Absent regulations, marijuana growers 'guessing' on what pesticides to use

With the growth of the legal marijuana industry outpacing government regulation, growers are tackling a new challenge of determining which pesticides are safe to use on their crops.

David Zalubowski/AP
Frank Conrad, head of pot-testing lab Colorado Green Lab, charts potency levels of marijuana while his co-worker, Cindy Blair, works behind, at the lab in Denver, June 17. In states that regulate marijuana, officials are just starting to draft rules governing safe levels of chemicals.

The commercial marijuana industry is growing quickly in the United States, and government regulation is starting to fall behind.

Four states and the District of Columbia have legalized the drug so far, and similar measures are gaining support across the country. But with legal market access comes legal market regulation, and the latter doesn't appear to be keeping pace with the former.

The latest bureaucratic wrinkle in the growth of the legal cannabis market is the use of pesticides and herbicides to prevent mold and microscopic bugs from destroying the large and lucrative crops. And as with staple crops across the country, these pesticides and herbicides can poison the crop and potentially affect consumers.

The only difference is that cannabis is not a legal substance across the country. Only a few states have voted to legalize the drug – often within strict parameters – and there are no uniform standards to ensure that pot growers are using herbicides and pesticides that are safe for consumers down the line. 

The US Environmental Protection Agency regulates which pesticides can be used on which crops, but so far individual states have been taking it upon themselves to formulate pesticide rules. Colorado and Washington are both working on their rules. California, the country’s largest marijuana producer, has no regulations for growing commercial cannabis.

“It’s a lot more difficult than it sounds, and it’s expensive,” Brian Smith, a spokesman for the Washington Liquor Control Board, told The Associated Press.

“We were taken by surprise, this whole pesticide issue,” said Ashley Kilroy, Denver’s director of marijuana policy, in a meeting with about 200 marijuana industry workers earlier this month. 

Colorado and Oregon require retail marijuana to undergo testing for pesticides, but the testing can be imprecise. An investigation by The Oregonian in June found pesticides in excess of legal limits on a range of marijuana products, from buds to marijuana oils.

“A combination of lax state rules, inconsistent lab practices and inaccurate test results has allowed pesticide-laced products to enter the medical marijuana market,” the paper reported.

Colorado has also had its pesticide problems. This spring the city of Denver quarantined tens of thousands of cannabis plants at 11 growing facilities after health inspectors suspected use of unauthorized pesticides. Tests found that plants from six locations were contaminated with pesticides not approved by the Colorado Department of Agriculture, according to Fox 31 Denver. Two producers voluntarily destroyed their plants, according to the AP, and eight businesses still have some plants in quarantine.

The EPA told Colorado and Washington last month that they could apply to have some marijuana-related chemicals approved through a process called a “special local needs registration,” but the process could take years.

There haven’t been any reports of human illness traced to chemicals used on cannabis, but pot growers say broad regulation needs to be enacted quickly.

“There is no federal agency that will recognize this as a legitimate crop,” Whitney Cranshaw, a Colorado State University entomologist and pesticide expert, told the AP. “Regulators just bury their heads, and as a result, pest-management information regarding this crop devolves to Internet chats and hearsay.” 

Indeed, several marijuana growers told the AP that many growers are guessing when they treat their plants, and that much more research is needed into what pesticides are safe to use.

One of the chemicals from the Denver quarantine, for example – a fungicide called Eagle 20 EW – is commonly used on grapes and hops but can become dangerous when heated and is banned for use on tobacco. There is no research on whether the chemical is safe to use on pot, which can be both smoked and eaten. 

Frank Conrad, lab director for Colorado Green Lab, a pot-testing lab in Denver, told the AP that, with the plant refined to the black market for so many years, the academic research into pesticides on cannabis is still very limited.

“We have an industry that’s been illegal for so many years that there’s no research,” he said. “There’s no guidelines. There’s nothing.”

This report includes material from the Associated Press.

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