PHOENIX (AP)- Hunched over a microscope, Steve Cottrell peered at a bud from a plant that is increasingly used as medicine in Arizona and across the nation.
He pointed at a computer screen that glowed with a magnified image of the marijuana bud. The sample, the size of a quarter, was covered with powdery white bumps -- a mold that was invisible to the naked eye.
Increasingly, medical-marijuana dispensaries and patients are turning to laboratories to evaluate medical-marijuana plants, identify potentially harmful substances and pinpoint the potency of plants and cannabis-infused products, from caramels and ``cherry roll'' candies to butter.
Cottrell, 42, and his company, AZ Med Testing, is one of a number of labs in the state that cater to the burgeoning medical-marijuana industry. The lab, located in a small office complex in north-central Phoenix, works with about a third of the state's 70-plus dispensaries, he says.
Many dispensaries market organically grown marijuana, an important selling point for patients with weak immune systems that can be further compromised if noxious elements are inhaled. Using high-tech instruments, Cottrell looks for mold, bacteria and fungus, which can weaken patients' respiratory systems. He also tests for pesticides that can degrade the nervous system. And he tests the medicine to determine the amount of active cannabinoids -- including CBDs, CBG, THC and THCA -- the chemicals responsible for many of the physical and psychological effects of marijuana.
Patients should know what is in their medicine, Cottrell said, just as they can with medicine bought at pharmacies and grocery stores. That, he says, is fundamental to helping patients choose the proper strain and dosage of marijuana to treat them.
``Patients with a compromised immune system, this can further their ailment and make it more dangerous for them to consume the medicine,'' he said. ``So that's why we need to make sure all of the samples that we're testing are free of mold and microtoxins'' that patients can't see unless ``they have a microscope and they know what they're looking for.''
When he discovers mold or pesticides, Cottrell informs his clients, who can decide to distribute the pot or destroy it.
``I'm either the most hated man in the industry, or the most loved,'' depending on testing outcomes, he said with a laugh.
Arizona does not require dispensaries to test for pesticides or fertilizers, although it does mandate they list chemicals used on plants. The state health director who oversees the medical-marijuana program said the public urged officials during the rule-making process to not require testing under the notion that it could increase medicine prices.
Asked if testing should be required in Arizona, Department of Health Services Director Will Humble said through a spokeswoman that it is up to consumers to decide if they want to buy cannabis from dispensaries that test.
Twenty-one states have passed medical-marijuana laws, plus Washington, D.C. While most states don't require testing, one national expert said she expects other states to follow the path of those like Massachusetts and Illinois, which require testing.
Betty Aldworth of the National Cannabis Industry Association said ``even if it's not required, it tends to be sort of a standard.''
Pharmacists can explain to patients the ingredients in painkillers, Aldworth points out, saying, ``Why is medical marijuana any different?''
``We have an expectation, especially when we are managing a chronic condition, that we are doing it with known quantities,'' she said. ``For medical marijuana, it's the exact same thing. From the consumer side, especially those living with severely compromised immune systems, they want to know their meds are clean and they are entitled to know.''
That's Cottrell's philosophy. His family owned biological-monitoring labs in Colorado that catered to the medical and dental industries. He became interested in starting a medical-marijuana-testing business after he lost his 11-year-old son to lymphoblastic Burkitt's leukemia. His son, Kindahl, was diagnosed in 2001 and died that same year, Cottrell said.
``I started investigating things that hurt the cancer, and things that kill cancer,'' Cottrell recalled. ``And I found that the cannabis helps with patients and was alleviating a lot of the things that helped destroy my son. My son's immune system broke down so quickly because he couldn't eat because the chemotherapy was as strong as it was.''
Nine years later, Arizona legalized medical marijuana. Cottrell dipped into his savings and launched his business. He began attending medical-marijuana conventions, meeting advocates and talking to patients and caregivers about the benefits of testing.
The state's program became mired in legal and political battles, hampering dispensaries' desire to get involved in a program that some worried could be shut down.
Still, in 2011, Cottrell opened his first lab out of the closet of a friend's business in Tempe. As confidence in the medical-marijuana industry grew, so did Cottrell's client list. He moved the business to the Phoenix location more than a year ago.
Even now, he said, neither he nor his business partner takes home a paycheck. He has a full-time job that pays his bills.
His clients pay between $40 and $80, depending on the type of test. He tests about 1 gram for each 2 to 3 pounds grown from individual strains -- an adequate representation, he says.
Back at his microscope, he picked up a bud. ``If this flower has pesticide, their entire crop is going to have pesticides on it. If this flower has mold on it, because it's so microscopic, everything's going to have mold on it.''
He hopes the state will mandate testing, especially if the state moves toward the legalization of recreational pot, which many advocates support.
That won't happen if Rep. John Kavanagh, R-Fountain Hills, has his way. He strongly opposes medical marijuana, saying the drug is still illegal under federal law. He told The Arizona Republic he plans to introduce legislation to eliminate the state's medical-marijuana program.
Asked about testing, he said, ``I no more support making people who use illegal substances feel safer than I do giving hypodermic needles to heroin addicts. The government should never test illegal behavior -- period.''
Politics aside, patients should care about what's in their medicine, said Lezli Engelking, who runs Bloom Dispensaries. She hires AZ Med Testing to test the dispensaries' cannabis. Bloom grows its marijuana, she said, and while growers know what is put into the plants, things can go wrong.
``We had an A/C unit that went bad, and even being out for an hour, it affected the plants,'' she said. ``We had to throw out that entire batch of plants. Mold can form, it just cannot taste right. And patient safety is number one. We make sure everything we provide is safe.''