The largest association of medical-marijuana companies in Canada has agreed to implement new standards on product safety and transparency, after a series of recalls due to banned pesticides that have shaken consumer confidence in the industry.

Directors of the Cannabis Canada Association, which represents 15 federally licensed medical-marijuana companies – including several of the country's biggest – voted unanimously in favour of the new health and safety standards at a board meeting Thursday.

The stricter measures include independent lab testing for banned pesticides, bacteria, mould, heavy metals and other contaminants, and – most importantly – disclosing those results to consumers.

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The decision to start disclosing test results to the public represents an abrupt shift in thinking for the sector and comes after The Globe and Mail began questioning the oversight of medical-marijuana safety testing. The Globe first reported in December that myclobutanil had been found in products sold by two companies, putting patients at risk, and that Health Canada was not requiring companies to test for such chemicals.

Myclobutanil is a banned pesticide that produces hydrogen cyanide when heated and can lead to serious health problems, particularly in cancer patients and those with compromised immune systems.

Going forward, the association will require its members to test for dozens of contaminants, including 51 pesticides, and expects all of its members to post that information online so that patients can see that the products were scrutinized by an independent and certified federal laboratory.

The industry group "will soon roll out new guidelines and standards aimed at enhancing consumer safety and increasing transparency within the medical-cannabis sector in Canada," the organization said in a statement.

"Members of the association must provide, as a requirement of membership, confirmation that their product testing protocols include bacteria, microbial, aflatoxins, heavy metals and pesticides, and it is recommended that the results will be published online so these are readily available for consumers."

The announcement comes after one of the group's members, Aurora Cannabis Inc., announced Thursday morning that it had started posting test results from an accredited lab for all of its products.

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The association's five-member board voted in favour of adopting the stricter guidelines and providing public disclosure so that consumers can be confident products they are taking contain no contaminants, said Neil Closner, chairman of the association.

"More information is always better," said Mr. Closner, who is also chief executive officer of MedReleaf, a licensed producer based in Markham, Ont.

While Aurora has already started disclosing its lab results, Mr. Closner said some companies could be delayed in posting them online as they revamp their webpages. However, companies will be expected to take such measures as soon as possible. As well, companies that don't test for pesticides will be expected to bring their standards in line with the new requirements.

Another member of the organization, OrganiGram Inc., said it expects to begin posting its testing data next week, to show that its products are free of contaminants.

The association represents 15 of the more than 30 licensed producers in Canada. (There are 38 commercial medical-marijuana licences issued by Health Canada, however, some companies hold multiple licences for different grow locations.)

Cannabis Canada's membership includes the following companies: ABcann, Aphria, Aurora, Broken Coast Cannabis, Canada's Island Garden, CannTrust, Emblem, Emerald Health, Green Relief, Hydropothecary, MariCann, MedReleaf, OrganiGram, WeedMD and 7 Acres.

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Though not all of the industry is represented by the association, Mr. Closner said he hopes the rest of the sector will follow its lead by adopting the new testing and disclosure requirements. The association's members will formally vote on the measures in early April, he said.

The move is an attempt to restore consumer confidence in the industry after two companies, Mettrum and OrganiGram, announced recalls this past year due to the discovery of banned pesticides in their products. The banned chemicals included myclobutanil, which is considered dangerous when used on plants that are smoked, such as tobacco and cannabis.

Medical-marijuana patients, including those who use it to treat late-stage cancer pain, post-traumatic stress disorder and epilepsy, among other conditions, and those who have compromised immune systems, told The Globe they were worried about ingesting the pesticides.

Because Health Canada had not required companies to test for myclobutanil, or disclose any testing results to the public, several patients said they weren't sure if the products sold by the industry could be trusted as completely safe.

Since then, Health Canada has attached new licence conditions to OrganiGram and Mettrum, which is now owned by Canopy Growth Corp., requiring the two companies to test all products before selling them. Health Canada also announced it would require random testing for banned pesticides for the rest of the industry, though some patients have said random testing isn't enough.

The steps taken by the industry on Thursday go further by making the test results available to the public, so that patients can see where the testing was done, and if the information is credible.

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Mr. Closner said his company, MedReleaf, was already testing for more than 100 contaminants in its products, though it wasn't making the lab results public. He said he supports the push to give consumers transparency.

"MedReleaf will soon begin to provide our patients with access to a simplified Certificate of Analysis [from an independent lab] representing all products being sold," the company said in a statement.