The parents of a young New Jersey man say marijuana caused the death of their son. However, most experts say you can’t die from cannabis alone.

Most medical experts agree that while marijuana can have negative health consequences, it’s unlikely to cause death. The psychoactive effects of marijuana can be concerning, but not necessarily harmful.

Dr. Edward J. Newton, a professor of emergency medicine at the University of Southern California and an expert in drug overdose, said that while marijuana has “a good safety record” from an overdose perspective, there are other risks involved with use.

“The complications are more that the person becomes delusional and impaired in terms of their judgement. Their risk-taking behavior increases, so they put themselves at risk of trauma mainly, rather than a physiological problem with the drug itself,” Newton told Healthline.

Newton emphasized that driving while under the influence, or other risky behaviors when using marijuana, are much more likely to result in harm and death than any direct effect of the drug on the body.

Colorado reported an increase in the number of emergency room visits related to cannabis for visiting tourists. Some were due to automobile accidents, while others were due to episodes of tachycardia, anxiety, or paranoia.

Kristina Ziobro discovered her son, Michael, 22, unconscious on his bedroom floor on April 10, 2017.

She called 911, but by the time emergency personnel arrived her son was already dead.

The state’s medical examiner later discovered the presence of cannabis in Michael Ziobro’s bloodstream.

Kristina Ziobro and her husband also discovered medical marijuana in their son’s room.

“He was such an advocate,” Kristina Ziobro said on NBC’s “Today” show. “He thought it was wonderful. He thought it was safe. He just thought it was natural and organic and it ended up killing him.”

Despite the parents’ belief, the Union County medical examiner, Dr. Junaid Shaikh, said he’s unsure what, if any, role marijuana had in their son’s death.

What is clear is that Michael Ziobro experienced a severe cardiac event, but there is currently no evidence to support that the event was triggered by marijuana use.

His death certificate does not list cannabis as the cause of death.

The Ziobros have since tried to pursue the cause of their son’s death with state legislators and police.

In a letter to New Jersey State Senator, Thomas Kean, Shaikh wrote:

“Although there is scarce research that indicates smoking cannabis can evoke cardiovascular complications, one is unable to attribute the ‘Cause of Death’ was due to smoking cannabis.”

For a drug to be listed as the primary cause of death, it must actually cause the death through overdose rather than simply being a potential contributing factor.

Marijuana advocates point out there are zero reported cases of marijuana-induced death.

“It is well-established in the world medical literature that cannabis is incapable of causing death by lethal overdose,” Paul Armentano, the deputy director of the National Organization for the Reform of Marijuana Laws (NORML), told Healthline.

He cites, among others, one study that concluded, “There are no cases of fatal cannabis poisoning in the human medical literature.”

Questions surrounding the safety and regulation of marijuana in the United States have soared recently as more states have legalized the drug for both recreational and medicinal purposes.

In the case of Michael Ziobro’s death, the question, more specifically, is: What are the deleterious effects of marijuana on the cardiovascular system?

One older study from 2001 found that marijuana can cause a heart attack, but the likelihood is extremely rate.

“Yes, cannabinoids can temporarily influence cardiovascular function, like blood pressure. But these responses are generally mild and not life-threatening, and subjects quickly become tolerant to them,” said Armentano, who has written about the subject at length.

A controversial study from August 2017 from the School of Public Health at Georgia State University, concluded that marijuana use is associated with a threefold risk of death from hypertension.

However, marijuana advocates called that study’s conclusions spurious, and questioned the legitimacy of their methodology.

What is known in the medical literature is that smoking marijuana can affect things like heart rate and blood pressure. Experts say individuals with certain heart conditions, especially older adults, should be judicious in smoking marijuana.

Armentano referenced two separate longitudinal studies examining marijuana use and cardiovascular health.

The first, published in 2017, followed more than 5,000 individuals for 25 years, beginning in the mid-1980s.

“Compared with no marijuana use, cumulative lifetime and recent marijuana use showed no association with incident CVD [cardiovascular disease], stroke, or transient ischemic attacks, coronary heart disease, or CVD mortality,” the authors of that study wrote.

Researchers involved in another longitudinal study from 2016 involving 1,037 individuals who were followed for 38 years came to a similar conclusion.

“We found no association between cannabis and cardiovascular risks [e.g., high blood pressure, higher cholesterol], which may appear at odds with evidence that cannabis use increases risk for cardiovascular complications,” the authors wrote.

But Michael Ziobro was a young man, without any obvious risk factors. The reason for his death remains a mystery.

Shaikh suggested that Ziobro’s death may have involved certain genetic factors, and urged the family to undergo testing for hereditary causes for his sudden cardiac arrhythmia.

The Ziobro family said they are following that advice, but they are adamant in believing marijuana caused their son’s death, and want the public to know the risks.

Editor’s note: This story was originally reported by R. Sam Barclay on May 29, 2018. Its current publication date reflects an update, which includes a medical review by Alan Carter, PharmD.