When Mandy McKnight's severely epileptic son was four, he suffered as many as 80 seizures a day. After prescription drugs failed, the Ottawa mother turned to cannabis oil, which she had heard could help. The impact was remarkable: Within 24 hours, the seizures subsided and it was 10 days until he had another.

But when Ms. McKnight began administering regular doses of cannabis oil to her son, she lived in fear of punishment. Although her son's medical cannabis was obtained legally through a prescription, she had to make the oil herself at home. And having that oil tested at a lab – to ensure its potency and that the dosage was correct – was technically illegal.

Ms. McKnight found a lab willing to do the work under the table on humanitarian grounds, but she worried. "Every time we had to mail the oil to the lab, I was always afraid that child protection services was going to come knock on my door and take my kids away," Ms. McKnight said. "I'd never broken a law in my life, but I was being forced to break laws to help [my son] live, which was crazy."

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Kecia Laitinen faced the same problem. The B.C. nurse, who augments her cancer treatment with a cannabis extract that she could not find from a licensed supplier, was barred by law from getting the product tested at labs. "I started thinking: 'Wait, I feel like I should have more rights here than I do.'"

Their plight illustrates how Canada's prohibitive testing laws for cannabis prevent those who need it most from getting the product screened to tell them exactly what it contains – even if it is obtained legally.

While Canadians can freely access accredited labs to screen everything from cosmetics and pharmaceuticals to food products, cannabis remains barred, even though it was legalized for medical use a long time ago and despite the government's plans to approve recreational use next year.

The federal government has started to change those laws, allowing some patients to use federally accredited labs for cannabis screening. The changes were announced two weeks after a Globe and Mail investigation this summer called into question Health Canada's long-held rules that prevented patients from having medical cannabis screened, even when their health was at stake.

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The changes go a long way toward helping many patients feel less like criminals, but they are just a promising first step.

For now, only people with a certificate from Health Canada that lets them grow their own cannabis or buy it from a designated grower can access the country's top labs. Patients wanting to submit products from a federally licensed producer, or one of the hundreds of storefront dispensaries that have proliferated across the country this year, are technically still barred from doing so.

By definition, that excludes people like Ms. Laitinen and Ms. McKnight. However, labs point out they have no way of distinguishing where the product comes from, so several of those facilities told The Globe they will test anything that comes their way provided the patient has the proper certificate. That is a significant development for patients, and some labs said they believe it is the right thing to do.

Ms. Laitinen was diagnosed with Hodgkin's lymphoma in 2015, and several months later began to seek out the cannabis extract. But when she was unable to get it from a government-sanctioned producer, she turned to storefront dispensaries, which are unregulated and considered illegal by Health Canada, although the federal government does not sanction or curtail them.

Ensuring the oil was safe and had been produced properly was difficult without sending it to a lab.

"I noticed a huge discrepancy," Ms. Laitinen said. "There were definitely moments where I thought, this is a bad batch. This isn't good. And I just knew it from the way it made me feel."

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Ms. Laitinen said she would have accessed accredited labs early on if she could have done it legally. "It's definitely scary," she said. "It's something that you're putting in your body and that you're trusting … and in some pretty dire situations for some people."

This year, Health Canada began allowing licenced producers to sell cannabis oils, another promising step for patients, but the limited selection means some people are still going to the dispensary market for strains they need – which exposes them to risks. Documents obtained by The Globe through the Access to Information Act show that Health Canada was warned nearly a year ago that dangerous chemicals not approved for any human use, such as the pesticide dodemorph, had been found in samples of dispensary cannabis sold in Vancouver. However, even though those lab results were sent to the department and to Health Minister Jane Philpott's office, Health Canada chose not to act on the information.

A separate Globe and Mail investigation this summer found that one-third of nine samples of cannabis from dispensaries in Toronto contained potentially harmful bacteria or mould that would not have met Health Canada safety standards, and posed particular risks to patients with compromised immune systems.

The investigation also revealed how restrictive the government's testing rules were, showing that labs were warned by Health Canada not to do tests for anyone other than a licensed medical marijuana company – a threat taken so seriously that the lab that tested for The Globe did so as a public service on condition that the newspaper would not identify the facility.

After more than a month of silence, Health Canada acknowledged two weeks ago it was concerned about the situation regarding patient safety and that protections are needed. "The test results provided to the Department by your paper bear this out," the government said in a statement to The Globe. A department spokeswoman said the government is working on new regulations that "can be expected to include strict safety mechanisms and quality control assurance."

Ms. McKnight's son can attend school because of the profound effect cannabis oil has had in reducing his seizures. Ms. McKnight and her husband were once forced to make cannabis oil in the family's kitchen, but can now buy most of what they need from a medical marijuana company, which is a welcome development.

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But one strain their son takes is still unavailable in oil form, so they must produce it themselves, which means they require testing to ensure they are not giving him too much tetrahydrocannabinol, or THC, which produces the drug's intoxicating effect, as opposed to cannabidiol, or CBD, which helps with the seizures.

"To me, this is his medicine. It's the only thing he takes now," Ms. McKnight said. "The only way to properly dose it is through testing."

Now that the government has started loosening the rules on lab screening, and is constructing new regulations, she believes labs should have standardized procedures to ensure they are all testing for the same properties and contaminants, and that results from one lab to the next are consistent.

"The testing was critical to his treatment," Ms. McKnight said of the screening she had done under the table at a sympathetic facility over the past few years. "But there's no standards. How do I know [the labs] are doing things right? You really are at the mercy of them."