06
Feb
Revealing “Dirty Weed”: Pesticides in Cannabis Raises Health Concerns, as Advocates Advance Organic Solution
(Beyond Pesticides, February 6, 2024) Months after publishing a June 2024 study regarding concentrations of pesticides discovered in legal (and illegal) cannabis products in California, the Los Angeles Times has released a follow-up exposé highlighting extensive pesticide contamination, including from “hidden” pesticides that regulators have not monitored. The authors conclude that in California’s legal weed market, over half of available smoking products are found to contain hidden chemicals—toxic pesticides present in products but not regulated or monitored by state authorities.
Since 2015, Beyond Pesticides has laid out health, safety, and environmental concerns related to the contamination of cannabis by pesticides (and fertilizers) alongside an imperative need to mandate an organic systems approach to cannabis production. Yet ten years later, it appears nationally that California state regulators are alone in moving forward in 2021 with state organic cannabis certification. There are other marketplace-based cannabis certification labels that require comparable organic certification practices (see Beyond Pesticides reporting here and here). For more information, please see past Pesticides and You reporting here and here.
The Los Angeles Times analyzed the results from state licensed laboratory testing of more than 370 legal cannabis products, representing 86 brands. In addition to the 66 chemicals required under California’s mandatory screening requirements, as described below, the laboratories screened for more than 290 additional pesticides: in total, 79 toxic chemicals were found in the products tested, 45 of which tested positive in cannabis products specifically. All but one of these “hidden pesticides” are prohibited from use on cannabis plants due to failing to meet California’s “use criteria” (see here and here).
Limited research exists on the safety of these pesticides when burned and inhaled. While pesticides used in tobacco production is often used as a reference for allowing pesticide use in cannabis production, a U.S. General Accounting Office (GAO) report over two decades ago flatly stated that the U.S. Environmental Protection Agency (EPA) does not fully evaluate residues in inhaled tobacco smoke “because of the severity and quantity of health effects associated with the use of tobacco products themselves.”
Given that cannabis is often used for medicinal purposes, the fact that EPA is not evaluating pesticide residues in tobacco raises grave concerns when a state points to its regulation as guidance. GAO stated in its report (p3), Pesticides on Tobacco: Federal Activities to Assess Risks and Monitor Residues, states the following: “[E]PA has generally concluded that the low levels of residues measured in tobacco smoke do not pose short-term health concerns. EPA does not assess the additional risk of either intermediate- or long-term exposure to pesticide residues in smoke because of the severity and quantity of health effects associated with the use of tobacco products themselves. In addition, the agency does not include short-, intermediate-, or long-term exposure to residues on tobacco in its assessments of total exposures to the pesticides. Officials and experts with whom we spoke generally agreed that pesticide residues on tobacco could incrementally increase health risks, though some also said the known harm from using tobacco products dwarfs any potential effect from exposure to pesticide residues in the smoke.”
The contaminants discovered in cannabis in California include the following insecticides:
- chlorfenapyr 2,000 times over EPA permitted residue level and an insecticide that is not allowed in food use or California cannabis;
- pymetrozine (839 times over the permitted residue level or EPA criteria), an insecticide not required for screening in California;
- trifloxystrobin (488 times over the permitted residue level or EPA criteria), a fungicide and known endocrine disruptor and developmental toxin;
- 2-phyenylphenol (268 times over the permitted residue level or EPA criteria), a fungicide, disinfectant and carcinogen; and
- bifenazate (237 times over the permitted residue level or EPA criteria), a restricted-use miticide that is a questionable developmental and reproductive toxin and endocrine disruptor.
In the California black market of illegally sold cannabis, the Los Angeles Times article concludes that of the 16 products tested from unlicensed sellers, roughly half are contaminated above the legal limits. However, unregulated products are more likely to contain one or more of the 66 regulated chemicals, whereas regulated products are more likely to contain one or more “hidden” chemicals, for which there is no required screening.
The list of 66 pesticides on the state’s required screening list includes 21 Category I pesticides, which are banned for use on cannabis due to significant risk—any chemical detection results in a failed test. The 45 Category II pesticides have specific “action levels” for ingestible and inhalable products, where use is allowed under certain conditions if residue levels remain below the prescribed limits. For example, the insecticide bifenthrin, a possible human carcinogen, and acephate, a neurotoxic organophosphate insecticide widely banned around the world (see here). Note: the list of what is required for screening does not encompass all the chemicals that may legally be used on cannabis crops.
Since the federal government classifies cannabis as a Schedule 1 narcotic, it is not recognized as a legal agricultural crop under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Consequently, EPA has not assessed the safety of any pesticides for use on cannabis plants, nor has it established tolerances or exemptions for pesticide residues on cannabis. The California Department of Pesticide Regulation (CDPR) allows a pesticide product to be used on cannabis only if its active ingredient is exempt from federal residue tolerance requirements and either exempt from federal registration requirements or registered for a use that is broad enough to include use on cannabis plants.
The Los Angeles Times reports that the contamination is so widespread that there is not enough clean weed to supply the vape market. Half of all vape products tested positive for pesticides not approved for use on cannabis; one example, pymetrozine, a reproductive toxicant and carcinogen banned in Europe, is present in 31% of vape products tested.. When confronted with the results, one cannabis company executive said that they were not in violation of state regulations as there is no testing requirement or residue limit for pymetrozine.
In addition, the investigation identifies instances when the state was notified of the usage of illegal pesticide products but failed to act. Not only did farmers in Santa Cruz county apply pymetrozine, but its illegal use was reported to the state via monthly pesticide use reports; however, there was no response from regulators. While CDPR uses a software program to flag pesticide use reports when a potentially illegal use is reported, the Los Angeles Times article highlights hundreds of reports not flagged by the system, support, resulting in non-enforcement of what appears to be extensive illegal usage.
Furthermore, even if the state chose to respond, there is no established process cited to identify the source and extent of contamination, in order to mount a response. The California Department of Cannabis Control has established a tracking system (operated by METRC, a state vendor) to collect information on every plant from “seed-to-sale,” which, in theory, could provide a means of tracking and removing contaminated products from the marketplace. However, the Los Angeles Times article found the system to be completely inadequate for tracking the distillate used in vapes, which can be made up from parts of hundreds of plants.
Since the above mentioned report in June 2024, the state’s Department of Cannabis Control has recalled hundreds of products from sale, primarily due to whistleblower complaints. However, early efforts by California regulators to establish a pesticide surveillance program were dropped; subsequently, a recent proposal to add ten chemicals to the mandatory screening list was subsequently whittled down to eight chemicals.
Attempts have been made to establish an organic certification program for cannabis products at the state level and in the marketplace. Since cannabis is illegal and classified as a Schedule I narcotic under federal law, it cannot be certified as “organic” under the National Organic Program and carry the USDA organic label. As of 2025, cannabis is legal for recreational use in 24 states, two territories, and the District of Columbia, and for medical use in 40 states, three territories, and the District of Columbia, according to the National Conference of State Legislatures.
Some states have taken steps to address this regulatory gap. The states of Connecticut, Maine, Minnesota, New Hampshire, Massachusetts, and the District of Columbia have adopted regulations emphasizing less-toxic methods of cannabis cultivation, prioritizing practices that avoid or prohibit pesticide use. Beyond Pesticides has pointed to these state-level initiatives are essential in the absence of federal guidance, presenting an opportunity for states to incentivize environmentally friendly and health-conscious cultivation practices.
California introduced stricter oversight with a series of laws enacted in 2018, requiring pesticide residue testing for cannabis products. In 2021, California state law required Department of Food and Agriculture (CDFA) and the California Department of Public Health (CDPH) to establish a certification program for cannabis that is comparable to the National Organic Program and the California Organic Food and Farming Act. Notably, only the National Organic Program can authorize use of the word “organic” on product packaging. This California OCal Registration Program, establishes a “comparable-to-organic” certification for cannabis products to enhance consumer trust in the state’s marijuana industry. However, Beyond Pesticides points out challenges with this program, particularly the need for more stringent scrutiny of inhalation and skin absorption risks for all cannabis users, especially medical patients. Advocates argue that California consumers would benefit from a dedicated OCal Standards Board to review pesticide and processing material restrictions in the context of cannabis consumption.
Jay Feldman, Executive Director of Beyond Pesticides, underscores the importance of addressing gaps in data collection for evaluating cumulative pesticide exposure risks from inhalable cannabis products. In Environmental Health Perspectives, Feldman emphasizes the need for a precautionary approach: “If [the California Department of Pesticide Regulation] does not have this kind of data, which is extremely expensive to produce and evaluate, then it should use its statutory authority to embrace a precautionary approach. They are establishing a false sense of security regarding the allowed residues, given that they have not looked at the aggregate cumulative risk of dietary and nondietary exposure in combination with cannabis residue.”
In January 2025, cannabis industry leaders established a nonprofit—the Environmental & Consumer Compliance Organization (ECCO)—to provide certification to those products that test for more than 200 chemicals. Some advocates observe that the multitude of certifications, including some that include and go beyond comparable organic certification standards, like national certifier Sun and Earth may confuse consumers and producers alike.
Ultimately, the regulatory gap presented by the legal status of cannabis federally raises critical concerns about potential pesticide exposure: from residues introduced through inhalation, ingestion, or absorption, to occupational risks for workers involved in its cultivation and identified harms to wildlife environmentally. In the absence of federal guidelines, Beyond Pesticides argues that any synthetic pesticide use on cannabis is effectively illegal under current federal law: “In the absence of federal regulations governing pesticides in cannabis production, the use of pesticides not registered by [EPA] is understood to be illegal.”
Beyond Pesticides urges all cannabis regulatory agencies to adopt an enforceable organic systems approach, mirroring the standards of certified organic agriculture, which prohibit synthetic pesticides and fertilizers. Additionally, the organization encourages states to adopt laws or regulations that require an organic systems approach to cannabis cultivation. This precautionary strategy has become increasingly vital, rather than relying solely on detecting and regulating prohibited pesticide residues in cannabis; implementing a framework that mandates adherence to national organic soil management standards would be a more responsible approach.
For detailed information on how pesticide residues in marijuana may affect your health, refer to Beyond Pesticides’ reports: Pushing for Organic Cannabis as Industry Grows and Pesticide Use in Marijuana Production: Safety Issues and Sustainable Options (and here). If you suspect that you or someone you know has been exposed to pesticides, consult our Pesticide Emergencies resource. Additional insights into the health impacts of herbicides, insecticides, rodenticides, and fungicides are also available on our website.
For further guidance on organic crop production, explore the organic agriculture page from Beyond Pesticides. To support the alignment of organic standards with the principles and requirements of the Organic Foods Production Act, visit our Keeping Organic Strong (KOS) initiative. KOS offers a straightforward vehicle for the public to provide input on critical issues addressed by the National Organic Standards Board and the National Organic Program under the U.S. Department of Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Sources
New tests find ‘hidden’ pesticides in more California weed brands. Regulators ignored warnings, Los Angeles Times, December 19, 2024
Search your stash: 538 cannabis pesticide tests show what’s in your weed, Los Angeles Times, December 19, 2024
Cannabis conundrum: Legal doesn’t mean clean; illicit isn’t always dirty, Los Angeles Times, December 19, 2024
Contaminated weed in you, Los Angeles Times, June 14, 2024
How dirty is your weed? A joint investigation finds high levels of pesticides in products, Los Angeles Times, WeedWeek, June 14, 2024
California recalls cannabis vape many months after it was told of contamination, Los Angeles Times, June 26, 2024
Consumers Left High and Dry: Public Health Issues Persist with Cannabis Products and Production Practices, Beyond Pesticides Daily News, February 7, 2024
Pushing for Organic Cannabis as Industry Grows, Beyond Pesticides, Pesticides and You, Winter 2018-2019
Pesticide Use in Marijuana Production: Safety Issues and Sustainable Options, Beyond Pesticides, Pesticides and You, Winter 2014-2015
Into the Weeds: Regulating Pesticides in Cannabis, Environmental Health Perspectives, April 25, 2019
