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Environment : Digging for Alzheimer's Data in Canadian Mine : Aluminum has been linked inconclusively to the brain disease. Now, miners who were forced to breathe heavy doses of the metal's dust for years are being tested.


TIMMINS, Canada — In 1980, two neuropathologists in New York made an intriguing discovery: Not only did aluminum show up in the brains of Alzheimer's disease victims, but it also was present in precisely those tangled brain cells that characterize the disease.

In the years since then, medical scientists have debated fiercely whether ingesting aluminum may somehow cause the dreaded, always-fatal Alzheimer's.

Some scientists, such as Daniel Perl, head of neuropathology at Mt. Sinai Medical Center in New York City, who directed that original aluminum-identifying study, think the evidence is overwhelming.

"It's all circumstantial evidence, but it all starts to come together," says Perl. "It's like every time a bank gets robbed, there's a guy standing on the corner with a bag of money. You start to think, 'Hey, maybe this isn't such a good guy.' "

But other scientists are just as convinced that the cause of Alzheimer's lies elsewhere, perhaps in a genetic defect or in a slow-acting virus. They point out that aluminum is one of the most abundant elements of the Earth's crust, and that people encounter it in any number of routine activities: when they take an antacid, when they spray on an antiperspirant, when they cook in an aluminum pan, sometimes even when they drink tap water, depending on how it was purified. Since all people ingest aluminum all the time, these scientists demand, then wouldn't all people develop Alzheimer's if aluminum were really the culprit?

That question is still unanswered, as is the broader question of what does cause Alzheimer's.

Now, in the northern Ontario town of Timmins, a group of gold miners enters the picture, presenting a tantalizing, as-yet-untapped body of evidence that may sway the Alzheimer's-aluminum debate one way or the other.

For years, even decades, the Ontario miners were deliberately made to breathe large amounts of aluminum dust every day. The thinking was that aluminum would protect their lungs from silicosis, one of the health hazards of their line of work. That thinking was misguided, but while it prevailed, the unfortunate miners were subjected to a huge dose of the metal.

So far, only one epidemiological study has been conducted on the miners' neurological health, and it has been completed only this fall, after four years of work here in Canada. But the findings, although entirely circumstantial, are arresting: Miners who inhaled the aluminum were more than twice as likely to have impaired cognitive ability than were miners who weren't exposed.

The Canadian researchers used simple tests of mental ability and made no attempt to diagnose Alzheimer's or any other ailment in the miners. Still, the lead author of the study says that some of the miners scored so poorly on the tests that it is reasonable to suspect some form of neurodegenerative disease.

"Right now, it looks like there may be a causal link between (aluminum) exposure and brain dysfunction," says Sandra Rifat, an epidemiologist at the Clark Institute in Toronto.

Rifat says it is essential now to go back to northern Ontario and study the miners who scored badly.

"The first concern, and it's a concern the men themselves must have, is whether they do have a diagnosable illness," she says. "I also think it's important to go back and follow these individuals over time." A conclusive diagnosis of Alzheimer's disease is possible only after the patient has died.

Work on the gold miners of northern Ontario has already attracted the attention of a variety of interested parties, not the least of which is the aluminum industry. Ever since the public became aware that aluminum might have something to do with Alzheimer's disease, consumers have been giving aluminum products a distinctly cold shoulder. And unionized workers in mining and the aircraft industry have agitated around the aluminum issue, calling for workplace cleanups and compensation for alleged health problems.

Companies that process aluminum or sell aluminum products, through their trade group, the Aluminum Assn., have been holding forums on aluminum and Alzheimer's disease, where scientists present their findings, pro and con.

The issue is the subject of hot debate.

Mt. Sinai Medical Center's Perl, for one, went on from aluminum identification to the study of a baffling wave of degenerative brain disease on the Pacific island of Guam. About 10% of Guam's local population now dies of one of two degenerative brain diseases. There are high levels of aluminum in the water there, and Perl has found the metal in the diseased islanders' brains.

In Britain, meanwhile, another group of researchers set about gathering data on the aluminum concentrations in the drinking water of 88 counties, then analyzed the numbers in the context of local Alzheimer's rates. They found a 50% increase in the risk of Alzheimer's in counties with high concentrations of aluminum in the water. The findings have been corroborated by similar studies in France, Norway and the United States.

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