zinc, plus others, which are commonly found naturally in fruits and vegetables.

Toxic heavy metals and routes of exposure

Toxic heavy metals are heavy metals that become poisonous to the body when they are not metabolised or excreted and so accumulate in organs and tissues. They enter the human body through food, water, air, or absorption through the skin. Routes of exposure are described below.

• Industrial exposure is a common route of exposure for adults. A number of heavy metals are used or produced as a by-product in many agricultural, manufacturing and pharmaceutical processes.

• The most common route of exposure to heavy metals in children is through accidental ingestion. Toxic levels of heavy metals can develop through normal hand-to-mouth activity of small children who play in contaminated soils or eat/chew on objects that are not food, e.g. bark chips, dirt or painted objects.

Signs and symptoms of heavy metal toxicity

Signs and symptoms of toxicity depend on the heavy metal involved and whether exposure causes acute toxicity or chronic and subtle effects.

The heavy metals that cause the most significant skin changes and are discussed in more detail include arsenic, silver, gold and mercury.