Breaking Down Pesticides: What Works, What Doesn’t, and Our Rec's

The cannabis and hemp industry is facing many technical challenges. As the environment warms, growers are confronting the reality: pest pressure is rising. Milder winters boost overwinter survival, longer growing seasons allow more pest generations per year, and expanding ranges introduce new pests into both outdoor and controlled-environment facilities. Even with robust integrated pest management, the likelihood is increasing that pesticides will be used downstream, which elevates the risk of pesticide residues finding their way into biomass, crude, and refined cannabis oils.

Media Bros is here to help solve your pesticide remediation needs.

We’ll introduce how extraction labs can address specific challenges by remediating common pesticide residues with the filtration media most often reported in use—activated carbons and popular sorbents— used to selectively reduce contaminants while preserving cannabinoid potency where possible. We’ll outline the fundamentals of media selection, process solvent selection, and share the tabulated results from our 3rd party validated experiments.

At Media Bros, our goal is to share knowledge to better equip processors with a simple framework for evaluating filtration-based pesticide remediation. As a reminder, this educational content is provided for informational purposes only and does not guarantee specific outcomes or results. Please always follow applicable laws and regulations.

Beyond the Spray: Pesticides

Pesticides are more than just a spray—they’re a toolkit of strategies, chemistries, and practices used to manage weeds, insects, fungi, rodents, and other pests that threaten crops. But which pesticides are commonly tested for in hemp and cannabis flower and extracts? In this section, Table 1 outlines common pesticides included in cannabis and hemp testing panels and explains why they may be used. Based on a survey of independent third-party laboratories across the country, we identified several pesticides that were most often reported above permitted limits and highlighted them here. In later sections, we will cover each of the highlighted pesticides and report commonly used filtration remediation strategies for each.

More on Highlighted Pesticides

Carbaryl: A Closer Look

Carbaryl is one of the pesticides most frequently flagged in cannabis compliance testing. First introduced in the 1950s as a broad-spectrum insecticide, it became widely adopted in agriculture for controlling a variety of pests on fruits, vegetables, and ornamental crops. Despite its effectiveness, concerns about toxicity and environmental persistence have led to tighter restrictions and, in some regions, outright bans.

In cannabis and hemp processing, Carbaryl residues can present a serious compliance risk. Extractors have reported using a variety of filtration media to reduce its presence, with activated carbons and magnesium silicates most often cited anecdotally as helpful remediation tools.

Chlorfenapyr: A Closer Look

Chlorfenapyr is a relatively modern insecticide, first commercialized in the 1990s, that works as a pro-insecticide—meaning it requires metabolic activation in the target pest before becoming toxic. It’s prized in agriculture for its effectiveness against difficult-to-control insects, including those resistant to other pesticide classes. While effective, its toxicity profile has raised concerns, particularly in greenhouse and food crop applications.

In cannabis, chlorfenapyr contamination is a red flag in compliance testing, with regulators setting very low tolerance limits. Extraction operators anecdotally cite the use of activated carbons and magnesium-based sorbents as the most common filtration strategies to help reduce chlorfenapyr residues in extracts.

Myclobutanil: A Closer Look

Myclobutanil is a systemic fungicide introduced in the late 1980s and widely used in conventional agriculture to combat powdery mildew and other fungal diseases. While effective in protecting crops, it has become infamous in cannabis because, when heated, it can degrade into potentially harmful compounds such as hydrogen cyanide. This has made it one of the most tightly regulated pesticides in cannabis testing programs across the U.S.

Processors working with contaminated biomass often turn to remediation. Anecdotally, activated carbons and magnesium silicate-based adsorbents are most often mentioned as tools to reduce myclobutanil residues during filtration, though results depend heavily on solvent systems and process parameters.

Pyrethrins: A Closer Look

Pyrethrins are naturally derived insecticides sourced from chrysanthemum flowers, used for centuries and commercialized globally in the 20th century. They’re considered less persistent in the environment than many synthetic pesticides, which made them attractive to growers. However, even though they’re plant-derived, pyrethrins are not without risk: in cannabis testing, residues are carefully monitored and often trigger compliance issues.

Within the extraction community, activated carbons and silica-based adsorbents are the most frequently cited options for pyrethrin remediation. Operators report that the choice of solvent—particularly ethanol—can influence how effectively pyrethrin residues are reduced.

Media Bros Remediation Strategies: Survey of Pesticide Remediation

Growers and processors strive for non-detect 3rd party residual pesticide test results in their flower and concentrate products. However, residual pesticide contamination can still occur, necessitating the development of low-cost and effective remediation strategies. Common pesticide remediation strategies include selective adsorbents and filtration media, pH-adjusted washes, liquid–liquid extraction, chromatography, and targeted thermal or photolytic treatments. These strategies are both low-cost and effective, utilizing both filtration and adsorbent approaches. But how effective is filtration? The effectiveness of a filtration strategy depends not only on the specific pesticide but also on the concentration present, the solvent selected, and the specific filtration media, among other key variables. Our goal in this next section is to equip operators with a toolkit of evidence-informed options to move failing lots toward compliance using popular filtration media to remove commonly cited problematic pesticides.

The filtration protocol was standardized to reflect common customer workflows. To summarize our experimental procedure, concentrates with intentionally high residual pesticide levels were used to assess removal efficiency for each filtration media and solvent system. Concentrates were dissolved in solvent at a 6:1 volume ratio (solvent: concentrate). Filtration media were added at a 2:1 mass ratio (concentrate: media), and the slurry was stirred at 40°C for 1 hour. The media was then removed, and the filtrate was evaporated to dryness before submission to a third-party laboratory. Results were compared to untreated controls, and percent removal was evaluated relative to state-specific allowable residual pesticide limits (Table 2.)

The filtration media tested were chosen based on customer feedback, and solvent systems were selected to represent the range of solubility conditions common in concentrate processing, from polar to non-polar. The media evaluated included Media Bros G-CRAC (a flowable, pH-neutral granular carbon), Media Bros CRAC (a high–surface–area, pH-neutral carbon powder), Magsil (magnesium orthosilicate powder), and Magsil-PR (activated magnesium orthosilicate powder, often cited as the most effective choice for pesticide remediation). The solvent systems tested were n-heptane (alkane), 190-proof ethanol (95% ethanol/5% water by volume), and 200-proof ethanol (anhydrous). Table 3 presents the filtration media and solvent systems that were tested.

And On to the Results…

Based on our quantitative testing, we created state-specific guidance tables that summarize, for each filtration media, solvent system, and pesticide, the potential reduction of residual pesticides relative to that state’s allowable limits.

For example, Table 4(f) reports results for Oregon. Suppose your extract contains chlorfenapyr at 1.2 ppm and you need a medium compatible with an n-alkane. In that case, consider G-CRAC in n-heptane (or another hydrocarbon), which is shown in the table to reduce levels to below 1.3 ppm.

Another example: Table 4(c) reports results for Colorado. If your flower contains carbaryl and you plan to produce a clean extract for hydrocarbon processing, consider using CRAC or G-CRAC.

One more example: Table 4(d) shows results for Michigan. If your extract contains pyrethrins at 1.3 ppm, consider remediating with either CRAC or G-CRAC using 200-proof ethanol as the solvent.

Please note: the tables reflect real test data but are not definitive, and we cannot guarantee specific outcomes. Use it as a strong starting point to set reasonable expectations.

Find your state below and let the table be your guide!

Concluding Remarks

Thank you for taking the time to read our posts. We hope they have been enlightening and educational. We are committed to helping artists create clean, compliant, and high-quality concentrate products. If you have questions, require additional technical guidance, or simply need assistance selecting the right media for your process, our team is here to support you. We appreciate your trust and look forward to partnering with you.