Yale Study Shows Rinsing Contaminated Syringes with Water And Bleach Still Effective Means of Killing HIV

Despite reports to the contrary, clean water and full strength bleach remain an effective means for injection drug users to disinfect syringes contaminated with the HIV virus, a Yale study has found.

For years, bleaching of syringes was suggested to injection drug users as a way to reduce HIV transmission through shared needles. In the mid-1990s, however, there were several studies suggesting that bleach, at least in the way injection drug users were using it, was not effective in disinfecting syringes.

“As a result of these warnings, many programs that had distributed bleach stopped doing so,” said Robert Heimer, senior author of the article in the December issue of the Journal of Acquired Immuno Deficiency Syndrome and associate professor in the Departments of Epidemiology and Public Health and Pharmacology at Yale School of Medicine.

To test the disinfection method, Heimer and his co-researchers developed a microculture assay sensitive enough to recover infectious HIV-1 from as little as 0.4 microliters of infected blood. Then syringes spiked with HIV infected blood were rinsed with water and/or bleach, simulating the practice of drug injectors. The syringes are rinsed by drawing the liquid into the syringe and then squirting it out again.

“What we found is that for the type of syringe usually used by drug injectors, even a one-tenth diluted solution of bleach successfully disinfects the syringe if the solution is drawn in and squirted back out,” Heimer said. “Even when we stacked the deck and left 10 times more blood in the syringe than is usually found, full strength bleach was effective in 152 of 153 attempts. We even found that rinsing three times with clean water reduced the likelihood of recovering live virus by 99 percent.”

Co-authors of the study were principal investigator Nadia Abdala, associate research scientist in the Department of Epidemiology and Public Health; John Carney, who recently received his Master’s Degree in Public Health from Yale, and Alice Gleghorn, an epidemiologist with the San Francisco Department of Public Health.