"Overall, 87% of inmates who recently injected drugs in a penitentiary reported opiates as one of their three most used drugs. Although the number of inmates who reported injecting only non-opiate drugs was small, comparisons between this group and opiate users suggests that injecting opiates may be associated with the use of someone else’s used equipment (see Table 9). Inmates who recently injected opiates were more likely, than those who recently injected non-opiates, to use someone else’s used needle, 81% vs. 48%, ?2 (1, n=251) = 13.92, p < 0.05, and works, 59% vs. 36%, ?2 (1, n=236) = 3.98, p < 0.05."


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.