Sudbury researcher has closer look at makeup of McIntyre Powder, once used in mining

Before each shift between the 1940s and 1970s, underground miners in northern Ontario breathed in a substance they thought was protecting their lungs, but none of them knew what exactly was in McIntyre Powder. Until now.

Laurentian University occupational health expert finds substance made of harmful nanoparticles

Andrew Zarnke, a researcher at Laurentian University and an occupational health coordinator recently published a paper on the makeup of McIntyre Powder. Janice Martell, founder of the McIntyre Powder Project, has been working to uncover the harmful health effects of the substance. (Angela Gemmill/CBC)

Before each shift between the 1940s and 1970s, underground miners in northern Ontario breathed in a substance they thought was protecting their lungs, but none of them knew what exactly was in McIntyre Powder. Until now.

Many of these mine workers developed respiratory or neurological illnesses, later in life.

It was a connection Laurentian University researcher Andrew Zarnke wanted to pursue.

The occupational health coordinator has recently published a paper on the physical and chemical makeup of McIntyre Powder.

He expected to find aluminum and aluminum hydroxide.

But he also discovered the powder was made up of microscopic, ultra-fine particles, known as nanoparticles.

Previous research has connected nanoparticles — of any substance — to harmful health issues, particularly when they're inhaled. This includes studies on diesel exhaust particulates, which is also a current health concern in mining.

"With nano-technologies these days, you know it brings McIntyre Powder into the arena with a lot of these more recent studies that are looking at health effects from nano-materials," Zarnke said.

'No longer a dirty little secret somewhere'

For the past five years, Janice Martell has been collecting health data from miners across northern Ontario who were exposed to the powder. Her father was forced to inhale the substance and later was diagnosed with Parkinson's Disease. She now feel her work to uncover the truth has been validated.

"It bears witness to what they went through and it also gives us some information to answer the next steps," she said.

McIntyre Powder, seen in these various canisters was used between 1943 and 1979 in mines, including in northern Ontario. (Supplied by Janice Martell)

Martell is especially pleased for what this means for the men who were exposed to the aluminum dust, and their loved ones.

"Being able to go back to miners, mine workers and their families and say 'Hey this is no longer a dirty little secret somewhere that they were sweeping under the rug,'" Martell said.

"And to be able to provide them with some answers as to what their loved one or themselves were exposed to."

More research needed

Zarnke says the next phase of the research involves biological studies to see how human cells react to McIntyre Powder.

"Next steps which involve some biological studies looking at possible geno-toxic effects from the combined stressors of McIntyre Powder or nano-materials and radiation."

"So we're now using the information from this new publication to generate hypotheses with regards to possible biological mechanisms and health affects," he said.

"Being able to provide something like this [research] and say here's one more piece of the puzzle is validating," Martell said.

The research is available online at the Journal of Occupational and Environmental Hygiene. It will be published in the November issue of the journal.

Zarnke and Martell will be in Elliot Lake Sept. 23 to hold a public information session. While in the community they also plan to meet with local physicians to discuss mining exposures and health.


Angela Gemmill


Angela Gemmill is a CBC journalist who covers news in Sudbury and northern Ontario. Connect with her on Twitter @AngelaGemmill. Send story ideas to


To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.

Become a CBC Account Holder

Join the conversation  Create account

Already have an account?