Introduction: the three phases of harm reduction. An examination of emerging concepts, methodologies, and critiques.

The prevention and reduction of harm related to the use and distribution of psychoactive substances has gone through three stages in the last 35 years of this century. The first saw the articulation of public health concerns for the legal drugs, alcohol and tobacco, and the provision of methadone to heroin users. The second phase, building on the public health lessons of other infectious diseases, focused on illicit drugs and the importance of specific strategies for the prevention of HIV transmission among injection drug users. The third, emerging phase is the shift toward an integrated public health perspective in the convergence of approaches to both licit and illicit drugs. The success of harm reduction as a unifying concept will depend on its innovative application in both prohibitory and regulatory frameworks, and careful evaluation of its effectiveness in a variety of cultural contexts. The papers in this special issue illustrate the types of research and critical thinking that are essential for the continued evolution of the harm-reduction paradigm.