Researchers have, for the first time, conducted a worldwide survey on illegal drug use, and they learned that the most popular one on the planet is marijuana. But the drugs that are killing the most people are strong painkillers, Vicodin, OxyContin, and codeine among them, the AP reports, as per the study published in the Lancet. In 2010, more than half of the 78,000 illicit-drug deaths came from painkiller abuse—though ecstasy and hallucinogens weren't included in the investigation.
Men in their 20s are the top drug abusers, and the Aussies, Brits, Russians, and Americans are the biggest offenders. Asia and Africa have the lowest rates of abuse. Limited data availability required researchers to turn to modeling methods. But "even if it is not very solid data, we can say definitely that there are drug problems in most parts of the world," says the study's lead author. He notes that countries with tougher anti-drug laws see more addict deaths than do countries which turn to needle exchanges and methadone clinics to help addicts. (Read more marijuana stories.)