Mandatory testing of cannabis in Oregon has revealed several biopesticides contaminated with more highly regulated chemicals, prompting regulators to halt sales of the products.

The problem has led the Oregon Department of Agriculture to believe such contamination probably is not limited to marijuana, this state or a certain pesticide product.

“In a way, this kind of tipped us off that we could be seeing this in other crops,” said Rose Kachadoorian, ODA’s pesticide registration and certification leader. “These pesticides are marketed nationally.”

To complicate the situation, such contamination renders the pesticides adulterated and misbranded under Oregon law but it’s allowable under a federal policy adopted two decades ago by the U.S. Environmental Protection Agency.

Before 1996, the EPA considered any level of impurity “toxicologically significant,” but then the agency changed its policy to allow up to 1,000 parts per million of contamination by certain other pesticides.

The federal policy recognizes that low-level contamination may occur at large facilities that aren’t dedicated to one chemical and it’s primarily concerned with toxicity to plants, Kachadoorian said.

Oregon and other states are urging the EPA to reconsider this “pesticide regulation notice,” or PR notice, to potentially exclude organic biopesticides from the policy, or herbicides sprayed over the top of genetically engineered crops, she said.

Contamination with an herbicide to which a crop isn’t resistant could damage the plant, while prohibited residues could result in rejection by domestic or foreign buyers, Kachadoorian said.

“It happens all the time that retailers are testing,” she said.

If a grower sprays a pesticide that’s labeled to have a short duration but the product is contaminated with a longer-lasting chemical, then the crop could exceed “tolerance” levels for the latter substance, Kachadoorian said. In other cases, the product may have no “tolerance” level for the contaminant.

“We’re concerned about truth in labeling,” she said.

Recreational and medical marijuana must undergo testing in Oregon.

The biopesticide issue came to light when a cannabis grower was adamant that he hadn’t used a permethrin pesticide for which his marijuana had tested positive.

It turned out the neem oil he’d applied as a biopesticide was contaminated. ODA conducted additional tests of other containers to confirm the impurity.

When contacted about the problem, the pesticide manufacturer pointed to EPA’s policy, Kachadoorian said. “We had never heard of that and none of the other states we are dealing with had heard about this.”

Over the past year, ODA has issued “stop sale” orders for six biopesticide products due to contamination discovered during cannabis testing. Four of the products were derived from neem seeds and one was a pyrethrum concentrate.

The contaminants included permethrin, bifenthrin, cypermethrin, cyfluthrin, chlorpyrifos, fenpropathrin, lambda-cyhalothrin, piperonyl butoxide and MGK-264, none of which were listed on the labels.

In the past, companies have spiked biopesticides with more powerful synthetic chemicals, Kachadoorian said. “That was certainly one of the things we looked at, because we’ve seen it before.”

However, manufacturers involved in the six “stop sale” orders were established firms that weren’t considered likely to purposely adulterate their products, she said.

The ODA hopes that companies continue to thoroughly follow their equipment clean-out procedures despite the EPA’s pesticide regulation policy, she said. “Are they using this PR notice as intended or are they using it a little more broadly?”

The six products that ODA found to be contaminated remain listed for organic production by the Organic Materials Review Institute, which is prevented by confidentiality from disclosing whether they’re under investigation.

Testing of additional products by ODA could mean this “will continue to be an issue in part because of our contaminated environment,” said Peggy Miars, the institute’s CEO, in an email.

“The testing program could also identify potential fraud, which is a serious violation,” she said. “OMRI continues to improve our investigative procedures in order to quickly and effectively respond to reports of potential contamination.”