The metal in our mettle

FDA Consumer, Dec-Jan, 1988 by Roger W. Miller

The Metal in Our Mettle

The human body carries around lots of metals. Not enough to make us clink and clank as we walk around, but just enough to keep us walking. That is to say that some metals are essential to the human body. We need them in what is called "trace amounts."

Other metals, such as those used to build your new car, have become essential to maintaining our modern way of living. However, trouble comes when we get too much of some metals in our bodies. Even metals essential to the body can be overdone, causing a host of maladies, including cancer.

It's not that we're gobbling up metals on purpose. Metal poisoning is usually the result of industrial exposure, although sometimes we get too much from medicines or from medical procedures such as hemodialysis (blood purification).

Some metals, particularly lead, get inside us from the air we breathe, the water we drink, and the food we eat.

Metals other than lead that can cause poisoning include, in alphabetical order: aluminum, antimony, arsenic, bismuth, cadmium, chromium, cobalt, copper, gold, lithium, manganese, mercury, molybdenum, nickel, silver, vanadium, and zinc. But zinc, vanadium, nickel, molybdenum, manganese, copper, cobalt, and chromium--in tiny amounts--are all essential to human life. They are not produced by the body and have to be obtained elsewhere.

For those who aren't metal experts, some uses for these metals, according to The Condensed Chemical Dictionary and other sources, are:

* Aluminum, as a primary metal and in the manufacture or processing of some foods, cosmetics and medicines, and for water purification;

* Antimony, for hardening lead, particularly in storage batteries and cable sheathings;

* Cadmium, for a multitude of uses, from electroplating to storage batteries to vapor lamps to a substitute for tin in solder, and if you're into making smoke bombs;

* Chromium, for making your car look fancier;

* Cobalt, as a superalloy for jet engines;

* Lithium, used to make H-bombs, glasses, and pharmaceuticals, and for coating arc-welding electrolytes;

* Manganese, a purifying and scavenging agent in the production of several metals;

* Molybdenum, used to harden steel and to stump spelling experts;

* Silver, traditional, of course, for 25th wedding anniversaries and other occasions for which you can't afford gold jewelry.

Writing in Wyngaarden and Smith's Cecil Textbook of Medicine, Donald B. Louria, M.D., notes that today's high-tech industries are using more and more metals. The amounts used in the United States and worldwide are staggering. For example, Louria notes that U.S. industry annually uses 5,000 tons of cadmium, a relatively minor metal. Because such vast tonnages are used in manufacturing, considerable amounts end up in our environment, in the form of fumes or other waste. One recent estimate put the amount of lead "being broadcast" into the earth's atmosphere at 400,000 tons a year.

Rivers are also dumping grounds. For example, Greenpeace, an environmental protection group, has concluded from weekly Mississippi River analyses done by the Jefferson Parish Water Quality Laboratory in New Orleans that the river system in 1987 was the depository for 11,473,440 pounds of aluminum, 42,801 pounds of chromium, 921,000 pounds of copper, 732,973 pounds of nickel, and 10,700 of cadmium.

Arsenic is found in nature in varying amounts in soil and water; high concentrations of the metal are sometimes found in well water. Arsenic is used to make some pesticides, and the gas from arsenic (arsine) has some industrial uses and has been used as a war gas (lewisite). The gas, which is highly toxic, can be spewed from sewage plants. In the heyday of moonshining, arsenic poisoning from the spirits of the day was not unknown. The stills were connected with lead soldering, and lead-containing auto radiators were often used as distillers. The lead, in turn, contained arsenic, which found its way into the product. And, as anyone who saw "Arsenic and Old Lace" knows, arsenic has more than once been used for intentional poisoning.

There have been therapeutic uses for metals. Bismuth and arsenic were once standard treatments for syphilis, resulting in some poisonings, just as overuse of bismuth to treat chronic digestive ailments results in poisonings today. Silver was widely used in medicine before the days of sulfa, antibiotics and antimicrobials. It is still used to treat burns.

Today, bismuth is still popular for treating stomach woes and is an active ingredient in some hemorrhoidal drugs, as is aluminum. Other products containing aluminum can be used to treat stomach ailments, foot rashes, excessive sweating, and ear infections. Gold salts continue to be used for some cases of rheumatoid arthritis. Lithium carbonate is the lithium derivative that provides therapy for some forms of manic depressive illness. (See "Calming the Roller Coaster Ride of Mood Swings" in the November 1988 FDA Consumer.) Zinc is the active ingredient in some drugs, including those to treat skin conditions and hemorrhoids. A number of heavy metals may also be found in vitamin and mineral supplements, although in most cases the metals aren't needed because the body invariably gets adequate amounts from foods. (See "Tracking Trace Minerals" in the July-August 1983 FDA Consumer.)