"At the time of the survey, 7% of all inmates reported being on MMTP. An additional 9% of all inmates reported not being on the program but previously trying to get on it at CSC. The remaining 84% of inmates reported never trying to join the program (63%), never using drugs (20%), and no longer needing the program (<1%).
"Participation in MMTP was associated with drug use in penitentiaries. Of inmates who were on MMTP, 60% reported not using opiates recently in a penitentiary; however, 40% did (see Table 10). Similarly, of those who were not on CSC’s MMTP but had tried to get on the program, almost equal proportions reported no drug use in a penitentiary (45%) and recent opiate use a penitentiary (44%). Conversely, the majority of inmates who never tried to get on MMTP at CSC reported no recent opiate use in a penitentiary (87%) and a minority (12%) reported recent opiate use in a penitentiary."
Thompson, Jennie, Zakaria, Dianne, and Jarvis, Ashley, "Use of bleach and the methadone maintenance treatment program as harm reduction measures in Canadian Penitentiaries 2010," Correctional Service of Canada, Research Report R-210, August 2010.