Cannabis sold at Bay Area dispensaries is regularly referred to as "medicine," however a lack of regulation and testing around the product has led to significant supply of marijuana on dispensary shelves being tainted and/or toxic to the people who consume it.

Following the recent HempCon at the Cow Palace in August, an array of medical marijuana products underwent testing by Hunters Point-based Anresco Laboratories. As San Francisco Magazine reports, some 80 percent of those tested from California-based growers and dispensaries, were tainted with mold, fungus, bacteria, pesticides, or harmful solvents  and the popular concentrates and oils used in vape pens and dabs can, because they're concentrated, contain much higher amounts of these toxins.

Risk of infection from smoking mold-, fungus- or bacteria-laden marijuana buds has not been widely discussed or understood until recently. There was a report out of UC Davis earlier this year about a spate of rare fungal infections in cancer patients' lungs that doctors traced to the patients' use of medical marijuana. In one of those cases where the patient's immune system was compromised by chemotherapy, the patient died from the infection.

"We sometimes see 20 or 30 percent of our samples coming through the lab significantly contaminated with molds," said Dr. Donald Land of Steep Hill Laboratories in Berkeley. But after sampling from 20 dispensaries across California and analyzing the cannabis down to its DNA, Land told CBS 5 at the time that he was shocked to find "ninety percent of those samples had something on them. Some DNA of some pathogen."

SF Mag goes further into Anresco's results, finding that pesticides and fungicides can appear in cannabis extracts at 1,000 times the level of concentration typically found in foods. These chemicals include things like myclobutanil, which sold under the brand name Eagle 20, and which can cause cancer and has reportedly sickened cannabis consumers in Canada.

Also present in some dispensary products are residual solvents like butane, which is used in making dabs to separate out the cannabinoids and terpenes from the plant material. Large amounts of butane are rare, and in states where recreational marijuana has been legalized, butane has been limited in consumer products to 50 parts per million. About 10 percent of the samples looked at by Anresco failed the butane test.

Hopefully, as California prepares for legal retail marijuana sales in 2018, more attention is going to be paid to testing and regulating what's being sold  but as SF Mag points out, this means that growers need to hurry up and start using fewer pesticides, and keeping molds and other toxins out of what they sell.

Related: California Is Growing Eight Times More Marijuana Than It Smokes, Growers Warn