Suddenly CBD seems to be everywhere.

I’ve come upon it in pharmacy chain stores and gas stations. My dog kennel sells CBD (cannabidiol) gummies for pets, and multiple massage spas in the D.C.-metro area offer “CBD-infused relaxation” through lotions, oils and sprays. There are at least four cafes within a 15-minute walk of the White House that sell CBD coffee.

Yet here’s a strange fact about the overnight ubiquity of these products: Selling them is illegal. That’s true even though the 2018 Farm Bill removed legal restrictions on CBD if it’s derived from hemp plants.

What’s equally strange: Buying CBD products is legal…at least sometimes.

This paradox is one of many in America’s long history of both utilizing and criminalizing cannabis. As marijuana, cannabis has been a tool for relaxation, as well as an element of mass incarceration — but also for medical benefits, like to fight the side effects of cancer chemotherapy.

That tension is something two professors and their students are trying to better understand at the University of Connecticut, which launched the nation’s only college course on growing weed earlier this year.

While “there are all sorts of classes to train lawyers to understand cannabis law and programs for medical practitioners to learn how to dispense medical marijuana,” said Gerry Berkowitz, a 20-year professor of plant science who co-runs UConn’s new course, this is the first in decades to focus on questions like: How exactly does this stuff grow and how can we use it?

They’re among many in the U.S. who are peering through the fog of the clinical claims, legal quagmires and social stigma around weed.

Cannabis, which has been cultivated by humans for at least 12,000 years, is “one of the oldest plants on record as having been used for human benefit,” said Shelley Durocher, a UConn research grower who manages the hemp greenhouse for the class. It’s a fascinating plant that occupies a unique space in the natural world, Durocher said, one that has helped shape the modern existence of Western countries like the U.S.

As hemp, its fiber made the sails that carried European colonists across much of the known world. It was so fundamental to America’s foundations that its image was printed on money. George Washington was notoriously bad at growing hemp, though.

“Began to separate the Male from the Female hemp…rather too late,” Washington penned in his diary in August 1765. (We’ll get to why that’s a problem later.)

Photo by poylock19/Adobe Stock A cheat guide to CBD If you’re looking for the abridged version of this story so you can pass your “pot” quiz, here are the main takeaways. The 2018 Farm Bill legalized the production and sale of hemp and its extracts. Hemp, by federal law, cannot contain more than 0.3 percent THC (tetrahydrocannabinol). Anything with more THC is classified as marijuana, is considered a schedule 1 drug by the Drug Enforcement Administration and is federally illegal.

Hemp, by federal law, cannot contain more than 0.3 percent THC (tetrahydrocannabinol). Anything with more THC is classified as marijuana, is considered a schedule 1 drug by the Drug Enforcement Administration and is federally illegal. A hemp crop can accidentally start growing marijuna packed with THC because of pollination and sexual reproduction. (Cannabis plants are typically either male or female). Unexpected pollination can easily happen in outdoor fields, given cannabis plants grow abundantly in the wild and their pollen can travel for miles. If your CBD comes from a marijuana plant, it’s illegal. If your CBD contains too much THC (more than 0.3 percent), it’s illegal.

packed with THC because of pollination and sexual reproduction. (Cannabis plants are typically either male or female). Unexpected pollination can easily happen in outdoor fields, given cannabis plants grow abundantly in the wild and their pollen can travel for miles. If your CBD comes from a marijuana plant, it’s illegal. If your CBD contains too much THC (more than 0.3 percent), it’s illegal. The extraction process for CBD and THC is essentially the same. As a consequence, CBD can be contaminated with THC, chemical solvents or pesticides if the extraction is done improperly.

As a consequence, CBD can be contaminated with THC, chemical solvents or pesticides if the extraction is done improperly. The only approved health use of CBD is the seizure drug Epidiolex , despite having many other suspected benefits. The FDA prohibits the sale of CBD in any unapproved health products, dietary supplements or food — which literally means everything except for this epilepsy drug.

, despite having many other suspected benefits. The FDA prohibits the sale of CBD in any unapproved health products, dietary supplements or food — which literally means everything except for this epilepsy drug. If CBD comes from a hemp plant with less than 0.3 percent THC, you can buy it under federal law — but some states still have legal restrictions on the possession of CBD.

Cannabis’ reputation has shifted significantly since then, from vital resource to societal ill to maybe something in between.

Berkowitz and professor Matthew DeBacco launched the class at UConn — called “Horticulture of Cannabis: from Seed to Harvest” — to fill a desperate need in the ever-budding cannabis industry, with U.S. sales expected to reach $80 billion by 2030. Three years ago, another of Berkowitz’s undergrad classes took a field trip to one of Connecticut’s medical marijuana producers.

“The owner said his head grower learned their trade by growing pot in their basement,” Berkowitz said. In pointing this out, he was not trying to throw shade on these employees, but rather emphasizing that many of the growing practices in the marijuana industry aren’t typically standardized nor backed by research.

Which brings us back to those CBD lotions and lattes — and how they can be both legal and illegal.

Due to the way cannabis plants naturally grow and breed, many CBD products in stores contain the same drug that makes marijuana federally illicit — THC or tetrahydrocannabinol.

And even if you make sure that your CBD is pure, some federal agencies and state laws still forbid it — even in places where medical or recreational weed is legal.

So before you add CBD to your routine, it might help us all to head back to school for a few science lessons that explain how cannabis is grown, how the compound is collected, and the ways it might benefit and harm your health.

What is cannabis?

Cannabis has many names, strains and varieties, including hemp and marijuana. But these days, they’re all considered one species: Cannabis sativa.

“Marijuana” is any cannabis plant with abundant amounts — technically, more than 0.3 percent — of the mind-altering drug THC. Though 11 states and Washington, D.C., have legalized recreational marijuna, this version of cannabis remains federally illegal and classified as a schedule 1 drug by the Drug Enforcement Administration.

“Hemp,” by contrast, cannot legally contain more than 0.3 percent THC. There are almost no restrictions on the hundreds of other compounds made by the plant, such as terpenes (which are responsible for weed’s “distinctive” aroma).

One noteworthy contradiction in weed law: Marijuana can also produce CBD. If your purified CBD comes from hemp plants, it is federally legal, but if it comes from a marijuana plant, it is illegal. That’s because marijuna plants themselves are prohibited by the DEA.

CBD versus THC

The most obvious hurdles to making pure and legal CBD arise from being unable to tell marijuana and hemp plants apart.

Just try it for yourself:

“So how do we make a distinction when … basically looking at the plant structure, you really can’t tell the difference?” DeBacco, one of the cannabis course professors, asked us on the campus quad after class (located in the university’s largest lecture hall, due to its popularity).

His answer: “You’ve got to go beyond what they look like to the chemical profiles.”

Scientists suspect cannabinoids protect the plant from UV rays, much like sunscreen does for human skin.

Both THC and CBD are members of a chemical family called cannabinoids. Cannabinoids are plants oils, and cannabis comes packed with more than 100 versions of them.

Scientists suspect cannabinoids protect the plant from UV rays, much like sunscreen does for human skin. They think that because up to a quarter of a cannabis plant’s weight can come from just cannabinoids — and cannabinoid levels change with light exposure. “At the top of the plant, you’ll get more cannabinoids, compared to flowers that are at the lower end of the plant,” graduate student Peter Apicella said.

Cannabis makes most of its cannabinoids in its flowers, which are more commonly called “buds.”

“If they don’t get pollinated, the buds will essentially just keep growing and keep producing cannabinoids,” Apicella said.

This is true of both CBD and THC. The only chemical difference between them comes down to a couple of chemical bonds.

All cannabinoids start out as a bit of sugar, which hitchhikes around the plants’ enzymes, changing its identity, bit by bit, with each ride. In some cases, this wandering sugar reaches a crossroads, where it can either can bum a ride from one of two enzymes: THC-a synthase or CBD-a synthase. One route leads to becoming THC, the other to becoming CBD.

But in hemp, THC synthase is genetically dormant, Apicella said. As a result, some hemp plants can make loads of CBD because there is no internal competition for making THC.

“With other highly valuable crops — like saffron or vanilla — you get a small percentage of the plant that’s actually usable yield,” Apicella explained. But with hemp, “it’s a huge amount.” Some strains have are upwards of 12 to 15 percent CBD by weight.

How a hemp crop can sometimes become marijuana

Thanks to the “miracle” of reproduction, a hemp crop can start off making only CBD and then unwittingly turn into a THC-laden field of marijuana.

Let’s just say that again because it is a bit mind-blowing. A hemp crop — that is federally legal and only makes CBD — can become marijunana. Studies have found that if two certifiable hemp plants hook up, most of their offspring will be able to make THC. In fact, some of these seedlings will ONLY make THC.

Cannabis is abundant in the wild — meaning an outdoor hemp field is one gust of pollen away from accidentally breeding marijuana.

The wild card for hemp growers is pollination. Most flowering plants boast both male and female parts. They’re hermaphrodites that can mate with themselves. But a cannabis plant is an exception, in that it is almost always either female OR male. And when the plants reproduce sexually, their traits mix and once dormant genes — like those behind THC production — can suddenly be replaced with active versions.

Any biological organism is going to fluctuate — a variable that farmers and growers are always really concerned about, Apicella said.

So to prevent sexual reproduction, UConn’s greenhouse smashes the (cannabis) patriarchy. You don’t want a male in your greenhouse, Apicella said: “If there’s a male, your whole crops can be destroyed.”

So UConn’s greenhouses only grows female hemp plants — all of them are clones. There’s even a small pistil — called a preflower — on young plants that allows horticulturists to identify females without a genetic test.

To grow an all-female group, “you snip a part of a plant off, and you put it in soil with a little rooting hormone and that cutting is actually genetically identical to that first mother plant that you took from,” Apicella explained, raising his arms and pointing to a long row of hemp plants. “So these are all genetically identical to one of the mother plants we have in here.”

Keeping a greenhouse all-female is easy, but it’s a different story growing hemp outdoors.

Cannabis is abundant in the wild — meaning an outdoor hemp field is one gust of pollen away from accidentally breeding marijuana.

The other way that THC can sneak into your CBD bottle

To collect CBD or THC from hemp, farmers harvest the plants and send them to an extractor, who collects the drugs and preps them for sale. The issue is that extracting CBD or THC is essentially the same process. If your supplier does it incorrectly, your CBD bottle might carry an illegal dose of THC.

“It happens all the time,” said Rino Ferrarese, COO of the medical marijuana extractor CT Pharma, who is frustrated by low-quality and tainted products flooding the CBD market. Under Connecticut law, Ferrarese’s company must ensure their products match the labels on their bottles — which they accomplish through pharmaceutical-grade extraction.

Ferrarese said many states across the country do not hold their CBD suppliers to the same standards and federal enforcement is lacking.

“What a lot of consumers don’t realize is that the FDA, who’s charged with protecting our safety with respect to food and medicine in the U.S., are not on top of policing those CBD products that you see in the gas station or at the grocery store,” Ferrarese said. “A lot of these products are also not under the purview of departments of public health either.”

As a lark, he and others at the company keep tabs on the sloppy and sometimes illicit products flooding the CBD market. Ferrarese said the results vary widely, and rarely do these products ever meet the claims on their labels.

Image by spyrakot/via Adobe Stock The math that’s fueling the CBD green rush A little math can explain why farmers and suppliers are excited about CBD. To make CBD, farmers can grow up to 4,000 hemp plants in an acre. A single hemp plant can make about a half kilogram of plant material for CBD extraction. A half kilogram of this cannabis material can yield about 75 grams of CBD, according to Rino Ferrarese, COO of the medical marijuana extractor CT Pharma. That much CBD can make about 350 bottles of lotion, he said, which each typically hold about 200 milligrams of the compound. That means a single acre of hemp can make about 1.4 million bottles of CBD lotion. If you sell each of those bottles for $30, that’s…a boatload of greenbacks.

“Whenever we see CBD at a gas station or in a retail location, we purchase it and we send it to our independent third-party laboratory,” Ferrarese said. “Sometimes it even contains THC in the bottle when it’s not supposed to. It’s really a crap shoot.”

Extractors can prevent THC from entering a CBD supply. To sap CBD or THC from plant material, all extractions use a chemical solvent. That sounds nefarious, but a solvent is any substance that can dissolve another. Water, for instance, is one of nature’s best solvents — but it wouldn’t be effective for something like this.

“In Connecticut, we’re limited to using only [liquid] carbon dioxide as a solvent for extraction or ethanol as a solvent, Ferrarese said. “In other states, such as Colorado and California, they’re allowed to use solvents like butane.”

Liquid carbon dioxide and ethanol come with distinct advantages. Carbon dioxide is very efficient at stripping cannabinoids from plants, but it must be kept at cold temperatures — -70 degrees Fahrenheit — to stay liquid.

Ethanol extraction, meanwhile, can be conducted at warmer temperatures in a process similar to making liquor, said Kimberly Provera, the operations manager at CT Pharma.

“There is a process called fractional distillation, where you can actually isolate different cannabinoids,” Provera said. “Each cannabinoid will separate based on a specific temperature…so you can isolate just CBD and THC.”

Once the gooey cannabinoids are separated, they add a little heat. The carbon dioxide and ethanol will eventually evaporate, leaving behind pure CBD or THC — but only if the extraction is done properly.

Poor extractions can also leave behind the chemical solvents…or even pesticides.

If your supplier makes a mistake, it might taint your CBD with THC — a consequence that can be problematic if your job randomly drug tests. Poor extractions can also leave behind the chemical solvents, which is hazardous in the case of butane, or even pesticides.

“There is a certain consumer expectation that we have here in America when we interact with our products, and cannabis should be no different,” Ferrarese said. “Cannabis, as a consumer packaged good, should have to meet those same standards for purity, identity and composition.”

Before you buy CBD, ask the store how its extracts were made and if they’re validated by a third-party tester.

Why you shouldn’t assume CBD is a cure-all

Raise your hand if you’ve heard someone state a version of the following:

“THC is psychoactive or mind-altering, hence it can make you high and why it is illegal. CBD, meanwhile, isn’t psychoactive.”

From a neuroscience perspective, CBD is absolutely psychoactive.

That’s not entirely accurate. CBD won’t intoxicate you, but from a neuroscience perspective, CBD is absolutely psychoactive, psychotropic or whatever adjective you want to use to say that it affects the mind and behavior. CBD just affects you differently than THC.

This lack of understanding has led to a lot of misconceptions about CBD, said Joseph Cheer, a neurobiologist at the University of Maryland School of Medicine who specializes in cannabinoids.

The first thing you need to know is that our bodies make their own natural versions of these compounds called endocannabinoids.

Akin to dopamine and serotonin, endocannabinoids can operate like neurotransmitters — the chemical messengers that activate or switch off our nerves. That, in turn, sparks or dampens the electric pulses that create our thoughts, behaviors and movements.

Photo by kostrez/via Adobe Stock Why hemp seeds and their oils are typically legal Cannabis pollination causes a plant’s flowers — its buds — to set seed and stop making cannabinoids. Hemp seeds and their oils have essentially zero cannabinoids and are only considered illegal if THC residue lands on them. Cannabis pollination can also stunt the growth of female plants, which is problematic if you’re cultivating the plant for fibers. George Washington made the mistake of allowing his hemp crop to undergo pollination, and it ruined his harvest.

Our nerves receive those chemical messages through neurotransmitter receptors — think of them like radio antennas. Cannabinoids have two known receptors called CB1 and CB2.

This is where the mental effects of THC and CBD differ. THC makes us high because it has a strong affinity for the CB1 receptor, but CBD is the opposite. CBD does not typically interact with the CB1 receptor…at least not directly. Research shows CBD can elevate the body’s self-made endocannabinoids, and scientists are also hunting for a “hidden” brain receptor for the cannabis extract.

The other evidence that CBD is psychoactive? It can battle seizures.

The FDA has only approved one drug made from CBD: an epilepsy medication named Epidiolex. No one knows for sure how it works, but Cheer and other researchers suspect that Epidiolex tweaks how much calcium can get inside of our nerves.

Without going too far into the particulars, our nerve cells use calcium to carry those electrical pulses throughout the body. If a nerve cell has too much calcium, it will fire electric pulses at too fast a rate, which can cause a state of distress called excitotoxicity.

CBD appears to maintain a healthy balance of calcium in nerve cells, which wards off the electrical overloads and damage that happen during seizures.

Cheer said there is also strong support that CBD reduces anxiety and stymies addiction to opioids and marijuana. It may also offer sleep benefits to patients with multiple sclerosis, Parkinson’s disease and Huntington’s disease.

But FDA approval for these treatments, other medicines like lotions and foods may take years, and “the pace of discovery has already been significantly hindered by the scheduling of the plant,” Cheer said.

Most CBD products are illegal — but only if someone is checking

So if you buy CBD…and it came from a hemp plant…and it’s pure…then you’re in the clear…right? Not quite.

Yes, purchasing CBD is federally legal as long as it doesn’t contain more than 0.3 percent THC, but some state laws have put restrictions on buyers. For example, Virginians can only buy and possess CBD if they have a prescription.

Federal provisions have a blindspot whereby a store can sell as much CBD as it wants, as long it doesn’t make any health claims about its products…

It gets more complicated for sellers.

The FDA has prohibited the sale of CBD in any unapproved health products, dietary supplements or food — which literally means everything except for the drug Epidiolex.

The FDA can officially go after any companies selling or marketing items that make health claims about CBD, especially if those products involve interstate trade of the cannabis extract.

But the agency has limited staff for enforcement. As of this writing, the FDA has only issued warning letters to violators, though it has hinted at pursuing broader enforcement with federal and state partners if the CBD craze continues. Local law enforcement in states like Iowa, Ohio and Texas have also raided hemp and CBD stores this year.

These federal provisions, as written, also have a blindspot whereby a store can sell as much CBD as it wants, as long it doesn’t make any health claims about its products, put it in food nor add it to dietary supplements.

University of Connecticut grad student Peter Apicella works with a cannabis plant in a UConn greenhouse growing THC-free hemp. Photo by Mark Mirko/Hartford Courant/TNS via Getty Images Connecticut’s road to a hemp industry As PBS NewsHour science correspondent Miles O’Brien has detailed in past reports, marijuana research has been stymied by the plant’s designation as a federally illegal drug. And until recently, the same restrictions have applied to hemp and CBD. The 2014 Farm Bill was the first piece of national legislation to permit hemp research, both for health and agriculture pilot programs. Last year’s updated law further loosened restrictions and expanded the grants available for such studies. Connecticut is looking to capitalize. Legislation to start the state’s industrial hemp program was passed rapidly by state officials this spring. “It solves a lot of issues for us in the state of Connecticut by creating an industry that can be quite lucrative,” said state senator Christine Cohen, who chairs the environmental committee that reviewed the bills. “The Connecticut Farm Bureau has been predicting $37,000 to $150,000 per acre and in gross value.” Cohen said this green rush could help dairy farmers in Connecticut and across the nation. Nearly 3,000 U.S. dairy farms folded in 2018 alone.

A spokesperson for the Drug Enforcement Administration told the PBS NewsHour that their agency would have a limited role with these infractions. Since the Farm Bill said CBD with less than 0.3 percent THC was no longer a banned substance, it’s no longer under DEA’s purview, a spokesperson said in an email.

“It is now regulated by the FDA, so we refer you to them for this request,” the DEA spokesperson wrote. Another factor: “DEA does not pursue individual users – we focus on larger-scale operations and drug trafficking organizations,” the spokesperson added.

All of this is important for CBD sellers and consumers because the FDA has a mandate to verify the safest dosage for the chemicals that we consume or apply to our bodies — whether they be applied to drugs, food and dietary supplements — under the Food, Drug and Cosmetic Act.

The rapid legalization of hemp and CBD has put the FDA in a tough position. Under its mandate, the agency must validate the safety of foods, drugs and dietary supplements. But CBD products are already flooding American stores.

Cheer and the FDA caution “against all of the off-the-shelf CBD products” because the cannabis extract — like any compound you put in your body — can come with adverse side effects.

Human studies have shown that taking CBD can cause liver problems, diarrhea, vomiting and fatigue. Rodent research also suggests CBD can cause harm to male and female reproductive organs.

When it comes to CBD in the U.S., “whatever I tell you today may change significantly a week from today,” Cheer said.