A comparative study of characteristics and risky behaviors among the Iranian opium and opium dross addicts.

Background: Iran ranks first per capita in the use of opiates, but we have little information about possible differences regarding the 2 most commonly used illicit drugs, namely opium and its dross (residue).

Design: This is a cross-sectional study.

Setting: A cross-sectional study about drug abuse and drug dependence in Iran was conducted from April 2006 to August 2008 in the prisons of 28 Iranian provinces, in the treatment centers, and in the streets.