Health Minister Jane Philpott's office was warned nearly a year ago that dangerous contaminants had been found in retail marijuana sold by unregulated storefront dispensaries, but the federal government appears to have done nothing to act on the concerns.

Documents obtained by The Globe and Mail through the Access to Information Act show test results from a Health Canada-accredited lab were sent to the government last fall, and to Dr. Philpott's office a few months later, revealed cannabis from several Vancouver dispensaries contained pesticides and fungicides "not approved for any human use."

The names of the dispensaries are redacted from the documents, but the results say high levels of banned chemicals – such as the pesticide carbamate, which is not permitted for use on cannabis, and dodemorph, a fungicide used on roses that is not approved for human consumption – were in 13 of the 22 the samples tested.

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While the total number of dispensaries was also redacted, it appears the samples were obtained from about a dozen Vancouver locations. In July, The Globe published the results of independent tests on cannabis bought from nine Toronto dispensaries that showed potentially dangerous contaminants in one-third of the samples.

The investigation detailed a lack of oversight by Ottawa, which has created a regulatory vacuum as the government works on its plans to legalize the drug. As a result, hundreds of unregulated dispensaries have opened, many looking to make a fast buck, and some pocketing more than $20,000 a day in sales.

Dr. Philpott has not responded to several interview requests from The Globe. However, less than two weeks after the investigation was published in the summer, the federal government rewrote the laws on testing, giving Canadians access to federal labs to test cannabis for potency and contaminants. While recreational users are not likely to seek testing, Canadians who require the drug as medication, including severely epileptic children, elderly patients and those with compromised immune systems, can now legally have it screened for harmful chemicals, bacteria and mould.

The new documents indicate Health Canada knew about problems with unregulated cannabis sales long before the government agreed to alter the rules on testing. The lab report obtained by The Globe was sent in October, 2015, to Eric Costen, who headed Health Canada's office of medical cannabis. The same results were sent in January to Geneviève Hinse, chief of staff to Dr. Philpott.

There is no evidence to suggest the government took any meaningful action on the information. Health Canada continued to block patients from getting the same access to laboratories that pharmaceutical companies have to test products to ensure that they are safe. Health Canada has said it considers dispensaries illegal, but has done nothing to halt their operations. Some patients say they can get certain products such as specialized extracts only from those stores.

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Health Canada has not explained why it did not act on the data, submitted by a third party, which a source said is a federally licensed producer of medical marijuana. Such licensed producers oppose allowing the dispensaries to sell the product before legalization. Dr. Philpott's spokesman did not respond to questions on the matter.

The Vancouver test results are particularly concerning given the evidence of unauthorized pesticides in the drug's production, a problem that has become a major concern in at least three U.S. jurisdictions where cannabis has been legalized for recreational and medical use.

According to the documents, the Vancouver analysis was conducted at MB Labs Ltd. on Vancouver Island in September, 2015. MB Labs is an accredited Health Canada laboratory capable of testing cannabis for contaminants and potency, and often conducts such tests for federally licensed producers.

The 22 samples screened include 14 strains of dried cannabis, and eight concentrates, which are oil extracts. Of those, nine of the 14 dried cannabis samples failed Health Canada safety standards for medical marijuana. Six contained amounts of carbamate that exceeded even the levels allowed for plants for which the pesticide is approved. Four contained high levels of potentially harmful fecal bacteria, which can be particularly problematic for the elderly and people with compromised immune systems. One sample also contained levels of yeast and mould, which can cause serious lung ailments, that exceeded Health Canada safety limits.

According to the documents, only one of the eight concentrates tested would have passed Health Canada standards for contaminants. Seven contained excessive levels of carbamate, while three also contained dodemorph, which is typically restricted to ornamental plants and banned for human consumption.

The presence of these contaminants in concentrates is particularly problematic because oils are sometimes a preferred way to administer the drug in some patients, such as children and the elderly.

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The evidence of pesticides is similar to problems in Colorado, Washington and Oregon over the past few years. After those jurisdictions legalized cannabis, unexpectedly high levels of pesticides not approved for use on the plant began showing up in products. The government and industry worked together to write new enforcement rules and safety regulations.

The tests of pot from Toronto dispensaries, conducted by The Globe at an accredited lab before the laws on testing were changed, did not find any pesticides, but the Health Canada testing regime does not screen for some of the most dangerous pesticides found in the United States. Three of the samples contained excessive amounts of some bacteria that can be harmful to humans. Based on federal rules, those samples would have to be recalled and destroyed. The Health Minister's office has not responded to questions on the matter.