of 13,475 active injection drug users from 28 sites across the country, the diversity of this population begins to emerge. Just over half (51 percent) of the injection drug users were African American, but a cross-site comparison indicated a range from 9 to 95 percent African American. One-quarter were Hispanic (ranging from 0 to 81 percent by site), and 22 percent were white (ranging from 3 to 65 percent by site). The percentage of females was 26 percent and ranged from 12 to 37 percent by site. The percentage of high school graduates was 45 percent and ranged from 31 to 67 percent by site. The percentage unemployed was 55 percent and ranged from 29 to 75 percent. The percentage that had previously been in jail was 81 percent and ranged from 64 to 94 percent. The percentage that had previously been in substance abuse treatment was 59 percent and ranged from 29 to 75 percent). The primary drugs injected were heroin (28 percent), cocaine (21 percent), and the combination (speedball) of heroin with cocaine (35 percent); these proportions varied substantially among sites, with 6 to 57 percent injecting heroin alone, the same range injecting cocaine alone, and 6 to 75 percent injecting the combination of heroin with cocaine (all data from Brown and Beschner, 1993:529).
Further analysis of the NADR database offers additional insight into patterns of drug use and high-risk behaviors for the transmission of HIV among injection drug users. For 25,603 members of the sample, half reported injecting daily (p. 118). Daily injection among African Americans and Hispanics was similar at 45 and 46 percent, respectively, and highest among whites at 63 percent. The difference in frequency of daily injection by gender was negligible.
An examination of types of sharing behaviors that place injectors at risk of HIV infection was conducted on 17,891 injection drug users in the NADR database who had reported a history of needle sharing (pp. 124-125). The most frequently reported risk behaviors included sharing cookers for the preparation of injectable solutions and sharing the rinse water used to flush syringes following injection, 90 and 78 percent, respectively. Although both these practices are considered to be of lesser risk than the sharing of syringes, it is notable that neither practice would be directly addressed by syringe exchange, and bleach distribution would be of value only as a potential means to decontaminate shared cookers. The greater risk behavior of reusing needles was reported by 68 percent of the sample, and 41 percent had rented needles in the past.
With regard to types of needle-sharing partners among 18,918 members of the NADR sample (p. 122), 68 percent reported having shared with friends, 67 percent with ''running partners," 52 percent with a spouse or partner, and 25 percent with strangers.
Although none of the NADR sites purport to have recruited a representative sample of injection drug users from the regions they covered, it is