by Rebecca Montville , Research Scientist & Donald Schaffner , Extension
Specialist in Food Science
Everyone agrees that handwashing is very important in preventing foodborne
disease. However, there are many misconceptions regarding proper handwashing
practices. Through better understanding of the factors influencing handwashing
and cross contamination from hands to food, kitchen safety can be improved.
Myth: Handwashing is only really important if you are sick.
Fact: It is important that good handwashing practices always be followed.
With many gastrointestinal illnesses (any illness that includes stomachache,
diarrhea or vomiting), the infected person may be contagious before showing
any symptoms. It is also important to realize that anyone caring for a child
with diarrhea can transmit disease as well. Individuals affected with hepatitis
A, for example, can spread the virus for 4 weeks before showing symptoms of
illness. It is especially important that hands be washed after going to the
bathroom and whenever coming into contact with body fluids.
People suffering from any illness should not come into contact with food for
others. In the commercial kitchen, food handlers should not be working with
food when ill. If worker s cannot take a day off, they should be reassigned
to a job that involves no contact with food. Under no circumstances should
an ill person handle food for others. This includes preparing food in the kitchen
at home. If one member of a household is sick, others in the house can be infected.
Ill food handlers have been the source of many foodborne disease out-breaks.
Myth: You only need to wash your hands after going to the bathroom or
after handling raw meat.
Fact: When handling food, there are many times when it is important for
people to wash their hands. Every one handling foods should wash hands when
entering the kitchen, even if only returning from a break. In addition to washing
hands after using the bathroom, any time someone touches the mouth, nose or
scalp, hands should be considered dirty. Also, anyone cleaning equipment or
food contact surfaces, should wash hands before returning to food preparation.
Myth: All bacteria on the hands are bad bacteria.
Fact: There are bacteria on everyone's hands that are actually helpful.
There are two different types: resident bacteria and transient bacteria. Resident
bacteria are bacteria that normally live on your skin. These bacteria generally
do not make people sick. They help keep the numbers of transient bacteria (bacteria
that are not naturally occurring on hands and are the result of some sort of
contamination) in check, by competing with them. When fewer resident bacteria
are present on people's hands, the number of transient bacteria can soar and
they may end up with warts or other skin problems (2,25). Almost all bacteria
that cause foodborne disease outbreaks are transient. The only exception is
an organism called Staphylococcus aureus. Staphylococcus aureus occurs
naturally on the skin. If large numbers of this organism get into food, it can
cause illness. The risk of infecting a food with Staphylococcus aureus increases
if the food handler has an infection like a cut, pimple or boil. Therefore,
foodhandlers with skin infections should not contact food.
Myth: Hand soap without an antimicrobial agent is not effective.
Fact: Studies have shown that antimicrobial soaps are only slightly more
effective than regular soaps (4,13,19,21,22). The most important aspect of handwashing
is the action of breaking up the layers of fats on the hands (done with soap).
This fat can entrap bacteria, so by removing some of it, bacteria are also removed.
Both antimicrobial and regular soaps will work to remove this layer. Antimicrobial
soaps can reduce bacteria further, but for the most part, the soap is not in
contact with bacteria long enough to kill them.
Myth: People can get germs from using the same bar soap as other people.
Fact: Research has shown that bacteria do not readily transfer from one
person to another by soap (3,11). It is likely that any bacteria picked up from
bar soap are washed away when you rinse your hands.
Myth: The hotter the water you use for handwashing, the better.
Fact: In the past the Food and Drug Administration has recommended that
water temperature be 120° F for handwashing. Recently they have changed their
recommendation 105° F (http://vm.cfsan.fda.gov).
There is no research to prove that higher temperatures improve handwashing
(18). Handwashing water is not hot enough to kill bacteria. However, hotter
water is more likely to cause excessive drying of the skin. It is harder to
remove bacteria from dry skin because of extra cracks and grooves, and dry skin
can make handwashing painful (14). As a rule, the best temperature to wash hands
is the warmest temperature that you find comfortable.
Myth: Hot air hand dryers are the most sanitary way to dry your hands.
Fact: Hot air hand dryers can actually increase the amount of bacteria
on your hands after handwashing (5,6,23). Bacteria can grow inside of hand dryers
because they provide a warm moist environment. When the dryer is turned on,
the air that comes out can be filled with bacteria (5,6,17,23). Paper towels
are a better way to dry your hands because they can physically remove bacteria
while not adding additional bacteria to the hands.
Myth: Alcohol hand sanitizers are an acceptable substitute for handwashing.
Fact: Alcohol sanitizers have been shown to work on clean hands; when
clean hands were contaminated with bacteria, alcohol hand sanitizers eliminated
bacteria fairly well (1,15). It is likely, however, that sanitizers don't work
as well on hands that are dirty and greasy. For this reason sanitizers should
be used only in addition to proper handwashing. It is also important to keep
in mind that alcohol can dry out the skin, which can cause an increase in bacteria
over time (12,16,21). There are even some studies that show that bacteria increase
after the first use (8,24). Because of so much conflict between different studies
on alcohol sanitizers, it is generally recommended that they only be used after
handwashing or when water is not available.
Myth: There is no point in washing your hands after going to the bathroom
because you need to touch the dirty doorknob on the way out.
Fact: The amount of bacteria that transfers from hands to surfaces is
actually quite small (7). If someone with dirty hands touches the doorknob,
only a small amount of the bacteria from dirty hands will end up on the doorknob.
Of the bacteria on the doorknob, only a small amount will then transfer to your
hands. Therefore, if you wash another person's hands and touch a doorknob with
bacteria on it, your hands will still be much more clean than if you didn't
wash them at all.
Myth: As long as foodhandlers wear gloves, there is no
chance of hands contaminating food.
Fact: Many food service establishments use cheap gloves which bacteria
can pass through (20). Gloves may also give food handlers a false sense of security
(10,12); they think that as long as they are wearing gloves, their hands are
clean. Anecdotal information shows that when people wear gloves, they are much
less likely to wash their hands. After gloves are put on, bacteria on the hands
increase quickly (9). If a glove is punctured, bacteria on the hands can pass
to food even more easily. It is also important to remember that gloves can pick
up bacteria from dirty surfaces and trans-fer them to food. For all of these
reasons, handwashing is still the best way to fight the contamination of foods.
If gloves are being worn in the kitchen, it is important to remember to change
them frequently, with proper handwashing between changes.
1. Aly, R. and H. I. Maibach. 1979. Comparitive study on the
antimicrobial effect of 0.5% Chlorohexidine gluconate and 70% isopropyl alcohol
on the normal flora of hands. AEM. 37: 610-613.
2. Aly, R., H. I. Maibach, H. R. Shinefield, and H. G. Strauss.
1972. Survival of pathogenic microorganisms on human skin. Journal of Investigative
Derma-tology. 58: 205-210.
3. Bannan, E. A. and L. F. Judge. 1965. Bacteriological studies
relating to hand washing. I. The inability of soap bars to transmit bacteria.
Am J Public Health. 55: 915-921.
4. Bartzokas, C. A., J. E. Corkill, and T. Makin. 1987. Evaluation
of skin disinfecting activity and cumula-tive effect of chlorhexidine and triclosan
handwash preparations on hands artificially contaminated with Serratia marcescens.
Inf. Cont. 8: 163-167.
5. Blackmore, M. A. 1989. A comparison of hand drying methods.
Cater. Health. 1: 189-198.
6. Blackmore, M. A. and E. M. Prisk. 1984. Is hot air hygienic?
The Home Economist. 4: 14-15.
7. Chen, Y., K. M. Jackson, F. P. Chea, and D. W. Schaffner.
2001. Quantification and variability analysis of bacterial cross contamination
rates in common foodservice tasks. J. Food Prot. 64:
8. Dyer, D. L., K. B. Gerenraich, and P. S. Wadhamas. 1998.
Testing a new alcohol-free hand sanitizer to combat infection. Assoc. Oper.
Room Nur. J. 68: 239-
9. Fendler, E. J., M. J. Dolan, and R. A. Williams. 1998. Handwashing
and gloving for food protection. Part I: Examination of the evidence. Dairy
Food Envir. Sanit. 18: 814-823.
10. Garcia-Graells, C., K. J. A. Hauben, and C. W. Michiels.
1998. High pressure inactivation and sub-lethal injury of pressure-resistant
Escherichia coli mutants in fruit juices. AEM. 64: 1566
11. Heinze, J. E. and F. Y. Yackovich. 1988. Washing with contaminated
bar soap is unlikely to transfer bacteria. Epidemiol. Infect. 101: 135-142.
12. Larson, E. 1989. Hand washing: It's essential — even when
you use gloves. Am J Nurs. 89: 934-939.
13. Larson, E., K. Mayur, and B. A. Laughon. 1988. Influence
of two hand washing frequencies on the reduction in colonizing flora with three
hand wash-ing products used by health care personnel. Am J Infect Control. 17:
14. Larson, E. L. 1985. Handwashing and skin physi-ologic and
bacteriologic aspects. Inf. Cont. 6: 14-23.
15. Larson, E. L., P. I. Eke, and B. E. Laughon. 1986. Efficacy
of alcohol-based hand rinses under fre-quent-
use conditions. Antimicrob. Agents & Chemother. 30: 542-544.
16. Larson, E. L., C. A. Norton-Hughes, J. D. Pyrek, S. M. Sparks,
E. U. Cagatay, and J. M. Bartkus. 1998. Changes in bacterial flora associated
with skin dam-age on hands of health care personnel. Am J Infect Control. 26:
17. Meers, P. D. and K. Y. Leong. 1989. Hot-air hand dryers.
J. Hospit. Inf. 14: 169-171.
18. Michaels, B., V. Gangar, A. Schultz, M. Arenas, T. Ayers,
and D. Paulson. Hand washing water tem-perature effects on the reduction of
resident and transient (Serratia marcescens) flora when
using bland soap, [In Press] Unknown 2000.
19. Miller, M. L., L. E. Milanesi, and L. A. James-Davis. 1994.
A field study evaluating the effectiveness of different hand soaps and sanitizers.
Dairy Food Envir. Sanit. 14: 155-160.
20. Montville, R., Chen, Y., and Schaffner, D. W. 2001. Glove
barriers to bacterial cross-contamination. Journal of Food Protection. 64( 6),
21. Paulson, D. S. 1994. A comparative evaluation of different
hand cleansers. Dairy Food Envir. Sanit. 14: 524-528.
22. Phillips, C. A. 1999. The epidemiology, detection and control
of Escherichia coli O157. J. Sci. Food Agric. 79: 1367-1381.
23. Redway, K., B. Knights, Z. Bozocky, A. Theobald, and S.
Hardcastle. 1994. Hand drying: A study of bacterial types associated with different
hand drying methods and with hot air dryers, Unpublished Re-port. The Applied
Ecology Research Group — The University of Westminster, London, UK.
24. Sheena, A. Z. and M. E. Stiles. 1983. Immediate and residual
(substative) efficacy of germicidal hand wash agents. J. Food Prot. 46: 629-632.
25. Snyder, O. P. 2000. A "safe hands" hand wash pro-gram for
retail food operations.
© 2002 by Rutgers Cooperative Extension, New Jersey Agricultural
Experiment Station, Rutgers, The State University of New Jersey.
This material may be copied for educational purposes only by not-for-profit
accredited educational institutions.