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Comparison of the effectiveness of bleach in preventing the transmission of HIV, hepatitis b, and hepatitis C.

Dinner KI, Tweed A, Paul A, Krajden M, Wong T, Murray WD; International Conference on AIDS (15th : 2004 : Bangkok, Thailand).

Int Conf AIDS. 2004 Jul 11-16; 15: abstract no. TuPeE5436.
Health Canada, Ottawa, Canada

Issues: The injection use of drugs represents a significant and increasingly important public health issue globally. It is a leading cause of HIV, hepatitis B (HBV), hepatitis C (HCV), and other bloodborne infections, and a health and social issue with dramatic costs and consequences for individuals, families and communities. In an effort to prevent transmission, harm reduction, including needle exchange programs (NEP), have encouraged people who use injection drugs to use bleach to clean needles and syringes, if new needles are not available. There is little direct evidence, however, demonstrating the effectiveness of bleach in preventing HCV transmission. Description: The Hepatitis C Program of Health Canada commissioned a review of the published peer-review literature, as well as resources by government agencies, and community groups. The effectiveness of bleach in preventing HCV HIV and HBV transmission is compared. Lessons learned: While studies on the effectiveness of bleach in inactivating HCV are limited, laboratory studies do demonstrate that bleach can reduce viral titres sufficiently to reduce viral infectivity, though there are no clear parameters that guarantee viral inactivation. Though bleach distribution programs are widespread-often accompanying harm reduction initiatives through NEPs-people who use injection drugs report using bleach inconsistently, and borrowing and sharing of needles and other drug use equipment persists. The published data show that neither bleach disinfection nor NEPs alone are sufficient to stop the transmission of HCV and other bloodborne pathogens completely. Recommendations: For HCV, bleach disinfecti on should not be recommended outside the context of a broad-based harm reduction strategy; more research is needed on the ability of bleach to disinfect needles and equipment, on proper bleaching procedures and on IDU behaviour; prevent the initiation of drug injection and establish harm reduction practices among injection drug users, which are critical to the control of HCV transmission.
 

The Effectiveness of Bleach in the Prevention of Hepatitis C Transmission

Tue Nov 18, 2008 8:38 pm (PST)

The Effectiveness of Bleach in the Prevention of Hepatitis C Transmission - Final Report
3. Summary of the Data on the Use of Bleach as a Disinfectant

In an effort to slow transmission of bloodborne pathogens among people who use injection drugs, harm reduction programs have tried to educate injection drug users about the dangers of sharing needles and other injecting equipment. These programs encourage the use of new needles for every injection or, when new equipment is not available, to use bleach to clean needles before each use. However, the effectiveness of bleach disinfection has not been adequately examined.

Liquid bleach is sodium hypochlorite (NaOCl) in a water-based solution. Most household bleach contains 5.25% NaOCl (range 3% to 6%)40, with available chlorine of approximately 50,000 parts per million (ppm)18.

Studies investigating the use of disinfectants for cleaning needles and syringes used by people who inject drugs have focused primarily on the ability of disinfectants and viricides to inactivate HIV. The goal was to find a method of disinfection that was effective, convenient and inexpensive. Bleach was deemed the best agent, as it met five important criteria: it is relatively non-toxic when injected in small quantities; it is a commonly used disinfectant for environmental surfaces; the disinfectant effect is quick; it is easily available; and it is inexpensive and convenient41,42. Bleach is distributed by needle/syringe exchange programs, often in conjunction with sterile needles and condoms43.

a) HCV Disinfection with Bleach
In vitro studies have shown that bleach is effective for inactivating many pathogens, including HIV and hepatitis B 44-46. However, relatively little is known about the inactivation of HCV by chemical germicides18. The lack of an in-vitro cultivation system for HCV limits the ability to investigate the efficacy of disinfection. Published information comes mainly from experiments in which the integrity of viral particles, antigens, nucleic acid and/or enzymes is used as a measure of the presence or absence of infectious virus. Such tests may show viral presence, but do not necessarily answer questions of infectivity18. Even polymerase chain reaction (PCR) detection methods cannot distinguish between infectious and inactivated virus47.

To address this challenge, some researchers have turned to animal models.

Unfortunately, the only truly appropriate animal model is the chimpanzee. Given their endangered status chimpanzee studies are both ethically difficult and very expensive18. More recently, other viruses including the bovine diarrhea virus (BVDV) have been used as surrogates for HCV18,48.

The current challenge of determining true infectivity limits our ability to evaluate appropriate dilution and exposure times. A 1:10 dilution of domestic bleach is commonly recommended for clean up of blood spills, and this concentration should be adequate to deal with HCV (and HBV) in blood18, although supportive evidence is lacking. However, blood remaining in a syringe poses different challenges than surface blood spills. The risks of transmission from an improperly cleaned and disinfected syringe are much higher than from traces of blood left on an outside surface. Studies have shown that undiluted bleach requires shorter exposure times than diluted bleach to be effective against HIV-1. It may also be more effective in the presence of residual blood in the syringe49. Presumably, the same would be true against HCV.

b) Factors Affecting HCV Inactivation
As with any disinfectant, there are factors that reduce bleach's effectiveness against HCV. These include the amount of organic material, e.g., fresh, dried or clotted blood, left in or on the equipment ('soil load'), how long the blood has been sitting in the syringe, the length of time bleach is in contact with the equipment, the "freshness" of the bleach and whether or not the bleach is used properly42,50.

Studies have shown that contact time and soil load are the two most significant of these. Disinfection with an effective compound for an inadequate time may not succeed in inactivating sufficient amounts of the pathogen to render it non-infective. Likewise, residual organic compounds, such as blood or infected tissue, can significantly impair any disinfectant's ability to inactivate HCV, HBV, HIV or other pathogens. Therefore, even highly effective chemicals can fail to properly inactivate HCV in the absence of proper cleaning (removal of residual blood) of the devices that are being disinfected18.

The stability of bleach also affects its effectiveness as a disinfectant for injection drug users. For example, dilution and storage in direct sunlight are known to reduce bleach stability and available free chlorine for disinfection44,51.

Current laboratory methods limit our ability to determine the effectiveness of bleach for inactivating HCV. In the absence of a simple in vitro cultivation system it is difficult for researchers to determine if changes in viruses' physical appearance, reduction of viral load and/or viral inhibition of host cell binding represent loss of infectivity. As well, laboratory test conditions often bear little resemblance to field use. Contact times between the virus and the test product are often too long to be realistic for field use. And the 'soil load' in test virus suspension may not be reflective of difficult-to-deal-with body fluids, such as blood18.

c) Studies on the Efficacy of Bleach for Disinfecting Injecting Equipment
There have been a limited number of studies that attempted to demonstrate the effectiveness of bleach or related germicides against HCV. Kapadia et al. examined associations between bleach use and HCV seroconversion using a nested case-controlc design. Compared to participants reporting no bleach use, they found that those who reported using bleach all the time had an odds ratiod for HCV seroconversion of 0.35 and those reporting bleach use less than all the time had an odds ratio of 0.7652. However, this study did not have sufficient power to determine if these results were statistically significant.

Agolini et al. showed that another chlorine-based compound, sodium dichloroisocyanurate (NaDCC), at a dilution resulting in 2500ppm chlorine inhibited the binding of HCV to host cells, which might imply reduced infectivity. This inhibition reached a maximum of just 91.7% after a contact time of 10 minutes53. As this chlorine compound is less sensitive than sodium hypochlorite (bleach) to inactivation by organic substances, household bleach might be even less effective.

In another study, Charrel et al. used molecular tests to evaluate the efficacy of two disinfectants for inactivating HCV: a 2% glutaraldehyde solution and a sodium hypochlorite with potassium permanganate and monosodium phosphate solution. Although the sodium hypochlorite-based disinfectant was able to inactivate HCV-positive serum, it did so only at concentrations greater than 90% (4500 parts/million active chlorine) after a contact time of 10 minutes54.

Given its disinfectant properties and its success against other pathogens, including hepatitis B, bleach may be effective for disinfecting HCV-infected needles and other IDU equipment. However, the available literature is not conclusive.

Notes
a.. Kapadia et al. matched 78 cases (IDU HCV seroconverters) with 390 persistently HCV seronegative injection drug users, all between 18 and 30 years of age. Up to five controls were matched to each case on gender, race/ethnicity, recent (within last six months) injection, date of study entry and length of follow-up.
b.. 'Odds Ratio' (OR) is the chance that an event will happen (e.g., infection/ seroconversion) compared to the chance that it will not happen (e.g., an odds ratio for group A vs. group B. of 4.0 means group A has 400% (four times) the chance of the event happening).