Advocates of the recreational drug — marijuana — have long supported its widespread use and legalization because its death rate was unheard-of — not to mention it’s considered safer than alcohol and has medicinal properties. The debate about the legalization of the drug has even reached a new high in the White House as President Obama publicly came forward and admitted, "I don't think it is more dangerous than alcohol," but a group of German researchers at the Dusseldorf and Frankfurt university hospitals have weeded out the truth: Smoking pot can kill. A study in the journal Forensic Science International found the first two fatal cases of cannabis intoxications that triggered abnormal heart rhythms — cardiac arrhythmia — in two healthy men.

"It's a diagnosis of exclusion so you have to rule out all other possibilities," Dr. Benno Hartung, an author of the study, told The Associated Press. Hartung and his colleagues performed numerous tests, including an autopsy, a toxicology exam, genetic tests, and a histological analysis of all organs to rule out other factors that might have contributed to the fatalities. In both cases, cannabis intoxication was the leading cause of cardiac arrhythmia, where both men either started breathing too fast or too slowly.

It is known that smoking marijuana could be lethal if used with other drugs, triggering heart conditions or causing cancer. The tar in joints contains a higher concentration of chemicals that are linked to lung cancer compared with tobacco tar. The American Lung Association says smoking pot deposits four times more tar in the lung than smoking the same amount of tobacco. Marijuana in high doses can also lead to temporary psychotic reactions such as hallucinations and paranoia, especially in younger people have who have a family history of schizophrenia.

In the study, the German researchers found the two healthy young men, aged 23 and 28, had enough tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, in their blood to believe they smoked pot within hours of their death. The two men did not have a history of heart problems or channelopathies — diseases that increase the risk of heart problems that affect ion channels. "We did every test we could," Hartung said about his efforts to unveil any possible underlying causes.

As a precaution, Hartung and his research team suggest people are high risk for heart disease should avoid the drug. Other medical experts, like Dr. David Nutt, chairman of Britain's Independent Scientific Committee on Drugs, who was not involved in the study, supports Hartung’s advisement. "People with vulnerable hearts should be informed of this risk with cannabis," he said, the AP reported.

Although the deaths of the healthy men confirmed cannabis triggered arrhythmias, it is not clear just exactly how this occurred. The researchers speculate there may be unknown channelopathies that could increase the risk of heart conditions triggered by the drug. Marijuana raises the heart rate by 20 to 100 percent shortly after smoking, says the National Institute on Drug Abuse (NIDA), and there is a 4.8-fold increase in the risk of heart attack during the first hour after smoking the drug. This risk could potentially increase in individuals who are more vulnerable to heart complications.

In the UK, a 31-year-old woman, is known to become the first in Britain to die directly from cannabis poisoning after smoking marijuana just moments before going to sleep each night, the Daily Mail reported. The coroner recorded Gemma Moss died because of the moderate to heavy levels of THC in her blood. Her case highlights the potential harm cannabis can cause as it increases heart rate and blood pressure.

The toxicity of smoking marijuana has been undermined by the public with little awareness about its potential hazardous effects on cardiovascular health. In the U.S., about one in every four people die of heart disease each year, says the Centers for Disease Control and Prevention, as it is the leading cause of death for Americans. Increasing awareness of marijuana’s effects on heart health may be a prevention tool to reduce the number of heart complications per year.

Source: Daldrup T, Hartung B, Kauferstein S, Ritz-Timme S. Sudden unexpected death under acute influence of cannabis. Forensic Science International. 2014.