From the archives: This article was originally published on July 27, 2016

Inside a sterile facility, the lab technician holds up a petri dish to show the intricate pattern of bacteria that are quickly multiplying.

"Looks like something is already growing," she says, surprised by how much has amassed in less than a day and a half.

In any other context, the dish would be a sight to behold, with an attractive swirl of shapes that resembles an oil painting. But the bacteria growing inside are Citrobacter freundii, a human pathogen that can lead to serious infections, particularly in the elderly and weak.

The bacteria, along with high levels of yeast and mould, were discovered in marijuana purchased recently from a cannabis dispensary in Toronto. In the span of a day, The Globe and Mail purchased several hundred grams of dried cannabis from nine dispensaries across the city, most of it marketed as medicinal. We then tested the products for harmful contaminants – chemicals, moulds, bacteria – in a federally certified laboratory, using the same guidelines prescribed by Health Canada for licensed marijuana growers and retailers.

Of the nine samples The Globe tested, one-third of them would not pass the safety standards set out by Health Canada for the regulated medical marijuana industry. Three samples tested positive for bacteria, in numbers that exceeded federal standards, and one of those also tested positive for potentially harmful mould. Six samples would have been deemed safe to consume by the federal government's standards for medical marijuana.

Strictly speaking, the acquisition and testing of this marijuana is illegal. Though consumers can now obtain dispensary cannabis easily, from stores that operate in plain sight, Health Canada does not consider dispensary cannabis legal. Federally licensed laboratories, the facilities best equipped with the equipment and expertise to examine these products for safety on behalf of public health, are not supposed to test marijuana for the public.

As such, we cannot name the facility, and we cannot disclose its location, for fear that the federal government would sanction the lab and revoke its licence, despite performing a valuable public service.

While microbiologists who subsequently analyzed The Globe's results have mixed opinions on what the risks are from the samples that failed – some say the products would likely be safe to consume, while others warn they could cause health problems – the test results, and the lengths The Globe had to go to get them, point to a serious lack of oversight of the burgeoning industry, which operates under a Wild West mentality where the provenance and efficacy of the product is unknown.

The tests raise doubt about the two main narratives put forward in the contentious debate over dispensaries that has erupted this year: the government's blanket assertion that virtually all dispensary product is unsafe and dangerous to the public does not bear out; nor does the dispensaries' overarching claim that their product is of unimpeachable quality, free of contaminant problems and in no need of federal oversight.

Throughout the course of The Globe's investigation, conducted over the past three months, a portrait of a perverse marketplace emerged – one in which the public and dispensaries are forbidden from legally testing cannabis for safety, leaving consumers exposed. Sources told The Globe that Health Canada has actively discouraged accredited labs from testing for the public and dispensaries.

Even when informed of the problems with their products, dispensaries would not say where their cannabis comes from.

More troubling, there is evidence Canada is using debatable testing methods, and may not be looking for the most dangerous contaminants, such as several controlled pesticides, creating a substantial gap in our current regimen.

Over all, the lack of oversight shows the government has allowed this to happen, even as the industry is essentially selling openly.

In a matter of months, dispensaries have become the country's largest neighbourhood drug dealers, flourishing in a regulatory vacuum created by the federal government's decision to legalize marijuana.

The Liberals' decision to soon legalize the drug, yet not oversee this so-called unregulated side of the business, has turned the black market to grey, leaving cities virtually powerless to stop dispensaries from springing up and the police reluctant to shut them down, apart from sporadic crackdowns based on municipal zoning laws.

Though hardly exhaustive, these tests are the first independent examination of dispensary cannabis in Canada that has been made available to the public.

The product was obtained with minimal paperwork. The dispensaries were not informed their products were being tested, and the samples were collected under guidelines set by the lab, which reporters were in regular contact with throughout the procurement phase.

The tests were conducted blind: Each sample was sent to the lab with no identifying information, other than a numbering system and the name of the strain, so that the specimens could be screened without the lab technicians knowing where they came from.

FAILED TESTS

The one-page form at WeeMedical dispensary said what was being purchased was medicine.

Inside the store, on Queen Street West, which operates from a dimly lit basement, customers are asked to fill out a document before they buy. The top half of the page asks for the person's name, address and telephone number. The bottom half is to be filled out by a doctor. That part can just be left blank, the clerk informs customers.

Dispensaries run the gamut in terms of aesthetics. Some, like Toronto's 416 THC on Dundas Street West, have a brightly lit, clinical feel, with a design that looks borrowed from the Apple Store. Others appear more hastily assembled, such as WeeMedical, which does a bustling business.

WeeMedical's product was one of three samples tested by The Globe that failed to meet Health Canada standards for federally regulated medical marijuana.

To properly test marijuana, a substantial amount is needed by the lab. A minimum 42 grams (an ounce and a half) of each sample must be procured for the full battery of tests, screening for contaminants such as yeast and mould, bacteria, pesticides, heavy metals and aflatoxins.

On the day The Globe visited WeeMedical, the lineup was six or seven people deep. When the jars of cannabis on the counter ran dry, new bags of dried flower were unloaded from a black suitcase that sat open on the floor.

A staff member behind the counter used a beer pitcher to weigh the chosen strain. The cannabis was then placed into a used Ziploc, and the strain was written in black felt-tip pen on the bag, crossing out the name of whatever it held before.

Dispensaries give their cannabis to customers in sealed bags that range from freezer bags to resealable foil sachets. After leaving the store, The Globe immediately sealed those bags inside a larger Ziploc bag. The product was never opened nor handled before it was shipped to the lab.

When the lab tested the WeeMedical sample, the results showed two areas of concern: The sample – a strain called Love Potion that is used by patients to alleviate stress or fatigue – displayed a total aerobic plate count (APC) that exceeded Health Canada limits by nearly 15 per cent. APC is used to gauge the cleanliness of the sample, though microbiologists see it as an imperfect test. While it provides a total count of micro-organisms in a sample, it doesn't necessarily distinguish if they are harmful or not. Some foods such as raw leafy vegetables and dairy products can carry high APC numbers, for example, without being problematic. In the case of a processed good, such as cannabis, which is dried, an APC test can denote whether good manufacturing practices were used. A high count is concerning. One that exceeds the limit is a red flag.

The WeeMedical sample tested at 570,000 colony-forming units a gram (cfu/g), surpassing the maximum allowable limit for APC of 500,000. Possibly more concerning, though, was the presence of high numbers of bile-tolerant gram-negative bacteria, a type of micro-organism that can include fecal bacteria that cause infections. That test is also imperfect, since it only gives a snapshot of potential illness causing bacteria, but doesn't necessarily tell you how serious they are, or which particular micro-organism was found.

When isolated in a petri dish at the lab, the bacteria appeared to resemble E. coli at first. However, a subsequent identification test revealed it to be Enterobacter cloacae, a pathogen found in plant material that can cause infections, particularly in those with compromised immune systems.

The operators of WeeMedical did not respond to a request to be interviewed on the results.

The second sample tested that did not meet federal health standards was purchased at Toronto Cannabis Dispensary (TCD) in Kensington Market, which bills itself as the city's "top medical marijuana resource." Unlike many dispensaries, the store posts testing data on its website assuring customers that the products have been screened for purity and efficacy.

The TCD sample, which came in a sealed bag identifying the product as medicine, breached health standards by exceeding the limit for bacteria. It contained high levels of two species: Staphylococcus epidermidis, and Escherichia hermannii.

Staphylococcus epidermidis is a harmless bacteria commonly found on skin, often associated with acne. While that may sound unpleasant, it poses no immediate health threat. Escherichia hermannii, however, is a known human pathogen sometimes found in infected wounds, which is also a fecal coliform found in the digestive tracts of humans and animals. But cases of infection are considered rare. In patients with weak immune systems, or where another infection is already present, the bacteria could present problems.

When informed of the results, TCD manager Luke Roberts was surprised. He said the store would have pulled the product had it known there was a potential quality issue.

"One-hundred per cent, it would come right off the shelves," he said. "If something comes in and it's not up to par with what we've been getting, we just won't put it on the shelf." Like most dispensaries, Mr. Roberts wouldn't identify his suppliers, saying only that they came from the previous regulatory regime, back when the federal government used to issue licences to approved patients to grow their own supply. Because dispensaries won't identify their growers, there is no way for the consumer to hold a supplier accountable if something ever goes wrong.

The third sample to fail federal health standards was a strain called Durban Poison, purchased from Cannabis Culture on Queen Street West, a dispensary that scored poorly on three tests.

Unlike other dispensaries, which purport to sell cannabis solely for medicinal purposes, Cannabis Culture is upfront about its intention to sell to anyone over 19, healthy or sick. On the day a Globe reporter visited, a half-eaten barbecue chicken in tinfoil and plate of chicken sat atop the counter where clerks weighed and packaged the marijuana. Staff did not wear gloves when handling the product, nor could they answer questions about where it came from, with one employee insisting it was harvested by growers for "the government" – which is not plausible under the current regulations.

The sample tested positive for bile-tolerant gram-negative bacteria exceeding Health Canada's allowable limit. The total aerobic plate count for the sample was 560,000 cfu/g, 12 per cent over the 500,000 limit. And one strain of potentially problematic bacteria was identified in elevated numbers – it was the sample that contained the pathogen Citrobacter freundii, a fecal coliform that produced the picturesque swirls when grown in a petri dish at the lab.

The Cannabis Culture sample was also the only one to exceed Health Canada's limit for total yeasts and moulds. The sample contained 440,000 cfu/g, which far exceeded the allowable limit of 50,000 cfu/g.

Yeasts and moulds are present in marijuana when the product is improperly dried or processed, and can cause a variety of illnesses in users, such as lung infections, particularly those with compromised immune systems.

Jodie Emery, who operates the Cannabis Culture store along with her husband, marijuana-legalization crusader Marc Emery, said the store does visual tests for mould, and staff sample the product to see if it burns cleanly. Beyond that, further testing isn't done. In general, Ms. Emery said she does not consider cannabis any more harmful than buying vegetables at a farmer's market, where bacteria and pesticides could be present. She disagrees that dispensaries need federal oversight on quality control.

However, Ms. Emery said she would have removed the cannabis in question from her store immediately if she knew it contained yeast and mould at such levels, as well as the bacteria in question.

"If I had that test result available to me in advance, I would not put that product on the shelf," Ms. Emery said.

Of the three dispensary samples tested by The Globe that did not meet federal standards, it is difficult to gauge the exact level of risk their contaminants pose to the public. The Globe polled 10 microbiologists and experts in contaminants from across North America, and opinions were mixed.

Most microbiologists agreed that the presence of mould, particularly the commonly found aspergillus species, is a serious concern because it can lead to debilitating lung problems. However, several argued that the bacteria found were not necessarily cause for panic, even if they were unappealing.

Some argued the bacteria found would likely be harmless to people with healthy immune systems, and would probably present no ill effects. Others suggested that contact with the bacteria, through handling the product, inhaling it or ingesting it, could lead to cases of fever or food-poisoning symptoms that the user would likely associate with something they ate, rather than the cannabis.

Some microbiologists said heat generated from smoking the cannabis would kill harmful micro-organisms, while others suggested heat isn't enough to completely sterilize the product, and the person can still intake bacteria from the unheated portions of the cannabis.

The test results "do indicate that this stuff is kind of generally dirty and has too many micro-organisms on it," said Mowgli Holmes, chief scientific officer at Phylos Bioscience in Portland, Ore., and a board member at the Cannabis Safety Institute, which works with researchers at Duke University and Harvard Medical School, among others. "It indicates poor handling, poor processing, poor practices, but if I had some and wanted to get high, I would smoke it and nothing bad would happen to me."

Benjamin Weeks, a microbiologist at Adelphi University in New York, disagrees.

"This is a list of bad things to put near your mouth," he said of the bacteria found in The Globe tests. "Exposure to some of this stuff will give you a very close relationship with your toilet bowl."

The effects of such contaminants can be difficult to predict, since a healthy person can fight them off and never know there was an issue. Melanie Eldridge, a microbiologist at the University of New Haven, said the results weren't alarming. "I wouldn't say there is much risk of infection … except potentially in an immunocompromised individual," Ms. Eldridge said.

Jessica Kristof, a microbiologist who works with Mr. Holmes at Phylos in Portland, said bacteria such as salmonella are the most worrisome to find in test results, for example, but added the amount of micro-organisms that showed up in the dispensary product were a concern. "They shouldn't be at those cell counts in the first place, even if they are not as bad as you think they are," Ms. Kristof said. "That shouldn't happen for the safety of the consumer."

A VACUUM

Regardless of the debate among scientists over the urgency of the health risks, the three products that failed the tests would not be permitted for sale under Health Canada's standards for regulated medical marijuana.

The dispensary community, in arguing for the right to sell cannabis ahead of legalization, often points out that Health Canada's licensed medical marijuana producers have been subject to several recalls of their own product since that market was set up in 2014, which shows the regulated industry isn't perfect.

This is true, though the number of recalls is small compared with the tens of thousands of shipments made by the 31 licensed medical cannabis growers in that time.

Since the medical producers began operating under government oversight, there have been three product recalls involving failed tests for mould or bacteria by the licensed producers, and one for incorrect labelling of THC, the psychoactive drug in cannabis that intoxicates the user.

In May, 2014, Ontario-based Peace Naturals Project Inc. recalled product because of "positive bacterial testing outside of acceptable limits," according to a Health Canada statement. In August that year, Whistler Medical Marijuana Corp. recalled a batch that tested positive for mould above the allowable limit. And in February, 2015, Peace Naturals recalled a strain that tested at 13 per cent THC, but was advertised at 9 per cent.

In March of this year, Tilray recalled three products because of an elevated level of bile-tolerant gram-tolerant bacteria, not unlike those found in The Globe's test of dispensary samples.

Though the government provides few details about the recalls that happen in the industry, including the type of micro-organisms involved, Tilray's occurred in a random test by Health Canada.

The difference for the consumer, however, is that Health Canada requires licensed producers to screen their products, either at an in-house lab whose data are monitored, or at a third-party federally licensed facility. These results must be shown to the government for analysis.

With the dispensaries, there are no requirements from Health Canada to test, and the majority of them don't monitor their product, nor produce test results for consumers. Though some dispensaries are doing brisk business, sometimes upward of $20,000 a day, according to industry sources, they operate in a bizarre world of no regulation, a scenario in which rules are made on the fly and current laws conspire against public safety.

In the case of Toronto Cannabis Dispensary, the lab results posted on its website claiming that the product is tested are out of date and do not come from a Health Canada-accredited lab. They focus mostly on the THC and cannabidiol (CBD), the therapeutic, non-psychoactive compound in cannabis. Several key tests for safety and purity are omitted. For example, the dispensary's tests for mould and mildew are listed as "visual" tests, for which all of its samples are granted a "pass" on the company's own website. Licensed labs do not consider these tests credible.

Ian Dawkins, president of the Cannabis Growers of Canada, an industry group that represents about 15 to 20 dispensaries, a small portion of the several hundred that now exist across Canada, says his organization is developing a code of conduct that would see cannabis they sell "analytically tested," but said the group can't get federal government support to implement a regime.

Mr. Dawkins said in an interview that he believes concerns over contamination are overblown. "How many people have died from cannabis in the last year? Zero. The answer is zero. So that's how concerned I am," Mr. Dawkins said. "Like any food product, you want it to be inspected and to be free of mould and mildew and free of pesticides and for there to be standards … but it's not plutonium."

Mr. Weeks, the microbiologist in New York, disputes that argument, saying that contaminants merit serious concern, even if people are not dying.

Mr. Dawkins told The Globe that some dispensaries test their product – his association has partnered with an accredited lab – and have recalled batches that indicate unsafe contaminants. "Absolutely. It happens all the time," he said. However, in a follow-up e-mail two days later, Mr. Dawkins then clarified that point. What he meant by "recalls," Mr. Dawkins said, was that dispensary operators would sometimes reject marijuana they purchase from growers after visually inspecting it, "because dispensary owners are usually very knowledgeable and can visually identify problems based on experience."

It's not clear how someone might spot microscopic particles of bacteria, such as E. coli, which would not be detectable to the human eye.

Even if some dispensaries want to get their product tested, though, they can't.

The problem dispensaries face is that the regulatory system devised by Health Canada – which is in charge of protecting public health – excludes them. Just as the public cannot legally test dispensary product at Health Canada accredited facilities, the dispensary industry also cannot legally access these laboratories. Industry sources told The Globe that accredited laboratories have asked Health Canada to let them test these products for safety, but have been warned not to do so. This leaves consumers, including many who are visiting dispensaries thinking they are buying a government-sanctioned product, exposed.

While some dispensaries appear out to make a fast buck, and are less concerned about the safety of their product, there are dispensaries in Canada that are eager to have their products tested, but because of Health Canada rules, the labs won't accept their products.

"There are a lot of dispensaries that care, and some have not been able to find a lab that would be willing," said Rielle Capler, a proponent of testing, and a member of the board of directors of the Canadian Association of Medical Cannabis Dispensaries, another group that represents a segment of the industry.

The problem is the labs could lose their Health Canada licence if they test for anyone without a narcotics licence.

"A lab who has a licence, which they want to keep because they are hard won, they want to be careful," Ms. Capler said.

"You have to ensure that everyone gets testing for biological contaminants – mould, pesticide residue. That is not an onerous requirement," she said. "If you're going to sell a product like food, you should have to get it tested in a laboratory."

Some of the earlier dispensaries, which began to spring up more than a decade ago as a way to serve the medical market in Vancouver, challenging federal laws, were careful, Ms. Capler says. They were hoping to build a model for the industry that was based on good practices. But since the federal government's plans to legalize the drug were unveiled, inciting a boom in dispensaries across Canada, different types of operators have flooded into the business with different motives and standards. It's impossible to consider all dispensaries as the same, Ms. Capler says.

"They're so not. … The early dispensaries were sticking their necks out … and then things went kind of crazy in Vancouver, and now Toronto."

Dispensary groups such as Ms. Capler's have drawn up codes of conduct for the industry to live by, as has Mr. Dawkins's association. However, not all dispensaries belong to these organizations, and the standards amount to little more than self-regulation, which is unenforceable. Most of the dispensaries The Globe visited are not listed as members of either association, including the three that failed the tests.

Mr. Dawkins said he has tried to speak to the government, but has been rebuffed in his requests for a meeting.

Health Canada says it does not test dispensary product itself – nor allow others to test it – because the government does not regulate that industry. It only regulates the licensed federal producers. Health Canada does not see possible health risks at the dispensaries as part of its job.

"These establishments operate outside of the legal framework and provide products from illegal sources that are untested, unregulated and may be unsafe," Health Canada spokesman André Gagnon told The Globe. "There are no controls in place to ensure quality."

It is a huge loophole for the industry. The federal government has essentially watched as an industry has flourished, while giving consumers no protection – and no ability to protect themselves.

"There's definitely dispensaries out there that are not following best practices that desperately need to be regulated," Mr. Dawkins said. "They [the federal government] are constantly scaring the labs by threatening to pull their accreditation. … The idea that we weren't willing to [have product tested] is completely ludicrous."

Ms. Emery, at Cannabis Culture, and Mr. Roberts, at Toronto Cannabis Dispensary, both said they would send product for testing at federally accredited labs if they were allowed.

"We'd be right on it," Mr. Roberts said. "If we have these labs in Canada, and we're moving towards legalization, then why can't everybody get access to it?"

"It would be great if the government would let everybody come forward," Ms. Emery said. "I'm not an advocate of letting things be disgusting and pretending that they're safe."

However, she argues that only marijuana being sold as medicine, as opposed to a recreational product, should be held to those standards – and that producers, not retailers, should be the ones testing, similar to the way coffee beans are inspected before they reach the local coffee shop.

"I would want to buy a product that's been tested, rather than buying something unknown," she said.

Jonathan Page, an adjunct professor at the University of British Columbia, recently started his own facility called Anandia Labs to test for the licensed producers and, eventually, he hopes, the dispensaries. He says there have been a small number of non-accredited labs emerge that are willing to do work for dispensaries, but they lack the high-tech equipment and methods to do it at the highest standards.

"Labs have come along to service the dispensaries, but they don't necessarily have good methods," Prof. Page said.

That makes the problem potentially worse because it creates a system where dispensaries can tell customers their products have been "lab tested" but there are no assurances the standards are sound, or verified, and that the results are accurate.

"It's a free-for-all. … There are no rules," Prof. Page said, arguing that many dispensaries will portray themselves as artisanal producers with high standards, but it's not enough.

"I think they live in a fairy world where they say, 'We have the most wonderful growers,'" he said.

With so much money moving through the dispensary world in Canada right now, some question whether the motives are necessarily to provide the best product. "It's driven 95 per cent by profit," Prof. Page said.

But he believes Health Canada's policy needs to change. Prof. Page said that if a mother came to him and wanted to test the potency and purity of cannabis oil purchased at a dispensary before giving it to her severely epileptic child, he wouldn't know what to do.

"I'm not an activist, I'm a scientist," Prof. Page said.

"But I don't think I could turn that request down, morally."

THE TROUBLE WITH TESTING

The laboratory where The Globe sent its samples to be scrutinized is a high-tech facility that uses some of the most advanced equipment and techniques available, such as high-performance liquid chromatography, to identify contaminants in trace amounts. It performs these tests for several of the federally licensed medical marijuana producers in Canada.

Only a handful of labs in Canada have the capability to test cannabis in this fashion. But all this technology and expertise can't protect the consumer if the government's regulations aren't monitoring for the right things.

Health Canada requires that medical marijuana be screened for about 70 pesticide compounds, to ensure that exposure levels are not above a certain threshold, usually a fraction of a milligram per kilogram of cannabis.

However, there is a troubling blind spot when it comes to screening out harmful additives in Canada.

Held to the standards set out by Health Canada, none of the nine samples of cannabis tested by The Globe turned up any problems with pesticide levels.

But the Canadian standards call for testing to ensure approved pesticides stay below predetermined levels. The standards don't call for the detection of some of the most widely used and problematic pesticides on the market, which are not permitted for use on this particular plant, but are often used by growers looking to cut corners.

In states such as Colorado, Washington and Oregon, where cannabis has been legalized, pesticides have emerged as a major concern. "Moulds, contaminants – all of those things have shown up, particularly at the beginning," said Andrew Freedman, director of marijuana co-ordination at State of Colorado. "But pesticides became our biggest problem."

Shortly after the state opened up its market, Colorado found high levels of potentially harmful pesticides in the supply being sold on dispensary shelves. That revelation forced the state to overhaul its testing regimen, when policy makers realized what was being missed.

Of particular concern was a pesticide called Eagle 20, which contained myclobutanil. While it's effective on flowers, and in small doses on some fruits, testing shows it produces potentially harmful hydrogen cyanide when heated, which was being inhaled directly into the lungs of the cannabis user.

It was a problem Colorado's government did not see coming, and had not prepared for, particularly since cannabis was always portrayed as a sort of cottage industry of growers who cared deeply about growing naturally.

"Myclobutanil cleaves off hydrogen cyanide," Mr. Freedman said. "So, yeah, we were concerned."

The state opened a formal investigation into growing methods, and its dispensaries soon began voluntarily pulling products that tested positive for contaminants. The discoveries also compelled dispensaries to begin testing their own product more.

The problem emerged because there were few rules on what growers could and could not use on their crops, or what contaminants were allowed, and at what levels.

"This is part of not having [marijuana] be regulated. … All the other crops have kind of gone through this process. But marijuana hasn't gone through that."

Part of what hurt Colorado, Mr. Freedman points out, was the speed at which the market had to be created, a reality Canada now finds itself confronting.

"People want a regulated product and they want it quickly," Mr. Freedman said. "So what normally would have been 10, 15 or 20 years of quality control coming online, they're now expecting that from us in the first three or four months."

In order to stem the problem, Colorado's Governor issued an executive order late last year, declaring contaminants "a threat to public safety." That gave the state the power to move quickly and rewrite laws.

"For us it was a pretty easy answer, that we should just treat this like every other crop is treated. If you can't prove it's safe, then we shouldn't allow it to go out for human consumption," Mr. Freedman said.

"And that's a lesson we learned from pesticides back in the sixties, that precisely because there's a delayed onset of effects, you now have to prove safeness and we'll move on from there."

The state soon found itself facing allegations of fear mongering from marijuana proponents who argued people weren't dying from consuming the drug, so such steps were merely an overreaction.

"A lot of people were telling us: 'Nobody's ever shown up to the hospital.' But we point out that data would be impossible to get – both in the short term and in the long term. It's very hard to show causation."

Alex Cooley, vice-president at Washington marijuana grower Solstice is one of those who cautions against overreacting to contaminants, but he agrees there should be oversight.

"I hate to sound like a tobacco executive on this statement, but we haven't seen a massive amount of people have harm associated with using it historically. There aren't bodies in the streets," Mr. Cooley said.

However, Mr. Freedman in Colorado responds to comments like those by pointing out that the cumulative impacts of contaminants on the body are not something that's been tracked, nor have patients been encouraged to self-report any conditions to doctors over the years when the drug was illicit.

"It doesn't mean it's not harming people, it just means that it's hard to show that direct causation," Mr. Freedman said.

"You're not going to take a hit and then go to the hospital directly, or have a bump in cancer rates or birth defects or the kind of things that show up only in census data much later."

In Washington State, the situation has been equally as problematic as in Colorado.

"We all anticipated that there would be people who violated the laws, and that has occurred," Mr. Cooley said.

"People might buy from Tom, and they say, 'Oh, Tom wouldn't do that to me. That's crazy. It's all completely safe and natural,'" Mr. Cooley said. "And Tom may believe he's not causing you harm either, but he doesn't know. Turns out Tom was taught by a person who didn't know what they hell they were doing."

The only answer Mr. Cooley sees is to introduce uniform testing standards across the industry.

Similar problems have been found in Oregon, which uncovered numerous different contaminants in its dispensary supply. Meanwhile, a 2015 study of marijuana concentrates in California, published in the Journal of Toxicological Sciences, determined that more than 80 per cent of the 57 samples tested "were contaminated in some form."

"There's a lot going on out there that people just do not even begin to understand yet. And they will – once it hits the fan," said Warren Porter, a molecular and environmental toxicologist at the University of Wisconsin. "And we're going to be seeing that in about 10 years. Big time."

The fact that Canada isn't checking for the same pesticides that raised concerns in the United States is concerning. Not testing for certain chemicals can send the wrong signal to consumers, said Rodger Voelker, lab director at OG Analytical in Oregon, who is credited with discovering the myclobutanil problem among growers in the United States, who weren't reporting its usage.

"I will tell you, everybody said they were not using pesticides," Mr. Voelker said. "My concern is that you end up with rules that give the public the pretense of assurance, but it's a misplaced assurance."

In Canada, myclobutanil use is an unknown. Though the product is said to be more difficult to obtain than in the United States, The Globe was able to purchase a supply of Eagle 20 readily through Amazon.

"I don't see any reason why [Canada] wouldn't want to learn from our experiences," said Mr. Cooley in Washington.

THE SEARCH FOR A BETTER METRIC

When Canada introduced the licensed medical marijuana industry, it needed a certain criteria of standards to oversee the new product. Policy makers in Ottawa reached for European and U.S. pharmacopeia rules as their guide.

These rules governed the levels of bacteria and moulds that could be contained in processed products, from herbal remedies to food, and they relied on tests, such as total aerobic plate count and bile-tolerant gram-negative bacteria, as their guide to determine if good production practices were being followed in the manufacturing of those products.

Because cannabis has been illegal for many decades, there's been very little research on what was the best way to test the plant for cleanliness and efficacy. Some of the microbiologists who spoke to The Globe say Health Canada is testing for the wrong micro-organisms, as well as ignoring certain problem pesticides.

"What's happened is that, because no one's worked on marijuana for over 100 years, when they say you can actually use it for medical purposes, we're looking around to say, 'We need a standard. We need something to say if marijuana is safe,'" said Keith Warriner, a microbiologist at the University of Guelph.

However, tests such as the one for bile-tolerant gram-negative bacteria can provide a lot of noise that doesn't actually tell you whether the cannabis should be consumed or not. Some vegetables, such as spinach, score very high on that test, which is why consumers wash or cook it before eating.

Instead, tests like that, and aerobic plate count, are considered indicators of possible problems, rather than confirming something is wrong.

"As an indicator, it's not that good," Mr. Warriner argued. So further screening, such as identification tests, are needed.

The Oregon Health Authority agrees. Recently, that state, which legalized recreational marijuana in 2015, replaced these tests with what it describes as a simpler, more effective indicator of bacterial contamination. It's called a "Water Activity" test, and it's designed to assess the most critical ingredient needed by bacteria: moisture.

The moisture is a crucial warning sign that the product has been cured improperly and therefore a breeding ground for micro-organisms.

Mr. Holmes, the Oregon microbiologist who is an advocate of Water Activity testing, describes the microbiology tests required by Health Canada as unnecessary, indirect and "not based on good science."

"Those tests are very broad categories," Mr. Holmes said, arguing that they "only pick up one-tenth of the species out there. Almost all of those species aren't dangerous and certainly aren't dangerous on pot. They're just wrong categories and don't make sense."

Oregon's method could change how cannabis is screened in a postprohibition world. Most importantly, the standard is not as complex, nor cost intensive, as the battery of tests marijuana samples are currently subjected to in Canada and other jurisdictions, meaning potentially more product could be screened, and more players in the industry could take part.

Better methods of screening, and a broader look at pesticides, are things Canada should focus on, Mr. Holmes said.

THE PROBLEM ON THE STREETS

The legalized marijuana market could bring in $5-billion in new tax revenue for Ottawa and the provincial governments, according to a recent study by CIBC World Markets.

When the federal government released its long awaited discussion paper in July on what the future legalized marijuana industry could look like after prohibition is lifted, what was notable in the 27-page document was how little time was spent discussing issues of product oversight and quality control, the building blocks of most other consumer goods industries.

The report, titled Toward Legalization, focused mostly on crime rates, prevalence of use, potential for addiction and concerns associated with adolescent consumption. Though Canada has among the lowest tobacco smoking rates in the world (15 per cent as of 2013, the most recent data available), it has one of the highest rates of cannabis consumption among developed countries, which is fuelled by the availability of the product. (Slightly more than one in 10 Canadians over the age of 15 reported cannabis consumption in the past year, according to a 2013 Unicef study.)

The Liberal government's legalization plan, a key piece of its election platform, means a policy framework must now be built to handle consumption rates that are expected to increase further next year, when legalization takes place.

Under a section of the federal government's report titled Possible Options, the authors suggest safeguards "could" be created to ensure marijuana is produced and stored in "sanitary" conditions, adding that it "could" also be subject to "analytical testing so that those consuming can be reliably advised of its contents." Few details are offered on how this might be achieved.

Marijuana may be easier to obtain in Canada now than at any other point since 1920, when it was declared illicit, but oversight of the product has not followed suit.

Despite sporadic police crackdowns on dispensaries, the industry has flourished in the absence of a regulatory framework.

Dispensaries are now more prevalent in some Toronto neighbourhoods than drug stores – in spite of the government's declaration that they are technically illegal.

A call by several premiers during interprovincial meetings in July, pressing the federal government to get its legalization policies formulated sooner than later, highlighted these concerns about the regulatory vacuum that exists.

After a public forum in late May, MP Bill Blair, the Liberal government's point man on marijuana legalization, was asked by The Globe how the government intended to respond to complaints that labs are not allowed to test dispensary marijuana on behalf of consumers.

"I was not familiar with the issue," Mr. Blair said. "But I'll certainly ask them about it."