Rising pot use – New health risks identified

Wall Street Journal

Rising Marijuana Use Presents Secondhand Risks

Studies probe harms to people near users, accidental ingestion by dogs

Cannabis companies in the U.S. lack access to banking and other financial services because the drug is federally illegal. That could change through new legislation or thanks to broader legalization efforts backed by the Democratically-controlled Senate. Photo Illustration: Laura Kammermann

By Renée Onque

Apr. 20, 2022

The risks marijuana can pose to people—and even pets—near users is getting more attention from researchers, as consumption rises along with legalization efforts in parts of North America.

Marijuana use among college-age adults increased by 6 percentage points from 2015 to 2020, according to a survey conducted by the National Institute on Drug Abuse, part of the National Institutes of Health. Living in a state that legalized recreational marijuana was associated with increased use in the past year and the past month among some groups including Hispanic people and non-Hispanic white people, according to a study in JAMA Network Open.

New research examines the possible health effects of wider use. Bong smoke contains tiny pollutants that can linger indoors for up to 12 hours, one study showed. Secondhand marijuana smoke may harm people outdoors or children in adjacent rooms, other research has suggested. And the legalization of marijuana in parts of North America has coincided with an increase of cannabis poisonings in dogs and other pets, a study published on Wednesday in the scientific journal PLOS ONE reported.

“Anything that a dog can get into, a child can probably get into as well,” said Jibran Khokhar, an author of the survey-based study and an assistant professor of biomedical sciences at the University of Guelph in Ontario.

Cannabis use can convey benefits that may outweigh potential risks, said Kevin Harbison, lead pharmacist and national clinical director at PharmaCann, a cannabis company based in Chicago. Dr. Harbison said cannabis has been helpful in treating pain and nausea in his patients, including those with cancer. To encourage safe storage, he said he tells his patients to get lock boxes and place their products out of the reach of children and pets.

One study compared the two years before recreational marijuana was legalized in Colorado to the two years afterward. The study, published in JAMA Pediatrics, found that among children tested at a children’s hospital and regional poison center marijuana exposure increased over that time from 1.2 to 2.3 per 100,000.

Surveys from 222 veterinarians in the U.S. and Canada showed that reports of cannabis poisonings in pets were much higher after October 2018, when Canada legalized marijuana. Pets with cannabis poisoning experienced symptoms including involuntary urination, poor muscle control and disorientation. Edible marijuana was the primary cause of cases. Most of the effects weren’t severe and were treatable in less than 24 hours, Dr. Khokhar said.

Risks from marijuana consumption can extend beyond the bounds of one home, some research suggests. A small study published in the journal Nature in 2020 found that children age 3 years and younger in New York City were being exposed to secondhand cannabis smoke more often in attached housing. Eleven out of 53 children in the study, which was published before New York state legalized recreational marijuana use in 2021, had detectable marijuana metabolites in their urine.

“Many of these children were probably not exposed by their parents. They were probably exposed by neighbors who were smoking,” said Karen Wilson, an author of the study and a professor of pediatrics at the University of Rochester School of Medicine.

There isn’t enough research to determine the effects of secondhand marijuana smoke on children, Dr. Wilson said, but tobacco smoke has been proven to be very damaging to their health. THC, a compound in marijuana that triggers a “high” sensation, could be particularly damaging in the first year of a child’s life, she added.

“Having THC in the body during that time could impact the brain’s development while it’s doing so much of its work,” Dr. Wilson said.

The Centers for Disease Control and Prevention is examining the health effects of cannabis use, said Brooke Hoots, an epidemiologist in the CDC’s Injury Center. “While the long-term health effects of exposure to cannabis secondhand smoke remain unclear, evidence suggests that burning any plant material releases toxic chemicals and emissions that can go deep into the lungs, impairing blood vessel function, increasing the risk of cardiovascular disease, and exacerbating heart and lung disease,” Dr. Hoots said.

Secondhand cannabis smoke may cause symptoms such as headaches or eye irritation for nonsmokers outdoors, a small study in Annals of Work Exposures and Health suggested.

In 2018, THC was detected in the air at a rock concert in a university’s football stadium using area-air sampling, according to Douglas Wiegand, one of the researchers and a behavioral scientist in the health-hazard evaluation program at the National Institute for Occupational Safety and Health.

THC markers were also detected in the urine of 10 out of 29 law-enforcement officers who were monitoring the event and participating in the study. THC markers weren’t found in the officers’ urine before the concert, indicating that secondhand cannabis smoke was the likely cause. Some officers indicated in a survey after the concert that they had experienced itchy, red eyes, dry mouth, headaches or coughing due to lung irritation.

Indoors, risks may be more pronounced. Cannabis smoke from bongs can include potentially dangerous fine-particulate matter that can linger in the air for more than 12 hours. A study, published in JAMA Network Open, demonstrated that within the first 15 minutes of marijuana being smoked using a bong in a home, levels of particulate matter can reach 570 micrograms.

Those levels are more than twice the amount detected amid intense wildfire smoke in the Bay Area in 2020, according to Katharine Hammond, an author of the JAMA study and professor of environmental health sciences at the University of California, Berkeley.

“There is this tendency to believe that secondhand cannabis smoke is not as dangerous as secondhand tobacco smoke,” Dr. Hammond said. “But there’s every reason to believe it is, at least, just as dangerous to human health as secondhand tobacco smoke.”