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Community-based studies have shown that hand sanitizers are acceptable in the absence of soap and running water. For alcohol-based sanitizers, the Food and Drug Administration (FDA) recommends a concentration of 60% to 95% ethanol or isopropanol for germicidal efficacy.
Staff at an adult health care facility found that a hand sanitizer containing 40% alcohol and purchased at a retail discount store increased the bacterial count (in a demonstration with cleansed hands pressed onto agar plates). They tested a variety of preparations to determine if a product fails as an antiseptic because of low alcohol concentration. Five hand cleansing treatments were compared: tap water, 40% ethanol, commercial gels with either 40% or 62% ethanol, and a commercial 40% gel supplemented to 62% ethanol. At the beginning of each work day, volunteers placed their dominant hands on soy agar plates for 5 seconds, followed by hand cleansing. Each alcohol-based hand treatment involved wetting the hands with the test product followed by vigorously rubbing hands together for 15 seconds. In the tap water treatment, hands were rubbed together for 15 seconds under running water, followed by air drying. Each participant completed each treatment in random order. Colony forming units (CFU) counts were compared before and after hand cleansing. Use of tap water, 40% ethanol, and 40% ethanol gel demonstrated no significant reductions in CFU. The 40% gel supplemented with ethanol to a concentration of 62% reduced CFU by 90%, similar to the 62% ethanol gel. The investigators also checked 18 retail chain stores and found substandard products at stores of a “deep-discount” chain which targets low income shoppers. An Internet survey found no substandard commercial products, although the alcohol content of less well known brands was not always available. Some Internet sites gave “recipes” for a scented children's hand sanitizer containing 33% isopropanol as the only active ingredient. Consumer education should stress that sanitizers need an alcohol concentration of at least 60% to be effective. (Reynolds SA, Levy F, Walker ES. Hand sanitizer alert [letter]. Emerg Infect Dis [serial on the Internet]. 2006 Mar 13. Available from http://www.cdc.gov/ncidod/EID/vol12no03/05-0955.htm) Comment: The authors reinforced what has been known for more than 50 years - 40% ethanol is a less effective bacterial antiseptic than 60% ethanol. Check the labels - even on ‘free’ samples. --J.O. |
