study carried out 2 years later (McCoy et al., 1994), researchers reported that 52 percent of the syringes showing visible traces of blood tested positive for HIV.
A separate category of drug injection practices can be termed indirect needle sharing because they do not directly involve passing a contaminated needle and syringe between individuals. Instead, indirect sharing involves common use of other drug preparation or injection equipment that can become contaminated. Examples include cookers, cotton, rinse water, and the drug-sharing practices called frontloading and backloading.
The cooker is a small container, typically a spoon or a metal soda bottle cap, in which a drug in the form of powder is mixed with water and heated into a solution. The heat is applied only to the point of allowing the drug to become soluble; additional heating (which might have a sterilizing effect) is not applied, as this would require time to cool that a drug user in partial withdrawal is often unwilling to tolerate. Although two drug injectors might each possess their own needle and syringe (and therefore deny that they are needle sharing), a potential for cross-contamination of needles and syringes is possible if each dips and draws solution from the same cooker in the same, or possibly later, injection episodes.
Cotton—sometimes cotton balls and other times cigarette filters or other similar materials—is placed into a cooker. Injectors draw up drug solution into their needles and syringes through the cotton, which is used to filter out particulate matter from the cooker. Cotton, which is submerged into the drug solution, typically is not discarded after each use. Instead, it is saved in containers to be soaked later to release residual drugs during periods when their availability is scarce. If contaminated needles are submerged in cotton, there is at least a theoretical possibility of contamination with viable virus that might lead to transmission.
Rinse water refers to containers of water from which one injector will draw up and squirt out tap water between the use of needles and syringes by different individuals. As needles and syringes are dipped into this rinse water, the water becomes contaminated. Contamination increases with greater use, especially over protracted periods between water changes, and also if rinse water that has been drawn into a syringe is squirted back into the same container that is to be reused for additional rinses. Moreover, rinse water is commonly used not only for rinsing, but also for the mixing of the drug solution to be injected. With regard to sharing rinse water, it is the injection of this contaminated water that poses the greatest threat for HIV transmission, especially in the case of cocaine injection, because cocaine is water