Abstract
An epidemiological cohort study of injection drug users in Montréal documented a significant statistical association between HIV seroconversion and needle exchange patronage from 1989 to 1995. The polemics generated by this counterintuitive quantitative data demonstrate the urgent need for a cross‐methodological dialogue between epidemiology and ethnography. Participant observation on the streets of Montréal documented the multiple HIV risks associated with the compulsive behavior and emotional craving often accompanying cocaine injection. Needle exchange programs by themselves cannot be expected to stem HIV infection in cities where intravenous cocaine is the drug of choice. Are there unintended consequences (effets pervers) to public health interventions? We need an open debate to improve risk‐reduction strategies. Public health should expand its scientific paradigm to include ethnographic documentation of the daily lives of vulnerable street addicts. On a deeper theoretical level, needle exchange polemics illustrate how power relations frame both HIV risk taking and science.