Denver halts some pot sales over bug spray worries

Trevor Hughes | USA TODAY

Show Caption Hide Caption 60k marijuana plants quarantined over pesticide fears Denver city officials have temporarily barred the sale of approximately 60,000 marijuana plants. Why? The plants might have been contaminated by unapproved pesticides.

DENVER — City officials temporarily halted the sale of millions of dollars worth of legal marijuana because of concerns that unapproved pesticides or fungicides have contaminated it.

This past Friday alone, city officials placed a "hold" on 60,000 plants at a single grow facility here after consulting with state agriculture inspectors and the U.S. Environmental Protection Agency. They previously had placed crops from six other facilities on similar holds, allowing the plants to keep growing but blocking their sale to consumers.

Some growers have destroyed their crops instead of waiting for test results, which are still pending.

A mature marijuana plant can be worth more than $4,000 but it's unclear where these plants were in the growing process. Because marijuana is such a lucrative crop, many growers improve their harvest by spraying young plants with chemicals that haven't been approved for use on marijuana.

But no pesticides have been approved for use on marijuana.

Those pesticides are used routinely on other crops, yet health officials worry those other crops aren't smoked or eaten in the way marijuana is.

"This is an initiative that Denver is taking on to really make sure consumers do not get into harm's way," said Danica Lee of the Denver Department of Environmental Health. "It is fair to say there are some practices out there that could pose a public health risk, and we are intervening in those cases."

Denver city officials' actions came after months of waiting for their state counterparts to launch a statewide monitoring program for contaminants. State officials repeatedly have delayed mandatory contamination testing for all marijuana sold for recreational consumption.

Health inspectors appear particularly concerned with a product known as Eagle 20, a commercial-grade fungicide not commonly sold in home-improvement or hardware stores. The city has targeted E20 because of concern that marijuana smokers could inhale the residue, causing damage no one really has researched, officials say.

Under Colorado law, people cannot use pesticides in a manner inconsistent with their federal labeling.

Pesticides are normally subject to federally monitored residue testing. But because marijuana remains illegal at the federal level, no one has been able to do those studies.

"These pesticides haven't been tested on marijuana, so we have no idea what the residue remains when the plants are harvested," said Mike Van Dyke, an environmental epidemiology and toxicology expert with the Colorado Department of Public Health. "No one is doing studies at the federal level."

Some pesticides probably could be used safely on marijuana, but only the federal government can order changes, Van Dyke said. That appears unlikely to happen any time soon.

Mike Elliot of the Marijuana Industry Group, a Colorado-based trade organization, said the pesticide problem may prove as tricky as access to banking. Most banks refuse to do business with marijuana businesses because of fears that federal regulators will shut them down.

"There is not a pesticide in the country approved for use on marijuana," Elliott said. "We're really stuck."

Most of Colorado's marijuana is grown indoors because the controlled environment gives growers more oversight on light, water and fertilization while also reducing the risk of mold and pest contamination. On a recent tour of the 40,000-square-foot Medicine Man operation in Denver, company spokeswoman Elan Nelson allowed visitors to peek into the grow rooms but barred them from entering because of concerns they might track mold or pests inside.

Mold contamination can render a plant unsellable, in part because it makes the buds less attractive and because it can impart an unpleasant taste when smoked.

Neither Colorado nor Washington state, which also has a legal recreational marijuana marketplace, require pesticide or fungicide testing. However, Washington state does test for other contaminants.

As USA TODAY found late last year, more than 13% of the marijuana and related products readied for sale in Washington state failed mandatory contaminant testing because they contained yeast, mold, salmonella and e. coli bacteria.

Colorado state regulators are beta-testing their contamination-testing system for marijuana but can't yet say when all recreational marijuana sold will be tested. Colorado voters approved high taxes on marijuana sales in part to help pay for that mandatory testing.

Black-market marijuana sold illegally across the country is not subject to health inspections or independent quality control.