Why You Can't Get Stoned from Smoking Hemp

We may earn a commission from links on this page.

It's an honest mistake, thinking that marijuana and industrial hemp are one and the same. And in some ways they are: both are species of the genus cannabis, they both have the iconic five-fingered pot leafs, and both are widely sought after the world over. But aside from their outward appearance, they two have very little in common, including where it counts the most.

A Quick History of Hemp

We've been cultivating hemp for more than 12,000 years, making it one of humanity's earliest domesticated plants. While the Chinese have used the material in everything from shoes to paper since at least the 5th century BC, it did not arrive in Western Europe until relatively recently.


Cannabis sativa, "grew and was known in the Neolithic period all across the northern latitudes, from Europe (Germany, Switzerland, Austria, Romania, Ukraine) to East Asia (Tibet and China)," stated Elizabeth Wayland Barber in her book Prehistoric Textiles: The Development of Cloth in the Neolithic and Bronze Ages with Special Reference to the Aegean, noting that it did not reach Western Europe until the Iron Age. "I strongly suspect, however, that what catapulted hemp to sudden fame and fortune as a cultigen and caused it to spread rapidly westwards in the first millennium BC was the spread of the habit of pot-smoking from somewhere in south-central Asia, where the drug-bearing variety of the plant originally occurred. The linguistic evidence strongly supports this theory, both as to time and direction of spread and as to cause."

When it did land in Europe, hemp became a very valuable crop as its fibers could be processed into rope and sailcloth, as Christopher Columbus did. What's more, hemp fibers have proven themselves longer, stronger, more absorbent and insular than cotton, which is why George Washington and Thomas Jefferson both grew it. The plant has even shown promise as both a biogas precursor, thanks to the long hydrocarbons in its oil, and as a soybean replacement, as it contains more fatty acids and dietary fiber than soy.


Today, hemp is big business. China is the single largest grower and exporter of industrial hemp, though more than 30 countries produce the crop. It goes into everything from foodstuffs to cosmetics to textiles. Hemp is legal to import into the United States; however, due to our draconian prohibition of cannabis, hemp is illegal to grow, at least on the federal level. Nineteen states have enacted legislation to promote the use of hemp while another nine—Colorado, Kentucky, Maine, Montana, North Dakota, Oregon, Vermont, Washington and West Virginia—have legalized its production outright.

A Weed by Any Other Name

As any self-respecting stoner can tell you, there are two strains of weed that get you high: the tall, scraggly sativas that originated in Southeast Asia and the short, bushy indicas from the Middle East. But there's actually a third strain, cannabis ruderalis, from which we derive industrial hemp. These three species all produce a pair of antagonistic chemical compounds— cannabidiol (CBD) and tetrahydrocannabinol (THC)—albeit in varying ratios.


Sativas are especially high in THC (containing anywhere from 10 to 30 percent THC), which produces the euphoric stoner "head high," and low in CBD, which has been shown to relieve a number of maladies. Indicas are also high in THC but have elevated levels of CBD, which provides a mellower "body high." Ruderalis is the inverse of sativas in that they contain virtually zero THC and massive amounts of CBD. This is the result of both the species' natural disposition and generations of breeding.


The certified low-THC varieties used in Europe and Canada contain maybe 0.2 to 0.3 percent THC when fully matured, and even the lesser-used varieties bred as biofuel precursors top out at 1 percent THC by volume. Trying to get high smoking a one percent THC concentration would be akin to getting hammered on O'Douls, as studies have shown that a sub-one percent concentration produces the same effects as placebo. What's more, the large amounts of the non-psychotropic antagonistic CBD compound further overwhelms the effects of the THC.

As Test Pledge, an arm of the Hemp Industries Association, suggested in a 2000 study, industrial hemp doesn't even contain enough THC to set off a common pre-employment urine test:

Even industrial hemp varieties, bred for low THC content, produce small non-psychoactive quantities of THC - short for delta-9-tetrahydrocannabinol, the main psychoactive ingredient in marijuana. If seeds are not properly cleaned after harvesting, excess trace residual THC sticks to their hulls and infuses oil and other products. Until 1998, when thoroughly cleaned seeds from Canada and the European Union became widely available, hemp oil containing more than 50 parts per million (ppm) of THC was often found in the market. While too low in THC to cause psychoactivity, studies have shown that such oil may produce a positive drug test for marijuana. Of course, that has also caused a few cases of alleged false-positives in workplace drug testing.

To determine whether current hemp foods can still cause positive drug tests, a Canadian governmental research program (ARDI) and members of the hemp industry commissioned a toxicological study. 15 individuals consumed hemp oil with a known THC concentration. Four different daily doses were given, each for a ten-day period, to allow the THC concentration to reach steady-state concentration in the body. At the end of each period, two urine samples were collected and analyzed. The study found that none of the 15 individuals who consumed up to 600 µg (micrograms, or one-millionth of a gram) of THC per day were even close to producing a urine sample that was "confirmed positive".

With current seed-cleaning technology and the correspondingly low trace THC levels in hemp oil and hemp nut, producing a confirmed positive test result would require that unrealistically high amounts of hemp oil or hemp nut be eaten. The practice of "confirming" all urine samples, which test positive in an initial screening test is followed by all federal and most private employers. Because some employers and law enforcement agencies rely on screening tests only, screening positive results caused by copious hemp food ingestion are conceivable, yet not likely.


Turns out the well-worn idiom, "you'd need to smoke a hemp joint the size of a telephone pole to get high" isn't that far from the truth. [Cannabis News - Test Pledge - Wikipedia - 420 Times - HuffPo - National Cancer Institute - Top Image: paul prescott/ Shutterstock]