Concern Grows Over Unregulated Pesticide Use Among Marijuana Growers Regulators in the 23 states where medical or recreational marijuana is allowed are having a tough time making sure pot buyers don't ingest harmful pesticides.

Concern Grows Over Unregulated Pesticide Use Among Marijuana Growers

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States that legalized marijuana are struggling to make sure pot buyers don't get sick from pesticides. Many commercial cannabis growers use chemicals to control bugs and mold, but the plant's legal status is unresolved nationally, so are guidelines for which pesticides are safe. From member station KUNC, Luke Runyon reports.

LUKE RUNYON, BYLINE: This grow room at Medical MJ Supply in Fort Collins, Colo., has all the trappings of your modern marijuana cultivation facility - glowing yellow lights, plastic irrigation tubes, and rows of knee-high cannabis plants. Nick Dice is the owner.

NICK DICE: We're seeing a crop that's in probably its third or fourth week of bloom right now.

RUNYON: The plants are vibrantly green, happy and healthy. And Dice says that's because the company's taken a hard line on cleanliness.

DICE: We have people - that's their only job, is to look for any infections or anything that could cause potential damage to the crop.

RUNYON: As any farmer will tell you, damage to the crop equals damage to the bottom line. Dice's employees used to spray the crop with mild chemicals.

DICE: We would switch between multiple pesticides and mildew treatments, and we would try and treat anywhere from every three to four days honestly.

RUNYON: Dice says he's seen other operations crumble as their cannabis succumbs to mildew or bugs. Pest controls ensure a good yield, and when it comes to cannabis, yields really matter.

How much do you think that this room is worth?

DICE: Oh, Lord. I'd have to count some plants really quick... See, three, two, oh, 160 to 180,000.

RUNYON: Yeah, that's $180,000. And protecting that yield is hard work. That's why many growers in states that have legalized recreational or medical marijuana use chemicals, but it's the federal government that tells farmers which pesticides are safe to use. And, so far, the feds want nothing to do with legalized marijuana. Colorado State University entomologist Whitney Cranshaw says that's left growers to experiment with little oversight.

WHITNEY CRANSHAW: In the absence of any direction, the subject of pesticide use on the crop has just evolved to whatever people think is working or they think is appropriate.

RUNYON: Tobacco farmers, for example, have a stable of pesticides the government says is safe to use, but Cranshaw says marijuana growers have none.

CRANSHAW: Sometimes they've used some things that are inappropriate, sometimes unsafe.

BRETT EATON: Anybody can get their hands on harmful chemicals, and they can just spray away all the way up until the last day of harvest.

RUNYON: Brett Eaton is a plant expert with American Cannabis Company, a Denver-based consulting group.

EATON: And, you know, what is that doing to the product, and what is that doing to the consumer who is consuming that product?

RUNYON: Those same safety concerns led Denver officials to place a hold on tens of thousands of marijuana plants earlier this year. An investigation is underway. Colorado doesn't require growers to test the crop for traces of pesticides before being sold, though state agriculture officials did recently release a list of pesticides deemed appropriate for use on cannabis. Washington State, Nevada and Illinois have similar lists. Eaton says regulators are playing catch-up.

EATON: Other agricultural industries already have policy in place for the safe use of spraying certain pesticides and fungicides. This, being a new industry, hasn't been addressed yet.

RUNYON: And with more states turning marijuana into a legal commodity crop, it'll take a mix of policy, science and industry self-regulation to figure out what's appropriate and what's not. For NPR News, I'm Luke Runyon in Fort Collins, Colo.

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