How Much THC Is In Hemp?

Answering how much THC is in hemp is a much trickier question than most people expect. This figure is based on a set of policies enacted on the arbitrary decision made by Canadian researchers back in 1976. Now, 45 years later, American farmers are still dealing with the consequences of that call. How did the U.S. authorities decide how much THC hemp can contain before the plant becomes federally illegal “marijuana?” 

In this blog, you will learn:

  • The legal distinction between industrial hemp and “high THC marijuana”

  • The regulatory headaches this limit can impose on farmers

  • Why industrial hemp growers must test for THC

  • If the cannabis and hemp industries fundamentally agree with the THC limit set out by lawmakers

Comparing hemp and “marijuana”

Before explaining how much THC is in hemp, it’s important to detail the difference between hemp and other cannabis historically and legally.

What is cannabis sativa? All cannabis sativa is classified as flowering plants within the Cannabaceae family. There is no taxonomic difference between hemp and its higher-THC cousin, although there are generally differences in phenotype, or how the plant appears. The shape of the plant’s leaves, its maximum height, or the “bushiness” of the plant are all examples of differences in phenotype between hemp and high-THC cannabis. Aside from these traits, all cannabis varieties are the same species of plant.

What are the uses for hemp and high THC cannabis? Historically, hemp and high-THC cannabis have different uses. Stalky, low-THC hemp was primarily used to make rope, ship sails, and textiles, while higher-THC marijuana had medicinal and spiritual applications in many cultures throughout the world. This rich history, which goes back thousands of years, influences how both varieties are currently regarded in the United States. Today, you’ll find hemp as the source of a dizzying array of agricultural products, including food, textiles, and building materials, while high-THC cannabis is primarily used for phytocannabinoid (and increasingly terpene) ingestion and extraction. 

What about CBD - where does that come from? One of the key similarities in use cases is in the extraction of Cannabidiol (CBD). When extracted from industrial hemp, CBD is legal in almost every state for interstate commerce (as of summer 2021, Idaho and Iowa were the only two holdouts), for use in products like tinctures, topicals, and vaping products. When sourced from high-THC cannabis, CBD can only be sold in state-regulated programs, subject to state requirements for testing, labeling, manufacturing, and other requirements. The CBD from both plants is the same; the only difference is the amount of THC content present in each source plant.

The law draws the line: How much THC is in hemp?

Despite its historic differences and the variations in appearance, the difference between hemp and other cannabis plants is purely a legal distinction. According to the U.S. Department of Agriculture (USDA), hemp, also referred to as “industrial hemp,” cannot contain more than 0.3% tetrahydrocannabinol (THC) by dry weight. By the USDA’s definition, “THC” includes any and all THC, including THCa, the precursor to THC. It is not limited to just delta-9 THC, the type that causes intoxication; prior definitions were specific to delta-9 THC. Any cannabis plant that contains more than 0.3% THC is considered federally restricted “marijuana,” a Schedule I controlled substance. Just a smidge above 0.3% THC, and the “hot hemp” can no longer be sold or used in interstate commerce.

The 0.3% THC distinction comes from a 1976 study conducted in Canada. This study determined that the researchers would “arbitrarily adopt” this figure as a method of determining industrial hemp from high-THC cannabis. Canada adopted this standard, and the United States followed suit.

The main takeaway: Authorities have designated that hemp cannot contain more than 0.3% total THC content.

Why the 0.3% THC limit causes headaches

The 0.3% THC cap on industrial hemp can place undue strain on farmers, especially those who have no intention to extract phytocannabinoids from the hemp biomass they grow. THC levels in industrial hemp begin to increase during the flowering stage and decrease afterward. Additionally, industrial hemp contains THCa, the acidic, non-active form of THC. THCa converts into active THC over time.

These two factors make timing one of the most important aspects of testing hemp for THC. Harvested at just the wrong moment, and industrial hemp may fail testing. The consequences of failing are significant: in many cases, the crop needs to be destroyed.

The arbitrary need to be held to a THC limit means that often plants are harvested before they are mature in such a way that they would be ideally used for fiber, seed, or other uses. It would be like harvesting all tomato plants when the tomatoes were still green because a chemical level in the red tomato may be slightly elevated. That chemical has no bearing on the maturity of the plant. It is just an artifact and a metric that has been chosen by lawmakers.

The main takeaway: The 0.3% THC cap places an undue burden on farmers, especially because such low amounts of THC are not significant enough to have an effect on consumers.

Do the hemp and cannabis industries agree with this distinction?

The seemingly arbitrary selection of 0.3% as the THC threshold for industrial hemp has faced backlash from multiple hemp advocacy groups and industry organizations, particularly since the 2018 Farm Bill descheduled industrial hemp and its extracts as a controlled substance.

For example, hemp farmer organization Vote Hemp has advocated to raise the 0.3% THC threshold to 1%. A petition on their website says that the old standard is one that “does not work for farmers or the hemp industry,” and that raising the limit to 1% is necessary so “farmers can grow hemp crops without fearing that they will later have to destroy them.”

In 2020, the Hemp Industries Association (HIA) filed a claim against the U.S. Drug Enforcement Agency (DEA), the body which set interim final rules for industrial hemp production in light of the 2018 Farm Bill’s descheduling. In their complaint, the HIA said that maintaining the 0.3% distinction for hemp farmers “threatens every stage of the hemp production supply chain.” This claim was dismissed, but similar charges facing in other courts brought by the HIA still remain. 

Numerous figures in cannabis science and research have spoken out against the 0.3% THC cap as well. Famed neurologist and cannabis researcher, Dr. Ethan Russo, has called a 1% THC cap for hemp a “scientifically defensible” position, citing that THC levels under 1% are generally not intoxicating enough to be impactful for adult-use consumers. 

Outside of the cannabis and hemp industries, “mainstream” agricultural organizations have taken stances in favor of increasing the THC limit in hemp, citing the strain such regulations can place on farmers. The American Farm Bureau Federation, for example, voted in favor of advocating for 1% THC limits, so hemp farmers have more time to obtain THC testing.

Lawmakers have come out in support of raising the THC limit on industrial hemp, too. U.S. Sen. Rand Paul (R-KY) drafted and filed the Hemp Economic and Mobilization Plan Act of 2020. Among other actions, the bill would require hemp products themselves, not the source plant, to test for THC. It would also create a margin of error, currently not supplied by the USDA outside of a “measurement of uncertainty,” to allow for more leeway in testing. Notably, Kentucky, which Paul represents, is one of the largest producers of industrial hemp in the United States. The act was reintroduced in the U.S. Senate on March 30th, 2021.

Testing for THC content in hemp

What are the guidelines? The USDA has released laboratory testing guidelines for hemp grown under a federal, state, or tribal program. The requirements say that the analytical laboratory performing the test should “perform chemical analysis on the sample using post-decarboxylation or other similarly reliable methods where the total THC concentration level considers the potential to convert delta-9-tetrahydrocannabinolic acid (THCa) into THC.” While the laboratory is not required to be ISO accredited, the USDA “strongly encourages” farmers to work with labs that meet the ISO 17025 standard. True Labs for Cannabis is in the process of setting up and becoming operational, and as part of this process, we are becoming an ISO 17025 accredited testing lab.

Testing hemp for contaminants: Testing for contaminants and In addition to testing for THC as required by law, hemp samples should be tested for contaminants that could affect product quality and safety. Chief among these is heavy metal contamination. This is because hemp is a bioaccumulator that draws out contaminants from the medium from which it is planted. This puts hemp at risk for higher levels of heavy metals that are unsafe for human consumption, such as lead, mercury, arsenic, and cadmium. While voluntary, these tests ensure that the products in question are pure and safe for human (and animal!) consumption and application.

Hemp testing with True Labs for Cannabis

As you look for a New Jersey laboratory that can test your industrial hemp samples for total THC, delta-9 THC, and contamination, reach out to True Labs for Cannabis. Our analytical laboratory is one of the few women-owned labs in the U.S. and among the few in New Jersey to have opened their doors purely to serve the needs of cannabis and hemp companies in the Garden State. Our facility brings the highest standards in purity and quality, using state-of-the-art technology to go above and beyond state (and in hemp’s case, federal) requirements to ensure your product is compliant, safe, and clean. 

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