Hand sanitizer

The Clean Hands campaign by the US Centers for Disease Control and Prevention (CDC) instructs the public in hand washing. Alcohol-based hand sanitizer is recommended only if soap and water are not available.[14]

When using an alcohol-based hand sanitizer:

1. Apply product to the palm of one hand.
2. Rub hands together.
3. Rub the product over all surfaces of hands and fingers until hands are dry.[14]

The current evidence for school hand hygiene interventions is of poor quality.[15]

Hand alcohol in a hospital

An automated hand sanitizer dispenser

Alcohol-based hand sanitizer is more convenient compared to hand washing with soap and water in most situations in the healthcare setting.[3] It is generally more effective at killing microorganisms and better tolerated than soap and water.[4] Hand washing should still be carried out if contamination can be seen or following the use of the toilet.[5]

Hand sanitizer that contains at least 60 % alcohol or contains a "persistent antiseptic" should be used.[16][17] Alcohol rubs kill many different kinds of bacteria, including antibiotic resistant bacteria and TB bacteria. 90% alcohol rubs are highly flammable, but kill many kinds of viruses, including enveloped viruses such as the flu virus, the common cold virus, and HIV, though is notably ineffective against the rabies virus.[18][19][20]

90% alcohol rubs are more effective against viruses than most other forms of hand washing.[21] Isopropyl alcohol will kill 99.99 % or more of all non-spore forming bacteria in less than 30 seconds, both in the laboratory and on human skin.[16][22]

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%).[23] 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.[23]

For health care settings like hospitals and clinics, optimum alcohol concentration to kill bacteria is 70% to 95%.[24][25] Products with alcohol concentrations as low as 40% are available in American stores, according to researchers at East Tennessee State University.[26]

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%[note 1] in one minute.[21]

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.[27]

Use of alcohol-based hand gels dries skin less, leaving more moisture in the epidermis, than hand washing with antiseptic/antimicrobial soap and water.[28][29][30][31]

There are certain situations during which hand washing with water and soap are preferred over hand sanitizer, these include: eliminating bacterial spores of Clostridioides difficile, parasites such as Cryptosporidium, and certain viruses like norovirus depending on the concentration of alcohol in the sanitizer (95% alcohol was seen to be most effective in eliminating most viruses).[32] In addition, if hands are contaminated with fluids or other visible contaminates, hand washing is preferred as well as when after using the toilet and if discomfort develops from the residue of alcohol sanitizer use.[33] Furthermore, CDC states hand sanitizers are not effective in removing chemicals such as pesticides.[34]

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.[35] Fire departments suggest refills for the alcohol-based hand sanitizers can be stored with cleaning supplies away from heat sources or open flames.[36]

Research shows that alcohol hand sanitizers do not pose any risk by eliminating beneficial microorganisms that are naturally present on the skin. The body quickly replenishes the beneficial microbes on the hands, often moving them in from just up the arms where there are fewer harmful microorganisms.[37]

However, alcohol may strip 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.[38][39]

In the United States, the U.S. Food and Drug Administration (FDA) controls antimicrobial handsoaps and sanitizers as over-the-counter drugs (OTC) because they are intended for topical anti-microbial use to prevent disease in humans.[40] The FDA requires strict labeling which informs consumers on 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 use by children only under adult supervision.[41] According to the American Association of Poison Control Centers, there were nearly 12,000 cases of hand sanitizer ingestion in 2006.[42] If ingested, alcohol-based hand sanitizers can cause alcohol poisoning in small children.[43] However, the U.S. Centers 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 traveling, to avoid their contracting disease from dirty hands.[44]

There have been reported incidents of people drinking the gel in prisons and hospitals, where alcohol consumption is not allowed, to become intoxicated leading to its withdrawal from some establishments.[45][46]

On April 30, 2015, the FDA announced that they were requesting more scientific data based on the safety of hand sanitizer. Emerging science also suggests that for at least some health care antiseptic active ingredients, systemic exposure (full body exposure as shown by detection of antiseptic ingredients in the blood or urine) is higher than previously thought, and existing data raise potential concerns about the effects of repeated daily human exposure to some antiseptic active ingredients. This would include hand antiseptic products containing alcohol and triclosan.[47]

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 is ordinarily used. 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.[49]

Alcohol free hand sanitizer

Some hand sanitizer products use agents other than alcohol to kill microorganisms, such as povidone-iodine, benzalkonium chloride or triclosan.[23]

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.

Laboratory studies have shown lingering benzalkonium chloride may be associated with antibiotic resistance in MRSA.[50][51] Tolerance to alcohol sanitizers may develop in fecal bacteria.[52][53] Where alcohol sanitizers utilize 62%, or higher, alcohol by weight, only 0.1 to 0.13% 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[54] Triclosan leads to various problems with natural biological systems,[55] and triclosan, when combined with chlorine e.g. from tap water, produces dioxins, a probable carcinogen in humans.[56] 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.[57]

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.[58] For DCDD, one of the non-toxic compounds of the dioxin family,[59] a conversion rate of 1% has been reported and estimated half-lives suggest that it is photolabile as well.[60] 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."[61]

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.[62]