There is little data about how smoking and vaping cannabis containing pesticides affects respiratory and overall health, yet available information about pesticides and cultivation practices has led cannabis testing labs and medical professionals to agree about what is healthier for patients.

Health Risks of Smoking and Vaping

“Most people who use cannabis for medical purposes have chronic conditions with ongoing symptoms. They don’t need to develop additional concerns,” says Dr. Ethan Russo, a board-certified neurologist, and director of research and development at the International Cannabis and Cannabinoids Institute in Prague. “Up to 70 percent of pesticides on cannabis will be transferred in the smoke to the lungs and into the bloodstream. They will not get burned up. There’s a great potential for (developing) cancer as well as a chronic cough, too much phlegm, and bronchial problems.”

(For more about MMJ testing, check out another of our articles, Testing Medical Marijuana for Pesticides)

Pills, sublingual applications, tinctures, and transdermal patches containing organic cannabis are likely to prove more beneficial for patients than smoking or vaping cannabis grown with or contaminated by pesticides.

Russo adds many patients use cannabis smoke or vape because these methods offer quick, almost instant relief. Instead, he says, patients should maintain therapeutic blood levels of cannabinoids by taking a pill or tincture three times a day.

Pesticides and The Body

Josh Wurzer, president, and co-founder of SC Laboratories, a cannabis testing lab in Santa Cruz, says there is no way to determine how pesticides will affect a patient once inhaled.

“There’s just no data on the respiratory dangers of these pesticides. There are no studies on what happens when a pesticide combusts, either. So, few crops (other than cannabis) are smoked. In addition, no two pesticides are exactly alike,” says Wurzer.

He added there is also little information about how the chemicals in one pesticide and in multiple pesticides interact with one another when ingested, and that chemicals may interact differently when burned together.

Outdoor growers should beware of the risk of contamination of pesticides from nearby pesticide sprays on close-by commercial crops or other applications.

Robert Martin, Jr., co-founder, and chief executive officer of CW Analytical Laboratories, a cannabis testing lab in Oakland, says very few barriers fully protect outdoor-grown cannabis plants.

“All it takes is for the wind to drift over from the wine (or other) fields,” he says.

Home growers should also grow with clean soil, according to Mary Lynn Mathre, an RN, and president and co-founder of Patients Out of Time, a non-profit organization that educates health care professionals and the public about the therapeutic uses of cannabis.

“The cannabis roots pick up everything from the soil, including heavy metals,” she says.

Mathre advises that plants be organically grown without the use of toxic pesticides. Growers should also take care in the curing and storage process to prevent mold.

But burning cannabis to ingest it introduces another level of risk according to Jeff Raber, CEO of The Werc Shop, a cannabis consulting firm based in Los Angeles.

“Hot air can be a super-irritant to the airways. For some patients, just inhaling cannabis smoke that contains pesticides could exacerbate their medical issues,” says Raber.

(For more on the health effects of consumption temperature in our article, Vaping vs. Dabbing: What You Need to Know About Temperature and Your Health.

Raber and Russo agree long-term exposure to pesticides on cannabis through repeated smoking or vaping is likely to lead to a slow build-up of harmful chemicals.

What You Can Do To Help

“It will help if patients determine their minimum effective dose,” says Raber. “Patients should start low and work their way up to more. It’s also good practice for a patient to keep track of how they are using cannabis. (Over time), a patient should document in a journal what (strain) they take in, how much, how they take it, and what their doctor said about their use.”

Uncleaned smoking devices and some rolling papers containing toxic chemicals may pose additional problems. Mathre advises that when smoking cannabis, a patient shouldn’t hold the smoke in their lungs.

“The therapeutic properties in cannabis are readily absorbed, but the longer one holds their breath, the greater the risk of absorbing toxic chemicals in the smoke,” she says, adding vaping a clean cannabis product can possibly mitigate potential problems incurred in smoking.

Fortunately, the ability to detect pesticides in plants is improving, according to Martin.

“Now we’re using NASA-grade machines, which has opened up a whole new way of looking at cannabis,” he says. “We are able to identify really low levels of pesticides in mature plants.”

Testing, however, remains complicated because different parts of a cannabis plant may have different amounts of pesticides. In addition, cannabis plants grown in the same bed may have different amounts of a pesticide. This is because some cannabis plants may be closer to the source of the contamination.

What’s more, patients using cannabis concentrates such as hashish or oil should be extra careful because it is likely pesticides in them will be concentrated as well.

Russo said awareness of the dangers of pesticides is growing, but patients need to learn more. He advised patients who grow and obtain safe medicine to educate themselves and others about the risks posed by pesticides.

“This is an indictment of prohibition. The reason that people don’t know about the dangers of pesticides is that we didn’t have a legal and regulatory market for this product. Cannabis needs to be available, but it also needs to be safe,” says Russo.