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A Minimum of Aluminum

The other week, a friend proudly told me that she'd tossed out her old aluminum cookware. "That stuff is dangerous,' she said. It's stainless steel and glass around this house from now on."

She was almost right, but throwing away the pots and pans really won't make much difference.

Aluminum is the most abundant metal on earth, but it binds so tightly to oxygen it's extremely difficult to remove from the rocks and soil where it occurs. For that reason, aluminum was extremely expensive and rare up to the late 1800s. It took the development of an effective electrolytic technique for refining aluminum and inexpensive ways of generating electrical power to bring down the price and increase the availability of the metal.

Its uses have been increasing ever since. Until a few years ago, the only hazard this inexpensive and versatile metal seemed to offer was that discarded aluminum products would overrun dumps and landfills.

Then some doctors began to suspect that aluminum might be responsible for an array of side effects in certain chronic kidney disease patients being treated by dialysis. They showed symptoms or anemia, soft or brittle bones, and in some cases, dementia. The great volume of water used in dialysis had exposed them to higher than normal concentrations of aluminum, and they had been taking large doses of antacids containing aluminum hydroxide. When researchers found that peculiar plaques in the brains of people with Alzheimer's disease also contain unusually high amounts of aluminum, the metal began to seem as dangerous as lead.

That's unlikely. Each liter of healthy human blood plasma contains about 10 micrograms of aluminum. A typical adult ingests 4 to 8 milligrams of aluminum every day in food and drink. If we took in and carried around that much lead, humankind probably would have died out long ago.

Fortunately, our bodies are very good at passing out the aluminum we take in. But that's true only if our digestive and excretory systems are working properly. By definition, excretory systems are not functioning well in people with chronic kidney trouble. They do have to be very careful about taking aluminum-containing medications, and their caretakers have to be wary of the aluminum content of water used in dialysis.

Because aluminum can replace the calcium in calcium phosphate, the chief structural material of bones, a buildup of this metal can cause bone disease. Since aluminum compounds are chemically similar to some iron compounds, medical researchers think that aluminum could interfere in blood-building processes. Anemia is thus a reasonable outcome of too much aluminum in the system.

No one has come up with convincing biochemical and physiological reasons for dementia associated with aluminum poisoning, and very few scientists think that the aluminum found in the damaged Alzheimer's cells actually causes the disease. It's suspected that whatever causes the disease also causes the aluminum buildup. The situation may be like seeing a bruise on the spot that hurts: the bruise is conspicuous, and is associated with the pain, but both pain and discoloration were caused by something else.

So, if you have malfunctioning kidneys, it may be wise to monitor your aluminum intake--but that doesn't necessarily mean tossing the family pots. Because aluminum reacts so readily with oxygen in the air, household pans and commercial food-processing kettles all maintain a protective layer of aluminum oxide, a tenacious compound that hugs the metal instead of flaking into the food.

Most food. aluminum oxide is broken down by acids and alkalis, so lemon sauce and stewed tomatoes are better prepared in pans of other material. (Cooking a batch of rhubarb--with no sugar--is an effective way to clean a discolored aluminum pan. don't eat the rhubarb. The pan will quickly regain its protective oxide layer.)

In Alaska, the ground is not particularly well endowed with natural aluminum. It's found everywhere, but not in significant concentrations. That means it's nearly inescapable in our water and food. But--as long as all our systems are working well, it won't harm us. You don't need to buy new pots and pans...unless the old ones are worn out.