In Colorado, the past 16 weeks have seen 15 recalls of cannabis products because of pesticides, including the largest such recall last week.

The state's one of several that now mandate or encourage testing of recreational marijuana for contaminants.

But in Arizona, the products of medical-marijuana sellers and cultivators never have been officially scrutinized. If the state approves recreational use in November, that's going to change — with a likely increase in pot pricing.

Buds, concentrates like shatter, and edibles could contain relatively high levels of pesticides and other contaminants, and the state's 85,000-plus qualified patients never would know. The 2010 Arizona Medical Marijuana Act requires no such testing because its drafters were worried it might drive up the cost of medicine.

Washington, like Arizona, had no mandated testing for its medical-marijuana program and no testing is required in its voter-approved 2012 recreational law. But with the launch of adult-use cannabis stores and interest by the public to avoid pesticides, Washington began a voluntary program in October that awards clean-testing dispensaries with an "enhanced seal of approval" to show customers.

Arizona medical-marijuana rules require that dispensaries inform the state about the pesticides it uses on crops it grows or sells, but that's it. There's no follow-up on the information or enforcement.

Oregon, meanwhile, has one of the strictest anti-contaminant programs in the country and will begin testing this year for 59 different pesticides. The move is expected to drive up prices noticeably in the short-term.

J.P. Holyoak, chair of the Campaign to Regulate Marijuana Like Alcohol in Arizona, says a testing mandate was built into the initiative because "consumer safety is paramount."

The campaign, which expects to put a legalization measure before state voters this year, creates a Department of Marijuana Licenses and Control to oversee compliance of both the recreational-use stores and the state's 85-plus medical-marijuana dispensaries. The new department, according to the planned initiative's text, must develop testing requirements "to measure potency and to ensure that products sold for human consumption do not contain contaminants that are injurious to health."

For now, the state Department of Health has no plans to require testing. In any case, without a mandate in the medical-pot law, a rule requiring testing could be considered burdensome by some dispensary operators, and that could spur a lawsuit against the state based on the 1998 Voter Protection Act.

There have been no reports of people hurt by pesticides in marijuana (or, for that matter, the marijuana itself). But in a culture where people spend big bucks on organic foods and bottled water, some cannabis consumers are concerned. Trouble is, dispensaries have no incentive to test for pesticides or toxins — and, in fact, have a disincentive to test.

"They could get ruinous bad news," says Jim Clark, owner and director of Delta Verde Labs in Phoenix.

With no state mandate, a cultivator or dispensary legally could sell cannabis with higher-than-average pesticide levels instead of chucking tens of thousands of dollars' worth of products into a trash bin. So they probably figure they're better off not knowing.

Clark's lab doesn't even offer pesticide testing because demand is so low, he says.

Growers, theoretically, already know what sorts of pesticides are in their products, meaning they also have little incentive to spend money on the test.

Arizona dispensaries often do contract with a number of small labs across the state to test their products for potency. They want to tell their customers which of their strains is more potent, and there's also a competition among dispensaries to offer the highest-quality, most potent weed.

Clark says local dispensaries do often want to test their concentrate products for smoking, like shatter and wax, for contaminants. This is because — unlike with minute amounts of pesticides in cannabis buds — consumers of concentrates can taste or perceive the harshness of the contaminants, like butane, left over in the extraction process, he says. The extraction chefs also are trying to make the purest, most-potent product possible, which can only be achieved with chemical testing.

"There are some producers of extracts and concentrates that have very, very clean products," Clark says. "Then others — not so much."

Here's a full list of the 15 recalled pot products in Colorado in the last four months.

