Most of the homegrown pakalolo tested by Hawaii’s first medical marijuana laboratory is tainted with pesticides and other dangerous contaminants.

Dana Ciccone, the head of the Steep Hill Hawaii lab, said that at least 75 percent of pot grown by patients or caregivers contains yeast, mold and pesticides. Meanwhile pot grown by the state’s retail dispensaries has tested clean, Ciccone said.

“Local weed is super dirty, but dispensary weed is the cleanest in the nation,” he told a medical cannabis legislative oversight group Wednesday.

Earlier this month, the state certified a second marijuana testing laboratory, Pharmlab Hawaii LLC, on Maui. The Department of Health anticipates certifying a third firm, Oahu-based Aeos Labs — operated by Clinical Labs of Hawaii — by January.

Medical marijuana must be tested for heavy metals such as arsenic, pesticides, solvents, moisture content, microbial contaminants, intestinal bacteria and pathogens, dangerous molds, and toxins before being sold to patients.

“Growing cannabis in Hawaii is challenging with the humidity, so the easy way to deal with it is with pesticides,” said Brian Goldstein, president of Oahu dispensary Noa Botanicals. “Some pesticides when burned result in carcinogenic compounds. Some people say, ‘I can get cannabis cheaper on the black market.’ We (the dispensaries) can’t use the pesticides that some people may use when they grow at home or outdoors. It might look the same. It might have the same name, but it’s not the same product.”

There were more than 19,000 registered cannabis patients at the end of September, a roughly 3 percent increase from the previous month.