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All about hand sanitizers

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A hand sanitizer or hand antiseptic is a supplement or alternative to hand washing with soap and water. Many preparations are available, including gel, foam, and liquid solutions. The active ingredient in hand sanitizers may be isopropyl alcohol (isopropanol), ethanol, n-propanol, or povidone-iodine. Inactive ingredients in alcohol rubs typically include a thickening agent such as polyacrylic acid for alcohol gels, humectants such as glycerin for liquid rubs, propylene glycol, and essential oils of plants. Alcohol-based hand sanitizers are more effective at killing microorganisms than soaps and do not dry out hands as much.

Common non-alcohol, rinse-free hand sanitizers use either small concentrations of the nitrogenous cationic surface-acting agent benzalkonium chloride, the chlorinated aromatic compound triclosan, or povidone-iodine. Some products claim to kill microorganisms naturally, although these claims are not substantiated in any FDA monograph. All hand sanitizer products require National Drug Code designation in the United States and natural product number designation in Canada.


Consumer alcohol-based hand sanitizers, and health care hand alcohol or alcohol hand antiseptic agents, are antiseptic products used to avoid transmission of pathogens. These exist in liquid, foam, and easy-flowing gel formulations. The level of alcohol varies between 60% and 85%. The most commonly used level is 62%.

Alcohol rub sanitizers kill most bacteria, and fungi, and stop some viruses. Alcohol rub sanitizers containing at least 70% alcohol (mainly ethyl alcohol) kill 99.9% of the bacteria on hands 30 seconds after application and 99.99% to 99.999% in one minute.

When hands are not visibly dirty, the United States Centers for Disease Control and Prevention and many other world public health authorities recommend alcohol hand sanitizers as an acceptable alternative to soap and water for hand hygiene.

The CDC Clean Hands campaign instructs the public how to use hand sanitizer properly:

When using an alcohol-based hand sanitizer:

  • Apply product to the palm of one hand.
  • Rub hands together.
  • Rub the product over all surfaces of hands and fingers until hands are dry.

Mayo Clinic adds:

  • Apply enough of the product to the palm of your hand to wet your hands completely.
  • Rub your hands together, covering all surfaces until they're dry.
  • If your hands are visibly dirty, however, wash with soap and water first.

For health care, optimal disinfection requires attention to all exposed surfaces such as around the fingernails, between the fingers, on the back of the thumb, and around the wrist. Hand alcohol should be thoroughly rubbed into the hands and on the lower forearm for a duration of at least 30 seconds and then allowed to air dry. To minimize carryover, jewellery should be removed from hands during use.

The Mayo Clinic recommends washing hands or sanitizing

  • before preparing food, eating, treating wounds or giving medicine, touching a sick or injured person, inserting or removing contact lenses
  • after preparing food (especially raw meat or poultry), using the toilet, changing a diaper, touching an animal or animal toys, leashes or waste, blowing your nose, coughing or sneezing into your hands, treating wounds, touching a sick or injured person, handling garbage or something that could be contaminated, such as a cleaning cloth or soiled shoes.

Despite common perceptions, alcohol-based hand sanitizers are well-adapted to the skin. Also, use of alcohol-based hand gels dries skin less, leaving more moisture in the epidermis, than hand washing with antiseptic/antimicrobial soap and water.


The Centres for Disease Control says the most important way to prevent the transmission of dangerous diseases is to frequently wash your hands with soap and water and/or use a hand sanitizer. If soap and water are not available it is recommended to use a hand sanitizer that contains at least 60 percent alcohol or contains a "persistent antiseptic". Alcohol rubs kill many different kinds of bacteria, including antibiotic resistant bacteria and TB bacteria. 90% alcohol rubs also have high virucidal activity against many different kinds of viruses (but are highly flammable), including enveloped viruses such as the flu virus, the common cold virus, and HIV, though is notably ineffective against the rabies virus. Alcohol rub sanitizers are not very effective against Norovirus (winter vomiting virus) unless they are combined with benzalkonium chloride in a hand sanitizer. Alcohol rubs also kill fungi. University of Virginia Medical School researchers concluded that hand sanitizing is more effective against fighting the common cold than hand washing.

Alcohol kills both pathogenic (disease causing) microorganisms as well as resident bacterial flora, which generally do not cause illness. Research shows that alcohol hand sanitizers do not pose any risk by eliminating "good" microorganisms that are naturally present on the skin. The body quickly replenishes the good microbes on the hands, often moving them in from just up the arms where there are fewer harmful microorganisms. However, alcohol also strips the skin of the outer layer of oil, which may have negative effects on barrier function of the skin. A study also shows that disinfecting hands with an antimicrobial detergent results in a greater barrier disruption of skin compared to alcohol solutions, suggesting an increased loss of skin lipids.

90% alcohol rubs are more effective against viruses than most other form of hand washing, but highly flammable and irritating on skin with prolonged use. Isopropyl alcohol will kill 99.99 percent or more of all non-spore forming bacteria in less than 30 seconds, both in the laboratory and on human skin. A controlled study of 200 workers at FedEx in 2004 showed that placing hand sanitizer dispensers in an office and educating workers about their use resulted in a 21% reduction in absenteeism. Controlled studies showed an even greater reduction in absenteeism (51%) in elementary schools and college dormitories (43%).

The alcohol in hand sanitizers may not have the 10–15 seconds exposure time required to denature proteins and lyse cells in too low quantities (0.3 mL) or concentrations (below 60%). Mackintosh (1984) found that application of 0.3 millilitres alcohol rub to the hands was no more effective than plain soap-and-water hand washing, but that increasing the volume to 0.5 millilitres increased the effectiveness of alcohols substantially. In environments with high lipids or protein waste (such as food processing), the use of alcohol hand rubs alone may not be sufficient to ensure proper hand hygiene).

For health care settings like hospitals and clinics, optimum alcohol concentration to kill bacteria is 70% to 95%. Products with alcohol concentrations as low as 40% are available in American stores, according to researchers at East Tennessee State University.

Not all forms of bacterial pathogens are equally susceptible. Certain spores of endospore forming bacteria, especially the endospores of gram-positive bacteria (e.g. Clostridium difficile) are relatively resistant to sanitizers and soap and water and remain biologically viable after their use. During the 2001 anthrax attacks on the United States Postal Service, authorities warned that alcohol hand rubs and soap and water would not kill anthrax endospores but they will kill the anthrax bacteria.

Some medical opinions question the effectiveness of alcohol-based hand sanitizers for preventing influenza. Arthur Reingold, vaccine specialist who has advised for the WHO, worries that "in the determination to tell people what they can do to protect themselves, people pooh-pooh things like masks, which really are effective against influenza, and are reluctant to get vaccinated." He claims that "washing hands really is wonderful for preventing many diseases, such as the common cold, but it's not very helpful to prevent influenza, [and that] studies done 40 and 50 years ago pretty much show it's impossible to get influenza through hand-to-hand contact". Instead, he says that "you must breathe the virus [right] into your lungs". In the same lay press article, Bonnie Henry, Director of Public Health Emergency Management at the B.C. Centre for Disease Control, agrees with Reingold that the principal way to get swine flu is by breathing the virus right into your lungs. However, she says animal studies have shown that the virus can infect you through your nose, your throat, and even through the tear ducts of your eyes. For example, research into the transmission of influenza from swine to humans has shown a statistically significant reduction in transmission if the handler wears gloves when working with sick animals, therefore implying that there is a distinct danger of catching the influenza virus via hand-to-face transmission. That opinion is shared by US Public Health, CDC and WHO officials, who therefore agree that washing the hands with soap and water or the use of a hand sanitizer (and not touching eyes, nose or mouth) are important measures to help prevent the spread of influenza.

Peter Palese, a professor of medicine and infectious diseases at the Mount Sinai School of Medicine in New York City, has said that hand washing isn't all that helpful against the flu because the flu isn't like other respiratory diseases. "The flu virus isn't very stable on the hand," he said. "The virus has a lipid membrane that flattens out when it's on your hand, and it gets inactivated." However Mark Nicas, an adjunct professor at the University of California-Berkeley School of Public Health, maintains that a significant number of flu cases are indeed spread by hands touching one another, and then touching your eyes, nose or mouth. "I think that hand contact accounts for maybe one-third of influenza infections," he says. Furthermore, whereas the influenza virus can survive for only minutes on a person's hands, researchers have found that it can survive for hours (some say even days) on many other surfaces. The University of Minnesota Center for Infectious Disease Research and Policy (CIDRAP) produced a document which says: "Studies have shown that influenza viruses can survive on environmental surfaces and can infect a person for up to 2 to 8 hours after being deposited on an environmental surface" if the person touches that surface and then touches his or her eyes, nose or mouth.

Research by Ronald Turner found that there was a statistically significant advantage to using hand sanitizers to prevent the flu or rhinovirus infection.


Alcohol-free hand sanitizer

Some hand sanitizer products use agents other than alcohol to kill microorganisms, such as povidone-iodine, benzalkonium chloride or triclosan.

The World Health Organization (WHO) and the CDC recommends "persistent" antiseptics for hand sanitizers. Persistent activity is defined as the prolonged or extended antimicrobial activity that prevents or inhibits the proliferation or survival of microorganisms after application of the product. This activity may be demonstrated by sampling a site several minutes or hours after application and demonstrating bacterial antimicrobial effectiveness when compared with a baseline level. This property also has been referred to as "residual activity." Both substantive and nonsubstantive active ingredients can show a persistent effect if they substantially lower the number of bacteria during the wash period. SHBAN (TM) Non-Alcoholic Persistent Antiseptic contains povidone-iodine that is an FDA Class I persistent antiseptic.

Laboratory studies have shown lingering benzalkonium chloride may be associated with antibiotic resistance in MRSA while no mechanism for resistance to alcohol has ever been described in bacteria. Where alcohol sanitizers utilize 62%, or higher, alcohol by weight, only .1 to .13% of benzalkonium chloride by weight provides equivalent antimicrobial effectiveness.

Triclosan has been shown to accumulate in biosolids in the environment, one of the top seven organic contaminants in waste water according to the National Toxicology Program. Triclosan leads to various problems with natural biological systems, and triclosan, when combined with chlorine e.g. from tap water, produces dioxins, a probable carcinogen in humans. However, 90–98% of triclosan in waste water biodegrades by both photolytic or natural biological processes or is removed due to sorption in waste water treatment plants. Numerous studies show that only very small traces are detectable in the effluent water that reaches rivers.

A series of studies show that photodegradation of triclosan produced 2,4-dichlorophenol and 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD). The 2,4-dichlorophenol itself is known to be biodegradable as well as photodegradable. For DCDD, one of the non-toxic compounds of the dioxin family, a conversion rate of 1% has been reported and estimated half-lives suggest that it is photolabile as well. The formation-decay kinetics of DCDD are also reported by Sanchez-Prado et al. (2006) who claim "transformation of triclosan to toxic dioxins has never been shown and is highly unlikely."

Alcohol-free hand sanitizers may be effective immediately while on the skin, but the solutions themselves can become contaminated because alcohol is an in-solution preservative and without it, the alcohol-free solution itself is susceptible to contamination. However, even alcohol-containing hand sanitizers can become contaminated if the alcohol content is not properly controlled or the sanitizer is grossly contaminated with microorganisms during manufacture. In June 2009, alcohol-free Clarcon Antimicrobial Hand Sanitizer was pulled from the US market by the FDA, which found the product contained gross contamination of extremely high levels of various bacteria, including those which can "cause opportunistic infections of the skin and underlying tissues and could result in medical or surgical attention as well as permanent damage". Gross contamination of any hand sanitizer by bacteria during manufacture will result in the failure of the effectiveness of that sanitizer and possible infection of the treatment site with the contaminating organisms.


Alcohol gel can catch fire, producing a translucent blue flame. This is due to the flammable alcohol in the gel. Some hand sanitizer gels may not produce this effect due to a high concentration of water or moisturizing agents. There have been some rare instances where alcohol has been implicated in starting fires in the operating room, including a case where alcohol used as an antiseptic pooled under the surgical drapes in an operating room and caused a fire when a cautery instrument was used. Alcohol gel was not implicated. To minimize the risk of fire, alcohol rub users are instructed to rub their hands until dry, which indicates that the flammable alcohol has evaporated. Fire departments suggest refills for the alcohol-based hand sanitizers can be stored with cleaning supplies away from heat sources or open flames.

The US FDA controls antimicrobial handsoaps and sanitizers as over-the-counter drugs because they are intended for topical anti-microbial use to prevent disease in humans. The FDA requires strict labeling which informs consumers as to proper use of this OTC drug and dangers to avoid, including warning adults not to ingest, not to use in the eyes, to keep out of the reach of children, and to allow children to use only under adult supervision. According to the American Association of Poison Control Centres, there were nearly 12,000 cases of hand sanitizer ingestion in 2006. If ingested, alcohol-based hand sanitizers can cause alcohol poisoning in small children. Despite widespread stories or rumours circulating regarding deaths or violent illnesses from ingestion, there is no evidence to support such claims. However, the Centres for Disease Control recommends using hand sanitizer with children to promote good hygiene, under supervision, and furthermore recommends parents pack hand sanitizer for their children when travelling, to avoid their contracting disease from dirty hands. Isopropanol, a moderate health risk, is found in some sanitizers.

There have been cases reported of people drinking the gel (with mixers) in prisons and hospitals to become intoxicated leading to its withdrawal from some establishments.


Hand alcohol in a hospital

Alcohol-based hand rubs are extensively used in the hospital environment as an alternative to antiseptic soaps. Hand-rubs in the hospital environment have two applications: hygienic hand rubbing and surgical hand disinfection. Alcohol based hand rubs provide a better skin tolerance as compared to antiseptic soap. Hand rubs also prove to have more effective microbiological properties as compared to antiseptic soaps.

The same ingredients used in over-the-counter hand-rubs are also used in hospital hand-rubs: alcohols such ethanol and isopropanol, sometimes combined with quats (quaternary ammonium cations) such as benzalkonium chloride. Quats are added at levels up to 200 parts per million to increase antimicrobial effectiveness. Although allergy to alcohol-only rubs is rare, fragrances, preservatives and quats can cause contact allergies. These other ingredients do not evaporate like alcohol and accumulate leaving a "sticky" residue until they are removed with soap and water.

The most common brands of alcohol hand rubs include Avant, Sterillium, Desderman and Allsept S. All hospital hand rubs must conform to certain regulations like EN 12054 for hygienic treatment and surgical disinfection by hand-rubbing. Products with a claim of "99.99% reduction" or 4Log reduction are ineffective in hospital environment, since the reduction must be more than "99.99%".

The hand sanitizer dosing systems for hospitals are designed to deliver a measured amount of the product for staff. They are dosing pumps screwed onto a bottle or are specially designed dispensers with refill bottles. Dispensers for surgical hand disinfection are usually equipped with elbow controlled mechanism or infrared sensors to avoid any contact with the pump.

Surgical hand disinfection
Hands must be disinfected before any surgical procedure by hand washing with mild soap and then hand-rubbing with a sanitizer. Surgical disinfection requires a larger dose of the hand-rub and a longer rubbing time than ordinarily. It is usually done in two applications according to specific hand-rubbing techniques, EN1499 (hygienic handwash), and EN 1500 (hygienic hand disinfection) to ensure that antiseptic is applied everywhere on the surface of the hand.

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