|Nutrition Evidence Library|
CLEAN: What techniques for hand sanitation are associated with favorable food safety outcomes?
Strong, clear and consistent evidence shows that hand washing with plain soap for 20 to 30 seconds followed by proper hand drying is an effective hand hygiene technique for preventing cross-contamination during food preparation. Strong, clear and consistent evidence shows that alcohol-based, rinse-free hand sanitizers are an adequate alternative when proper hand washing with plain soap is not possible.
Overall strength of the available supporting evidence: Strong; Moderate; Limited; Expert Opinion Only; Grade not assignable For additional information regarding how to interpret grades, click here.
Evidence Summary Overview
A total of 17 studies were reviewed regarding in-home techniques for hand washing that are associated with favorable food safety outcomes such as reduced subsequent risk of home-based food-borne illnesses. Three received (+) quality ratings (two randomized controlled trials (RCT), one meta-analysis) and 14 received Ø quality ratings (two systematic review studies, one meta-analysis, three RCTs, one set of randomized controlled experiments, two prospective cohort studies, one before-and-after study, one cross-sectional and before-and-after study, three non-randomized trials). Studies were conducted in schools and other community settings as well as in homes and under laboratory simulation conditions.
School and Other Community Settings: Meta-analysis
Aiello et al, 2008 conducted a meta-analysis to examine the impact of hand hygiene interventions on gastrointestinal and respiratory illness. Of the 30 studies included, 67% were conducted in developed countries, 63% were conducted in child-care centers or schools and 59% targeted children under five years old. Compared with non-intervened controls, washing with non-antibacterial soap and water together with education was the most beneficial intervention for reducing the risk of gastrointestinal (GI) (RR=0.61; 95% CI:0.43,0.88, N=6 studies) and respiratory illness (RR=0.49; 95% CI:0.40,0.61, N=1 study). Education alone was not as effective and antibacterial soaps did not reduce the risk further. Alcohol based hand sanitizers (ABHSs) were less effective than non-antibacterial soap at reducing GI risk. This meta-analysis strongly suggests that in settings where non-antibacterial soap is available, ABHSs or antibacterial soaps are not needed for routine hand sanitation.
Schools have been identified as potential candidates for promotion of hand hygiene through rinse-free antimicrobial hand sanitizers. Meadows and Le Saux (2004) conducted a systematic review of six controlled trials, three of which were RCTs, conducted in US schools to assess the impact of rinse-free anti-microbial hand sanitizers on school absenteeism due to respiratory and/or GI illness. Four of the six studies used alcohol-based and two used benzalkonium chloride based hand gel sanitizers. All six studies found a significant impact of the rinse-free anti-microbial hand sanitizers at reducing school absenteeism due to communicable diseases (absenteeism reduction range: 20%-56%). Findings should be interpreted with caution due to study design and statistical analysis limitations in the studies reviewed. Tousman et al, (2007) found that a hand washing education program among second graders reduced school absenteeism and was associated with lower microbial loads in hands, compared to the reference group formed by first graders in the same schools. Sandora et al, (2008) found that providing school classrooms with alcohol-based hand sanitizers and quarternary ammonium surface wipes was linked with reduced student absenteeism due to GI but was not associated with reduced incidence of respiratory infections. White et al, (2005) found that provision of ABHSs among college students was associated with a lower incidence of respiratory infections. In their study, they assigned students in two dorms to be exposed to a hand washing campaign that emphasized respiratory infection prevention. In these dorms alcohol gels were made available at the bathroom and dining room and students were provided with them for their rooms and in travel packs. Two additional dorms served as controls. In contrast, Vessey et al, (2007), in their randomized crossover trial comparing the efficacy of a hand sanitizer to standard hand washing in reducing illness and subsequent absenteeism in school-age children, found that no significant differences were noted between the groups (soap and water vs. hand sanitizer), indicating that the number of student absences was not appreciably affected by hand-cleansing technique used. However, those authors noted that hand sanitizers are a viable alternative to routine hand cleansing using soap and water (Vessey et al, 2007). Brown et al, (2007) found among college students, that plain and anti-microbial liquid hand cleansers as well as ABHS reduced hand bacteria count after a 20 second hand wash or rubbing. However, counts were reduced significantly more with ABHS.
Sandora et al, 2005 conducted an RCT where the intervention group received alcohol-based hand sanitizers for use at home and the control group received nutrition education only. The study targeted families with young children attending day care centers. Findings showed that the intervention was effective at reducing the incidence of secondary GI, but not respiratory infections. They suggest that ABHSs represent a reasonable option when plain soap and hand washing facilities are not readily available. Larson et al, (2004) concluded from their Latino household randomized trial that providing a bundle of antibacterial home cleaning and handwashing products, including liquid triclosan-containing soap, did not reduce the risk of respiratory and viral GI infections. By contrast Lee at al, (2005) concluded that alcohol-based hand gels protected families against transmission of respiratory, but not GI, infections in the home. This observational prospective study was based on families with children between six months and five years of age.
Hand Hygiene and Cross-contamination
Laboratory and computer simulation studies:
Haas et al, 2005 computer simulation concluded that alcohol based but not triclosan-based hand sanitizers are more effective than sanitizers not containing anti-microbials at reducing risk of transmission of E. coli pathogenic strains from ground beef to mouth. Simulation was based on a quantitative microbial risk assessment meta-analysis. By contrast, Schaffner and Schaffner (2007) found in their laboratory and computer simulation study that the effectiveness of an ABHS to prevent transfer of Enterobacter aerogenes from frozen hamburger beef patties (inoculated with this non-pathogenic strain used as a surrogate for Escherichia coli O157:H7) to ready to lettuce was similar to the one previously found by the same group for hand washing with soap or glove use and that all interventions (handwashing, use of gloves or sanitizer) were more effective than no intervention at all. In contrast with Aiello’s et al, (2007) findings, Fischler et al, (2007) concluded from a series of four randomized experiments that triclosan-containing hand sanitizer was more effective than non-antimicrobial soap at reducing loads Shigella flexenerei and Escherichia Coli and their transfer rates to freshly cut cantaloupes, after inoculating them in the participants’ hands.
Dharod et al, 2009 found that the presence of S.aureus in chicken and salad during meal preparation, as well as in kitchen, counters or cutting boards and sink was positively associated with the presence of this bacteria in the hands of meal preparers at baseline. Likewise baseline coliform count on the counter or cutting board was positively associated with baseline coliform count in participants’ hands. Coliform count in chicken increased significantly during meal preparation among meal preparers that tested positive but not among those who tested negative for coliforms in their hands at baseline. These findings suggest that proper hand hygiene is essential for prevention of cross-contamination in the home kitchen.
Antibacterial Soaps and Microbial Antibiotic Resistance
Per two studies, soaps with antimicrobial additives are not needed for proper hand hygiene at home and should be avoided due to possible microbial resistance to antibacterials associated with their long-term use (Aiello et al, 2007; Thorrold et al, 2007). Aiello et al, (2007) conducted a systematic review (N=27 studies) to assess the efficacy of antibacterial soaps and whether antibacterial soap is associated with microbial antibiotic resistance. Of the four randomized community trials included, three were conducted in the US and one in Pakistan, all of them included families with children under four years of age. None of the studies found a benefit of triclosan/triclocarban-containing soap over non-antibacterial soap at reducing the incidence of infectious diseases over a one year period. Further studies are needed to find out the effectiveness of triclosan/triclocarban-containing soap among the elderly and other immunocompromised individuals. Whereas none of three population-based studies with a one-year follow-up period find antibiotic resistance, seven out of 11 laboratory based studies did find antibiotic resistance associated with the use of triclosan-containing soap. Thorrold et al, (2007) concluded that incorrect usage of antimicrobial household detergents may result in selection of bacteria with reduced susceptibility to both antibiotics and anti-microbials. In contrast, Aiello et al, (2004) concluded that the absence of a statistically significant association between elevated triclosan MICs and reduced antibiotic susceptibility may indicate that such a correlation does not exist or that it is relatively small among the isolates that were studied. However, those authors also indicated that a relationship may emerge after longer-term or higher-dose exposure of bacteria to triclosan in the community setting (Aiello et al, 2004).
Evidence Summary Paragraphs
Aiello et al, 2004 (positive quality), an RCT conducted in the US, examined hand cultures from individuals randomized to using either antibacterial or non-antibacterial cleaning and hygiene products for a one-year period. Antibacterial products included a hand soap containing 0.2% triclosan. At baseline, there were 238 households randomized and 224 completed the study. There was no statistically significant association between triclosan MICs and antibiotic susceptibility.
Aiello et al, 2007 (neutral quality), a systematic review of 27 international studies examining either the effectiveness of triclosan or the risks of antibiotic resistance associated with exposure to triclosan, concluded that soaps containing triclosan within the range of concentrations commonly used in the community setting (0.1% to 0.45% weight/volume) were no more effective than plain soap at preventing infectious illness symptoms and reducing bacterial levels on hands. In addition, several laboratory studies reported evidence of triclosan-adapted cross-resistance to antibiotics among different species of bacteria.
Aiello et al, 2008 (positive quality), a meta-analysis of 30 international studies published between 1960 and 2007, examined the effect of hand-hygiene interventions on rates of GI and respiratory illnesses. Improvements in hand hygiene resulted in reductions in gastrointestinal illness of 31% (overall rate ratio=0.69, 95% CI: 0.58, 0.81) and reductions in respiratory illness of 21% (overall rate ratio=0.79, 95% CI: 0.66, 0.95). The most beneficial intervention was hand-hygiene education and non-antibacterial soap use (rate ratio=0.61, 95% CI: 0.43, 0.88); use of antibacterial soap showed little added benefit when compared with use of non-antibacterial soap.
Brown et al, 2007 (neutral quality), a cross-sectional and before-and-after study, determined public attitudes about available hand cleansers through a telephone survey of 40 participants and written survey of 60 college students, as well as the effectiveness of three hand cleansers (liquid hand soap, antibacterial soap and alcohol gel) in reducing bacteria on hands in 90 college students. Most respondents believed that regular hand soaps were not as effective as antibacterial soaps in reducing bacteria on hands, but all three hand cleansers reduced bacteria on hands when a 20 second hand wash procedure was followed. There were NS differences in post-hand wash relative colony numbers for regular and liquid antibacterial hand cleansers, however, alcohol gel reduced relative colony numbers significantly more than either regular or antibacterial cleanser (P<0.05).
Dharod et al, 2009 (neutral quality) an observational prospective cohort conducted in the US which examined the association of microbial contamination of meal preparers' hands with microbial status of food and kitchen and utensil surfaces during preparation of a "Chicken and Salad" meal. An observational home food safety assessment was conducted with 60 Puerto Rican women in which participant's hands were tested to estimate total bacterial and coliform counts and the presence of Campylobacter, Salmonella, Listeria and S. aureus before and after preparing a "Chicken and Salad" meal; microbiological testing was also conducted on samples from kitchen or utensil surfaces and food ingredients before and during meal preparation. Authors found that S. aureus in chicken and salad during meal preparation and in the kitchen, counters or cutting boards, and sink was positively associated with S. aureus on participants’ hands at baseline (P<0.05); baseline coliform count on the counter or cutting board and sink was significantly higher when participants' hands tested positive for coliform at baseline; and coliform count in chicken increased significantly during meal preparation among meal preparers that tested positive but not among those who tested negative for coliform on their hands at baseline. Authors concluded that meal preparer's hands can be a vehicle of pathogen transmission during meal preparation.
Fischler et al, 2007 (neutral quality), a set of randomized controlled experiments conducted in the US, evaluated the effectiveness of a commercially available anti-microbial hand soap containing triclosan as the active antimicrobial ingredient and a plain non-medicated hand wash (plain soap) at reducing bacteria on hands following a 15- or 30-s hand wash and examined the subsequent transfer of the surviving bacteria from the washed hands to a ready-to-eat food item, freshly cut cantaloupe melon balls. Seven to 13 subjects >18 years of age were randomly assigned to receive a single hand washing treatment with either anti-microbial hand soap or a plain soap following hand contamination with S. flexneri or E. coli as part of a series of four experiments were performed using different soaps and different lathering times. In all the experiments, the anti-microbial hand soap was significantly better than plain soap and water at eliminating bacteria on hands and subsequently at reducing the transfer of bacteria from hands to food; the anti-microbial soap achieved 3.84- and 3.29-log reductions vs. E. coli after a 15-s wash and 3.31- and 2.83-log reductions vs. S. flexneri after a 30-s wash, whereas the plain soap failed to achieve a 2-log reduction against either organism, regardless of the wash time; significantly fewer bacteria were transferred to the melon balls from hands washed with anti-microbial soap than from hands washed with plain soap. Authors indicate that the data demonstrate there is a greater potential to reduce the transmission and acquisition of disease through the use of an anti-microbial hand wash than through the use of plain soap.
Haas et al, 2005 (neutral quality), a meta-analysis of five studies and quantitative microbial risk assessment, estimated the benefits resulting from the use of hand cleansing products (e.g., soaps) containing anti-microbial ingredients using a model for the scenario of hand contact with ground beef during food preparation, considering transference of bacteria to the hands, removal and inactivation by handwashing and subsequent transference from the hands to the mouth. There was a reduction in risk from the use of any hand washing protocol as compared to no hand washing. Anti-microbials reduced the risk of infection and illness, however, benefits from the use of triclosan-containing products were less than from the use of products in which alcohols or chlorhexidine were active ingredients.
Larson et al, 2004 (positive quality), an RCT conducted in the US, examined rates of infectious disease symptoms from households randomized to using either antibacterial or non-antibacterial cleaning and hygiene products for 48 weeks. At baseline, there were 238 households randomized and 224 completed the study. Rates of any infectious disease symptoms did not differ between intervention and control groups. That is, providing a bundle of antibacterial home cleaning and handwashing products, including liquid triclosan-containing soap, did not reduce the risk of respiratory and viral GI infections.
Lee et al, 2005 (neutral quality), an observational, prospective cohort study conducted in the US, assessed occurrence of respiratory and gastrointestinal illnesses in families with children enrolled in child care and studied predictors of lower rates of illness transmission in the home. A total of 261 families were enrolled in the study and 215 families (82%) completed at least four weeks of illness transmission data. Only two-thirds of respondents believed that contact transmission was important in the spread of cold and fewer than half believed that it was important in the spread of stomach flus. Reported use of alcohol-based hand gels reduced transmission of respiratory illness among family members.
Meadows and Le Saux, 2004 (neutral quality), a systematic review of six studies examining whether antimicrobial rinse-free hand sanitizer interventions are effective in preventing illness-related absenteeism in elementary school children. All studies found a statistically significant effect of the anti-microbial rinse-free hand gel; trials varied with respect to intervention, including germ and hygiene education that was provided with sanitizer; but due to the large amount of heterogeneity and low quality of reporting, no pooled estimates were calculated. The authors noted that the available evidence for the effectiveness of antimicrobial rinse-free hand sanitizer in the school environment is of low quality.
Sandora et al, 2005 (neutral quality), a cluster, RCT conducted in the US, determined whether a multi-factorial campaign centered on increasing alcohol-based hand sanitizer use and hand-hygiene education reduces illness transmission in the home. A total of 292 families were randomized to a treatment group or a control group; all families were included in the intent-to-treat analysis. Those in the treatment group received a supply of hand sanitizer to use in the home and bi-weekly hand-hygiene educational materials at home for a five-month period, while those in the control group received bi-weekly education about a healthy diet and were asked to not use hand sanitizer during the same period. The secondary GI rate was significantly lower in intervention families compared with control families (incidence rate ratio: 0.41, 95% CI: 0.19, 0.90), while the overall rate of secondary respiratory illness was not significantly different between groups.
Sandora et al, 2008 (neutral quality), an RCT conducted in the US, assessed the effectiveness of a multi-factorial infection-control intervention, including alcohol-based hand sanitizer and surface disinfection, in reducing absenteeism caused by GI and respiratory illnesses among elementary school students. A total of 285 third, fourth and fifth grade students participated in study in which clustered randomization was used to assign classrooms to intervention or control groups and randomization was stratified by team size; children and teachers used hand sanitizer and surface disinfection, respectively and number and reason for absences was recorded. Compared with control group, unadjusted absenteeism rate for GI illness was significantly lower in the intervention group (rate ratio: 0.86 [95% CI: 0.79-0.94]; P<0.01); after adjusting for race, health status, family size, and current hand-sanitizer use in home, absenteeism rate for GI illness remained significantly lower in the intervention group compared with control group (rate ratio: 0.91 [95% CI: 0.87-0.94]; P<0.01).
Schaffner and Schaffner, 2007 (neutral quality), a before and after study (and computer simulations) conducted in the US, evaluated the effectiveness of an alcohol-based hand sanitizer on hands contaminated with a non-pathogen surrogate for E. coli O157:H7, where the source of bacteria was frozen hamburger patties. Thirty two subjects (12 males, 20 females) handled nine frozen beef patties at least three times with microbiological sampling of one hand after pattie handling, then sanitization of both hands, then microbiological sampling of the other hand; computer simulations were also used to perform risk calculations. The average reduction of E. aerogenes after using the sanitizer was 2.58 log CFU with ±0.65 log CFU variability per hand. None of the interventions (hand washing, gloves, sanitizer) were completely effective, but all interventions were more effective than no intervention at all; that is, the mean reduction for hand washing and the use of gloves or sanitizer was about 3 log (1,000 times) greater than the result for no intervention at all. Authors concluded that use of an alcohol-based hand sanitizing gel is an effective intervention for hands that have been contaminated with E. coli O157:H7 from frozen hamburgers.
Thorrold et al, 2007 (neutral quality), a non-randomized trial conducted in South Africa, examined efflux pump activity in fluoroquinolone and tetracycline resistant Salmonella and Escherichia coli samples to see if there was a reduced susceptibility to household antimicrobial cleaning agents. Efflux pump activity was measured by ethidium bromide accumulation assays in eight bacterial strains of Salmonella and nine bacterial strains of E. coli. Active efflux of ethidium bromide was associated with antibiotic resistant organisms, suggesting that efflux mechanisms may be responsible for the antibiotic resistance; the authors concluded that incorrect usage of anti-microbial household detergents may result in selection of bacteria with reduced susceptibility to both antibiotics and anti-microbials.
Tousman et al, 2007 (neutral quality), a non-randomized trial conducted in the US, to determine if a multiple-week learner-centered hand washing program could improve hand hygiene behaviors of second-graders in a public school system. Volunteers went into 19 different classrooms for four consecutive weeks and taught a learner-centered program that included interactive class discussions and activities using GlitterBug® training devices and agar plate materials. There was a statistically significant 34% decrease in the absenteeism rate for students in the intervention group during the third and fourth weeks of the intervention (P=0.027); 58% of the agar plates were cleaner after hand washing (P<0.001); and qualitative data from parents and teachers indicated that a majority of the students were engaging in handwashing behavior.
Vessey et al, 2007 (neutral quality), a randomized crossover trial conducted in the US, compared the efficacy of a hand sanitizer to standard hand washing in reducing illness and subsequent absenteeism in school-age children. Eighteen classrooms of second and third graders from several elementary schools were included in the study (approximately 363 students); for two months, half of the classes from each school used an anti-microbial gel hand sanitizer while the other classes used soap and water, and then the students switched cleaning methods for the following two months. Absentee information was collected by school secretaries through the duration of the study. No significant differences were noted between the groups, indicating that the number of student absences was not appreciably affected by the hand-cleansing technique used. Authors note that obtaining accurate data for absenteeism due to communicable disease was difficult.
White et al, 2005 (neutral quality), a non-randomized trial conducted in the US, evaluated whether a campaign to increase hand hygiene practices, coupled with the introduction of an alcohol-based antibacterial gel, reinforced by messages to continue washing and sanitizing, would decrease the incidence of upper respiratory illnesses (URIs) in a residence hall population on the campus of a major western university. Experimental subjects were exposed to a health campaign to increase awareness of the importance of hand cleanliness in avoiding colds or flu; received free hand sanitizer in their rooms and in travel packs and had access to gel hand sanitizer in dormitory bathrooms and dining room, and then completed, over eight weeks, weekly reports on handwashing and sanitizer use and any experience of cold or flu symptoms. The experimental group had significantly better hand hygiene than control group reflecting a difference in hand-washing behavior and in hand-sanitizer use; increased their knowledge about hand hygiene and the spread of URI from pre to post-study assessments than did controls; and reported 26% fewer illnesses than the control group (illness rate of 20.2% vs. 27.5% in control group across the study, x2=19.97, P<0.0001); and women washed their hands more frequently than men, but did not differ significantly in use of gel hand sanitizer.
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Research Design and Implementation Rating Summary
For a summary of the Research Design and Implementation Rating results, click here.
Aiello AE, Larson EL, Levy SB. Consumer antibacterial soaps: effective or just risky? Clinical Infectious Diseases 2007; 45:S137–47.
Aiello AE, Coulborn RM, Perez V, Larson EL. Effect of hand hygiene on infectious disease risk in the community setting: a meta-analysis. Am J Public Health. 2008 Aug;98(8):1372-81. Epub 2008 Jun 12.
Brown JM, Avens JS, Kendall PA, Hyatt DR, Stone MB. Survey of consumer attitudes and the effectiveness of hand cleansers in the home. Food Protection Trends. 2007. 27(8): 603-611.
Dharod JM, Paciello S, Bermúdez-Millán A, Venkitanarayanan K, Damio G, Pérez-Escamilla R. Bacterial contamination of hands increases risk of cross-contamination among low-income Puerto Rican meal preparers. J Nutr Educ Behav. 2009 Nov-Dec; 41 (6): 389-397.
Fischler GE, Fuls JL, Dail EW, Duran MH, Rodgers ND, Waggoner AL. Effect of hand wash agents on controlling the transmission of pathogenic bacteria from hands to food. J Food Prot. 2007 Dec; 70(12): 2,873-2,877.
Haas CN, Marie JR, Rose JB, Gerba CP. Assessment of benefits from use of anti-microbial hand products: Reduction in risk from handling ground beef. Int J Hyg Environ Health. 2005; 208 (6): 461-466. Epub 2005
Larson EL, Lin SX, Gomez-Pichardo C, Della-Latta P. Effect of antibacterial home cleaning and handwashing products on infectious disease symptoms: A randomized, double-blind trial. Ann Intern Med. 2004 Mar 2; 140(5): 321-329.
Lee GM, Salomon JA, Friedman JF, Hibberd PL, Ross-Degnan D, Zasloff E, Bediako S, Goldmann DA. Illness transmission in the home: a possible role for alcohol-based hand gels. Pediatrics. 2005 Apr;115(4):852-60.
Meadows E, Le Saux N. A systematic review of the effectiveness of antimicrobial rinse-free hand sanitizers for prevention of illness-related absenteeism in elementary school children. BMC Public Health. 2004 Nov 1; 4: 50.
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Sandora TJ, Taveras EM, Shih MC, Resnick EA, Lee GM, Ross-Degnan D, Goldmann DA. A randomized, controlled trial of a multifaceted intervention including alcohol-based hand sanitizer and hand-hygiene education to reduce illness transmission in the home. Pediatrics. 2005 Sep; 116 (3): 587-594.
Schaffner DW, Schaffner KM. Management of risk of microbial cross-contamination from uncooked frozen hamburgers by alcohol-based hand sanitizer. J Food Prot. 2007; 70: 109-113
Thorrold CA, Letsoalo ME, Dusé AG, Marais E. Efflux pump activity in fluoroquinolone and tetracycline resistant Salmonella and E. coli implicated in reduced susceptibility to household antimicrobial cleaning agents. Int J Food Microbiol. 2007 Feb 15; 113 (3): 315-320. Epub 2006 Nov 27.
Tousman S, Arnold D, Helland W, Roth R, Heshelman N, Castaneda O, Fischer E, O'Neil K, Bileto S. Evaluation of a hand washing program for second-graders. J Sch Nurs. 2007 Dec; 23 (6): 342-348.
Vessey JA, Sherwood JJ, Warner D, Clark D. Comparing hand washing to hand sanitizers in reducing elementary school students' absenteeism. Pediatric Nursing 2007; 33 (4): 368-372.
White C, Kolble R, Carlson R, Lipson N. The impact of a health campaign on hand hygiene and upper respiratory illness among college students living in residence halls.. J Am Coll Health. 2005 Jan-Feb;53(4):175-81. Erratum in: J Am Coll Health. 2005 Jul-Aug;54(1):64.