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PHOENIX - 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.
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