National Institute on Drug Abuse conducts major opium use study.
D006556:Heroin Dependence / Q000453:epidemiology / Q000534:rehabilitation; D006801:Humans; D009892:Opium; D012008:Recurrence; D019966:Substance-Related Disorders / Q000453:epidemiology* / Q000534:rehabilitation; D014481:United States; D014482:United States Substance Abuse and Mental Health Services Administration
D009892:Opium