People who consume marijuana medically or recreationally may be exposing themselves to unknown health risks from toxic pesticides.

The EPA would ordinarily evaluate pesticide safety but has never done so for marijuana because the plant is illegal under federal law. So, states with legalized marijuana industries have been tasking newly created cannabis regulators, health officials and others with setting testing standards for pesticide residues present on the plant.

Now, state pesticide officials, who normally assure that EPA guidance is followed, as well as former career EPA staff, academics and environmental groups, say that without the federal guidance, marijuana users could be exposed to unknown harms.

“Frankly, we don’t know,” said Rose Kachadoorian, president of the Association of American Pesticide Control Officials and pesticide program manager for the Oregon Department of Agriculture. “We don’t have the data. That’s why you have to have pesticide regulators step back and find out what might be a level that is not constituting risk.”

The federal government should be doing more to make it clear that these standards, sometimes referred to as “action levels,” may not be protective and ask states to convey that information to the public, they say.

“If you talk to any pesticide regulator and they would look at those action levels … I don’t think you would find one person that thinks they would be protective of public health,” Kachadoorian said.

Whether marijuana products are safe for consumption has become a national concern, as federal regulators investigate whether a recent outbreak of lung disease tied to vaping of THC — the psychoactive chemical in marijuana — is being caused by contaminants.

The industry, transitioning from operating in the shadows toward various stages of legality across the U.S., says that growers go to great lengths to protect consumers.

Morgan Fox, a spokesman for the National Cannabis Industry Association, said in a Sept. 4 email that his group hasn’t seen “any data suggesting that existing pesticide regulations are creating any widespread public health issues after years of regulated markets existing in a number of states.”

“States are doing their best to implement strict rules for pesticide use and make sure that licensed cultivators are abiding by them,” Fox said. “There is also an increasing drive among cultivators to avoid pesticides where possible.”

But the state pesticide officials and others say it’s concerning that other state regulators are setting quality standards without sufficient health data. Jon Jacobs, a former career EPA attorney who worked in the agency’s criminal enforcement division and recently started a cannabis industry consulting firm, said illicit growers likely used “massive amounts of pesticides to grow their illegal cannabis crops, but because it was black market, nobody was paying attention.”

Use of these pesticides probably continues with little oversight, he said.

“No one’s going to pay attention until we start having more consumers injured, either through smoking or ingestion or dermal exposure,” Jacobs said.

Multiple paths

Like any other agricultural sector, the marijuana industry has to deal with mold, insects and other pests. Pesticides are a common tool used by farmers to address that issue, but products commonly used in commercial agriculture can be toxic if consumed in certain amounts and there is little study on what amount, if any, can be present on marijuana products without harming consumers.

Part of the issue is that marijuana is consumed in many ways. Users ingest concentrated edibles, apply topical creams or heat and inhale it in smoke or vapor form. And the EPA has little experience studying the impact of pesticides on health when consumed in these myriad methods.

“We see there is a giant gaping hole inside of what we would all need to know for setting action limits,” said Jeffrey C. Raber, former executive director of the Association of Commercial Cannabis Labs and current operator of a marijuana research firm based in California. “If I’m going to use it for inhalation, that bypasses the liver, goes straight into my bloodstream … I’ve got very different toxicological concerns.”

“EPA would have to add a whole lot of new exposure scenarios in order to figure out the best ways to assess the risks of potential exposures,” said Tina Levine, who previously managed the health effects division within the EPA’s Office of Pesticide Programs.

“Many states don’t have a very developed pesticide infrastructure within their government, and they rely on EPA. In this case, since the federal EPA doesn’t have a role, they can’t do that,” she said.

In the EPA’s absence, state pesticide officials have tried to educate the industry and the public that no pesticide is legal to use on marijuana. Some have released lists of products that are generally low risk and that EPA has approved for a broad range of uses.

Setting standards

But in states like Oregon, Colorado, California, Nevada, Washington and others, agencies that don’t typically regulate pesticides are setting standards for labs that test marijuana for contaminants. Pesticide regulators like Kachadoorian say that some of those pesticides may be unsafe at any level.

“We’re concerned about these levels, that there would be something termed ‘action level’ and how it might be misconstrued,” Kachadoorian said.

Those regulators, as well as industry groups, say these standards are an improvement from having black-market products without any testing at all.

Brian Smith, a spokesman for the Washington State Liquor and Cannabis Board, which regulates the state’s marijuana industry, said “anyone that’s been in the industry … can tell you that marijuana’s been lathered in pesticides for decades.”

Smith said approving pesticides for growers without help from the federal government has been a major challenge for the agency.

“Doing something that is illegal at the federal level and not having the kind of support that the EPA would provide on something like this has been very challenging,” he said.

State pesticide officials recently elevated their concerns to EPA’s leadership. An EPA-funded working group overseen by the Association of American Pesticide Control Officials, sent a letter in July stating that tolerable pesticide residues were being set higher than what was allowable on other crops, with little input from the state agencies experienced in pesticides.

Though the standards were not designed to give growers permission to use pesticides illegally, they were being misinterpreted as such, creating a potential threat to consumers. The EPA should tell states they’re setting testing standards in conflict with federal pesticide law and should put pesticide regulators fully in charge of regulating the chemicals’ use on agriculture, the group said.

An EPA spokesman declined to comment on the letter. While the agency recently began the process of approving pesticides for use on hemp, a crop derived from the same plant as marijuana but with virtually no THC, spokesman Robert Daguillard said in an Aug. 21 email the agency’s policy on marijuana hasn’t changed.

“Marijuana remains subject to the Controlled Substances Act,” he wrote. “EPA is not offering a list of pesticides for use on marijuana.”