Colorado Marijuana Will Likely Require Heavy Metals Testing in 2019

Commercial marijuana products sold in Colorado may have to start undergoing heavy-metals testing as soon as 2019, according to the state Marijuana Enforcement Division.

Although not as intimidating as Slayer and Megadeth, heavy metals such as cadmium, arsenic and nickel can be harmful if inhaled, ingested or applied to the skin regularly. According to the National Institutes of Health, long-term exposure to heavy metals can lead to liver or kidney damage, abdominal pain, nausea and vomiting, diarrhea, heart abnormalities, a disrupted nervous system, anemia and more.

But what do heavy metals have to do with legal pot?

Using growing nutrients to enhance the flavor, yields, potency and other desirable characteristics of marijuana is common practice for both commercial and home-growers, but the regulations regarding those nutrients are very loose in Colorado. The Colorado Department of Agriculture regulates fertilizer for home and commercial use, but doesn't have any specific rules governing marijuana nutrients, unlike agriculture departments in California, Oregon and Washington.

Since 2014, the MED has had a list of acceptable metals limits for marijuana, but testing has never been required. As the MED nears the end of its fall rule-making sessions, however, it's considering proposed changes to industry regulations, including making such tests mandatory for all harvests of medical and retail marijuana. If the proposal is approved, testing "must include, but need not be limited to" arsenic, cadmium, lead and mercury, and mandatory testing would begin on July 1, 2019. Any marijuana that fails the test would be recalled and/or quarantined for further testing and possible destruction, similar to the way products that fail pesticide testing are.

Phillip Jacobson, cultivation director for Denver dispensary L'Eagle, thinks that some Colorado cultivators may have issues because of the fertilizer they're using, whether they're purchasing those nutrients or making them in-house. "I actually love the idea that they're going to start looking at this, because there are dozens of fertilizers out there that have measured amounts of cadmium, arsenic, nickel — all kinds of bad heavy metals," he says.

Organic plant food such as fish oils and bat guano can carry potentially dangerous metals, too, thanks to the polluted food, water and air consumed by those animals. "It's not just a fertilizer issue," Jacobson notes, "because the ocean is so polluted that the fish will have mercury in their systems, so organic stuff can have it, too."

Although Jacobson believes that pot with high levels of metal is being sold in Denver, he says that may not be because growers want to cut corners. Because of a lack of research, a lot of growers simply don't know about the residual metals left from nutrients they're using, he explains.

"I think they're using it without knowing. Go to the California and Washington websites, and see what's inside what you're using," he adds. "I think this still remains to be seen, because nobody has any idea what [these metals] are doing. Do extracts contain them? I'm not even sure if these metals are stored in trichomes."

Jacobson isn't sure whether marijuana extracts carry heavy metals, but he is certain about the plant itself, explaining that it's a bio-accumulator that sucks up nutrients in surrounding soil, leading to higher contents of cadmium and arsenic than in the soil itself.

The proposed testing regulation didn't receive any pushback during the MED's rule-making meeting on October 16, but the agency will review written feedback over the next several weeks before issuing any official language regarding new marijuana regulations. 

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