Question How do heavy metals (such as mercury, arsenic, and lead) effect humans?
What is a heavy metal? A heavy metal is any metal with a specific gravity of 5.0. Some examples are lead, mercury, and arsenic.
Mercury (Hg) Mercury is the 80 th element on the periodic table of elements. It is a liquid at room temperature. Elemental mercury is poorly absorbed through the skin and gastro-intestinal track. It is readily absorbed by inhalation, injection, or ingestion of salts. It was a common ingredient in 19 th century felt production and exposure resulted in encephalopathy, aka “mad hatter’s disease”.
Arsenic (As) Arsenic is the 33 rd element on the periodic table of elements. At room temperature it is a solid state. Its most toxic forms are water soluble salts. Arsenic is readily absorbed by groundwater, and enters humans by the gastro intestinal track. It has been used as a murder weapon and is a contaminant in ground water in some parts of India.
Lead (Pb) Lead is the 82 nd element on the periodic table of elements. At room temperature it is a solid state. Lead is most toxic as lead salts. These were commonly used as pigments in paint. Its use was discontinued. It is absorbed through the gastro-intestinal track.
Enzymes An enzyme is a protein (made of chains of amino acids) which when folded has binding sites which affect a substrate. A substrate is a molecule which when bound, is altered by the enzyme into a product(s). Enzymes lower the activation energy in a reaction, and are responsible for most complex chemical reactions which occur in cells. The enzymes nature is not changed by the reaction.
Heavy Metal Toxicity Heavy Metals are non-competitive inhibitors in enzymes. They bind to oxygen, nitrogen, and sulfur atoms within the protein amino acids. This changes the shape of the binding sites, and renders them unable to bind a substrate.
Enzyme Damage Enzymes altered by the binding with heavy metals function poorly, or not at all. Poorly functioning enzymes cannot metabolize substrate or produce desirable products. This leads to cell damage, and ultimately tissue damage and illness.
Treatment Remove the source of the exposure. A treatment used for heavy metal poisoning is called chelation. It is a process of removing heavy metals from the enzymes. It is injected into the blood stream, and removes the heavy metals by allowing them to attach onto the chelate. Once the heavy metals are attached the body can work to excrete the heavy metals.