Advances in hand hygiene: Reducing contamination to food, people and the work environment

The importance of hand hygiene in the transmission of infection in the medical field has been recognised since Semmelweis’s observations in 1847 that the implementation of hand washing brought about a reduction in the deaths of women from puerperal fever1.

In the food industry, links between food workers and the spread of diseases, including the impact of poor hand hygiene has been well established2,3. Additionally, the food industry has recently acquired a better understanding of the ways by which food products may become contaminated from environmental sources, i.e., via surfaces, air, fluids and people4.

The need for hand wash facilities in the food industry is well recognised and addressed in the Food Hygiene Regulations 19955. However, hand hygiene policies and the facilities provided for hand hygiene in food handling environments vary greatly. It is generally accepted that, as a bare minimum, hand hygiene policies should include the washing of hands before handling food and that the facilities provided should be specifically for hand washing and include water, soap and a method of hand drying. In the EU, the basic requirements for washroom facilities within food handling areas are set in legislation. Additional advice is given in the requirements of the British Retail Consortium6. The overriding requirement is that the facilities provided shall be sufficient to accommodate the required number of per­sonnel, shall be designed and operated to minimise the risk of product contamination and that such facilities shall be maintained in good and clean condition. However, factories may provide anything from basic hand washing facilities, i.e. sinks supplied with soap and hot and cold water, to automated hand washing systems that monitor individuals hand wash frequency and performance. Similarly, for hand drying the facilities provided can range from the provision of paper towels to the use of novel air drier systems. These facilities are best located in an area segregated from the production area, to reduce the spread of aerosolised bacteria from the hands. Increasingly, food factories are additionally providing bactericidal soaps, gloves of different types, and anti-microbial hand rubs.

Over and above the provision of facilities, however, how effective are hand hygiene practices at actually reducing contamination to food, people and the work environment? As part of the development of a new guideline on hand hygiene7, Campden BRI undertook a review of some of the methods reported to improve hand hygiene, in terms of compliance and efficacy, and minimise contamination to the washroom environment. Some of the findings of this review are summarised in this article.

Compliance

In spite of the acknowledgement that hand hygiene is essential in controlling cross con­tamination, and the development of models that predict that the level of hand hygiene com­pliance can have a large impact on the prevention of foodborne illness8, there are a number of published accounts showing that lack of hand hygiene compliance is a major problem, particularly within the health service9,10,11. In food manufacturing, the nature of working practices and the resultant movement patterns of per­sonnel is felt to result in higher rates of compliance but it is still an area of concern. As a result, a number of systems aimed at improving and monitoring hand hygiene compliance have been investigated and developed.

A study by Venkatesh et al.12 investigated hand hygiene compliance in a hospital. Part of the study evaluated the effectiveness of electronic prompts that reminded staff to use the gel. An electronic monitoring device was placed in twelve rooms in a hospital. The device detected and recorded opportunities when hand hygiene should be carried out. Over a period of two weeks, 8,235 hand hygiene opportunities were collected that were con­sidered for compliance examination. The study found that the introduction of an electronic reminder to sanitise hands led to an increase of hand hygiene compliance rates from 36.3 per cent to 70.1 per cent.

Automated hand wash units are available that can be programmed to deliver soap, water and, in some cases, the mechanical action required to achieve optimal hand hygiene. One such system (Safeway Hygiene Services) has also incorporated the means to monitor hand wash compliance. The hands are inserted into the unit and washed automatically. If the hands are removed from the unit before the washing cycle is complete, a buzzer sounds and a failed hand wash is recorded. The machine can also monitor individuals hand wash compliance with the use of magnetic personal ID tags, which are detected by the hand wash unit and can be used to identify its use by an individual. This individual assessment of unit use is said to aid compliance while the optimised, automated hand wash procedure ensures a consistently effective hand wash.

Hand washing

The primary reason for washing hands is to prevent cross contamination of pathogens to food products and food contact equipment, which in the food industry could lead to food poisoning incidents. Additionally, the design of the hand washing facility should minimise contamination of the user and the wash room environment.

Campden BRI recently assessed the hand wash efficacy of an automated hand wash system (Safeway Hygiene Services) against a standard UK National Health Service (NHS) handwash protocol in a traditional sink using the methodology of BS EN 1499:199713 (hygienic biocidal handwash test) and 35 volunteers. The generation of large (ballistic) and small (aerosolised) water droplets, and their associated microbiological components, by these techniques and their impact on the hand wash user and the washroom environment was also assessed using moisture indicator paper and microbiological air sampling.

A 30 second standard NHS hand wash achieved a 2.42 log reduction in the number of marker bacteria initially inoculated onto the hands. There was evidence of a statistical difference between this result and the one determined when the automated hand wash unit was used with a 30 second program, i.e. 2.67 log reduction. Both techniques gave rise to microbiological contamination of the environment and user (including areas of the sleeves and body likely to come into contact with food), though the automated hand wash unit gave rise to much lower levels than the traditional sink method.

Hand drying

Studies have recognised the importance of hand drying in hand hygiene procedures. One thousand times as many microorganisms can be spread from damp hands than dry hands (www.Foodlink.org.uk, 2008). However, there has also been considerable debate about the best method of hand drying. A number of studies have been undertaken to compare different hand drying methods14,15,16,17,18 however, different assessment methods were used and conflicting results published.

In 2008, Campden BRI investigated the generation and spread of airborne contamination during hand drying using a number of different hand drying techniques, i.e. paper towels, warm air and an air knife system (Dyson). The generation of large (ballistic) and small (aerosolised) water droplets, and their associated microbiological components by these techniques and their impact on the hand wash user and the washroom environment was measured using moisture indicator paper and microbiological air sampling.

The results showed that there were no practical differences between the use of the air knife system, the warm air hand dryer and the paper towels with regard to microbial aerosol gen­eration. The very low numbers of airborne microbes that were generated by each of these hand drying methods would make an insignificant contribution to the overall background microbial loading of the air in any food processing environment. Water droplet contamination of the environment was significantly greater for the air dryers than for paper towels. Ballistic water droplet generation and spread by any hand drying technique should be considered, as contamination of surfaces with water may subsequently en­courage microbial growth.

Effective hand washing and drying is very important in minimising the transfer of con­tamination. Recontamination of the user and the washroom environment during these activities can be minimised through the selection of hygienically designed facilities and the correct siting of equipment, preferably in areas segregated from the food production areas.

Hand disinfection

Hand disinfection refers to the application to the hands of a chemical substance having antimicrobial activity. With regards to the food industry, the choice of hand disinfection products is limited; they must not be toxic nor taint the food product, and should have activity against a wide range of microorganisms. Well established hand sanitisers include chlor­hexidine, quaternary ammonium compounds (QUATs), iodophors, triclosan and alcohol. Over the last few years, the number of hand dis­infection products on the market has increased and the use of disinfectant hand gel/rub/ foam/wipe systems has become very popular within both food handling and clinical settings.

Alcohol based hand disinfection products have been shown to be effective against some Gram positive bacteria, including pathogens such as MRSA, and the spectrum of Gram negative bacteria. The application of alcohol based products containing between 60 per cent and 80 per cent of usually ethanol or isopropanol are very effective in reducing the immediate level of microorganisms on hands. However, alcohol has little residual effect and the application of alcohol alone is not suitable for removing physical dirt19,20.

Recently a number of other agents have been investigated with respect to their ability to be used as hand disinfectants. This may have been driven by concerns about alcohols effectiveness against spores and non-enveloped viruses, occupational use of alcohol based skin products, or alcohol use by some religious groups. Whatever the reason it has led to the development of a number of new non-alcohol based products.

It has been shown that adding silver containing polymers to an ethanol carrier had the effect of persistent antimicrobial activity on human skin21. Nano sized silver ions are known to be used in products to help eradicate bacteria that are multiply-resistant to antibiotics, but because of the largely unknown side-effects of this material, their safe use with respect to the user and the environment needs to be con­sidered. Consequently, further research in this area should be undertaken in order to demonstrate the efficacy and safety of silver nano ions.

Of more practical use is a recently launched hand hygiene product (Byocare, Byotrol), which consists of a selection of EPA registered biocides attached to a polysiloxane polymer. This product has just been Halal certified and was the recipient of the Society of Food Hygiene and Technology award for best new product (2009).

Glove use

One of the more recent changes in the approach to hand hygiene in the food industry is the increasing use of gloves. Whether this change has been driven by a real or perceived improvement in hand hygiene is unclear. Many reasons are cited for the use of gloves, including to protect the workers from hot, cold or harmful substances or as a barrier to cover wounds or as a customer requirement or worker preference.

However, as part of a three year Campden BRI research project, over 100 hygiene swabs were taken from hands and gloved hands in three different ready-to-eat (RTE) food factories (25cm2 area swabbed per sample). Rather than take samples directly after hand washing or from freshly gloved hands, samples were taken at approximately hourly intervals throughout the production period. The results show that the hands and gloved hands (three different types of glove sampled – nitrile, latex and rubber) of process workers in a variety of RTE food factories can be contaminated with high numbers of microorganisms and that gloves can be more highly contaminated than hands (see Table 1, page 63).

Like hands, the use of gloves also gives rise to the transmission of microorganisms by workers. Laboratory studies conducted by the Food Hygiene Department, Campden BRI, to quantify the transfer of microbial contamination from hands and gloved hands to an agar food model indicate that up to 39 per cent of test organisms (Escherichia coli K12, Staphylococcus spp. and Listeria inoccua) are transferred from glove material on contact but only approximately 11 per cent are transferred from hands (Smith, 2007)

It is therefore important that the reasons for wearing gloves are well understood and the issues surrounding their use addressed. Generally, operatives are well informed about personal protective equipment and the need to wear gloves when handling hazardous chemicals or agents to protect their hands. Operatives may not be so well informed about the issues concerning the wearing of gloves for food safety. If gloves are to be used as part of the hand hygiene procedure, this informa-tion should be provided as part of hand hygiene training.

In conclusion, a number of technologies aimed at reducing contamination to food, people and the work environment are appearing on the market, but each should be con­sidered carefully, with regard to its performance, prior to use.

References

1. Semmelweis, I.P. (1861). Die Aetiologie, der Bergriff und die Prophylaxis des Kindbettfiebers. C.A. Hartleben, Pest, Vienna and Liepzig (translated by F.P. Murphy (1981) Birmingham: Classics of Medicine Library).
2. Greig, J. D., E. C. D. Todd, C. A. Bartleson, and B. S. Michaels (2007). Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 1: Description of the problem, methods and agents involved. J. Food Protect. 70:1752-1761.
3. Todd, E. C. D., J. D. Greig, C. A. Bartleson, and B. S. Michaels (2007b). Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 3. Factors contributing to outbreaks and description of outbreak categories. J. Food Prot. 70:2199-2217.
4. Smith, D. L. (2007). Ranking of cross- contamination vectors of ready-to-eat foods: a practical approach. Guideline No. 54. CCFRA Group.
5. Anon (1995). The Food Safety (General Food Hygiene) Regulations 1995. SI no. 1763. ISBN 0-11-053277-9. London: HMSO.
6. British retail Consortium (2008). BRC Global Standard for food safety: Issue 5. the Stationary Office. ISBN: 9780117037915.
7. Smith, D. L. (2009). Hand Hygiene: guidance for best practice. Campden BRI Guideline No. 62. Campden BRI, Chipping Campden, Glos. GL55 6LD, UK.
8. Schaffner, D. W., Macinga D. R., and Arbogast J. W. (2000). Modelling hand hygiene; the influence of biological and psychological factors on illness rate. Proceedings of the Conference for Food Protection meeting. Milwaukee, WI, USA. April 7-12, 2000.
9. Sproat, L. J., and T. J. Inglis (1994). A multicentre survey of hand hygiene practice in intensive care units. J. Hosp. Infect. 26:137-148.
10. Voss, A. and Widmer, A.F. (1997). No time for hand washing!? Hand washing versus alcoholic rub: can we afford 100% compliance. Infection Control and Hospital Epidemiology 18, 205-208.
11. Boyce, J. M. and D. Pittet (2002). Guideline for hand hygiene in healthcare settings: Recommendations of the healthcare infection control practices advisory committee and the HICPAC/SHEA/APIC/IDSA hand hygiene task force. Morb. Mortal. Wkly. Rep. 51:1-45.
12. Venkatesh, K.A., Lankford, G.M., Rooney, M.D., Blachford, T., Watts, M.C. and Noskin, A.G. (2008). Use of electronic alerts to enhance hand hygiene compliance and decrease transmission of vancomycin-resistant Enterococcus in a haematology unit. American Journal of Infection Control, 36, 199 – 204
13. EN 1499:1997 Chemical disinfectants and antiseptics – Hygienic hand wash -Test method and requirements (phase 2/step 2).
14. Meers, P.D. and Leong, K.Y. (1989). Hot-air hand driers. Journal of Hospital Infection, 14, 169-181.
15. Blackmore, M.A. (1989). A comparison of hand drying methods. Catering and Health, 1, 189-198.
16. Ansari, S.A., Springthorpe, S.V., Sattar, S.A., Tostowaryk, W. and Wells, G.A. (1991). Comparison of cloth, paper, and warm air drying in eliminating viruses and bacteria from washed hands. American Journal of Infection Control, 19, (5), 243-249.
17. Taylor, J.H., Brown, K.L., Toivenen, J. and Holah, J.T. (2000). A microbiological evaluation of hand driers with respect to hand hygiene and the washroom environment. Journal of Applied Microbiology, 89, 910-920.
18. Taylor, J.H., and Kaur, M. (2000). Hand and footwear hygiene: An investigation to define best practice. R & D Report. CCFRA, Chipping Campden, Glos GL55 6LD.
19. Guzewich, J. and Ross, M.P. (1999a). White paper, section 1. A literature review pertaining to foodborne disease; outbreaks caused by food workers, 1975-1998. Food and Drug Administration, Centre for Food Safety and Applied Nutrition.
20. Guzewich, J. and Ross, M.P. (1999b). White paper, section 2. Interventions to prevent or minimise risks associated with bare hand contact with ready-to eat-foods. Food and Drug Administration. Centre for Food Safety and Applied Nutrition.
21. Manivannana G. (2000). Immediate, persistent and residual antimicrobial efficiency on surfacine hand sanitizer. Infection Control and Hospital Epidemiology, 21, 105.