Health Canada says it will begin random testing of medical marijuana products to check for the presence of banned pesticides after product recalls affecting nearly 25,000 customers led to reports of illnesses and the possibility of a class action lawsuit.

Late last year, licensed medical marijuana producers Organigram of Moncton, N.B., and Toronto-based Mettrum voluntarily recalled products due to the presence of low levels of the prohibited chemicals myclobutanil, bifenazate and pyrethrins, all of which are prohibited in tobacco and marijuana.

In January, nearly all of Organigram's products sold in 2016 were pulled in a higher-level voluntary recall.

Dawn Rae Downton plans to have her leftover medical marijuana tested to see what else is in it. (Elizabeth Chiu/CBC)

On Health Canada's Jan. 9 recall notice, the department said it had "not received any adverse reaction reports for products sold by Organigram Inc."

However, CBC News has confirmed that a Halifax woman, Dawn Rae Downton, who had received one of the Health Canada notices, had earlier complained to Health Canada about non-stop nausea and vomiting.

'I am living proof' of adverse effects

Downton, 60, had a medical marijuana licence for her inflammatory arthritis. She said she's upset she received nothing more than a form letter in November.

"I am living proof there have been very adverse effects. I lost eight months of my life," she said. "I'm living proof that Health Canada is not protecting medical marijuana patients."

She also said she reported her side-effects to Organigram, one of 38 licensed producers in Canada, but did not receive a response.

A spokeswoman for Organigram said the company president was unavailable for an interview, but the company was working with Health Canada throughout the recall and hopes "to close this chapter very soon."

Health Canada 'regrets this error'

In response to CBC inquiries last week, Health Canada said Tuesday it had received a report of side-effects prior to issuing the recall and "regrets this error."

Downton received this recall notice from Organigram on Jan. 9. Nearly 3,900 Organigram customers were affected by the recall. (Elizabeth Chiu/CBC)

In addition, as of Jan. 31, the department said it had received one adverse reaction report — related to the recall — from among Organigram's 3,895 medical marijuana customers. Reported symptoms include "weight loss; nausea; vomiting; throat irritation; and respiratory tract irritation," according to an email from a Health Canada spokesperson.

The spokesperson also said 10 adverse reaction reports specific to the recall had been received from among the 21,054 Mettrum customers.

Health Canada says there were 119,709 people with a medical marijuana licence as of Nov. 30, 2016. That means about 20 per cent of all medical marijuana licence holders in Canada are affected by the recalls.

Random testing announced

Late Tuesday evening, Health Canada released an additional statement announcing a new measure beyond the recall. The department said "it will begin random testing of medical cannabis products produced by licensed producers, to provide added assurance to Canadians that they are receiving safe, quality-controlled product."

The statement said the testing will be done to ensure only authorized pest control products are used during the production of medical cannabis.

"The expanded product testing program will further enhance the department's existing regime of regular unannounced inspections of licensed producer facilities, as well as the controls in place by licensed producers," reads the statement.

'I never want to be that sick again'

In October, Downton went to a gastroenterologist. She had been sick to her stomach for eight months, a period when she had been smoking and eating medical marijuana.

The medical specialist diagnosed her as having an atypical case of cannabinoid hyperemesis syndrome, and told her to stop consuming marijuana. The doctor had never seen this type of illness in someone who wasn't a longtime pot user.

Downton had become so sick that she had lost 30 pounds and was bedridden.

"I never want to be that sick again," she said.

The diagnosis of cannabinoid hyperemesis syndrome was made before the recall. It wasn't publicly known at that point that the marijuana, believed to be organically grown, contained trace amounts of myclobutanil and bifenazate.

Large concentrations may have health effects

Myclobutanil is a fungicide permitted on food crops. But when burned, it produces hydrogen cyanide.

According to Health Canada, hydrogen cyanide interferes with how oxygen is used in the body and may cause headaches, dizziness, nausea and vomiting. Larger concentrations may cause gasping, irregular heartbeats, seizures, fainting and even death.

Now, Downton suspects it was the joints she smoked — tainted with myclobutanil — that caused her eight-month illness.

Since she stopped using the marijuana, she said, she hasn't had constant nausea and vomiting.

Studying hydrogen cyanide signs

Frank Conrad, the lab director at Colorado Green Lab who has studied the question of pesticides and medical marijuana, agreed Downton's symptoms are signs of possible hydrogen cyanide exposure.

"Nausea and vomiting are two things that can be a byproduct of this," he said from his Denver-based office.

Conrad, who has a masters in biomedical sciences from the University of Colorado, said the body can clear hydrogen cyanide in small levels within hours, but in severe cases, it can cause increased blood pressure and heart rates.

Frank Conrad, lab director at Colorado Green Lab, said nausea and vomiting can be symptoms of hydrogen cyanide exposure. (David Zalubowski/The Associated Press)

In rare cases, it's fatal, although Conrad said there are no documented cases of death caused by hydrogen cyanide poisoning from marijuana produced with myclobutanil.

He said Colorado Green Lab is developing a test for cannabis strains to determine whether they are susceptible or resistant to powdery mildew. The idea is that growers can watch for early signs of disease, and apply organic preventative treatments so they "never have to resort to myclobutanil."

Possible class action lawsuit

Patients affected by the recalls are banding together. So far, more than 90 medical marijuana patients have contacted Wagners, a class action and medical malpractice law firm in Halifax.

"That is an awful lot in a short period of time," said Ray Wagner, the founder of the firm. "It's shocking to a number of people who have compromised immune systems and are ill from other disease processes to find out that the product they thought was organic is not."

Halifax lawyer Ray Wagner is considering whether to launch a class action lawsuit over the recall. (Steve Lawrence/CBC)

He's still assessing the potential for a class action, and said a health claim may be challenging because of the different underlying medical problems among the patients.

None of the allegations have been proven in court. A judge would have to approve the class action for it to proceed.

Wagner also believes he's got a good shot at another type of claim — disgorgement — which is a refund of amounts paid, plus a portion of profits.

Wagner said many people who have contacted him have autoimmune disorders.

"They're more vulnerable to these types of circumstances and that is why, in most cases, why they seek out a particular product that is organic."

Downton plans to follow up with her doctor to determine if there's medical proof her illness was caused by pesticides and hydrogen cyanide.

She plans to ship the remainder of her dried cannabis from Organigram to a testing lab to see what else is in the product. As well, she has volunteered to front a potential class action lawsuit as the representative plaintiff.