Pesticides in the cannabis industry are commonly integrated into cultivators’ pest management strategies. Cannabis farmers use conventional pesticides and biopesticides to keep insects, fungi, weeds, and other pests from destroying their crops and livelihood.
To make matters worse, cannabis is a powerful phytoremediator capable of absorbing contaminants like heavy metals and pesticides from the soil. Some pesticides can remain in the soil for years and pose several health risks for consumers. While soil remediation may help to clean up pesticide contaminated soils, pesticides can be transferred to the plant and concentrated in derivative products.
As cannabis production goes global, consumer safety and health are a growing concern. Pesticide remediation methods like microbial decontamination after harvesting the biomass and flash chromatography while processing the crude extract can remove these harmful substances to enhance the product’s purity and quality.
Pesticide Use In Cannabis Cultivation
Cannabis plants are vulnerable to pests such as spider mites, thrips, aphids, fungus gnats, and diseases like powdery mildew, bud rot, and verticillium wilt throughout their life cycle. Without regular observation and care, a pest infestation can completely damage a crop. For this reason, many farmers use pesticides to protect their cannabis plants from these predators.
Since cannabis is a Schedule I substance under the Controlled Substances Act (CSA), federal regulations are lacking on safe pesticide use for cannabis production. Without proper federal guidance, farmers are left to use unregistered pesticides that may be harmful to consumers when inhaled or eaten.
Since hemp production became legal with the 2018 Farm Bill, the U.S. Environmental Protection Agency (EPA) has approved 59 pesticide products for use on hemp. Fifty-eight are biopesticides, and one is a conventional pesticide. Still, more federal intervention is needed to determine safe pesticide use in cannabis production.
As a warning for the industry, studies have shown that a surprising number of cannabis concentrates test for various pesticides, in very high concentrations in some cases. Excessive pesticides in concentrates must be removed during the extraction phase to produce safe and compliant products.
Integrated pest management using organic practices can eliminate the risk of pesticide contamination but can be more labor and time-intensive and require a lot more experience and diligence. Black market producers may spray harmful pesticides without hesitation since these products do not have to undergo analytical testing for contaminants and pesticide removal.
Pesticides may end up in the final product due to a variety of reasons, including accidental application of pesticides at a higher-than-recommended amount, close application of pesticides, and pesticide drift from the intended target such as nearby gardens and farms.
Dangers of Pesticide Exposure
Leftover pesticides in cannabis may be consumed by consumers through various delivery methods, including oral, sublingual, topical, and inhalation. For instance, when users inhale pesticide-laced cannabis flower or concentrates, it can go directly into the bloodstream. When consumed via edibles, residual pesticides may also be a health hazard.
In a handful of states, cannabis products can contain residual pesticides under a certain cut-off concentration. In Oregon, residual pesticide levels should not exceed 0.1 ppm. There are no federal guidelines on chronic exposure to residual pesticides from cannabis, so we do not know a safe cut-off point.
Studies on the health risks of inhaling common pesticide residues are lacking. In the small number of studies performed, however, research suggests that common pesticides can have toxic effects on public health, especially medicinal users with compromised health.
A 2015 study analyzed 57 concentrate samples for cannabinoids and residual solvents or pesticides. According to the research, “over 80% of the concentrate samples were contaminated in some form.” Pesticides were found in one-third of the samples. The most common pesticide found was paclobutrazol, not registered for use by the EPA on food crops.
Prior studies indicate that “up to 70% of [paclobutrazol] may be transferred into the smoke stream when present on cannabis.” Three common pesticides were found, including permethrin, bifenthrin, and diazinon. Medicinal patients may be especially susceptible to the toxicity of these contaminants.
Since cannabis is mainly consumed via inhalation (smoking and dabbing), users may be more exposed to higher toxicity levels. Inhalation bypasses the first-pass metabolism effect in the liver compared to oral consumption. In addition, cannabis smokers do not use a filter, increasing the concentrations of pesticides compared to filtered smoking.
Cannabis cultivation commonly uses a pesticide called piperonyl butoxide. While it is deemed safe by the FDA and many other states, it has shown to have health risks such as liver disease, cancer, and neurotoxicity.
Even natural pesticides like pyrethrins can pose certain health issues for consumers. According to the Agency for Toxic Substances and Disease Registry, pyrethrin exposure can affect brain and nerve function.
How Cannabis Extraction Concentrates Chemical Pesticides
Cannabis processors employ various extraction methods (BHO, CO2, ethanol) to strip the cannabinoids and terpenes from various grades of biomass. However, the extraction process can also concentrate many of the residual pesticides in the crude extract. For pesticide remediation, chromatography is one of the best methods to use.
Research has shown that pesticides can become concentrated to dangerous levels in extracts. A study from the Cannabis Safety Institute found that “the mean levels of pesticides in concentrates is higher than that found in flowers.” The “mean level observed on concentrates is roughly 10x higher than the mean for cannabis flowers.”
Researchers believe that pesticides become more concentrated in extracts like cannabinoids because they share similar chemical properties in terms of polarity and solubility. Even with these similarities, concentrates contain only about 2-5 times more cannabinoids than flowers. Pesticides contain 10 times higher concentrations in concentrates than flowers.
Pesticides may be more readily extracted by these extraction methods, resulting in a higher concentration compared to the efficiency of cannabinoid extraction. In addition, extensive contamination of closed-loop equipment and solvents can cause cross-contamination of pesticides in the end products.
Several states have varying regulations on testing cannabis samples for residual pesticides, heavy metals, mold, and other contaminants. Independent analytical laboratories use cutting-edge techniques like liquid chromatography-tandem mass spectrometry (LC-MS/MS) to screen for dozens of pesticides.
Pesticide use in cannabis cultivation poses serious public health and environmental concerns. In light of these vulnerabilities, consumers need standard consumer protections that significantly reduce or eliminate the use of pesticides in favor of an organic process that uses sustainable practices.
In the meantime, pesticide remediation methods throughout the supply chain can improve contaminated material and make them safe for consumption. Pesticide remediation efforts vary in sophistication, cost, and effectiveness. Flash chromatography is a highly recommended remediation method in the industry.
Pesticide Remediation Methods
Cannabis concentrates are becoming increasingly popular compared to traditional flower products. With the rise of the cannabis derivatives market, processors must find cost-effective and efficient methods to produce concentrated products that comply with state regulations and are safe for human consumption.
Pesticide remediation in cannabis concentrates can be accomplished with various methodologies, including:
Microbial decontamination is essential to passing analytical testing for high concentrations of mold, bacteria, and yeast that can be harmful to consumers. Microbial contamination can occur throughout the supply chain, from harvesting, drying, and curing methods to product storage and distribution due to environmental conditions.
Post-harvest microbial decontamination methods include:
- Ozone chamber decontamination: Ozone chamber decontamination occurs in a sealed chamber where the cannabis is exposed to ozone gas. Ozone gas can damage cell walls and kill its interior components (DNA, RNA, enzymes, etc.). Ozone gas has been shown to kill various microorganisms found in cannabis.
- X-ray chamber decontamination: X-ray chamber decontamination places the cannabis sample in a lead-lined chamber to be exposed to high-energy electromagnetic radiation. When the system is sealed, the x-rays destroy the microbes.
Flash chromatography is primarily used in the pharmaceutical industry for purification, decontamination, and chemical analysis. More recently, it has been adopted in the cannabis industry to isolate certain cannabinoids and remediate undesirable substances like pesticides from the concentrate.
Flash chromatography uses filter media in a chromatography column to remove the unwanted compounds while preserving many terpenes without using highly volatile chemicals like pentane. During flash chromatography, the cannabis extract moves through a stationary phase in filter media.
The mobile phase (crude extract) passes through the media. Compounds will travel through the stationary phase at different rates, some slower or some faster than others. Then, the desired compound (CBD or THC) is eluted into a collection vessel. The solution must be purged from the residual solvent to create a pure end product.
Cannabis extracts may contain various pesticides, each with a different polarity and solubility. If the stationary phase has a similar polarity to the pesticide chemical, processors may need to perform several runs of pesticide remediation with flash chromatography or use more aggressive remediation such as glass reactor remediation.
Glass Reactor Remediation
Glass reactor remediation involves running the cannabis extract through a glass reactor to remove water-soluble pesticides. Most pesticides are water-soluble, including myclobutanil, and able to be removed in a glass reactor.
The process involves mixing a solvent (pentane or hexane) and crude extract. In the reactor, the cannabinoids will not go into the water. Water-soluble compounds like pesticides will precipitate out. In addition, terpenes will also be removed to produce the distillate.
After the cannabis oil and solvent are mixed, the mixture settles, leaving a cloudy bottom layer with a pink or red color. This fraction will be drained with the water through the bottom. The top layer has hexane and cannabis oil. The process is repeated multiple times to pull out as many contaminants as possible.
In terms of pH, processors usually do not exceed a pH of 10 because they can begin to pull out THC at that level. Experts recommend a neutral pH or a slight variation, depending on the pesticides in the solution. A suboptimal pH level can cause isomerization in the flask when distilled and color changes.
The remediation process also requires a salination and desalination station to create and dispose of the saline solution. Processors will need equipment to evaporate the solution. For instance, California allows for a sand pit to pull out the salt.
Glass reactor remediation speeds up the process compared to flash chromatography and can remove most pesticides and contaminants, producing a refined distillate. In addition, glass reactor remediation may result in lower yield loss than in a chromatography column.
Aggressive Remediation Removes Terpenes and Cannabinoids
Cannabis pesticide remediation can use various filter types to remove the pesticides, each with varying degrees of effectiveness in remediation. While more aggressive filter variants such as bentonite-based filters provide stronger remediation of contaminants, they come at the expense of the extract’s cannabinoids and terpenes.
Lighter zeolite-based filter media like CRX, for example, does an excellent job of remediating color and other contaminants such as pesticides without a significant degradation of cannabinoids and terpenes. If stronger pesticide remediation is necessary, it may strip away the extract’s most valuable compounds.
Superior Remediation for Cannabis Extracts
Color remediation in cannabis extraction is an emerging technology with many pitfalls but even more success and promise. Finding the right SOPs, closed-loop equipment, and CRC filter media can make a world of difference in crafting clearer and more flavorful extracts while removing certain pesticides.
Media Bros is at the forefront of color remediation technology. We are proud to provide extractors with high-grade filter media and hardware that removes contaminants such as chlorophyll and pesticides without a major loss in cannabinoids and terpenes.
Shop our line of CRC technology for an efficient way to clarify your extracts while preserving its most valuable ingredients.