Michael Ziobro was just 22 when his mother, Kristina, found him unconscious on his bedroom floor.
“I went to say goodnight to him and I am the one who found him on the floor,” Kristina Ziobro recalled.
“I called 911. They came and tried to revive him. But he was gone.”
The Ziobros later found medical-grade marijuana in Michael’s room, and the medical examiner found evidence of cannabis in his blood. Kristina and her husband are convinced the highly active marijuana caused Michael’s heart to go into arrhythmia and killed him.
"It’s crazy. People think, 'Oh, pot can’t hurt you. It's natural'," said Ziobro, who lives in Springfield, New Jersey.
But the medical examiner said he cannot say for sure whether cannabis was involved in Michael's sudden death and notes there’s little evidence about what marijuana does or doesn’t do to the heart.
States are moving ahead with decriminalizing or outright legalizing not just the medical use of marijuana, but recreational use. Medical marijuana is legal in 28 states and Washington, D.C., although it is illegal under federal law, and about 10 percent of U.S. adults consider themselves current users of the drug.
At least 44 percent of high school seniors say they’ve tried cannabis, according to the National Institute on Drug Abuse, and 6 percent say they use it daily.
Advocates laud what they see as an excellent safety profile for marijuana, brushing aside medical research that indicates it does have its dangers, especially in adolescents and young adults.
The Ziobros say their son Michael was among those hurt by a drug they thought was perfectly safe.
“He was such an advocate,” Kristina said. "He thought it was wonderful. He thought it was safe. He just thought it was natural and organic and it ended up killing him.”
There’s limited evidence on the benefits of marijuana. The gold standard for medicine is that the benefits of any treatment should outweigh the risks, but researchers say federal restrictions on using marijuana in medical studies have handicapped their ability to assess its values and dangers.
"Steps are being taken towards legalization and decriminalization of marijuana in the United States, and rates of recreational marijuana use may increase substantially as a result," said Barbara Yankey of Georgia State University, who led a team that published a study this week on marijuana’s possible effects on the heart.
"However, there is little research on the impact of marijuana use on cardiovascular and cerebrovascular mortality."
"He thought it was wonderful. He thought it was safe. He just thought it was natural and organic and it ended up killing him.”
Yankey’s team found people who had ever used cannabis had more than triple the risk of dying from high blood pressure compared to people who had never used it.
Their study, published in the European Journal of Preventive Cardiology, has many limitations and relied on surveys of people who may have smoked marijuana just once in their lives. But it highlights the lack of solid data.
"Support for liberal marijuana use is partly due to claims that it is beneficial and possibly not harmful to health,” Yankey said in a statement.
Kristina Ziobro thinks the push to make cannabis more available could endanger vulnerable people.
“I just think people are glossing over everything that’s going on with marijuana,” she said.
Michael Ziobro’s death certificate does not list cannabis as the cause of death and Union County Medical Examiner Dr. Junaid Shaikh said he cannot say what caused the young man’s heart to start beating so erratically that it stopped.
Victor and Kristina Ziobro are unhappy with the explanation and asked state legislators, as well as the police, to investigate.
“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,” Shaikh wrote in a letter to New Jersey state senator Thomas Kean after an inquiry.
“In my opinion, it is highly warranted that family members consult a geneticist and possibly consider cardiovascular genetic testing for hereditary causes of cardiac arrhythmia,” Shaikh added in the letter, which the Ziobros provided to NBC News. His office did not immediately respond to NBC's request for further comment.
“Marijuana raises heart rate for up to three hours after smoking. This effect may increase the chance of heart attack."
Kristina Ziobro says the family is following that advice — they have a daughter, also — but she says the marijuana they found was highly potent. She notes studies have shown the marijuana available to the public is indeed becoming stronger.
“The marijuana available in dispensaries can have THC (tetrahydrocannabinol, the psychoactive ingredient in marijuana) content well above 20 percent — even higher in the concentrates —as opposed to the 3 percent to 5 percent that is typical of the wild plant.” Dr. Rosalie Pacula at the RAND Corporation in Santa Monica, California, said in a statement posted on the website of the National Institute for Drug Abuse.
Ziobro provided images of the two packets marijuana found in Michael’s room. They were labeled as having a THC concentration of 28 percent and 24 percent.
“The amount of THC in marijuana has been increasing steadily over the past few decades,” NIDA adds.
“For a person who is new to marijuana use, this may mean exposure to higher THC levels with a greater chance of a harmful reaction. Higher THC levels may explain the rise in emergency room visits involving marijuana use.”
This can raise the risk of a heart attack, NIDA, one of the National Institutes of Health, maintains.
“Marijuana raises heart rate for up to three hours after smoking. This effect may increase the chance of heart attack,” it says.
Ziobro said she simply wants people to know about the risks.
Michael smoked pot to help with painful irritable bowel syndrome symptoms, she said. There’s no hard medical evidence to support that use.
However, Dr. Michael Bostwick, a psychiatrist at the Mayo Clinic in Rochester, Minnesota, says people who like the effects of marijuana may indeed find benefits from using it.
“It’s psychoactive, so even if it doesn’t cure what you have got, it’ll make you feel different,” he said.
“I think there are people who like how it makes you feel. But that doesn’t translate into any proof for any conditions. We have many anecdotes and groups of people who report amazing benefits, but we don’t have, in most cases, rigorous studies to confirm that.”
Bostwick says there is plenty of reason to think marijuana could have therapeutic uses. Cells all over the body have receptors — a kind of biological doorway — for many of the active ingredients in cannabis.
But that’s also reason to believe it could have undesirable side-effects.
“We now know that the younger you are, the greater the possibility of becoming addicted,” he said.
“There is increasing evidence that it has effects on the developing brain, so that using it during adolescence is a bad idea,” Bostwick added. For people with a genetic tendency for psychosis, symptoms can emerge earlier with cannabis use, he said.
“That’s not to say that it causes psychosis, but it aggravates it and brings it out earlier,” he said.
A 2013 study found the brains of young heavy marijuana users were altered in sub-cortical regions — part of the memory and reasoning circuits. And there is no doubt it can cause dependence and addiction, NIDA and other experts say.
Bostwick became one of Mayo’s top experts on marijuana after his son became addicted. He says his son is now sober at age 24, after good treatment.
“There will be people who have been badly hurt and there will be people who claim they have been helped and I think both will be true."
The experience leaves Bostwick “on the fence” about the benefits versus the risks of cannabis.
Two studies conducted by the Veterans Health Administration and published in the Annals of Internal Medicine this week found little evidence that cannabis helps either pain or post-traumatic stress disorder. However, other studies have shown that cannabinoids can help treat chronic pain.
Other studies have found cannabinoids can help reduce seizures in children with certain severe forms of epilepsy. Cannabinoid pills can also help prevent and ease nausea caused by chemotherapy.
But the drug is intoxicating, can endanger drivers, and one team of doctors found hospital ER visits from panicked pot tourists doubled after Colorado legalized recreational marijuana.
“There will be people who have been badly hurt and there will be people who claim they have been helped and I think both will be true,”Bostwick said.
“Our work is only as good as the studies that are done, but if they can’t be done, then we really can't be definitive about anything."