"Our results probably explain reports of increased injection drug use, drug-related crime and other public-order concerns in neighbourhoods where activities related to illicit drug use and the sex trade emerged or intensified in the wake of the crackdown. Such displacement has profound public-health implications if it 'normalizes' injection drug use among previously unexposed at-risk youth. Furthermore, since difficulty in obtaining syringes has been shown to be a significant factor in promoting syringe sharing among IDUs in Vancouver, displacement away from sources of sterile syringes may increase the rates of bloodborne diseases. Escalated police presence may also explain the observed reduction in willingness to use a safer injection facility.33 It is unlikely that the lack of benefit of the crackdown was due to insufficient police resources. Larger crackdowns in the United States, which often involved helicopters to supplement foot and car patrols, have not had measurable benefits and have instead been associated with substantial health and social harms."
Wood, Evan, Patricia M. Spittal, Will Small, Thomas Kerr, Kathy Li, Robert S. Hogg, Mark W. Tyndall, Julio S.G. Montaner, Martin T. Schechter, "Displacement of Canada's Largest Public Illicit Drug Market In Response To A Police Crackdown," Canadian Medical Association Journal, May 11, 2004: 170(10), pp. 1554-1555.