The main factor associated with HIV infection among injection drug users is the practice of sharing injection equipment. This multiperson use of syringes is particularly dangerous because residual blood retained in the syringe from one person can be unintentionally and, even with rinsing, inconspicuously passed along to the next person using the syringe. This sharing behavior is in part a consequence of the restricted availability of sterile needles and syringes. An injection drug user infected with HIV can cause a cascade of new infections in many other individuals, not only through sharing of injection equipment, but also through sexual and perinatal transmission.
Needle exchange programs, in which used needles are exchanged for new, sterile ones, are one level of response to this crisis in some communities. They have been implemented in many countries (including France, the Netherlands, Great Britain, Australia, and Canada) as part of a more comprehensive public health effort to reduce the spread of HIV and other blood-borne infections among drug users, their sexual partners, and the general population. In the United States, approximately 75 needle exchange programs have been initiated in 55 cities, although many are small and the programs have not been endorsed by the federal government as a viable intervention for the prevention of AIDS. Obstacles to this approach include legal, economic, and behavioral factors.
For injection drug users who cannot or will not stop injecting drugs, the once-only use of sterile needles and syringes remains the safest, most effective approach for limiting HIV transmission. However, with significant legal impediments to syringe availability, bleach distribution programs were conceived as a means for injection drug users to disinfect needles and syringes between use. If properly used, bleach is effective in the disinfection of HIV and other pathogens—but the effectiveness of bleach as used by injection drug users under street conditions has not been optimal.
The use of federal funds to support needle exchange programs has been specifically prohibited or restricted by the language contained in a series of statutes enacted by Congress since 1988. The ban on federal support remains in effect ''… unless the Surgeon General of the United States determines that such programs are effective in preventing the spread of HIV and do not encourage the use of illegal drugs." This current prohibition applies regardless of whether the programs operating in individual states are legally authorized. As a result, needle exchange programs in communities across the country cannot use federal funds to support services involving the provision of sterile needles, but are limited in their funding to state, municipal, and private sources.