Needle exchange or needless exchange? The state of the debate.

Needle exchange programs have been implemented in many cities around the world to slow the spread of human immunodeficiency virus (HIV) infection among injecting drug users. Whether these programs are succeeding in reducing HIV incidence is a matter of debate, as is the appropriateness of sanctioning the provision of drug injection equipment in the midst of a "war on drugs." In a debate swollen with emotional arguments on both sides of the issue, scientific research is essential, lest discussion of needle exchange becomes needless exchange at the policy level. This article briefly outlines and critiques the common arguments for and against needle exchange. Following this, a new circulation theory of needle exchange is advanced, along with supporting evidence from an ongoing study in New Haven, CT, U.S.A. Finally, several open questions relating to the operation of needle exchange programs and the behavior of program clients are suggested for further investigation.