Rinsing needles and syringes with bleach is not an effective way to prevent HIV and hepatitis C transmission. While some studies show that bleach can kill HIV and hepatitis C in needles and syringes in a laboratory setting, this effectiveness does not translate to the real world.
The World Health Organization, the Public Health Agency of Canada, and the Best Practice Recommendations for Canadian Harm Reduction Programs do not recommend the use of bleach as an HIV and hepatitis C prevention strategy.
This article reviews the evidence on the effectiveness of bleach to kill HIV and hepatitis C in needles, and to reduce the risk of HIV and hepatitis C transmission among people who inject drugs. We present implications for harm reduction programming and policies, and provide key messages for discussing the lack of effectiveness of bleach as well as other harm reduction strategies with clients who inject drugs.
Is Bleach Effective as an HIV Prevention Strategy?
Real-world studies among people who inject drugs have demonstrated that using bleach to rinse needles has little or no protective effect against HIV transmission; 1-4 however, bleach has been found to be effective at killing HIV in syringes in laboratory settings.5
One study conducted in the community found that people who reported always using bleach to rinse their needles had no reduced risk of HIV transmission compared to those who reported sometimes or never using bleach,2 while another study found a modest reduction in HIV risk for those who reported using bleach or alcohol to rinse needles all of the time compared to those who did sometimes or never.3 Additionally, one study found that in a U.S. population of people who inject drugs the prevalence of HIV increased over a two-year period where the use of bleach to rinse needles increased significantly, which suggests that rinsing with bleach was ineffective at killing HIV.4
Laboratory studies have demonstrated the factors that enable bleach to kill HIV in a controlled setting. In most cases, undiluted (or full-strength) bleach is more effective at killing HIV in syringes than diluted bleach. Other factors that have been found to impact bleach effectiveness include: the length of time blood remains in the syringe before rinsing with bleach, the volume of blood left in the syringe, the duration of bleach contact with the syringe, and the number of rinses with bleach.5 In studies where syringes containing residues of HIV-infected blood were left to sit for a period of time at room temperature or had a greater volume of blood left in the syringe, undiluted bleach needed a longer contact time and/or more rinses to kill HIV.6,7 Allowing syringes to sit before rinsing them with bleach can contribute to the presence of dried or clotted blood, which appears to make bleach less effective.5
Is Bleach Effective as a Hepatitis C Prevention Strategy?
Real-world studies on hepatitis C transmission and bleach use among people who inject drugs have found mixed results.8-11 Two studies found that people who inject drugs who reported always rinsing used needles with bleach were less likely to become infected with hepatitis C compared to those who reported they did not always use bleach to rinse needles.9,10 However, two studies have found an increased risk of hepatitis C among those who reported always using bleach to rinse needles compared to those who reported they did not.8 Another study in a population of prisoners found that those who reported always using bleach to rinse equipment did not have a reduced risk of hepatitis C infection compared to those who reported using bleach less than every time.11
There is currently only one study testing the ability of bleach to kill hepatitis C in syringes in a laboratory setting. This study found that diluted bleach was effective at killing hepatitis C in all syringes tested, with both fixed needles and detachable needles (which can leave a greater volume of blood in the syringe), after one rinse.12 In this study, bleach was able to kill hepatitis C with only one rinse and with a high volume of blood left in the syringe. However, since syringes were rinsed with bleach immediately after contamination, we do not know how effective bleach is at killing hepatitis C in syringes which have blood that has dried or clotted.
Why Isn't Bleach Effective in the Real World?
Several factors may contribute to the ineffectiveness of bleach observed in real life compared to laboratory experiments.
In a real-world setting, using bleach to kill HIV or hepatitis C in used needles involves many steps and is a time-consuming process. It is commonly recommended that people should first rinse a used needle twice with water, shaking the syringe to loosen any dried blood, followed by two rinses with full-strength bleach (with a contact time of at least 30 seconds each time) and two final rinses with water.
Research has found that even when people who inject drugs report rinsing their used needles and syringes, many are not cleaning them in an effective way.1,13-19 Potentially ineffective techniques that have been reported or observed include: not completely filling the syringe with bleach, 13 failing to hold bleach within a syringe for the recommended 30 seconds,14-19
Additionally, research suggests that other injecting equipment (such as cookers and filters) can be a source of HIV and hepatitis C infection when shared, and that the contamination of these materials may contribute to HIV and/or hepatitis C transmission even when needles and syringes are disinfected with bleach.20,21
What Makes It Difficult to Rinse Needles Effectively in the Real World?
Studies have found that people who inject drugs effectively learn and retain information about proper rinsing techniques when taught.13,14,22 However, adherence may not be practised for many reasons.
Qualitative research has found that needle cleaning behaviours are influenced by the circumstances surrounding a particular injection event. Many people who inject drugs may not effectively implement the recommended steps because the process of using bleach to properly clean needles is time consuming. People who inject drugs report feeling the pressure to inject as quickly as possible for many reasons including: being in withdrawal and feeling sick, injecting with other people waiting to use the same needle, sharing a limited quantity of drug, and being concerned about arrest or detection by the police or others.23 For example, in prison settings, injection drug use needs to be completed discreetly and quickly due to surveillance from prison guards. These time constraints can make someone less likely to clean a used needle properly or to rinse it at all before using it again.
Other reasons people do not rinse used needles with bleach include: using drugs in a setting without access to bleach or clean water, such as a public place or in prison; being high and not interested in cleaning; not having access to personal needles; or using drugs in a social context where other people are not cleaning their needles.23,24
What Recommendations Exist Regarding Bleach Use for HIV and Hepatitis C Prevention?
Bleach is not internationally recognized as an effective method to prevent HIV and hepatitis C transmission.
The World Health Organization (WHO) does not recommend the use of bleach as a strategy to reduce the risk of HIV transmission due to a lack of evidence demonstrating its effectiveness in the real world. An evidence review conducted by the WHO in 2004 states:
"At best, these strategies can only be regarded as acceptable in community or correctional settings where the introduction of needle and syringe programs (NSPs) is considered impossible because of fear or hostility on the part of community members or authorities. Public health practitioners in these settings should continue to advocate for the introduction of NSPs as the most reliable and evidence-based way of maintaining control of HIV among [people who inject drugs]."1
In 2004, the Public Health Agency of Canada (PHAC) reviewed the evidence on bleach as a method to prevent hepatitis C, HIV and hepatitis B transmission. PHAC states:
"Bleach disinfection should not be recommended outside the context of a broad-based harm reduction strategy. Although partial effectiveness cannot be excluded, the published data clearly indicate that bleach disinfection has limited benefit in preventing HCV transmission among injection drug users... Bleach distribution and education programs for people who use injection drugs must be careful not to impart a false sense of security regarding bleach's protective efficacy."25
Finally, Canada's Best Practice Recommendations for Canadian Harm Reduction Programs (Part 2, released in 2015) states:
"There is a lack of evidence to support the provision of bleach as an effective measure to reduce HIV and HCV transmission in the community and in prison and therefore we do not recommend bleach distribution as a prevention method".26
What Does This Mean for People Working in Harm Reduction?
Policy Making and Program Planning
This evidence review indicates that cleaning needles with bleach is not an effective way to prevent HIV and hepatitis C from passing from person to person. An evidence-based best practice for preventing HIV and hepatitis C is to use new drug use equipment for every injection. It is important for this evidence to be reflected in harm reduction policy and programming. Where needle and syringe programs (NSPs) are not available or do not have full coverage, policy makers and program planners may want to seriously consider advocating for improving the coverage of NSPs in their jurisdiction or investigate other ways of increasing access to new equipment.
Key Messages for Conversations With Clients
The most effective way to prevent HIV and hepatitis C transmission is to use new injecting equipment every time a person uses drugs. Agencies that distribute needles should encourage and allow clients to take enough needles to meet their needs plus extras for emergencies. However, there are many places in Canada where NSPs are not available and it is difficult to get new equipment, such as in prisons and in rural, remote or other communities with limited NSP coverage. When new drug use equipment is not available, discussing other options with clients is an important part of engaging people in harm reduction, and in HIV and hepatitis C prevention.
There are other strategies harm reduction workers can suggest to support people who want to avoid lending or borrowing drug use equipment when it is not possible to get new equipment. These include:
- Switching to drugs that can be swallowed (parachute), eaten, smoked or snorted until they can get new injection equipment.
- Keeping their own needle or syringe and not letting anyone else use it. Identify a personal needle by marking it with tape, a marker or nail polish. Rinse the needle with cold water after using it so blood does not dry in the syringe and clog it. (Note: This will not kill hepatitis C or HIV.) The needle can also be re-sharpened by scraping the point and beveled edge along a matchbook where you would strike the match.
- Not re-using cookers, filters, or other equipment that has already been used by another person.
- When possible, stocking up on needles, syringes, cookers, filters, water, swabs and ties when they can get to a NSP.
- Buying new needles at a pharmacy. Some pharmacies may also give them away for free.
Some clients may ask about using bleach as a harm reduction option. It is important to have a conversation with them about the limited effectiveness of bleach at reducing their risk of getting HIV or hepatitis C. If cleaning a needle with bleach is still the only option a person would like to use, it is very important that they follow the correct steps to cleaning a needle with bleach. For more information on those steps see "How to clean a needle with bleach".
For a discussion on the issues related to the use of bleach to rinse needles and syringes, see Views from the front lines: Bleach as a harm reduction strategy for people who inject drugs.
Best Practice Recommendations for Canadian Harm Reduction Programs
Camille Arkell is CATIE's Knowledge Specialist, Biomedical Science of Prevention. She has a Master's of Public Health degree in Health Promotion from the University of Toronto, and has been working in HIV education and research since 2010.
Scott Anderson is CATIE's hepatitis C researcher/writer. Prior to working at CATIE, Scott was a research coordinator at the Centre for Addiction and Mental Health, where he led studies examining healthcare access for marginalized groups.
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