Health Canada is warning that a popular hair-straightening treatment contains dangerous amounts of formaldehyde, a known carcinogen.

In lab tests, the Brazilian Blowout Solution was found to contain 12 per cent formaldehyde -- only 0.2 per cent is permitted in cosmetics.

On its website, Brazilian Blowout advertises that all of its products have been tested as "formaldehyde free."

Derek Bodnarchuk, owner of Aru Spa and Salon in White Rock, told that the product was heavily marketed as being formaldehyde-free.

"That was their competitive advantage," he said. "It's alarming for us, because we're the type of place that's trying to promote a healthy, natural lifestyle."

The national health agency has received complaints of breathing difficulties, burning eyes, nose and throat, and even one case of hair loss associated with the treatment, which can keep hair straight for months. The agency believes that the reactions are triggering when the solution is heated during blow-drying and flat-ironing.

Formaldehyde has been linked to cancer when inhaled over a long period of time.

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Health Canada is now asking hair salons to stop using the Brazilian Blowout Solution immediately, and is advising customers who have suffered adverse effects to contact their doctors.

Vancouver stylist Isolde Semple said Thursday that she's completely stopped using the treatment.

"I think it's absolutely devastating that it got approved," she told "There's a lot of victims here, and I'm absolutely upset at the people who produced the product."

Semple said that the treatment does have an awful smell, but she didn't think it was anything serious.

"It makes your eyes kind of water, but it's the same thing as when you're cutting an onion," she said. Some customers have reported feeling slightly ill afterwards. "Now people are realizing, maybe it wasn't what I ate."

Semple said she was charging around $350 for the treatment, and could now be out quite a bit of money.

"If I can't return the product, I'm sucking it up as a very big lesson learned," she said.

Now Semple will have to find a new way to help customers straighten their hair.

"It did a great thing to the hair -- that's the worst part."

Other Brazilian Blowout products are not affected by the Health Canada warning.