Introduction
Serious environmental pollution over the past 20 to 25 years stimulated continuing research and literature on the toxicology of heavy metals.  In South Africa unscrupulous mining activities contaminated many rivers and dams with heavy metals.  One example is the destruction of the Wonderfonteinspruit^[1] area with most of its dams.  Man has succeeded in poisoning himself with heavy metals repeatedly throughout history.

Heavy metal exposure is not an entirely modern phenomenon:  Historians have cited the contamination of wine and grape drinks by lead-lined jugs and cooking pots as a contributing factor in the “decline and fall” of the Roman Empire; and the Mad Hatter character in Alice in Wonderland was likely modelled after nineteenth-century hat makers who used mercury to stiffen hat material and frequently became psychotic from mercury toxicity.^[2]

What are Minerals?
Minerals play an important role in the wellbeing of man and animals. Our bodies need calcium, magnesium, phosphorous, iron, zinc, daily, just to mention a few.  But, we also need to know that this mineral intake should not exceed the RDA (Recommended Daily Allowance), otherwise these essential minerals become toxic.  The most common heavy or toxic metals are: mercury, nickel, lead, arsenic, cadmium, aluminium, platinum and copper (the metal form, not the ionic form required by the body).  These metals have no function in the body and are hazardous to your health.^[3]  

Minerals, unlike vitamins, are inorganic compounds that cannot be created or destroyed in the body.  The only mechanism by means of which the body can handle excessive quantities of any mineral is through elimination processes.  The body is poorly equipped to reduce excessive levels of some essential minerals, for example iron.   In such cases, the safety limit is low when compared to the safety limit of the vitamins, as discussed above.  In the case of other essential minerals, such as magnesium, elimination through the kidneys is so effective that it is difficult to reach a really toxic level in any patient who has normal kidney function.  In general, minerals are more toxic than vitamins and it is not wise to exceed the RDS values by more than a factor of two to three.^[4]

In this article we will differentiate between toxic minerals (i.e. minerals that have no function in the body), and high doses of essential minerals that become toxic.

What are Toxic Minerals?
At the World Congress on Environmental Health held in Durban in February 2004, Professor Jerome Nriago of the University of Michigan stated that Africa is being swamped by a growing tide of toxic metal pollution.^[5]  Ten to thirty percent of the children may already be suffering from lead poisoning.  A large percentage of the African population drink rainwater which often contains lead at levels well above internationally recommended guidelines.  This fact is quite alarming.  

In general, minerals are more toxic than vitamins and it is not wise to exceed the RDA values by more than a factor of two to three^[6].

Mercury, lead, cadmium and other heavy metals, especially in drinking water, are an important cause of ill health, including cancer.  The breast-cancer patient needs to be fully aware of this and needs to take stringent precautionary measures to limit exposure to these dangerous metals.  We must assume that all drinking water is contaminated and therefore the use of a good water filter is a necessity. We must also discard the idea that bottled drinking water or “natural” waters from fountains and streams are pure.  This is not necessarily so.^[7]

What are heavy metals?
Heavy metals are defined as those elements with a high (>5,0) relative density.  These metals can either chronically or acutely poison the body.  They may enter the body either by ingestion or inhalation.  The toxic metals to be discussed are:

• lead,
• mercury,
• cadmium,
• nickel,
• aluminium, and
• arsenic (although arsenic is not a true metal, it is a semi-metal with some metallic properties).

Heavy metals are toxic because they tend to bioaccumulate in the body.  Bioaccumulation is the accumulation of toxic substances in the body such as pesticides, heavy metals and other organic toxins.  They are taken up and stored faster than they are broken down (metabolised) or excreted.^[8]  These metals are stored in the soft tissues of the body where they compete with other ions and bind to proteins resulting in impaired enzymatic activity and damage to organs throughout the body.

Sources
^[1]   See Internet for details and Carte Blanhce of  12 August 2007: Toxic Water.
^[2]   Dr Maile Pouls. Oral Chelation en ook Wikipedia: Mercury Poisoning and Dr David J Ferner, Instructor, Department of Emergency Medicine, Tift Regional Medical Center: e-Medicine.
^[3]   James Jordan, Create Vibrant Life: www.createvibranthealth.com
^[4]   Serfontein, W (2001). New Nutrition, Tafelberg Publishers, Cape Town, p.91.
^[5]  The Mercury, 24 February 2004.
^[6]   Serfontein, W (2001). New Nutrition -  Transform Your Life,. Tafelberg, Cape Town, p.91.
^[7]   Serfontein, W (2001). New Nutrition, Tafelberg Publishers, Cape Town, p. 202.
^[8]   Lenntech: Heavy Metals: www.lenntech.com