OHS Canada Magazine

Feature

When the Dust Settles

From 1978 to 1979, Jim Hobbs was one of many miners in northern Ontario who inhaled finely ground aluminum dust known as McIntyre Powder, which was believed to protect them from silicosis.


Canisters containing this powder were punctured, and a compressed-air system would send out a thick, black cloud of respirable aluminum dust into specially constructed chambers or change rooms where miners breathed in the dust. During the dispersal process, all ventilation would be halted.

“Every shift, every day, you have to breathe it for about 10 minutes. It is crazy,” says Janice Martell, the daughter of Jim Hobbs, who worked in underground nickel and uranium mines in northern Ontario between 1959 and 1990.

Like other miners of his time, Hobbs had to inhale McIntyre Powder, a finely ground dust of aluminum oxide and aluminum, prior to each shift as a prophylaxis — an action taken by specified means to prevent the onset of a specified disease — against silicosis. In 2001, Hobbs was diagnosed with Parkinson’s disease.

“It was this mass treatment. You would go into a specific chamber built for the specific purpose of giving you aluminum dust,” Janice says. “These were not measured doses, like an immunization needle. This is just sent out, and God help you if you breathe too deep.”

For non-mining sectors such as pottery manufacturers, foundries, silica-brick manufacturers and refractories in Canada and the United States, the inhalation of McIntyre Powder was voluntary. But the prophylactic program was administered differently from how it was used in mining.

“You would have individualized ‘treatments,’” says Martell, describing apparatuses with mouthpiece hoses attached to ball mills that ground aluminum into a fine dust that miners would suck in for a couple of minutes, according to the McIntyre Powder Project website. She cites a man in the United States who was exposed in this way while working in factories in Pennsylvania from the mid-50s’ to 1970.

“We know that people had immediate health effects when they breathed it in,” says Dave Wilken, the chief operating officer of Occupational Health Clinics for Ontario Workers Inc. (OHCOW) in Toronto. “It is a very unpleasant thing. They coughed up black sputum after and during their shifts.”

The McIntyre Powder aluminum-prophylaxis program was an initiative of the McIntyre Research Foundation (MRF). It was established in 1939 as a non-profit corporation known as McIntyre Research Limited and sponsored by McIntyre Porcupine Mines Limited, which patented aluminum therapy as a preventive measure against silicosis in miners. The co-inventors of the aluminum-dust treatment were Dr. W.D. Robson and J.J. Denny, who were the mining company’s plant physician and engineer respectively. The company became the first licensee to administer McIntyre Powder in 1943. In 1946, shareholders turned over their interest in McIntyre Research Limited, which was dissolved to form MRF.

“McIntyre Research Foundation was not an independent scientific research body — it was comprised of mining industry executives and industry doctors,” Martell says.

An article entitled The Objectives and Achievements of the McIntyre Research Foundation by Francis B. Trudeau, reprinted in 1955 from the American Medical Association’s Archives of Industrial Health, lists the original directors of the Foundation. Of the six directors, four are the president, vice-president, general manager and mine doctor from the McIntyre-Porcupine Mines Limited. The remaining two are Dr. Dudley Irwin from the University of Toronto’s Banting Institute and Dr. J.W.G. Hannon, the medical director of the MRF, who conducted aluminum inhalation therapy with ceramic and silica brick industry workers in the United States beginning in 1940, with the permission of McIntyre Research Limited.

The MRF ceased operations in 1992, but the legacy of inhaling the toxic dust lingers. In 2011, Martell learned that her father had been exposed to aluminum dust while he was an underground miner in Elliot Lake.

“I was shocked to find out myself that this could happen to my dad, and I thought people need to be aware of this, because the last of these guys are dying,” says Martell, who suspects that exposure to McIntyre Powder could have caused her father’s Parkinson’s disease. “If you are inhaling a neurotoxin through the nasal passages that have direct access to the brain and Parkinson’s is a neurological disorder, I thought there might be a connection.”

Hobbs had submitted a compensation claim to the Workplace Safety and Insurance Board (WSIB) in Toronto, but was denied. The claim was brought to the tribunal level, but it did not proceed to the hearing stage. When Martell started researching the WSIB’s policies, she realized that the board has an operational policy, which explicitly states that available medical and scientific evidence does not establish causal associations between occupational aluminum-dust exposure and dementia, Alzheimer’s disease or conditions with neurologic effects.

With the knowledge that individual claims of miners who had been exposed to McIntyre Powder would never be compensated, Martell founded the McIntyre Powder Project in April 2015 and created a registry to provide a centralized place for miners and other workers who had been exposed to register their names voluntarily, document their health issues and provide data for further research into the long-term health impact of aluminum-dust exposure. The first name on the registry was her father’s. As of February 2017, there were 355 names.

“About a third of the people on my registry are deceased, and it is their family members registering them,” Martell reports. “I am really starting to see the health patterns,” she notes, adding that two-thirds of the names on her registry have lung and respiratory issues, while one-third have neurological conditions like Parkinson’s disease, Alzheimer’s disease and short-term memory problems.

Failed experiments

Between 1943 and 1980, McIntyre Powder was used as a prophylaxis in some gold and uranium mines, as well as certain base-metal and radium mines in Ontario, Quebec, British Columbia, Manitoba and the Northwest Territories. Miners in other parts of the world, including the United States, Belgian Congo, Western Australia and Mexico, were also given the treatment prior to each shift.

The genesis of inhaling aluminum dust as a preventive treatment against silicosis dates back to a string of experiments starting in the early 1900s. In 1918, Scottish physiologist John Scott Haldane postulated the theory that the dust of certain mineral rocks had an antidotal effect on the fibrogenic action of siliceous dust, according to a paper published in the British Journal of Industrial Medicine in 1956.

In 1936, experiments involving the dusting of 13 rabbits with mine quartz — six of which were exposed to pure quartz, while the remaining seven were dusted with quartz containing less than one per cent of metallic aluminum — were conducted at the McIntyre Porcupine Mine in Schumacher, Ontario. According to results of a study published in The Canadian Medical Association Journal in July 1937, the rabbits dusted with quartz containing metallic aluminum had shown minimal or no fibrosis of the lungs.

These findings spurred another paper, Aluminum Therapy in Silicosis: An Experimental Study, published in 1944 in the Journal of Industrial Hygiene and Toxicology, yielding results with aluminum hydroxide that were similar to those reported by Ontario researchers.

As a result of these experiments, McIntyre Powder became a preventive medicine against silicosis in Canada until 1979, when the Ontario Ministry of Labour halted the practice shortly after the Canadian Broadcasting Corporation’s The Fifth Estate aired a documentary on September 18, 1979, revealing the health risks of inhaling aluminum powder by miners in northern Ontario.

“It was bad science,” Martell says of the research that went into the McIntyre Powder prophylaxis program.

Like Canada, Western Australia was one of the places that had used McIntyre Powder in mines. Dr. Criena Fitzgerald, an honorary research fellow with the University of Western Australia in Perth, is the author of Turning Men into Stone, a book that documents the social and medical history of silicosis in Western Australia from 1890 to 1970. She describes the prophylactic program involving McIntyre Powder as “a poorly researched, poorly understood” treatment.

“The men who used it were just guinea pigs, frankly,” Dr. Fitzgerald says. “When they instituted aluminum dust, there was no proper epidemiological study or testing of it before.” She thinks that there is a need for a historian to examine the role of the McIntyre Institute in bringing about this questionable treatment and those who were benefiting from it. “Certainly not the workers.”

Baby steps

The number of names on Martell’s registry today is a far cry from the time when she started researching on this historical practice for the McIntyre Powder Project. “When I was looking into it in 2011,” Martell says, “I could find next to nothing.”

She spent a year reviewing archival records from the MRF and speaking with former mine workers as well as government bodies involved in making decisions regarding the prophylaxis program, according to a December 6 statement from Workplace Safety North, a non-profit health and safety association in forestry under the WSIB. In April 2015, Martell went public with her registry.

Since then, Martell has partnered with United Steelworkers (USW), which has sponsored two McIntyre Powder intake clinics in Ontario, with support from OHCOW and the Sudbury-based Office of the Worker Adviser (OWA), an independent agency of the Ontario Ministry of Labour that provides free, confidential services on workplace-insurance matters and oh&s reprisal issues. The first intake clinic was held last May in Timmins, and the second one was held in October in Sudbury.

The intake clinics provided a formal process through which miners who had inhaled aluminum dust provided their personal information, work history and health issues and signed consent forms to be part of a study. This information was pulled together to see if any discernible patterns emerged. One of the conditions that came out was Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease in which the nerve cells that control the muscles die. Two out of 100,000 people per year were diagnosed with ALS, “which is statistically significant,” Martell says.

While many workers were exposed to McIntyre Powder aluminum dust in the past, “we don’t know about it or its relationship to health problems. There has not been much research,” Wilken says. “What is known, in terms of toxicology, is that aluminum is toxic and that it is also neurotoxic.”

Although Martell’s registry cuts across Canada, the majority of the names hail from Ontario. “Timmins and Elliot Lake are a focus for me,” says Martell, who expresses her desire to expand the reach of her registry beyond the province. ”But to travel to some of these places is hard,” she says, adding that many exposed miners are already in their 70s or 80s. While USW had sponsored two intake clinics, “everything else I am doing on my own dime.”

Helping hands

J.P. Mrochek, a WSIB worker representative for USW Local 6500 in Sudbury, recalls the day when Martell approached USW for support without knowing exactly what kind of help she would get. “I remember when Janice sat down in the office here, and I proposed to her an intake clinic,” Mrochek says. “I have done intake clinics in the past, and I thought it was a good fit for her challenge.”

Once the idea was born, physicians and nurse hygienists from OHCOW and representatives from OWA and USW District 6 pitched in to what started off as an off-the-top conversation. “And we never looked back,” Mrochek says.

Representatives from the WSIB also attended the clinics to answer general questions and provide assistance as required, although the collection of information and the submission of any claims to the WSIB are at the discretion of the OWA and OHCOW, says Christine Arnott, the WSIB’s senior public-affairs consultant. “We understand that this is an important issue to the community and are committed to supporting workers and their families,” Arnott says.

At the intake clinics, an exposure-profile section will be created for each participant to document where they have worked in the past, the level and the duration of exposure, how aluminum dust was dispensed and whether a worker was exposed to other contaminants like uranium, for example. This is followed by the body-mapping section, in which participants share their health issues with physicians and hygienists from OHCOW, who will chart these ailments on body maps to identify disease clusters.

“The primary objective was to gather valuable data from the workers’ perspective, ground zero,” Mrochek explains. “Because every mine has a different story. The way that they forced the workers to inhale aluminum dust was a little different in Timmins, compared to Elliot Lake.”

Cast in Stone

In 1985, the Ontario legislature established the Industrial Disease Standards Panel (IDSP) to investigate and identify occupational diseases after workers at two companies — Boeing of Canada, deHavilland Division (now known as de-Havilland Inc.), which manufactures aircraft, and McDonnell Douglas Canada Ltd., which manufactures aircraft wings composed of aluminum — expressed concerns about their exposure to aluminum dust and aluminum welding fumes.

As Ontario’s Workers’ Compensation Board (WCB), now known as the Workplace Safety and Insurance Board (WSIB), had no policy for aluminum claims, the workers’ concerns were referred to the IDSP on December 16, 1988 by Dr. R.G. Elgie, then chair of the WCB, according to an interim report to the WCB on aluminum dated May 1992.

As part of the preliminary investigations, the panel reviewed medical literature about aluminum and its effects, visited both aircraft-manufacturing plants and looked at the provincial labour ministry’s hygiene reports on plant conditions at McDonnell Douglas from between 1985 and 1992 and at Boeing-deHavilland from between 1984 and 1992.

The WCB report noted that the number of studies to establish consistent results was insufficient and that exposure to aluminum was usually accompanied by exposure to other potentially toxic substances, which made it hard for the panel to identify aluminum conclusively as the causal agent of any occupational disease. But the panel acknowledged that there was some epidemiological and anecdotal evidence to suggest that high levels of occupational aluminum exposure might lead to cognitive or neurologic effects and that the lack of evidence did not mean a relationship between occupational aluminum exposure and cognitive deficits or neurologic effects did not exist.

“It only means that medical science cannot yet answer these questions,” the interim report from 1992 stated. “If evidence can be obtained which identifies a disease that has a probable connection to workplace exposure to aluminum, this Panel will promptly reconsider its opinion and these interim findings.”

For Janice Martell, the founder of the McIntyre Powder Project, the WSIB’s existing operational policy that dementia, Alzheimer’s disease and conditions with neurological effects are not occupational diseases when they are alleged to have resulted from occupational aluminum exposure flies in the face of logic. According to Martell, the WSIB applied this policy to all incidents occurring on or after September 23, 1993, which was right after the IDSP had completed its review of aluminum.

“The panel accepted that there is some epidemiological and anecdotal evidence to suggest that high levels of occupational aluminum exposure might lead to cognitive or neurological effects. So despite all of those findings, they developed this policy,” Martell stresses. “My personal take on that is that they gave this to thousands and thousands of workers, and they know that if it comes out that this is a problem, they are sunk. The WSIB does not have the funds to pay out claims for this kind of exposure.”

Now that the intake clinics have concluded, the bulk of the work has now shifted to OHCOW, which will analyze the data collected. The information gathered from intake clinics will be entered into a database to see if there are any common denominators in terms of neurodegenerative disorders, reports Wilken, who confirms that nearly all of the intake-clinic participants indicated that they had been exposed to aluminum dust. “It was a widespread practice for many years over a number of mines, so there are thousands of exposed workers in various degrees out there,” he says.

While McIntyre Powder was meant to protect against silicosis, it was introduced in mines at a time when other advances in controlling silica were also greatly expanded, such as better ventilation practices and wet drilling. “There is probably some extent to which people who were promoting this were fooled into thinking that they were having a positive effect, when these other advances were really tampering down the number of silicosis cases,” Wilken suggests.

One of the challenges in finding out whether there is indeed a link between aluminum-dust exposure and neurodegenerative diseases is that McIntyre Powder has not been used for more than 35 years, and many of the miners who were exposed have already passed on. “So that is an unknown, at this point, to what degree in the possibility for us to gain more knowledge about this,” Wilken says. But one thing is certain: “There is absolutely no evidence that this aluminum dust did what it was intended to do.”

Conflicting views

Exposure to aluminum is usually not harmful, since only very small amounts of aluminum that has been inhaled, ingested or dermally contacted will enter the bloodstream. But exposure to high levels of aluminum can certainly affect health, according to a fact sheet from the Agency for Toxic Substances and Disease Registry in Atlanta. Workers who breathe in large amounts of aluminum dust can have lung problems, such as coughing or abnormal chest X-rays, while those who have inhaled aluminum dust or fumes have demonstrated decreased performance in some tests measuring functions of the nervous system.

Research on the health effects of exposure to aluminum dust, however, is far from consistent. While some studies show that people who have been exposed to high levels of aluminum may develop Alzheimer’s disease, other studies have disputed these findings.

For example, a 1996 mortality study out of the United Kingdom investigated the association between occupational aluminum exposure to McIntyre Powder and the death certification for dementia and Alzheimer’s disease in two groups of miners who had worked in two tin mines in Cornwall, England from 1941 to 1984. McIntyre Powder had been used as a prophylactic against the development of pulmonary silicosis from the 1940s until 1964 in Geevor tin mine, but not in South Crofty mine. Researchers found that none of the miners who had been exposed to McIntyre Powder at Geevor were certified to have died from senile dementia or Alzheimer’s disease, but two dementia-related deaths were recorded for South Crofty, which did not use McIntyre Powder.

But a 2013 study out of the University of Western Australia, Long-Term Effects of Aluminum Dust Inhalation, sings a different tune. The study looked at the link between aluminum-dust inhalation and cardiovascular, cerebrovascular and Alzheimer’s diseases in a cohort of Australian male underground gold miners. Their mortality rates were compared with that of the Western Australian male population from 1961 to 2009.

Results indicated that there was increased mortality from Alzheimer’s disease among miners who had been exposed to aluminum dust, although it was not statistically significant. Rates for cardiovascular and cerebrovascular death were also above population levels, but were similar for subjects with or without a history of aluminum-dust inhalation. The study concluded that inhaling aluminum dust offers no protective effect against silicosis. Conversely, exposure to aluminum dust could hike the risk of cardiovascular disease and dementia of the Alzheimer’s type.

Due to the limited and conflicting knowledge that available research has yielded on McIntyre Powder and the mounting pressure for compensation from miners who were systematically exposed to aluminum dust, the WSIB has commissioned a review of scientific evidence to examine whether workers with occupational exposure to aluminum have an increased risk of developing adverse health conditions, including neurological effects. The external review is expected to be completed this year.

“Pending the outcome of the scientific review, the Operational Policy Manual Document 16-01-10, Occupational Aluminum Exposure, Dementia, Alzheimer’s Disease and Other Neurologic Effects will not be used to guide decision-making on any claims. The WSIB will consider whether any policy changes are required based on the outcome of the external review,” Arnott says.

For Mrochek, an academic study to probe deeper into the effects of inhaling McIntyre Powder should have been done 30 years ago when many more workers were still alive and well, but late is better than never. That said, the possibility that research may find no conclusive association between aluminum dust and the onset of neurological disorders like Parkinson’s disease or ALS cannot be discounted.

Should that happen, “at the very least, we could say that we gave it a shot,” Mrochek says.

Jean Lian is the editor of OHS Canada.