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.
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.
And there have been other findings: brain diseases among dialysis patients living in places with heavy concentrations of aluminum in the water, for instance, or Alzheimer’s-like tangles in the brains of animals injected with aluminum.
But no sooner does one of these studies appear than other scientists find reason to challenge it. In the British drinking-water study, for example, critics have argued that the water-content data might be flawed, that the researchers might have missed some Alzheimer’s patients, that soil chemistry might be confusing the results, and even that Welsh-speaking patients might be misdiagnosed as demented by English-speaking doctors.
Perhaps most perplexing of all, critics noted, no matter how much aluminum the British subjects might be getting in their water, they would always be getting much more through food additives. So why should a little bit of water-borne aluminum matter?
Perl responds that aluminum is highly complex, appearing in many different forms in the environment, and probably affecting the body differently depending on how it is ingested. He became interested in the possibility that aluminum might be more dangerous if inhaled, and he put aluminum-impregnated implants into the nasal passages of rabbits. He found that the metal traveled very efficiently to the rabbits’ brains along their olfactory nerves. But he didn’t look at what the aluminum did to the rabbits’ brains once it was there.
Thus, Perl was excited when he heard about Rifat’s work with the elderly gold miners.
“It’s a fascinating finding,” he says. “These people should definitely be followed up.”
Back in the 1930s, hard-rock mining operations were plagued with silicosis outbreaks among their workers. Silicosis is a chronic lung disease caused by the breathing of silica dust. Gold miners are particularly susceptible, since gold-bearing ore is loaded with silica.
Here in Timmins, the McIntyre Porcupine Mine set up a research institute devoted to the study of silicosis prevention. Early tests on the inhalation of aluminum dust looked promising.
“They came up with this bright idea that if you coated the lungs with this stuff, then when the miners coughed it out, they would cough out the silica they encountered at work,” says Ed Vance, a former gold miner. Vance, who moved to Ontario from his native England to take a job in the mines, was amazed to be subjected to a cloud of sooty-black aluminum oxide on his first day at work.
Each day when the miners entered the headframe--a tall building where they reported to work, changed their clothes and caught elevators underground--they were required to sit for 10 minutes in the locker room while aluminum dust was blown around them.
“My husband just hated it, I can tell you,” remembers Winifred Latendresse, a miner’s widow from South Porcupine, near Timmins. “It used to burn his nose terrible. He used to spit up this awful black stuff. He said the taste was terrible. Some days, he’d come home and he just couldn’t eat his food. He’d say, ‘I’ll just wait,’ because he still had the (aluminum) taste.”
However disagreeable the inhalation exercise may have been for the men, it caught on at an unknown number of other gold mines--and, later, uranium mines--where silicosis was a concern. Here in Ontario province, where the practice began, it didn’t end until 1980, when officials decided there was no evidence that the aluminum dust was doing any good.
Soon after that, epidemiologist Rifat heard about the miners and decided to track enough of them down to make a sample. Combing the records of chest clinics in the mining area here known as the Porcupine District, she came up with the names and addresses of 1,353 men who had been miners since the 1940s. Of those, she located 647 who were alive and willing to participate in her study.
Rifat put the miners through three cognitive tests. Two of them tested memory, asking the miners, for instance, to spell simple words backward. The third test examined the miners’ logical thought, asking them to complete patterns.
Not only did about twice as many miners from the aluminum-breathing group score in the “impaired” range, their amount of exposure seemed to worsen their difficulties. Rifat is quick to point out that the cause of their impairment is not yet known; it could be anything from a serious infection to Alzheimer’s. Despite her caution, word of her study has caught the attention of aging miners and miners’ widows here in Timmins.
“I don’t know if aluminum dust done something to me,” says Ange Aime Camirand, a feeble Timmins ex-miner who suspects that he has silicosis. “But I know sometimes when I want to tell some people’s names, I don’t remember. And I worked with them for years! Do you think the aluminum could make me forget?”
The Price of Mining Gold
Miners at the McIntyre mine inhaled aluminum dust for decades in a misguided effort to stop the lung disease silicosis. Now, many of those miners are being studied in effort to find a link between aluminum and Alzheimers disease. A miner, right, takes a smoke break outside the mine’s headframe building.
