Hemp is a cannabis plant variety that is grown for its fiber that is extracted from the stalk and is used to make rope, stout fabrics, fiberboard, paper, plastic, insulation, and many other products. Cannabis plants of the hemp variety are very tall and narrow and usually produce very few flowers (or buds).
Currently, hemp is imported from the EU, Eastern Europe, or China, or grown in the U.S. by hemp farmers. Roughly 39 U.S. states allow hemp cultivation and production.
In the U.S., hemp plants must contain less than .03% THC by volume. Consequently, hemp plants, when used to produce cannabis products (such as oils), are typically used to produce products with other cannabinoids, such as CBD and CBG. Products that include cannabinoids other than THC are non-impairing and can still offer medical benefits.
For example, there are many high-CBD products on the market. Some of these products are hemp-derived (meaning that the cannabinoids are extracted from mostly the stalk of a hemp plant), and some of the products are flower-derived, meaning that the cannabinoids are extracted mostly from flowers produced by cannabis plant varieties other than hemp.
To produce a hemp plants in the United States, a grower must be licensed in their state either as an industrial hemp farmer or as a cannabis grower. Of course, not all states provide these licenses, and each type of license has unique parameters, rules, and regulations. While it is against federal law to use hemp leaves and flowers to make any drug product, hemp manufacturers attempt to sidestep these laws by claiming that they extract the cannabinoids only from the stalk. Some U.S. manufacturers simply ignore federal law and produce hemp oil from high-resin, CBD-rich cannabis plants and call it hemp (these products are extracted from flowers and typically have slightly more than .03% THC).
Patients at Radicle Health often ask about hemp-derived CBD products because you can order them online and ship them to any home address. What are the benefits and disadvantages of hemp-derived CBD products, especially when compared to flower-derived CBD products?
The one benefit of hemp-derived cannabis products is access. These products are available in all 50 states. Patients who live in states where cannabis is not legal or in areas where access is an issue can still obtain hemp-derived cannabis products. For example, in states with no access to cannabis products, some patients might combine hemp-derived CBD with Marinol and Nabilone to achieve better results than with the pharmaceuticals alone.
What are the disadvantages of hemp-derived cannabis products?
First, hemp-derived products often contain heavy metals, pesticides, mold, bacteria, and other toxins.
Cannabinoids, terpenes, flavonoids, and other compounds are produced by cannabis plants and stored as resin in trichomes, which are microscopic mushroom-shaped protuberances that form on the flowers, the stems, leaves, stalk, and root of cannabis plants. The trichomes that form on the stalk, stems, roots, and leaves of cannabis plants are different than those that form on the flowers—they are shaped differently and they do not contain the number or diversity of chemical compounds as those found on flower trichomes—there are far fewer trichomes on the leaves, stalk, and stems than on the flowers. For example, the trichomes on the flowers contain approximately 18 times the amount of cannabinoids than those found on the leaves and stalks.
Therefore, it takes a large amount of hemp plant to produce a very small amount of cannabis oil. Some hemp manufacturers will point out the obvious—cannabis molecules, such as CBD, are the same whether they come from hemp stalks or from flower. So, why does it matter whether you produce cannabis products from a large batch of hemp plants or from small batch of cannabis flower?
Hemp plants are bio-accumulators—they readily absorb nutrients, metals, and toxins from the soil. In fact, for almost two decades, industrial hemp has been planted near the abandoned Chernobyl nuclear power plant in Pripyat, Ukraine to help reduce soil toxicity.
When hemp plants are sourced from unregulated markets (and, they often are), they can be riddled with heavy metals, mold, bacteria, pesticides, and other contaminants, which can block receptors and cause any number of health issues.
A second disadvantage of buying hemp-derived cannabis products is that they are often mislabeled.
All flower-derived cannabis products must undergo rigorous testing and be sold only through licensed dispensaries or delivery companies. You can obtain the test results to verify that they’ve been tested for mold, bacteria, pesticides, and metals. You can also verify the terpene and cannabinoid content.
Hemp-derived cannabis products, however, are regulated in the U.S as diet supplement—you can buy hemp-derived CBD products from a gas station, a health food store, or on the internet (in many states, including California, the one place where you cannot buy hemp-derived products is from a cannabis dispensary). The FDA is not authorized to review dietary supplement products for safety and efficacy before they reach the market place. Many of these products offer no assurances about efficacy, do not list ingredients, and do not provide any testing results.
By February 2016, the FDA had tested 24 products that claimed to contain CBD. Only two of the 24 CBD products contained the amount of CBD claimed on product labels (more specifically, 11 of the products did not list the amount on the label, eight failed outright, and three others failed but were close to the stated amount). These results were duplicated in another study published in JAMA in 2017. 
Bottom line: when possible, try to get cannabis products made from cannabis flowers. Radicle Health recommends that, when buying any cannabis product, choose only products for which you can:
Verify the source. Look for products grown in the U.S., especially from states with legal cannabis. These states typically have stringent laws regulating the production of cannabis products.
See test results. This includes testing for mold, bacteria, pesticides, heavy metals, cannabinoids, and terpenes.
Verify the extraction methods. Avoid products extracted with hydrocarbons (such as butane, hexane, and propane) or isopropyl alcohol.
Verify that there are no additives in product. This is especially important when buying concentrated cannabis products, such as vape pen cartridges.
Contrary to belief, these products are not, in fact, legal in all 50 states. The 2014 Farm Bill is often cited as evidence that CBD-derived from industrial hemp is now legal. This federal bill, however, legalized only a narrow set of hemp cultivation activities—basically, it is legal to grow hemp under a state pilot program or for academic research. Some states have set up their own hemp guidelines. Colorado, for example, has a robust industrial hemp program where the first U.S.-bred certified hemp seed has been manufactured.