Cannabis quality control: State must regulate heavy metals
New York’s legalization of adult-use cannabis prompts a long list of important policy questions for the state: how to spend the revenue, how to regulate sales, and how to assure product quality.
Like other states that now tax and regulate marijuana for adult recreational use, New York will create rules governing the legal pot business. Along the way, the Empire State should not overlook an unheralded — but important — regulatory issue: heavy-metals in soil.
A key component of the rationale to legalize cannabis is consumer protection, by assuring product quality and guarding against contaminants. That should include heavy metals.
The cannabis plant, in addition to its better-known attributes, is a bioaccumulator — meaning simply that it’s quite effective at absorbing heavy metals from soil.
It’s not cause for alarm; heavy metals occur naturally in soil, typically at trace levels that are not toxic. But mining, disposal of industrial waste, land application of fertilizers, animal manure, pesticides, wastewater irrigation, coal combustion residue, and other human activities can contaminate soil. And most metals don’t undergo microbial or chemical degradation.
For that reason, limits on heavy metals are an emerging feature of cannabis controls in various states. California mandates sample testing for cadmium, lead, arsenic, and mercu
ry. If cannabis fails testing, it cannot be released for retail sale. Montana requires random testing for heavy metals for usable marijuana and extracts. Ohio tests samples for threshold levels of arsenic, cadmium, lead, and mercury, requiring the tests for one half of one percent of the net weight from each batch intended for sale.
States are enforcing this, too, including ordering recalls. Medical marijuana officials in Ohio issued a recall of cannabisinfused chocolate edibles last fall from eight dispensaries, citing too much cadmium. Days later, Colorado issued its first marijuana recall for heavy metals, sanctioning a cannabis wholesaler for potentially unsafe levels of arsenic. And in 2019, Michigan regulators pulled four medical marijuana products due to concern about heavy metals and pesticide.
Cannabis is a job-creating growth industry, and a new revenue stream for government. Its cultivation, as in other agriculture, faces many variables and risks. Effective tactics for protecting cannabis consumers from excess heavy metals include soil testing, using quality nutrients, and avoiding contaminated water.
Quality control is a linchpin of legalized marijuana. Without it, consumers get hurt, the underground market gains appeal, and government forfeits tax revenue.