When I first read that a Louisiana doctor had witnessed the first-ever case of a fatal cannabis overdose, I did the knee-jerk—my least favorite dance move—and immediately called bullshit. The rationalizations came later, but my first reaction was blind, animalistic hate. “Liar!” I screamed. “Fink!”
St. John the Baptist Parish Coroner Christy Montegut told The New Orleans Advocate that a woman who died last February fell victim to fatal THC exposure. “It looked like it was all THC because her autopsy showed no physical disease or afflictions that were the cause of death. There was nothing else identified in the toxicology—no other drugs, no alcohol,” Montegut told reporters. “There was nothing else.” A toxicology report said she had 8.4 nanograms of THC per milliliter of blood.
A similar scare happened in 2017. A case report was published in March of that year in the journal Clinical Practice and Cases in Emergency Medicine—co-authored by a pair of doctors at the Rocky Mountain Poison and Drug Center—that detailed the death of an 11-month-old child two years ago due to myocarditis (inflammation of heart muscle). The doctors working on the case reportedly found a large concentration of THC in the child’s urine and blood, leading some to proclaim it a “marijuana overdose.”
According to the report, the child had been living in an “unstable motel-living situation,” and the parents admitted to keeping drugs, including cannabis, in the house. Myocarditis—the actual cause of the child’s death—can be caused by a viral infection, immune disorder and a number of other complications. “We extensively ruled out almost every other cause that we can think of,” Dr. Christopher Hoyte, co-author of the report told reporters. “We found no other reason why this young kid ended up having inflammation on his heart.”
I had trouble believing either of these stories, because I know that a theoretical lethal dose of cannabis for humans is ridiculously high. The Schaffer Library of Drug Policy says: “According to which US Government authority you want to believe, the lethal dose of marijuana is either about one-third your body weight, or about 1,500 pounds, consumed all at once.” The University of Michigan’s Mind the Science Gap blog says the LD50—or lethal dose for half of the population—of delta 9-THC (the chemical that converts to THC when burned) is theoretically between 15 and 70 grams. These numbers are based on the LD50 of delta 9-THC for rats, mice and monkeys. For obvious reasons, no human trials have ever been conducted.
And it seems my skepticism (read: knee-jerkiness) was well-founded. In response to the Louisiana case, Keith Humphreys, a former senior policy adviser at the White House Office of National Drug Control Policy, also spoke with the Advocate. Humphreys said it would be highly unlikely for a cannabis overdose to occur for the first time, considering the number of people currently using cannabis in the United States.
“We know from really good survey data that Americans use cannabis products billions of times a year, collectively. Not millions of times, but billions of times a year,” said Humphreys. “So, that means that if the risk of death was one in a million, we would have a couple thousand cannabis overdose deaths a year.” He blamed the coroner’s inability to find another cause of death on “some imperfection” in the assessment.
And in the Colorado case, it turns out the doctors who wrote the case report didn’t even attribute the child's death to cannabis.
“We are absolutely not saying that marijuana killed that child,” Dr. Thomas Nappe—director of medical toxicology at St. Luke’s University Health Network in Bethlehem, Pa., and second co-author of the report—told the Washington Post. Dr. Hoyte took to Twitter to say: “News story totally sensationalized. Kid had myocarditis after marijuana exposure. We just said more study is needed. Not that marijuana was the cause of the death. News story totally overblown.”
The report does advise physicians to counsel parents on preventing exposure of children to cannabis and suggests that further study into potential links between THC and unexplained pediatric myocarditis should be conducted. But if one actually reads the report, they find that the high concentration of THC in the child’s body was observed and documented but was never posited as the cause of death.
The confusion seems to stem from the report’s statement that “this is the first reported pediatric death associated with cannabis exposure.” There is a difference between “associated with” and “caused by,” a point that Nappe made when speaking to the Post.
The Drug Enforcement Agency continues to maintain that there have been no reported instances of cannabis-caused deaths.