What Really Is "Pure" Cannabis
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One of the terms that is often used in the cannabis industry is “purity.” From a scientific perspective though, purity doesn’t actually have a lot of meaning; it simply implies that a substance is free of contaminants. And when it comes to a regulated consumable product like cannabis, that’s really a no-brainer.
When many people discuss purity in cannabis, they’re often talking about the more complete makeup of the plant or product. Making sure the contaminants are below a safe and acceptable level is part of the story, but the ideal goal is to have full knowledge of all the compounds that are present in a cannabis sample. This includes THC and CBD, as well as dozens of other molecules that must be tested and measured. After all, people deserve to know what they are putting into their bodies. This is where advanced analytical testing comes in.
To get this comprehensive view, a sample goes through a series of tests to provide the necessary data. It’s a complicated and highly scientific procedure — those who aren’t familiar with cannabis testing are often surprised to find how closely it resembles standard pharmaceutical work, with measures in place to protect sample quality and built-in procedures to validate the results.
All of this testing falls into two main categories: testing for safety and testing for efficacy. There are different tests for unprocessed cannabis and for the products (isolates and distillates) derived from cannabis, and these tests should happen at every step of the cannabis production lifecycle in order to protect the consumer and ensure a quality product.
Testing purity to ensure safety
Cannabis is an agricultural product and ensuring purity of the plant material shares a lot of similarities with the tests performed on any consumable agricultural product. The main priority is to make sure it’s safe to consume.
Safety tolerances are set regionally and are called “action limits” in the industry because they determine the limit at which action must be taken to protect the consumer.
Action limits also differ by intended consumption — what’s safe to ingest isn’t necessarily safe to inhale, because of how the compounds are converted and how the body processes certain chemicals. You generally can’t determine how unprocessed cannabis will eventually be consumed, so it must always pass the most stringent safety tolerances.
There are five main contaminants to test for: heavy metals, pesticides, residual solvents, mycotoxins, and microbial contamination.
Heavy metals: Major heavy metal contaminants include arsenic, lead, cadmium and mercury. These often appear in the plant as a result of contaminated soil, and they’re especially dangerous in products intended for inhalation. It’s important to ensure soil quality before growing, as polluted soil can easily ruin an entire crop yield.
Pesticides: It is easier to control for indoor and organic grows, but pesticides can be a persistent problem in outdoor crops. This is because even the most cautious operation is still at the mercy of their neighbors; winds can carry pesticides from adjacent farms and contaminate cannabis crops. And because action limits on pesticides are stricter for inhaled products than ingested products, this cross-contamination can be a major issue.
Residual solvents: Most common cannabis extraction methods require the use of a solvent, such as ethanol, CO2, propane, butane or other elements. After extraction, it must be ensured that the solvent is no longer present in the material as the residue could be harmful to the consumer. This test is not required for, and does not apply to, cannabis flower, as no extraction is done and no solvent is used.
Mycotoxins and microbial contaminants: Mycotoxins come from fungi and mold, and they can be downright deadly. Microbial contaminants include bacteria and other dangerous microorganisms. The presence of either in a sample often indicates issues with cleaning procedures or a contaminated environment.
It’s vital to repeat safety testing when extracting isolates and distillates to create products like edibles, beverages, topicals and transdermals. Extraction is a matter of concentration and filtration — as you process the plant to concentrate its potency, you must filter out all traces of these contaminants or their concentration can increase as well.
Testing to ensure efficacy
Once a product is found safe to consume, we can start thinking about the quality of the desired effect. In other words, does a cannabis product work as expected? This is where it becomes important to understand everything that is happening within your sample.
These tests focus on determining the content and concentration of cannabinoids and terpenes. More than 100 cannabinoids have been discovered so far, and there is an incredible amount of research being conducted into the specific effects and applications of each one. Terpenes are aromatic compounds that help give cannabis strains their recognizable characteristics. By profiling the cannabinoids and terpenes present in a sample, it helps licensed cannabis producers inform their consumer about exactly what they’re getting.
In a very real sense, this is what “purity” means to a lot of people. You want the consumer to know what to expect and to ensure that there is a consistency to the product. But with cannabis, as with any agricultural product, it is extremely difficult to create the exact same thing time and time again. Every crop yield will be slightly different, and even products created through extraction could fluctuate from batch to batch.
This is why it’s vital to test continuously. The more you test, the more complete your understanding of your product will be. In this regard, cannabis purity is really a matter of transparency: It is exactly what you say it is, and you have the data to prove it.