The Effectiveness of Bleach in the Prevention of Hepatitis C Transmission - Final Report

5. Comparison of the Efficacy of Bleach in Preventing Hepatitis B and HIV Transmission

a) Hepatitis B

Like HCV, infection with hepatitis B virus (HBV) can become a chronic illness which affects overall health and can cause cirrhosis and carcinoma62. Unlike HCV, HBV is vaccine-preventable. Thirty-four percent of HBV infections in Canada are attributable to injection drug use^63.

As with HCV, relatively little is known about the inactivation of HBV by chemical germicides¹⁸. It does appear that HBV can be inactivated by household bleach^22,64,65. Sehulster et al. reported that concentrations of 5600ppm or more of available chlorine (approximately 1:9 dilution of household bleach) were able to reduce hepatitis B surface antigen reactivity in plasma after an exposure time of one minute or more⁴⁵. Using a chimpanzee model, Bond et al. found that exposure to bleach for 10 minutes at 20° C resulted in complete HBV inactivation⁶⁵. Payan et al. reported that sodium hypochlorite at 4700ppm free chlorine (approximately 1:11 dilution bleach) reduced viral titres 1000 to 10,000-fold, although more diluted concentrations were not effective, resulting in less than 10-fold viral reduction⁶⁶. And Thraenhart et al. reported that a 1% sodium hypochlorite solution (approx. 1:5 dilution of household bleach) caused Dane particle (the complete, infectious HBV virion) alteration in 60% and disintegration in 50% after an exposure time of five minutes. Disintegration increased to 90% when a 2% solution was used⁶⁷.

Caution is still needed in interpreting the results of HBV disinfection studies; as with HCV studies, most of these studies use proxies for infectivity and therefore may not represent true viral inactivation. They also used exposure times that may not be realistic in IDU settings.

Research into the effectiveness of using bleach to eliminate hepatitis B transmission has implications for hepatitis C as HCV is probably at least as easy to inactivate as HBV¹⁸.

b) HIV

HIV infection typically results in immunosuppression, leaving infected individuals vulnerable to opportunistic infections and cancers. As with hepatitis, IDU is an important mode of transmission for HIV. More than one third (35%) of all AIDS cases reported in the United States in 1995 and 30% of annual positive HIV tests in Canada are associated with IDU^68,69.

The CDC, NIDA and CSAT advocate the use of bleach for disinfecting drug injection equipment. In a joint bulletin released in 1993, these organizations stated that, "bleach disinfection of needles and syringes continues to have an important role in reducing the risk for HIV transmission for injecting-drug users who reuse or share a needle or syringe⁵⁷."

Some studies have shown that bleach can inactivate cell-associated HIV in syringes within just 10 seconds of exposure. However, this contact time is insufficient when the contaminated syringes are left standing for three hours at room temperature. Syringe disinfection, then, is dependent on the extent of cleaning in relation to organic contamination⁴².

Current data suggest that a minimum bleach exposure time of 30 seconds is required to consistently inactivate HIV, even with full strength bleach^46,49. This contact time is often not achieved by injection drug users. A 1991 Baltimore study illustrated that bleach use does not eliminate HIV risk among drug users, even among those who report using it all the time⁵⁹.

Abdala et al. attempted to replicate a real-world injection drug use situation. They used syringes containing 2ml, 20ml and 40ml of HIV-1 infected blood, rinsed them quickly (taking only the time to draw in and immediately expel rinse liquid) with water, diluted bleach (1:10) and/or undiluted bleach and then tested them for viable HIV-1. More rinses and greater bleach concentrations showed the best results: less than 1% of syringes rinsed three times with water or once with undiluted bleach contained viable HIV-1. Diluted bleach was no better than water after one rinse, and only marginally better after two or three rinses⁷⁰. Importantly, although even undiluted bleach did not inactivate 100% of HIV-1 in 100% of the syringes, it did reduce the viral load significantly. Such a decrease could decrease the risk of HIV transmission among people who use injection drugs⁷⁰.

These laboratory-based studies address only the ability of bleach to eliminate HIV in syringes. Epidemiologic studies in real world settings have found that self-reported use of bleach has not been associated with a reduction in HIV prevalence⁷¹. Titus et al. reported that among a sample of New York injection drug users, increasing levels of bleach use were not consistently associated with decreasing odds ratios for HIV seroconversion72. And a prospective study by Vlahov and colleagues (1991) reported no significant difference in seroconversion rates among injection drug users reporting the use of disinfectants all of the time, some of the time, or never^46. These results suggest that the effectiveness of bleach observed in laboratory studies is not achieved in real-life situations.

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