Cannabis Pesticide Testing

The cannabis industry broadly refers to all insecticides, fungicides, and acaricides as pesticides. Pesticide analysis is typically performed with LC-MS/MS where the cannabis sample is prepped in an extraction solvent that is at a lower dilution factor compared to what is used for cannabinoid potency analysis since the concentrations of trace pesticides are much lower. As with the cannabinoids, the sample goes through reverse phase LC column to separate out the compounds. These compounds then get introduced in the tandem mass spec system, where they get separated by mass to charge ratio in quadrupole number one, get fragmented at compound specific parameters in quadrupole number 2, and then those ion fragments get separated and detected once they pass through quadrupole number 3. This gives a “fingerprint” of the pesticide based on the retention time on the LC column, mass to charge ratio of the parent ion, the detection of at least 2 fragment ions at specific instrumental parameters, and the ratio of those 2 ions.

Depending on the pesticide list, a separate GC-MS/MS would need to be employed because pesticides such as captan, chlordane, chlorfenapyr, parathion methyl, and pentachloronitrobenzene are difficult analyze with electrospray ionization used LCMS systems. With LC-MS/MS highly diluted liquid samples are injected onto a column in an HPLC system, the compounds get separated, and then these compounds are ionized, selectively transported through a system of quadrupoles, and then come in contact with an electron multiplier detects the signal.

California, Oregon, Washington, Nevada, and Colorado are the furthest along for adopting steps to regulate pesticide use in cannabis. Florida, Illinois, Massachusetts, Maryland, New York, and Pennsylvania are taking steps to regulate pesticides in cannabis. Oklahoma is currently requiring the testing of 13 pesticides for all cannabis products.

Patient protection is the motive for testing all medical marijuana for pesticides. Research denoting what constitutes a “safe” pesticide level does not exist for cannabis or other smoked / inhalable products. There have been toxicological studies done showing safe amounts of pesticides for food products consumed. Smoking a product is significantly different than eating a product. An inhalable product completely bypasses your liver which is able to break down trace amounts of contaminants at levels examined by toxicological studies done to edible agricultural products. A prime example of this difference can explained with the pesticide myclobutanil. This pesticide is generally safe of fruits and vegetables where it is typically washed off before consumption. However, when it is burned, hydrogen cyanide is a combustion product.

Pesticide regulations in California and Oregon are some of the strictest in the country. Even though California has enacted the strictest pesticide regulations in the country they are also fair. They take into account the people will use some pesticides on outdoor grown cannabis and that is the potential for over spraying from neighboring farms. They segregated a list of 66 pesticides in two categories. Category 1 involves 21 pesticides which are completely banned. These pesticides are not approved for use on food crop and any detection in cannabis would cause the batch to fail. The other 45 pesticides are classified as category 2 which impose specified limits for a passable range. Although, these limits have faced criticisms for allowing something that has had no toxicological scientific studies done on inhalation exposure, with or without burning. Ingestible products such as foods have pesticide reference doses established by the US EPA and other regulatory agencies. Unfortunately, for cannabis that is either smoked or vaped, there is no toxicological data for pesticides to use as a template for formulating acceptable limits. Oklahoma has enacted less stringent regulations and only requires the testing of the following 13 pesticides: Spiromesifen, Spirotetramat, Tebuconazole, Etoxazole, Imazalil, Imidacloprid, Malathion, Myclobutanil, Azoxystrobin, Bifenazate, Abamectin, Permetrin, Spinosad. These pesicides must not exceed 0.5 ppm (parts per million). This list is expected to grow if the state’s surveillance laboratory notices the appearance of other pesticides in randomly tested samples.

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