This is not a discussion of loud, electronic rock ‘n’ roll music, but one of impact to all people living in this day and age who are being exposed to heavy metals such as lead, mercury, and cadmium. Though not normally found in or used by the human species, they are becoming more widely present in our environment, leading to serious concerns. There are possibly more problems from these metals, which interfere with normal bodily function, than have been considered in most medical circles. Reviewing all of our vitamins and minerals has shown us that most every substance that is useful can be a toxin or poison, as well. The metals discussed in this section are known primarily-almost exclusively-for their potential toxicity in the body, though commerically they may have great advantages.
Previously, the medical community’s concern over metal toxicity was in regard to acute industrial exposure, where certain dramatic measures were performed to stimulate elimination of those metals. More recently, there has been concern over lead intoxication in children from sucking or eating lead-based paint, for example, and legislation has been enacted to reduce this possible contamination, though these measures will probably have a greater effect on future generations.
For most of these potentially toxic minerals, there are many common uses and possible contamination sources throughout our society; our concern must be with more widespread and long-term observation of and protection from these dangers. Lead, mercury, cadmium, arsenic, and, more recently, aluminum are the main toxic minerals. Beryllium, bismuth, and bromine must be considered as well. And there are other heavy and radioactive metals that could bring future difficulties.
Most of these minerals were present in our environment only in minute amounts until recent centuries, when the orientation toward industrialization and production brought about our many technological advances. But technology, like medicine, has its side effects. Mining these metals from the earth and using them in society-as leaded gasoline or silver-mercury tooth amalgam, for example-have brought all of us into regular exposure with them-unless, of course, we live in a completely unindustrialized environment, harder and harder to find as we approach the twenty-first century. At present, these toxic metals have polluted our atmosphere, our waters, our soil, and food chain.
We cannot realistically put all the lead and cadmium for example, back into the earth and cover it up. We need to deal with their presence. At best, we can find better ways to evaluate them in our water, our air, our food, and our body; learn more about where we obtain them; and work preventively to avoid excessive exposure. Most of these heavier metals are quite stable and decompose fairly slowly, if at all, so they remain in the environment. Luckily, the human body is able to clear much of the modest amount we pick up by eliminating it through our urine, sweat, and feces. Absorption of these metals is usually pretty low as well. But when our natural means of elimination are reduced or our exposure is increased, we may run into trouble.
The basic way that these heavy metals cause problems is by displacing or replacing related minerals that are required for essential body functions. For example, cadmium can replace zinc, and lead displaces calcium; when this happens, the cadmium or lead is stored in the bones or other tissues and becomes harder to clear, while the important functions of the minerals that are replaced cannot be carried out.
Blood or urine analysis is not very reliable for measuring toxic levels of most of these heavy metals, especially with long-term exposure and tissue buildup. Hair analysis, though controversial, offers the best available evaluation for accumulation of heavy metals, and in many studies, hair levels do correlate fairly well with tissue stores. The heavier the element, the more reliable is the hair analysis. Measuring these toxic minerals is probably the most useful aspect of hair analysis. In the future, we may find even better ways to measure, treat, and prevent this dangerous heavy mineral contamination.
Most of the available information concerns the main heavy metals, aluminum, arsenic, cadmium, lead, and mercury. For each of these, I provide a general introduction to the history of the metal and how it is handled by the body.
Then, insofar as information is available, I discuss:
- Sources of contamination
- Methods of toxicity
- Symptoms of toxicity
- Amounts leading to toxicity
- Who is susceptible
- Treatment of toxicity
- Ways to prevent toxicity (exposure)
There are no known nutritional deficiencies or bodily uses of these metals, with the possible exception of arsenic, which may be both essential and toxic, so is it necessary to discuss requirements. The remaining heavy metals-antimony, beryllium, bismuth, bromine, thallium, and a few even more minor ones-less commonly produce toxicity problems, and they are described only generally.