A super-chill blew through the reefer mad Super Bowl cities of Denver and Seattle last week with the report that a young woman had died of apparent cannabis toxicity in England.

This one seems real to, not like the early January hoax that “reported” 37 deaths from marijuana in Colorado soon after the law decriminalizing the drug in that state went into effect.

Gemma Moss, a 31-year-old mother of three and, reportedly, a regular marijuana user in the last months of her life, was found dead in her bed in late October. A coroner’s evaluation concluded late last week that the death was attributable to cannabis, an extremely rare determination. The pathologists based their finding on “moderate to high” levels of cannabinoids in blood which, given her otherwise normal heart, lungs, and liver, led him to conclude that pot was the culprit.

In England, at least, hers was the first death-by-weed recorded in a decade.

In the US, there are no official reports of fatalities though an unreferenced (and not locate-able by me—so hedge here) Wiki-answers states that the CDC has counted 26 deaths from 1999 to 2007. But before celebrating, please note, there is a plausible basis for sudden death from cannabis. Like many drugs, marijuana might exert a dangerous effect on the heart in one of two ways: in certain people predisposed to heart rhythm problems, the increase in pulse and blood pressure common during use might trigger a dangerous and even lethal rhythm disturbance.

In addition, there was a study in 2001 that loosely connected recent (consumed within the last hour) use of marijuana and heart attacks. Further work by the same Harvard-based group, published in 2008, suggested that persons with a recent heart attack might have an increased risk of death if they smoked marijuana. But even this group, which also is interested in caffeine, anger, and other stimulants as triggers for heart attack, in a 2013 publication seemed less certain about the association.

Call it a very mild “maybe.”

One under-represented group though clearly has died of its share of cannabis overdose. A recent report from vets in Colorado noted a distinct increase in canine overdoses, following the legalization of medical marijuana in the state. The paper described 125 dogs who ate too many pot-laced brownies, and the like, and were brought to a specific veterinary center over a six year period. Two dogs died; the others recovered. Urine toxicology screens were not found to be reliable. Autopsies were not performed so the exact cause of the deaths remains uncertain but it’s likely the dogs met a cardiac death.

A related problem in children has already evidenced itself, too. Kids, it seems, are grabbing baked goods that look and taste just like regular junk food, not realizing it’s junk food on drugs, leading to poisoning.

A concern already has been put forward to child-proof the next generation of pot treats that come in various shapes and sizes. Surely regulation will move—quickly and hopefully before a tragedy—to keep little kids out of the weed.

The evidence does seem to suggest that, like most everything, marijuana in extremely high doses can tip a person or a dog over into a sudden death. But the amount of drug needed combined with the necessary anatomic derangement of a person’s heart will make this extremely rare—much less common than death by bee sting or penicillin ingestion. As the product becomes more commercialized and ever stronger premium brands are put forward, the risk might increase a tad, but any serious illness will remain an extremely uncommon event.

There is a substantial public health danger though that many are overlooking, and not the possible problems with driving under the influence of cannabis—which is still being determined. The decriminalization of marijuana is happening at the exact time that achievements nationally and globally have been made in the reduction of tobacco consumption. Yet, as some fuddy-duddy physicians in England have pointed out in their 2003 article comparing tobacco to marijuana, the tobacco plant and the marijuana plant contain many of the same chemicals—about 400 in all for both leaves.

The effects of many of these chemical compounds are uncertain and even unknown.

Plus, some smokers say the best way to maximize their high is to inhale as deeply as possible for as long as possible—the same opposite strategy practiced by most tobacco users. Plus there are no filters—yet—on the marijuana cigarettes, assuring that all those “impurities” are toked right in, deep into the lungs.

Truth is, there is no telling whether the epidemic of heart disease, lung diseases including lung cancer, and the entire litany of tobacco-related morbidities that has been successfully curbed as tobacco consumption has declined in the US will flower a second time in the 2040s and 2050s as the weed generation grows older. Surely there will be no two-pack-a-day marijuana smokers—at least among those capable of leaving their couch and having a life.

But, as the Brits wrote a decade ago, if the same rate of leaf-related deaths observed in tobacco-tokers were applied to those inhaling marijuana, 30,000 people in Great Britain a year would die—a reminder not only of the lethality of tobacco but also the short-sightedness of those convinced that widespread marijuana use will have no consequences.

No, people will not drop dead left and right from acute stoned-ness as did poor Gemma Moss; but the jury on long-term marijuana safety is still out and will remain in session for several more decades.

But consider: inhaling one leaf has had the largest deleterious impact on human health of any single product in human history. Anyone who thinks that today’s new fun inhaled leaf will not have a least some long-term impact on lung and even heart health is ignoring the obvious.

Or stated another way—they must be inhaling.