Cannabis cultivation has become the largest cash crop industry in Maine, and one of the state’s most valuable alternative revenue sources. However, like any agricultural sector, cannabis cultivation faces the challenge of pest management in both indoor and outdoor grows. A standard practice in traditional agriculture has been the application of pesticides. However, this does not directly translate to cannabis as the safety of pesticides on plants used for smoking, vaping, inhalation, etc. has not been studied. In addition, pesticide application in the cannabis industry comes with its own set of regulations.
Pesticides used in cannabis cultivation can generally be classified into three major categories: insecticides, fungicides, and acaricides. Insecticides are used to kill insects that can damage the plants, such as spider mites and aphids. Fungicides are used to prevent or treat fungal diseases, such as powdery mildew and botrytis. Lastly, acaricides are used to control populations of mites. Some pesticide products are also combined with plant hormones and growth regulators, such as Daminozide (Alar) or Paclobutrazol. These substances also present similar regulatory and safety concerns.
The use of pesticides in cannabis cultivation is a controversial topic across the nation. Unlike other agricultural crops, there is no federal regulation governing the use of pesticides in cannabis cultivation, and the Environmental Protection Agency (EPA) has not approved any pesticides for use on cannabis plants. This means growers must rely on state regulations, which vary widely depending on the state. Here in Maine, there is a list of 66 total compounds that are monitored for use in cannabis cultivation (check out this page to get the full list).
Depending on the compound, pesticide residues can pose a significant risk to human health. Ingesting or inhaling pesticide residues has the potential to cause a range of health problems, including respiratory issues, neurological disorders, and reproductive problems. Inhalation is considered the most sensitive exposure pathway into the human body. Unlike ingestion, which goes through the digestive system before entering the blood, anything inhaled will go directly to the body’s bloodstream. Long-term effects of exposure to pesticides and exposure through inhalation are not well understood. Research is ongoing to determine their potential impact on human health but, to date, no actionable research has been presented to indicate any pesticide is safe for use in cannabis cultivation.
A common misconception about pesticide usage with cannabis is that pesticides can be used during “non-flowering” stages of growth. It is important to note that no matter what stage of growth cannabis plants are in, using pesticides around these plants runs a high risk of testing positive on a pesticide test. Furthermore, indoor grows that use pesticides in an empty room (e.g. bug bomb between grow cycles) have a high chance of contamination. These compounds rest in soil, water, HVAC systems, and remain on surfaces for weeks. Plants exposed to these environmental sources will accumulate and collect pesticides in the plant tissues over time. Of note, some pesticides have half-lives of several years, which can pose a great challenge when trying to remove pesticides from a contaminated environment. Complete disassembly and washing in oxidizing or other agents is often the only course of action but, is not always completely effective.
Cannabis is an amazing bio-accumulator, which means the plant has a tendency to extract and concentrate compounds like pesticides in its tissues. When a pesticide is sprayed it can be absorbed by the plant through the leaves, stems, and roots. Once inside the plant, the compounds can move through the vascular system and accumulate in various plant tissues. As the plant grows, the concentration of pesticides in its tissues can increase, leading to higher levels of pesticide residues in the final product. Contaminated biomass that is processed through extraction can increase the levels of pesticides per gram of material even more and contaminate extraction equipment and subsequently processed batches.
Pesticide contamination has even been observed in plants when the cultivator has not applied any. In these cases, there is almost always an environmental contamination source. For example, a neighbor treats their lawn and the aerosol is pulled into the HVAC system and circulated with plants. Even organic soils have had pesticides detected in them. It is important to certify and check your raw materials for pesticides prior to use.
On the testing side, it is important to understand that pesticide analysis is designed to detect specific compounds. In some cases, certain compounds can be found in both “classic” pesticides as well as “organic” sprays. Always be aware of the full ingredient list before using anything in or around your grow. You can always opt for an R&D test first if you are considering bringing a new product into your facility!
At Nova, we take several steps to ensure analysis and detection of pesticides are accurate and precise. Detection of these compounds is done using a technology called mass spectroscopy coupled with high-performance liquid chromatography. Identification of compounds in client samples is made against a known certified reference material (CRM). This means we match the molecular weight of the compound and its chromatographic properties in the CRM against the sample under analysis. If the responses align and meet several acceptance criteria, a positive identification can be made.
In addition, quality control is used to ensure the assay is performing to specification. This means prepared samples containing CRM at known concentrations are analyzed alongside client samples. Proper identification and quantification of these quality control (QC) samples indicates the assay is working and client samples can be verified.
Sample handling and cross-contamination are other concerns that are carefully handled. For this reason, all labware that comes in contact with the client sample is a clean one-time-use piece of labware. Contamination checks are conducted contemporaneously with each analyzed sample. This means known negative samples are processed alongside unknown samples to ensure no in-lab source of contamination is made throughout the process.
The use of pesticides in cannabis cultivation is a complex issue that requires careful consideration. While pesticides are essential for protecting crops, they can also pose a significant risk to human health. To avoid pesticide contamination in cannabis cultivation, growers should test for pesticide residues and avoid any products that contain non-approved compounds. Nova Labs offers pesticide swabbing for cannabis facilities which can help track down environmental contamination sources. The cost for facility swabbing, soil, air, and water testing upfront is less than an entire wasted crop due to pesticide contamination. Currently, Maine does not allow remediation for contaminated material and requires that it be destroyed. If you’d like to set up a facility visit call the lab at 207-466-4661 or email us at email@example.com. In addition, we can test any commercial products used as well as your soil and water.
By understanding pesticide usage in the cannabis industry and taking the steps to avoid any unintentional contamination, cannabis growers can continue to produce safe and high-quality products for their consumers. Nova is here for you every step of the way to answer questions, perform R&D testing, and conduct facility visits upon request.
Taylor, A., & Birkett, J. W. (2019). Pesticides in cannabis: A review of analytical and toxicological considerations. Drug Testing and Analysis, 12(3), 180–190. https://doi.org/10.1002/dta.2747
Overton, P. (2020, December 8). Marijuana has grown to become Maine’s most valuable crop. Portland Press Herald. https://www.pressherald.com/2020/12/08/marijuana-maines-most-valuable-crop/#:~:text=Cannabis%20is%20now%20Maine’s%20most,to%20state%20sales%20tax%20figures.
Seltenrich N. (2019). Into the Weeds: Regulating Pesticides in Cannabis. Environmental health perspectives, 127(4), 42001. https://doi.org/10.1289/EHP5265
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