| Terms | |
|---|---|
| Foodborne illness | |
| Hazard Analysis and Critical Control Points (HACCP) | |
| Critical control point | |
| Critical factors | |
| Food, acidity, time, temperature, oxygen and moisture | |
| pH | |
| Water activity (aw) | |
| Pathogens | |
| Clostridium botulinum | |
| E. coli | |
| Hepatitis A | |
| Norovirus | |
| Parasitic infections | |
| Blastocystis | |
| Cryptosporidiosis | |
| Trichinosis | |
Hand washing for hand hygiene is the act of cleaning the hands with or without the use of water or another liquid, or with the use of soap, for the purpose of removing soil, dirt, and/or microorganisms.
Medical hand hygiene pertains to the hygiene practices related to the administration of medicine and medical care that prevents or minimizes disease and the spreading of disease. The main medical purpose of washing hands is to cleanse the hands of pathogens (including bacteria or viruses) and chemicals which can cause personal harm or disease. This is especially important for people who handle food or work in the medical field, but it is also an important practice for the general public. People can become infected with respiratory illnesses such as influenza or the common cold, for example, if they don't wash their hands before touching their eyes, nose, or mouth. Indeed, the Centers for Disease Control and Prevention (CDC) has stated: "It is well documented that one of the most important measures for preventing the spread of pathogens is effective hand washing." As a general rule, handwashing protects people poorly or not at all from droplet- and airborne diseases, such as measles, chickenpox, influenza, and tuberculosis. It protects best against diseases transmitted through fecal-oral routes (such as many forms of stomach flu) and direct physical contact (such as impetigo).
In addition to hand washing with soap and water, the use of alcohol gels is an effective form of killing some kinds of pathogens.[1]
In symbolic hand washing, using water only to wash hands is a part of ritual handwashing as a feature of many religions, including Bahá'í Faith, Hinduism, and tevilah and netilat yadayim in Judaism. Similar to these are the practices of Lavabo in Christianity, Wudu in Islam and Misogi in Shintō.
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The application of water alone is inefficient for cleaning skin because water is often unable to remove fats, oils, and proteins, which are components of organic soil. However, since pathogens removed from the skin have to be rinsed away, there must be a reasonable flow of water.[2]
Therefore, removal of microorganisms from skin requires the addition of soaps or detergents to water. Currently most products sold as "soaps" are actually detergents, so that is the substance most used to wash hands.
Hot water that is comfortable for washing hands is not hot enough to kill bacteria. Bacteria grows much faster at body temperature (37 C). However, warm, soapy water is more effective than cold, soapy water at removing the natural oils on your hands which hold soils and bacteria.[3] Contrary to popular belief however, scientific studies have shown that using warm water has no effect on reducing the microbial load on hands.[4][5]
Solid soap, because of its reusable nature, may hold bacteria acquired from previous uses.[6][7] Yet, it is unlikely that any bacteria are transferred to users of the soap, as the bacteria are rinsed off with the foam.[8]
Antibacterial soaps have been heavily promoted to a health-conscious public. To date, there is no evidence that using recommended antiseptics or disinfectants selects for antibiotic-resistant organisms in nature.[9] However, antibacterial soaps contain common antibacterial agents such as Triclosan, which has an extensive list of resistant strains of organisms. So, even if antibiotic resistant strains aren't selected for by antibacterial soaps, they might not be as effective as they are marketed to be.
A comprehensive analysis from the University of Oregon School of Public Health indicated that plain soaps are as effective as consumer-grade anti-bacterial soaps containing triclosan in preventing illness and removing bacteria from the hands.[10]
A hand sanitizer or hand antiseptic is a non-water-based hand hygiene agent.[11] In the late 1990s and early part of the 21st century, alcohol rub non-water-based hand hygiene agents (also known as alcohol-based hand rubs, antiseptic hand rubs, or hand sanitizers) began to gain popularity. Most are based on isopropyl alcohol or ethanol formulated together with a thickening agent such as Carbomer into a gel, or a humectant such as glycerin into a liquid, or foam for ease of use and to decrease the drying effect of the alcohol.
Hand sanitizers containing a minimum of 60 to 95% alcohol are efficient germ killers. Alcohol rub sanitizers kill bacteria, multi-drug resistant bacteria (MRSA and VRE), tuberculosis, and some viruses (including HIV, herpes, RSV, rhinovirus, vaccinia, influenza, and hepatitis) and fungus. Alcohol rub sanitizers containing 70% alcohol kill 3.5 log10 (99.9%) of the bacteria on hands 30 seconds after application and 4 to 5 log10 (99.99 to 99.999%) of the bacteria on hands 1 minute after application.[12]
Hand sanitizers are most effective against bacteria and less effective against some viruses. Alcohol-based hand sanitizers are almost entirely ineffective against norovirus or Norwalk type viruses, the most common cause of contagious gastroenteritis.
The CDC recommends hand washing over hand sanitzer rubs, particularly when hands are visibly dirty.[13]
The increasing use of these agents is based on their ease of use and rapid killing activity against micro-organisms, however they should not serve as a replacement for proper hand washing unless soap and water are unavailable.
Frequent use of alcohol-based hand sanitizers can cause dry skin unless emollients and/or skin moisturizers are added to the formula. The drying effect of alcohol can be reduced or eliminated by adding glycerin and/or other emollients to the formula. In clinical trials, alcohol based hand sanitizers containing emollients caused substantially less skin irritation and dryness than soaps or antimicrobial detergents. Allergic contact dermatitis, contact urticaria syndrome or hypersensitivity to alcohol or additives present in alcohol hand rubs rarely occurs.[8][14] The lower tendency to induce irritant contact dermatitis became an attraction as compared to soap and water hand washing.
Despite their effectiveness, non-water agents do not cleanse the hands of organic material, but simply disinfect them. It is for this reason that hand sanitizers are not as effective as soap and water at preventing the spread of pathogens, since the pathogens still remain on the hands.
The efficacy of alcohol-free hand sanitizers is heavily dependent on their ingredients and formulation. In the past, alcohol-free hand sanitizers tended to significantly under-perform alcohol or alcohol rubs as germ killers in clinical studies using standard protocols such as EN1500. More recently, advanced formulations have been developed, some of which have been shown to out-perform alcohol. An example of this is HandClens, with a patented SAB (Surfactant, Allantoin and Benzalkonium Chloride) formulation. Other alcohol-free hand sanitizer products that use benzalkonium chloride as the active ingredient include Hy5, Soapopular, DEBSBS and EcoHydra. A further aspect of efficacy sometimes overlooked is the effect of repeated use. The efficacy of alcohol as a hand disinfectant has been shown to decrease after repeated use, probably due to progressive adverse skin reactions, whereas the efficacy of an alcohol-free hand sanitizer based on Benzalkonium Chloride as its active ingredient has been shown to increase with repeated use.[15] In a recent study, the effectiveness of alcohol was shown to decrease after repeated use. The study demonstrated that, unlike Benzalkonium Chloride, alcohol does not have persistent or cumulative antimicrobial activity after application.[16] Purell has been shown to fail to meet the FDA 21 CFR 333.470 performance standards for health-care personnel antiseptic hand washes not just as a consequence of the decrease in effectiveness with repeated use, but due to a lack of persistence in antimicrobial activity after application and the decrease in effectiveness with heavy soil loads.[15] In the same study, HandClens was shown to meet and exceed the FDA performance standards.
Conventionally, the use of soap and warm running water and the washing of all surfaces thoroughly, including under fingernails is seen as necessary. One should rub wet, soapy hands together outside the stream of running water for at least 20 seconds, before rinsing thoroughly and then drying with a clean towel, disposable or otherwise.[17] It has been shown that the use of a towel is a necessary part of effective contaminant removal, since the washing action separates the contaminants from the skin but does not completely flush them from the skin - removing the excess water (with the towel) also removes the suspended contaminants. After drying, a dry paper towel should be used to turn off the water (and open the exit door if one is in a restroom). Moisturizing lotion is often recommended to keep the hands from drying out, should one's hands require washing more than a few times per day.[18]
Enough hand antiseptic or alcohol rub must be used to thoroughly wet or cover both hands. The front and back of both hands and between and the ends of all fingers are rubbed for approximately 30 seconds until the liquid, foam or gel is dry.
Effective drying of the hands is an essential part of the hand hygiene process, but there is some debate over the most effective form of drying in washrooms. A growing volume of research suggests paper towels are much more hygienic than the electric hand dryers found in many washrooms.
In 2008, a study was conducted by the University of Westminster, London and sponsored by the paper towel industry the European Tissue Symposium, to compare the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers.[19] The key findings were:
The scientists also carried out tests to establish whether there was the potential for cross contamination of other washroom users and the washroom environment as a result of each type of drying method. They found that:
In 2005, in a study conducted by TUV Produkt und Umwelt, different hand drying methods were evaluated.[20] The following changes in the bacterial count after drying the hands were observed:
| Drying method | Effect on Bacterial Count |
|---|---|
| Paper towels and roll | Decrease of 24% |
| Hot-air dryer | Increase of 12% |
Medical hand washing is for a minimum of 15 seconds using generous amounts of soap and water or gel to lather and rub each part of the hands.[21] Hands should be rubbed together with digits interlocking. If there is debris under fingernails, a bristle brush may be used to remove it. Since germs may remain in the water on the hands it is important to rinse well and wipe dry with a clean towel. After drying, the paper towel should be used to turn off the water (and open any exit door if necessary). This avoids re-contaminating the hands from those surfaces.
The purpose of hand washing in the health care setting is to remove pathogenic microorganisms ("germs") and avoid transmitting them. The New England Journal of Medicine reports that lack of hand washing remains at unacceptable levels in most medical environments, with large numbers of doctors and nurses routinely forgetting to wash their hands before touching patients.[22] One study showed that proper hand washing and other simple procedures can decrease the rate of catheter-related bloodstream infections by 66 percent.[23]
The World Health Organization has published a sheet demonstrating standard handwashing and handrubbing in health care sectors.[24] The draft guidance of hand hygiene by the organization can also be found at its website for public comment.[25] A relevant review was conducted by Whitby et al.[12] Commercial devices can measure and validate hand hygiene, if demonstration of regulatory compliance is required.[26]
The addition of antiseptic chemicals to soap ("medicated" or "antimicrobial" soaps) confers killing action to a hand washing agent. Such killing action may be desired prior to performing surgery or in settings in which antibiotic-resistant organisms are highly prevalent.[27]
To 'scrub' one's hands for a surgical operation, it is necessary to have a tap that can be turned on and off without touching with the hands, some chlorhexidine or iodine wash, sterile towels for drying the hands after washing, and a sterile brush for scrubbing and another sterile instrument for cleaning under the fingernails. All jewelry should be removed. This procedure requires washing the hands and forearms up to the elbow, usually 2–6 minutes. Long scrub times (10 minutes) are not necessary. When rinsing, water on the forearms must be prevented from running back to the hands. After hand washing is completed, the hands are dried with a sterile cloth and a surgical gown is donned.
Medical hand-washing became mandatory long after Hungarian physician Ignaz Semmelweis discovered its effectiveness in preventing disease in a hospital environment.[28]
Liquid hand antiseptics are much more effective germ killers than gel and foam hand sanitizers. To use in a medical or surgical setting a sterile stainless bowl is filled with antiseptic and both hands are dipped and rinsed in the liquid up to the elbows. The hands and lower arms are removed from the liquid, rubbed and allowed to dry. After, drying in approximately 30 to 60 seconds the healthcare provider is gloved and gowned.
Alcohol rubs and hand antiseptics (biocides) kill microorganisms. Current scientific evidence has not demonstrated a link between the use of topical antimicrobial formulations and antiseptic or antibiotic resistance. Antiseptics (biocides) have multiple (thousands) of nonspecific killing sites on and in the microbial cell which cannot easily mutate. Antibiotics and antibacterial soaps (triclosan) have one very specific killing site on and in the microbial cell which can easily mutate. Antibiotic resistance has no effect on the effectiveness of antiseptics.[29][30]
Alcohol rubs and combination hand sanitizers are effective at killing some germs on the hands.[1] Many clinical studies have shown that alcohol rubs containing two germ killers (i.e., alcohol and chlorhexidine gluconate or benzalkonium chloride) are significantly better germ killers than alcohol rubs containing alcohol alone.[14]
However alcohol rub sanitizers are not appropriate for use when the hands are visibly dirty, soiled. Visible soiling of any sort on the hands must be washed with soap and water because alcohol-based hand rubs are less effective in the presence of organic material. In addition, alcohols may not be effective against non-lipid-enveloped viruses (e.g., Noroviruses) as enveloped viruses but they are still effective. Hand antiseptics and soap and water will not kill the endospores of bacteria (e.g., Clostridium difficile and Anthrax) and the spores of protozoa (e.g., Giardia lamblia) but soap and water may wash them down the drain. When such microorganisms are likely to be encountered, soap and water hand washing followed by use of a good hand antiseptic is preferable.[8]
Hand washing with hand sanitizer (hand antiseptic) is effective in cleaning [killing] staph aureus and the bacteria that are causing these staph infections, but alcohol-based hand sanitizers and soap and water are not effective in killing spore forming organisms because alcohol or soap will not destroy bacterial spores. Washing hands with soap and water may wash the spores down the sink.[31]
In the U.S. alcohol rubs have been banned from some schools because of flammability concern. The fire department allows Tallahassee Memorial Hospital to have a certain amount of hand sanitizer per smoke compartment, and supply it up to that limit.[31]
Hand washing using hand sanitizing wipes is also recommended by CDC as a convenient alternative during traveling in the absence of soap and water[32] in nonacute health care settings.[33]
This hygienic behavior has been shown to cut the number of child deaths from diarrhea (the second leading cause of child deaths) by almost half and from pneumonia (the leading cause of child deaths) by one-quarter.[34] There are five critical times in washing hands with soap and/or using of a hand antiseptic related to fecal-oral transmission: after using a bathroom (private or public), after changing a diaper, before feeding a child, before eating and before preparing food or handling raw meat, fish, or poultry, or any other situation leading to potential contamination and see below.[35] To reduce the spread of germs, it is also better to wash the hands and/or use a hand antiseptic before and after tending to a sick person.
For control of staphylococcal infections in hospitals, it has been found that the greatest benefit from hand-cleansing came from the first 20% of washing, and that very little additional benefit was gained when hand cleansing frequency was increased beyond 35%.[36] Washing with plain soap results in more than triple the rate of bacterial infectious disease transmitted to food as compared to washing with antibacterial soap.[37] Comparing hand-rubbing with alcohol-based solution with handwashing with antibacterial soap for a median time of 30 seconds each showed that the alcohol hand-rubbing reduced bacterial contamination 26% more than the antibacterial soap.[38] But soap and water is the more effective than alcohol-based hand rubs for reducing H1N1 influenza A virus[39] and Clostridium difficile spores from hands.[40]
In symbolic hand washing using water only to wash hands is a part of ritual handwashing as a feature of many religions, including Bahá'í Faith, Hinduism and tevilah and netilat yadayim in Judaism. Similar to these are the practices of Lavabo in Christianity, Wudu in Islam and Misogi in Shintō.
The phrase "washing one's hands of" something, means declaring one's unwillingness to take responsibility for the thing or share complicity in it. In the New Testament book of Matthew, verse 27:24 gives an account of Pontius Pilate washing his hands of the decision to crucify Jesus: "When Pilate saw that he could prevail nothing, but that rather a tumult was made, he took water, and washed his hands before the multitude, saying, 'I am innocent of the blood of this just person: see ye to it'." Also see Psalm 26:6.
In Shakespeare's Macbeth, Lady Macbeth begins to compulsively wash her hands in an attempt to cleanse an imagined stain, representing her guilty conscience regarding crimes she had committed and induced her husband to commit.
It has also been found that people, after having recalled or contemplated unethical acts, tend to wash hands more often than others, and tend to value hand washing equipment more. Furthermore, those who are allowed to wash their hands after such a contemplation are less likely to engage in other "cleansing" compensatory actions, such as volunteering.[41][42]
Excessive hand washing is commonly seen as a symptom of obsessive-compulsive disorder (OCD).
41. Devnani M, Kumar R, Sharma RK, Gupta AK. A survey of hand-washing facilities in the outpatient department of a tertiary care teaching hospital in India. J Infect Dev Ctries 2011;5(2):114-118.