Growing Pains: Regulating the Use of Pesticides on Marijuana

In 46 states, marijuana smokers still have to worry about being arrested and jailed for their use of marijuana. The latest Uniform Crime Report released a few days ago found more than 700,000 Americans were arrested on marijuana charges during 2014 — a marijuana arrest every 45 seconds. Of those arrests, 88 percent were for simple possession for personal use – just average Americans who enjoy smoking a joint when they relax at the end of the day, just as tens of millions of Americans enjoy a beer or a glass of wine.

And when our personal freedom is at stake, ending arrests has to be the priority for all of us.

New Challenges with Legal Marijuana

But as we move forward to fully legalize marijuana in more and more states, a number of consumer protection issues come to the fore in those states to assure the marijuana and marijuana products we are offering to consumer are safe, free from potentially harmful molds, pesticides, insecticides or other contaminants, and are accurately labeled.

As with any plant, marijuana is prone to pests and disease, and pesticides and herbicides are routinely used to prevent bugs and mildew from destroying plants, which could cost the grower millions of dollars.

Because marijuana has for decades been considered illegal contraband, there is almost no research available dealing with the potential harm to the marijuana consumer from these potential additives. The closest body of relevant science involves the potential risks from food treated with additives, and from tobacco treated with additives.

And because marijuana remains illegal on the federal level, the federal Environmental Protection Agency, the agency charged with protecting Americans and our environment from potentially dangerous pesticides, has essentially rebuffed state authorities when they have approached the agency for advice and assistance in getting this right. The states are largely having to develop their own list of which additives are safe to use on marijuana, and which are not.

And not surprisingly, there have been some growing pains. As with other legal industries, some in the marijuana industry have used their increasing influence to delay and water-down potential regulations intended to protect consumers, and advocated for less stringent protections.

But that is just part of the usual give-and-take between those who represent the industry, and those of us who represent consumers. Over time these and other similar issues can be resolved in a manner that protects the health of the consumer, while still allowing a robust marijuana cultivation industry.

Problems in Oregon

A recent investigative piece in the Oregonian found that many of the marijuana products being sold to medical patients in Oregon, (they have only recently begun selling for recreational use) with the required lab certificate indicating they had been tested and were safe, in fact were adulterated, sometimes in far greater amounts than is allowed for those same additives on food or tobacco products. This was especially a problem with extracts and concentrates.

“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 Oregonian concluded, calling for far more detailed and stringent state regulations to regulate the testing facilities themselves, to assure reliable results. Those new, more comprehensive regulations are expected to be promulgated by the Oregon Liquor Control Commission, the state agency designated to regulate the new legal recreational marijuana industry, in 2016, as they officially roll-out the new recreational stores.

Similar Experiences in Colorado

In Colorado, recognizing the problem of different labs coming up with conflicting test results from the same marijuana, the legislature recently passed, and the governor signed, legislation creating statewide marijuana lab standards for marijuana potency, homogeneity and contaminants. And the state Department of Agriculture recently proposed a draft list of about 75 pesticides deemed to be safe for use on marijuana, based on their previous approval for use on food intended for human consumption, down from the current list of 200 acceptable pesticides. The state is finally acting, prodded by the city of Denver that had begun adopting its own standards, and requiring a few growers and retailers to recall some contaminated products.

The Cannabist and the Denver Post report that the pesticide regulations were delayed by a year, and ended-up being less restrictive than originally proposed, because of pressure from the marijuana industry in CO, fearful some of the pesticides currently in common use would be prohibited, putting their crops at risk. The marijuana industry “was the biggest obstacle we had,” in devising pesticide regulations, according to former Colorado Agricultural Commissioner John Salazar.

Two growers based in Denver – Mahatma Concentrates and Treatments Unlimited – are now under investigation by the Colorado Department of Agriculture for excessive pesticide residue on their products, and in at least one case, the products have been recalled.

Washington Tries to be Proactive

The Washington State Liquor and Cannabis Board (recently renamed to include our favorite herb), the agency that has licensing, regulatory and enforcement authority over recreational cannabis growers, processors and retailers, seeking to be proactive, initially attempted to seek guidance from the EPA in 2014, but were advised the federal agency does not consider marijuana to be an herb, spice or vegetable, but rather a controlled substance, and would provide no guidance.

Eventually the state regulatory agency issued a comprehensive listing of 309 pesticides that are permitted to be used in the production, processing, and handling of marijuana. According to a statement issued by the Seattle and King County Public Health Department, “These pesticides were selected because their use on marijuana plants would not be in direct conflict with federal law (they are allowed on other food products) and they are considered to pose minimal risk to health when used as directed.” Marijuana retailers are required to document all pesticides used on marijuana products that they sell and provide that information to customers and regulators upon request.


This column first appeared on

5 thoughts

  1. Thanks for highlighting this important health issue Keith.
    Actually the EPA has thoroughly and completely weighed in on the use of pesticides on cannabis.

    The EPA’s chief of the Office of Pesticides Program in Washington, DC, shocked the stake holders in both Colorado and Washington State by explicitly outlining the process in which states need to seek approval for federally registered pesticides to be used on cannnabis. Jack Housenger’s letter came in May after Colorado’s officials asked the feds for advice. Officials in the state governments in Washington State were carbon copied as well.

    The letter explains that for a pesticide to be used on a new product, a specific data set of scientific information must already exist. The state must show similar exposures and use patterns of already allowed pesticides on food or tobacco products. If similar products are not found, the state must conduct the scientific studies proving safety themselves. (That could take decades and millions of dollars.)

    Housenger’s letter actually opened a can of worms that ultimately resulted in Colorado’s issuing proposals this week to cut by two thirds the pesticides they allow to use on cannabis. The discussions that followed the EPA’s advisory criteria focused on the fact that most of the products sold in the recreational stores are not buds but high THC concentrates, or edibles made from those concentrates.

    Concentrates are made from a chemical washing of the cannabis plant’s surface which is where the THC rich tricomb crystals are found. The surface resin is sticky, firmly holding on to any pesticides applied. Worse yet, the chemical processes used to wash the THC from the surface has a 5 time greater affinity for pesticides than THC!

    When the officials in Colorado realized that a chemical wash of a plants surface that was created to be inhaled deep into the lungs had no similar use patterns to food or tobacco, they had no option but to severely restrict the pesticides allowed to those with no tolerance levels.

    Other states need to follow suit and the states not in compliance with this EPA guideline regarding the use of pesticides on cannabis needs to be sued.

    Hope that helps.

    Gil Mobley, MD

  2. The EPA has indeed provided a road map to registration using the “Special Local Need” registration process, as allowed per the federal law governing pesticide use in the US (i.e., FIFRA). However, there are two major barriers that must be overcome to use this process: (1) a “sponsor” and (2) “data.” A “sponsor” in this case is a current EPA registrant for whichever pesticide one is interested in adding a use for application to cannabis (or hemp for that matter). “Data” in this case being either actual empirical data following Good Laboratory Practices and adhering to the test protocols mandated by FIFRA ***or*** a surrogate set of data that provides the same level of comfort and detail that EPA needs to conduct one of various risk assessment scenarios.

    Several sponsors have evidently discussed this process with the Colorado Department of Agriculture. I’m not aware of any SLN applications that have been submitted. Data for any particular high-value chemistry could be generated collectively by a group of industry stakeholders in conjunction with a sponsor.

    Contact M³ for more details. (

  3. Great posts everyone.

    Indoor grown marijuana can be grown with minimal pesticides… Preferably those that are cellulose or plant based oils, and NOT petroleum based ones… If simple guidelines are met such as keeping other plants OUT of the growroom, using gloves that stay in the growroom and washing your hands. Sometimes common sense is the best weapon against spider mites, which can devistate a crop. This is especially true for outdoor operations if the pesticides one uses, responsibly or not, is killing the garden flies and lady bugs that eat those pesky mites.
    Hemp is much hardier for outdoor grows and requires little to no pesticides if you can keep the right ph balance in the soil, which can be done by allowing the lower leaves to fall and compost, therefore eliminating the artificial excuse for petroleum based fertilizers.
    Wonderful news about Colorado and the EPA. I believe the standard has been set for smokeable concentrates that use too much pesticides; Stop using too much pesticides.

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