But it also means those labs, some of which had been operating for years before being licensed, can no longer test for individuals.
That leaves curious consumers, hemp growers and anyone who makes their own oils, edibles and tinctures with little recourse.
It means licensed labs cannot test for caregivers treating cancer patients or parents such as the Wilsons who have flocked to Colorado to obtain medical marijuana for their gravely ill children.
"This was one of the reasons we moved here — not only access to medicine but access to labs," said Brian Wilson, who uprooted his family this spring from New Jersey, where he helped reform the state's medical marijuana laws. "This is a major concern for parents."
The Wilsons, for now, are not at risk. Vivian has access to oils from a Colorado Spring dispensary that has received international attention for a strain called Charlotte's Web. The oil is rich in cannabidiol, or CBD, but low in THC, marijuana's main mind-altering chemical.
Still, Brian Wilson said he previously made about half of his daughter's medicine and considers it a safety net in case other sources run out. Some parents, he said, are experimenting with their own oils while on a waiting list for Charlotte's Web, which its creators say is tested for dosage, molds, pesticides and solvents.Minors are eligible for a Colorado medical marijuana card if two physicians sign off on it. As of Feb. 28, there were 248 medical marijuana patients under age 18 in Colorado, up from 39 a year earlier.
Vivian, like other young medical marijuana refugees to Colorado, has Dravet syndrome, a rare genetic disorder typically untreatable by anti-epileptic drugs. She began suffering massive seizures at 2 months old.
She wears an eye patch over her left eye to control her sensitivity to patterns, eats a diet high in fat and protein, and ingests cannabis.
"There is no prescribed solution yet," her father said. "Even for the kids having a lot of success, they are all on different stuff. You need that ability to find out what's going to work."
Unregulated and unlicensed labs have offered testing on medical marijuana in Colorado for years. But testing was always voluntary.
The state began licensing labs to carry out mandatory testing of recreational marijuana, legalized by the passage of Amendment 64 in November 2012. The testing, which will be rolled out in phases over the next few months, began Thursday with the testing of edibles for potency.
So far, the state has licensed seven labs. State officials informed some of them of the prohibition on testing for individuals in March.
A provision in state rules allows labs to also test for medical marijuana businesses, but testing continues to be voluntary for dispensaries.
The state Marijuana Enforcement Division requires licensed labs to track all samples through the state's inventory tracking system, which all licensed marijuana businesses must use. Because of that, individuals are effectively blocked from going to labs, the state says.
Medical marijuana patients, then, cannot test their own dispensary-bought marijuana — a valued option for some because there is no state rule mandating that the products be tested.