"Illicit opioids is sort of an up-and-coming wave but [the epidemic of opioid addiction] didn't start there and it is not going to end there. The doctors were persuaded and were actually incentivized to prescribe opioids very, very freely," he said, referring to investigations that have found pharmaceutical companies were involved for years in encouraging physicians to prescribe the drugs inappropriately. A study published Wednesday in the American Journal of Public Health found that one in 12 doctors received money from drug companies marketing opioids between 2013 and 2015.