The reuse of needles and syringes that are intended for use by a single individual on a single occasion is an inherently unsafe practice. The repeated use of needles and syringes commonly violates their sterility and predisposes the user to life-threatening infections from a wide variety of bacterial and viral pathogens. The sharing of injection equipment by injection drug users provides an efficient means of transmitting HIV, hepatitis B and C viruses, and the human T-cell leukemia viruses (HTLV-I and HTLV-II). The only reliable ways to limit the transmission of HIV and other viral infections among injection drug users are either to refrain from injecting drugs or not to share injection equipment with other users. If an injection drug user is unable or unwilling to refrain from using injection drugs, the use of a sterile, disposable needle and syringe for each injection represents the next best alternative. However, in circumstances in which supplies of sterile needles and syringes are inadequate or unavailable, disinfection strategies provide another means to decrease the risk of transmission of HIV and other infectious agents between injection drug users who are compelled to share injection equipment.
Bleach disinfection of contaminated needles and syringes is the most commonly used and familiar strategy employed by injection drug users, and, if used according to current recommendations made by the Centers for Disease Control and Prevention, the National Institute on Drug Abuse, and the Center for Substance Abuse Treatment, is likely to be effective in disinfecting contaminated injection equipment. Definition of the precise efficacy of bleach as a disinfectant of HIV-contaminated needles and syringes has been hampered by the lack of a laboratory model that faithfully recapitulates the real-life circumstances of injection drug use. Unfortunately, too little attention and too few resources have been devoted to studies to define the simplest, most effective disinfection methods for injection equipment used by injection drug users.
The inability of initial epidemiologic studies to demonstrate a significant protective effect of disinfection practice against HIV infection of injection drug users is disconcerting. Unfortunately, evaluation and epidemiologic studies performed to date do not clearly identify the reasons for the similar rates of incident HIV infections reported between those who always clean their needles and syringes and those who never do. It is not yet known whether this results from inadequate disinfection techniques used by injection drug users who become infected, their overestimation of the frequency of their use of needle and syringe disinfection in interviews with researchers, or physical or biological factors that compromise the ability of bleach, a potent disinfectant in other circumstances, to effectively disinfect contaminated injection equipment. Certainly, a number of observational