Found by another one of our advocates and his 10-year old daughter doing outreach in the community. There was a study conducted comparing two cities, Miami (w/o needle exchange) vs San Francisco (with needle exchange), and found that only 13% of inappropriately discarded syringes were found in SF as compared to 93% in Miami! Disposal, just another thing needle exchange programs are good at.
The study, “A Comparison of Syringe Disposal Practices Among Injection Drug Users in a City With Versus a City Without Needle and Syringe Programs,” was published in Drug and Alcohol Dependence (2011; http://dx.doi.org/10.1016/j.drugalcdep.2011.12.001).