(NEWSER– 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.

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