The company behind the headline-making cronut burger at the Canadian National Exhibition in Toronto is standing by its record even as officials investigate nearly 100 cases of food poisoning.

Epic Burgers and Waffles posted a statement on its Facebook page Thursday, defending its product and promising co-operation with an ongoing investigation by Toronto Public Health.

"In the time that we've been operating at the CNE, we have had a clean bill of health and all our staff have been fully trained in food safety," the statement reads in part. "We buy our products from only the top suppliers and we've never had any issues in the past, nor do we wish to have any in the future. We take health and safety very seriously. It's very important to us that our food is not only enjoyed, but also trusted."

Thirty-four people initially reported symptoms of food-borne illness after eating at the annual fair on Tuesday. Paramedics treated 12 people and recommended that five be taken to hospital. A cronut burger stand at the annual fair remains closed while health officials investigate to determine whether the food played a role in the illnesses.

"Based on information to date, Toronto Public Health has concentrated our investigation around one food premise located at the CNE. However, all possible sources of illness are being investigated," said Dr. Lisa Berger, associate medical officer of health. "Overall risk to the general public is low."

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The Epic Burger location at the CNE is closed as Toronto Public Health investigates reports that people who ate at the annual fair were feeling sick. (Trevor Dunn/CBC)

Some of those who became sick told health officials they had eaten the trendy cronut hamburger, which features a croissant-doughnut mix for a bun.

The food outlet, which was subject to a three-hour inspection Wednesday morning, was closed by the CNE, not Toronto Public Health, as a precaution, although health officials have yet to confirm the source of the illnesses.

The result of Toronto Public Health tests on food samples from the Epic Burgers and Waffles stand won't be available until Friday at the earliest.

Health expert suspects toxin in food

Based on news reports of patients' symptoms, Tim Sly, a professor at Ryerson University’s school of occupational and public health, said he suspects the illnesses were caused by a toxin in the food due to the short time between when it was eaten and when patients reported feeling sick.

"With short onset times, you're looking at something that may have grown in the food and survived the cooking," he said in an interview Thursday on CBC Radio's Metro Morning.

"I'd put my money on a poison or toxin that has grown in the food, and then it doesn't matter if the food is cooked. It's still going to be there."

While Sly said most of these types of food contamination are not fatal, they cause discomfort for patients.  

"You're not sure which end to put over the toilet," he said.

The CNE, commonly called the Ex, opened last Friday and runs through Sept. 2. It typically draws more than a million visitors each year.

In recent years, the Ex has offered a number of unusual food items, including deep-fried butter and bacon milkshakes.