A third class-action lawsuit launched Tuesday over tainted medical marijuana raises new questions about Health Canada's recent conclusion that patients who consumed products containing banned pesticides were unlikely to experience any adverse health consequences.

A Nova Scotia man listed in the proposed suit says he became violently ill and unable to keep food down after taking federally regulated medical marijuana purchased from Toronto-based Mettrum Ltd. Those claims, unproven in court, are similar to allegations made in two other proposed class actions already launched over the pesticide problem.

The symptoms also resemble a growing file of evidence being gathered by a group of military veterans who are investigating the situation after being exposed to the tainted products. Several of them say they became bedridden, stricken by nausea and suffered bouts of "scary" breathing difficulties, among other symptoms.

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Globe investigation: What's in your weed?

Globe investigation: What's not in your weed?

Scott Wood, a former military policeman who is leading the independent investigation, has gathered evidence from roughly 100 people, including dozens of affected veterans. The group wants federal Health Minister Jane Philpott to step in, saying the department has not investigated the problem properly, or fairly, on behalf of patients before concluding that there was a low risk of serious health problems.

Drawing upon his police background, Mr. Wood said he has spent the past few months cataloging evidence from patients exposed to the banned chemicals in products sold by Mettrum and OrganiGram Inc.

He said thousands of veterans use medical cannabis instead of opioids to ease the pain of injuries suffered while serving, or to manage post-traumatic stress disorder. The group disputes Health Canada's claim that the risk of health problems was low and believes the department reached that conclusion without speaking to patients.

Mr. Wood said more people have joined the effort this week, after he spoke publicly about the investigation in The Globe and Mail, including additional military veterans.

The symptoms being catalogued include severe bouts of breathing difficulties that have sent people, including Mr. Wood, to the emergency ward, painful rashes around the neck and other parts of the body, abdominal pain and persistent bouts of nausea and vomiting. In his case, Mr. Wood said he stopped taking the products when the symptoms emerged, but problems such as breathing difficulties persisted.

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"These symptoms didn't come out of nowhere. They have to be caused by something," Mr. Wood said, adding he and many other patients experienced none of the health issues prior to taking the products. "How would Health Canada explain so many people with eating [dysfunctions] all of a sudden, who can't eat?" Mr. Wood said, noting that one patient reported losing more than 40 pounds.

Patients who visited their family doctors have come away with few answers, he added, which suggests more examination of the problem is needed.

A spokesperson for Ms. Philpott said on Tuesday the Health Minister had no comment.

The latest proposed class action is against Mettrum and is led by Halifax-based Wagners Law Firm, which is seeking a class action against OrganiGram on similar grounds. Toronto-based law firm Roy O'Connor announced a proposed class action against Mettrum two weeks ago. All three cases are seeking certification by the courts.

Canopy Growth Corp., which acquired Mettrum in January, and OrganiGram have both said they plan to fight the suits. Mettrum issued a statement saying it is satisfied with Health Canada's determination that the recalled products were "not likely to cause any adverse health consequences."

In its statement of claim against Mettrum, Wagners said Nova Scotia resident Neal Partington suffered "persistent and severe nausea and vomiting," before halting use of the product, which he was taking for chronic neck and back pain.

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The suit alleges there is no explanation, other than the product, for the problems. "Mr. Partington attended multiple medical appointments and the emergency room on various occasions. He was referred to medical specialists and underwent various diagnostic tests, yet received no confirmed diagnosis to explain his nausea and violent illness," the statement of claim says.

"Patients thought they were purchasing safe, healthy medical cannabis from a licensed producer subjected to strict regulations. And in fact, that's not what they received," said Ray Wagner, lawyer for the suit, which seeks to recover money charged for the products, among other damages.

Little is known about the health risks of the banned pesticides involved when inhaled because these products – including myclobutanil and bifenazate – are not approved for use on cannabis and haven't undergone the appropriate safety studies for humans. Though Dr. Philpott would not comment, Health Canada provided a statement Tuesday saying its determination that the risks were low was based on existing animal toxicity studies for myclobutanil, involving oral ingestion, absorption through the skin, and inhalation, as well as the low amount of the chemical present.

For Mr. Wood, who has not joined the class actions, getting to the bottom of the health problems on behalf of those he says have gotten sick is a more pressing concern.

"If someone was to take me in front of a government panel, I would bring my own medical documents, I would bring the pictures I have received from people [of rashes and other symptoms] and I would tell them – not just for me, but for all the people affected – this is what's going on," Mr. Wood said.