'It's unheard of': Death of Edmonton worker from walnut shells baffles allergy expert

The death of an Edmonton man who suffered a fatal allergic reaction after visiting a worksite where walnut shells were used to blast paint off walls is baffling, an allergy expert says.

'The risk of developing a severe reaction from inhalation of most foods is just not there'

Justin Mathews was taken off life support on Oct. 07 after he suffered anaphylactic shock after inhaling walnut shell-based product on a work site. (Sam Martin/CBC)

The death of an Edmonton man who suffered a fatal allergic reaction after visiting a worksite where walnut shells were used to blast paint off walls is baffling, an allergy expert says.

Justin Mathews, 33, was doing air quality tests at the old Rossdale fire station on Oct. 2, when he started having trouble breathing and went into anaphylactic shock.

He suffered brain damage after going into cardiac arrest and was taken off life support five days later.

'It's unheard of'

The case is a medical anomaly, said Dr. Yarden Yanishevsky, medical director of pediatric allergy at the University of Alberta.

"It's unheard of for a person with nut allergies to develop anaphylactic shock after merely inhaling the material. I've never heard of such a thing," said Yanishevsky in an interview Tuesday with CBC Radio's Edmonton AM.

"It's exceedingly unlikely that they will develop a severe allergic reaction from inhaling the material because peanuts and tree nuts and allergens in general are not aerosolized.

"The risk of developing a severe reaction from inhalation of most foods is just not there."

The exception, he said, is seafood that is being cooked.

Mathews, who had a lifelong nut allergy, was working with an environmental engineering company, ESP HiTech Inc.

He had already done some work at  the Rossdale fire station, which has been vacant since the '90s and is set to reopen next year.

Mathews' family says he was inside the fire station, which is being renovated, for close to 20 minutes while testing air quality with a co-worker.

He was unaware a product containing walnut shells was being used to sandblast the walls.

When he started having trouble breathing, he rushed outside and collapsed.

He lost consciousness and eventually fell into a coma. As his brain activity continued to decline, his family made the difficult decision to take him off life support.

'Very unfortunate'

If Mathews inhaled enough of the airborne walnut particles, it could have triggered a severe reaction, Yanishevsky said.

However, anaphylactic shock is rare in this kind of exposure, he said.

"Sometimes you will just have a cough or an asthma attack," Yanishevsky said. "It depends how allergic the person is, and what volume was inhaled, but it can lead to a severe reaction like in this case, which is very sad and very unfortunate.

"This story will probably create a lot anxiety for people with food allergies that they can go to places and become very sick, but it's extremely, extremely unlikely for someone to have severe reactions through the inhalation of food."

Yanishevsky said there should be warnings on jobs sites for anyone who may come close to an area where allergens may be airborne.

"To my understanding, when he entered the building, he had no idea what was in the building," said Yanishevsky.

"If someone is using a product like this, obviously it should be marked and people should know the risk, and where they should not enter."

Trent Bancarz with Alberta Occupational Health and Safety said investigators do suspect the death was caused by a severe allergic reaction to walnut shells at the fire station, although it's still early in the review.

'Very rare and unusual'

"This is a very rare and unusual type of incident," Bancarz said. "Certainly I've never come across this before."

Silica used in sandblasting is known to cause health problems such as silicosis and lung cancer. The construction industry years ago moved to using substitutes such as walnut shells, coconut shells and corn cobs, he said.

The family said it doesn't know if Mathews or his employer were aware that walnut shells had been used at the fire hall, if he was wearing a mask or if any warning signs were posted.

They were told Advanced Remediation Solutions did the blasting work. When asked if a manager at the company was available for comment, a man who only gave his name as Dean said staff are co-operating with provincial investigators.

He said it's not conclusive that walnut shells caused the death, since nut oils that cause allergic reactions are removed from shells during processing. And there have been no recorded allergic reactions to their decade-long use for blasting in North America.

"I don't want to take anything away from the family, but the jury's still out on this," he said.

Listen to Edmonton AM with host Mark Connolly, weekday mornings at CBC Radio One, 93.9 FM in Edmonton. Follow the morning crew on Twitter @EdmAMCBC.

With files from the Canadian Press