Antibacterial soaps can reduce risk of foodborne illness

Friend of the blog Don Schaffner has published some new research that shows  the use of antibacterial soaps can reduce the spread of harmful bacteria – that often leads to foodborne illness – more effectively than using non-antibacterial soaps.

The research, published in the peer-reviewed Journal of Food Protection (Vol. 77, No. 4, 2014, pp. 574-582), used new laboratory data, together with simulation techniques, to compare the ability of non-antibacterial and antibacterial products to reduce the risk of the infectious disease shigellosis, which is often spread during food preparation.

antibacterial.soapLead researcher Donald Schaffner of Rutgers University’s Department of Food Science says the data show that the use of three antibacterial wash products result in a statistically significant reduction in the presence of Shigella (the bacterium that causes shigellosis) compared to the use of the non-antibacterial soaps.

“This exciting research blends quantitative microbial risk assessments with an impressive set of laboratory data to show that antibacterial treatments are more effective than non-antibacterial treatments in reducing disease,” said Dr. Schaffner.

In the study, 163 subjects were used to compare two non-antibacterial products and three antibacterial products, with a study design intended to simulate food handling. The participants’ hands were exposed to Shigella and then treated with one of the five products before handling food melon balls. The resulting levels of Shigella on the food were then measured.

The levels of Shigella were then used to predict the outcome from an event in which 100 people would be exposed to Shigella from melon balls that had been handled by food workers with Shigella on their hands.

The data show all three antibacterial treatments significantly lowered the concentration of Shigella compared to the non-antibacterial treatments. Based on this model, the paper predicted that by washing with the antibacterial treatments, the number of illnesses could be reduced tenfold.

“This research provides strong evidence that antibacterial soaps are significantly more effective than non-antibacterial soaps in reducing Shigella on the hands and its subsequent transfer to ready-to-eat foods,” the authors write.

The American Cleaning Institute ( and the Personal Care Products Council ( provided funding for the research as part of the groups’ ongoing commitment to product and scientific stewardship to affirm the safety and benefits of these products.

An abstract summarizing the paper, “Quantitative Microbial Risk Assessment of Antibacterial Hand Hygiene Products on Risk of Shigellosis,” can be found online at

Proper handwashing requires proper tools

The state government in New South Wales – that’s where Sydney is – has come out with a new push for handwashing as a cornerstone of food safety.

I agree. But proper handwashing requires proper tools – vigorous water-flow, soap and paper towels.

jon.stewart.handwashing.2002Almost no Australian restaurants have all three components, based on my anecdotal but extensive observation (and wet shorts because I don’t use blow-driers).

NSW Minister for Primary Industries, Katrina Hodgkinson visited the NSW Food Authority’s stand at the Sydney Royal Easter Show and said, “Handwashing is the most simple and yet the most effective means of reducing your risk of food poisoning.”

If it was simple, so many people wouldn’t get sick; proper handwashing requires access to proper tools.

80 crypto cases a year; handwashing is never enough: UK health chief warns over risk of infection from region’s petting farms

We have a paper coming out shortly about best practices at petting zoos and farm visits and state fairs and just hanging out with animals.

I’ll follow my own best practice and wait until it’s published to talk about it, but Dr Ken Lamden, the health chief of Cumbria and north Lancashire in handwashing.ekka.jpgthe UK is urging parents to be aware of potential infections that can be caught at farm attractions.

Over the past 20 years, an average of around 80 cases of cryptosporidium infection linked to visits to petting farms have been reported to Public Health England each year. This is out of a total of around two million visits to the 1,000 plus farm attractions in the UK, with peak visitor times during school and public holidays.

Dr Lamden, of PHE’s Cumbria and Lancashire Centre, said: “Visiting a farm is a very enjoyable experience for both children and adults alike but it’s important to remember that contact with farm animals carries a risk of infection because of the micro-organisms – or germs – they carry.

 “Anyone visiting a petting farm should be aware of the need to wash their hands thoroughly using soap and water after they have handled animals or been in their surroundings. Children are more at risk of serious illness and should be closely supervised to make sure that they wash their hands thoroughly.

“It is also very important not to rely on hand gels and wipes for protection because these are not suitable against the sort of germs found on farms.” 

Parents in Ohio say their kids not allowed to wash hands at school

First thing I do when a kid is checked into a new daycare or school is check out the handwashing facilities. Proper handwashing requires access to proper tools: vigorously running water, soap and paper towels.

Sorenne says at her kindergarten (prep here) she always washes her hands, uses soap, but because there is only blow driers she often dries her hands on her clothes (blow driers suck, the friction from wiping with paper towel provides an extra level of safety).

Too often, hypocrites preach about the importance of handwashing without checking to courtlynn.handwashensure the tools are available.

Two parents of students attending separate Toledo Public elementary schools in Ohio say their children are not being allowed to wash their hands after using the restroom, an allegation the school district denies.

Holly, who has two kids that attend East Broadway Elementary School, said she was surprised when her children told her that they couldn’t wash their hands while at school. “They told me they are only allowed to put hand sanitizer on twice a day after we use the bathroom,” said Holly.

The mother shared the information with her sister, Heather, who has a fourth grader enrolled at Burroughs Elementary.

Heather’s son told her that while at school he had witnessed another boy walk to the sink to wash his hands after using the restroom. The boy was stopped by a school staff member who called him over, squirted hand sanitizer in his hand, and walked away, according to Heather’s son.

When asked if they were sure of what their children were alleging, the women said that their kids have always been honest about what goes on at school.

Toledo Public Schools denies that students are prohibited from washing their hands. In an email to WNWO, TPS spokesperson Patty Mazur wrote, “Teachers take students to the bathroom as a class and then watch as students exit the restroom and wash their hands. If a student didn’t wash their hands properly, they are asked by their teacher to re-wash.”

Despite the response from TPS, Heather remains convinced that her son is not allowed to wash his hands while at school. “It needs to be addressed, ” she said. “This is disgusting. It makes me wonder if this is why my child has been sick so much this year.”
TPS said it holds hand-washing classes for elementary school students at the beginning of the year. Signs are posted in the restrooms reminding students to wash their hands after they use the bathroom.


‘Why do we have to wash our hands? We wear gloves’ bad inspection forces Wisconsin McDonald’s to close, give refunds

A McDonald’s at 3131 Mayfair Road in Wauwatosa was, according to the Journal Sentinel, closed briefly two weeks ago because of issues with handwashing, and the restaurant was forced to give customers refunds at the counter, public records from the city showed.

The restaurant closed March 12 for several hours while a hand sink was being repaired. There were none working in the kitchen for washing hands or in the rest of the restaurant,handwash_south_park(2)except in the bathrooms. Restaurants in Wisconsin are required to have sinks designated solely for washing hands.

The inspection yielded several other violations, including dirty utensils, accumulations of food debris and grease, wiping rags in sanitizer buckets that didn’t have any sanitizer in them and a lack of basic knowledge about food safety.

According to the inspection report, one employee said, “Why do we have to wash our hands? We wear gloves.”

The inspector also instructed staff to throw out undated foods from the refrigerators.

Owner Deborah Allen said in a statement, “Nothing is more important to me than operating a safe and clean restaurant. We follow rigorous standards for food safety and quality, and we take great pride in the food and beverages we serve to our customers every day. We take these matters very seriously, and took immediate action to make the appropriate corrections.”

The inspection report is available at the Journal Sentinel’s restaurant inspection page,, which houses restaurant inspection data from the four-county Milwaukee area and is updated monthly. Wauwatosa is not included with other cities and towns in the four-county database because the city has said it is not able to release its database. Instead, the city provides inspection reports weekly.


No: Is hot water more effective for washing hands?


We’ve written about this before, but here is another take on the effectiveness of warm or hot water in handwashing.

Researchers surveyed 510 adults and asked them questions about their hand washing behaviours and perceptions.  People were asked how often they wash their hands, for handwashing.sep.12how long and how hot the water should be.

According to the published report, “70% of respondents said they believe that using hot water is more effective than warm, room temperature, or cold water, despite a lack of evidence to back that up.  The research showed a, “strong cognitive connection between water temperature and hygiene in both the United States and Western Europe.” 

So while many believe hot water is more effective for hand washing the study actually concluded, “the temperature of water used is not related to how well pathogens are eliminated during the process.”  Additionally, warmer water can irritate the skin and can affect its protective layer, which may cause it to be less resistant to bacteria.  Skin irritation has been reported as  one of the main reasons many healthcare workers forgo hand hygiene for example.

 Interestingly if you look at the official guidelines for hand washing from the CDC and WHO, both do not actually specify a water temperature.  They do recommend using soap and water and scrubbing using proper technique for at least 20-seconds, followed by drying hands thoroughly.

Despite this there is still lots of confusion as some public health organizations still recommend, “elevated water temperature.”  The FDA Food Code for example, which is a model used to enforce health standards in restaurants recommends the , “hand washing sink be equipped to provide water at a temperature of at least 100°F or 38°C.”

One subscriber to this blog recently commented, “I have come across a food safety consultant who insisted that the temperature should be 60°C (140°F).  Observations revealed that staff proceeded to use cold water saying hot water was too hot!  Microbiological swabbing of hands revealed an increase in Campylobacter, E.coli and Listeria counts on hands that were washed in basins when very hot water was demanded by the consultant, compared to hands exposed to water at 40 to 45 °C.”

Barry Michaels, a microbiologist and expert in infectious disease performed the only known comprehensive review of published recommendations or testing standards  on hand washing and rinsing water temperatures from 1938 to 2002.   He found that there was no consensus but instead temperatures ranged from ambient  to “as hot as you can stand” or “as hot as possible”.  Many recommendations in food and healthcare environments were not concerned with the water temperature at all, while an equal number only specified that water in the lukewarm to warm temperature regions be used.  Then there was a select group including ASTM test methods, American Society of Microbiology, the FDA Food Code  and  experts in food and healthcare who felt that hot jon.stewart.handwashing.2002water from 40 to 50 degrees °C (~100-120 degrees °F) should be used.  Reasoning was that hot water was needed to melt fats in food soils and increase antimicrobial effectiveness.  In testing on efficacy and skin health Barry Michaels and team found that hot water should not be used.

Michaels commented, “The damage at 60°C would probably be enough to stop workers from washing hands all together.  Results indicate that water temperature has only slight effect on transient or resident bacterial reduction during normal hand washing when bland soap is used.  We have also tested with four other soap products each having different active ingredients (PCMX, lodophor, Quat & Triclosan) and overall, the four soap products produced similar efficacy results”.

“Although there were slight increases in Log10 reductions (ascribed to antimicrobial speed of chemical reaction), skin moisture content decreased while Visiometer skin dryness score and transepidermal water loss (TEWL) increased at higher temperatures. Results were not statistically significant for any parameter, but all trends were unmistakable.”

“In summation, water temperature should be comfortable to allow or encourage frequent hand washing with mild, but effective soaps (designed for soils to be encountered).  Vigorous hand washing is the preferred method.  In terms of ideal temperature, I would say from ~70 to 105 °F or ~20 to 40.5 °C.  This is comfortable without the risk of skin damage,” concluded Michaels.

Reference for the research cited is: Michaels, B.; Gangar, V.; Schultz, A.; Arenas, M.; Curiale, M.; Ayers, T.; Paulson, D.  Water Temperature as a Factor in Handwashing Efficacy.  Food Service Technology 2002; 2:139-149.

Hot water is ‘unnecessary and wasteful’ for handwashing – study

We’ve said for a decade hot water is not a factor in reducing microbial loads during handwashing. Friend of the blog Don Schaffner at Rutgers agrees.

And now, so do researchers at Tennessee’s Vanderbilt University.

We admit, warm water is often a preference, but scientifically, it does not handwash.south.parklower microbial loads.

And we all want to be evidence-based.

As reported in the European Cleaning Journal, using hot water for hand washing is unnecessary while potentially being harmful for the environment, but nearly 70 per cent of Americans believe hot water to be more effective than cold or warm water – despite having no evidence to back this up.

According to research assistant professor Amanda Carrico: “It is certainly true that heat kills bacteria, but if you were to use hot water to kill them it would have to be way too hot for you to tolerate.”

She explains that pathogens can be killed by water at temperatures of 99.98°C – but hot water for hand washing is generally between 40°C to 55°C, and even at these temperatures the sustained heat required to kill some pathogens would scald the skin.

Carrico’s team found water as cold as 4.4°C to be just as effective at reducing bacteria as hot water if the hands were scrubbed, rinsed and dried properly. And they noted that hot water could even have an adverse effect on hygiene. “Warmer water can irritate the skin and affect the protective layer on the outside, which can cause it to be less resistant to bacteria,” said Carrico.

And she adds that no water temperature is specified in official guidelines from the Centre for Disease Control and Prevention nor the World Health Organization, which simply recommend using soap and water and scrubbing vigorously for at least 20 seconds followed by a thorough dry.

Now, about that 20 seconds …

handwash_infosht-2-7-08 copy

Employees fingered in Norovirus outbreak linked to bread

A massive norovirus outbreak amongst school children in Japan has been, according to health authorities, linked to three factory staff who handled bread as part of their jobs. Japan News reports that norovirus was detected in stool samples of the three staff members – signs of the virus were not founds in an additional 16 food handlers who also submitted samples.hlebozavod-0024

The bakery is suspected to have been the cause of a mass food poisoning that affected many primary schools in the city, according to the Hamamatsu city government.
The city government announced Sunday that workers at Hofuku, a company that produced bread deemed to be the cause of the norovirus outbreak, were found to be infected with the virus.

Yoshinao Terada, chief of the city government’s living and health section, said at a press conference, “It is highly likely that persons with the virus took part in the production process leading to contamination of the bread.”

The company ordered the three workers to stay home from work and specialists began sterilizing the plant. 

Asymptomatic norovirus carriers have been linked to lots of outbreaks in the past.  It’s also possible that the individuals were ill, recovered, and still shedding viruses in their stool. My NoroCORE colleague Robert Atmar and colleagues reported in 2008 that noro could be recovered from folks infected with the virus for up to 56 days (with a median of 28 days) – long after symptoms subsided.

Regardless, there are some hygiene issues going on at Hofuku.

Food Safety Talk 53: Raw milk Hamsterdam

Food Safety Talk, a bi-weekly podcast for food safety nerds, by food safety nerds. The podcast is hosted by Ben Chapman and barfblog contributor Don Schaffner, Extension Specialist in Food Science and Professor at Rutgers University. Every two weeks or so, Ben and Don get together virtually and talk for about an hour.  They talk about what’s on their minds or in the news regarding food safety, and popular culture. They strive to be relevant, funny and informative — sometimes they succeed. You can download the audio recordings right from the website, or subscribe using iTunes.

They dove in to follow-up with additional information they received from Cheryl Deem from the American Spice Trade Association (ASTA) on the spice story in FST 52. Cheryl explained why ASTA didn’t have a response to the FDA risk assessment as reported in this NYT article and shared a guidance document ASTA had prepared in 2011.

The discussion then turned to yet another pruno-related botulism outbreak in a Utah prison. Pruno has been discussed in FST 27 and the investigation of that outbreak has just been published in this paper, including the experimental Pruno recipe.

In the IAFP History segment, Don shared Manan Sharma‘s article on the 1970′s, which marked changes to food consumption, food safety and environmental trends, including HACCP and microwaves. After a short 1970′s detour to Jack Kirby’s Fourth World Omnibus Vol 1, Ben marveled about the advances in microwave technology, including the magnetron. While Ben’s new microwave exceeded his cooking expectation, Trader Joe’s cooking instructions for Mac & Cheese fell short. In contrast to Trader Joe’s, who don’t have a social media presence, Don did like Publix who asked for a haiku on Twitter.

Don then shared his latest irritation with It was prompted by their latest campaign called Bac Down and their lack of understanding that Listeria monocytogenes can grow at temperatures as low 32 °F. The guys challenged listeners to send in their creative Bac-themed puns for great prices!

Ben then wanted to talk about Jeffery Arthur Feehan who tried to shoplift meat in his pants. But Ben wasn’t quite so worried simply because store employees put the meat back on the shelf (a big yuck factor!), but that Jeffrey took the meat to the restroom for his pants stuffing misdemeanor. Jeffrey’s comment to the judges reminded Ben of a famous Animal House quote.

The discussion then turned to a recent paper on raw milk consumption and illness. While the underreporting aspect got some publicity, Ben suggested that all the information wasn’t going to change minds. This had been highlighted in this article on Michigan consumers of raw milk and that’s got to do with raw milk proponents not trusting health officials. Ben discussed the “The Abuela project“, an example of an innovative approach to overcoming the difficulty of developing successful education campaigns. The challenge of course is how to develop a campaign when raw milk sales are illegal (as is the case in some states). Maybe a Raw Milk Hamsterdam is the solution?

FDA CDER wants to know if antimicrobial soaps are effective: Schaffner responds

Friend of the Don Schaffner of Rutgers University writes in this guest post:

The FDA might not be sure if antimicrobial soaps do anything, but I am. My colleague R. Montville[1] and I published a meta-analysis on the topic in 2011. As we noted in our manuscript, although differences in efficacy between antimicrobial and nonantimicrobial soap were small (∼0.5-log CFU reduction difference), antimicrobial soap produced consistently statistically significantly greater reductions when compared to plain soap. This difference was true for any of the antimicrobial compounds investigated (chlorhexidine gluconate, iodophor, triclosan, or povidone) where we had more than 20 observations to analyze.24673_1363044526205_4550195_n

But the story doesn’t end there. The American Cleaning Institute who funded[2] the meta-analysis study wanted to dig a bit further. A second article has been accepted for publication in the Journal of Food Protection, and is in the galley proof stage. That article, entitled “Quantitative Microbial Risk Assessment of Antibacterial Hand Hygiene Products on Risk of Shigellosis” used previously unpublished laboratory data, together with simulation techniques, to compare the ability of nonantibacterial and antibacterial products to reduce shigellosis risk. Our simulation assumed 1 million Shigella bacteria on the hands of a food handler who washed their hands and then handled melon balls, which were then eaten. When a plain soap hand treatment was simulated, we predicted that 50 to 60 cases of shigellosis would result (of 100 exposed). Conversely, each of the antibacterial treatments (0.46% triclosan, 4% chlorhexidine gluconate, or 62% ethyl alcohol) was predicted to result in an appreciable number of simulations for which the number of illness cases would be 0, with the most common number of illness cases being 5 (of 100 exposed). These effects maintained statistical significance down to as low as 100 Shigella per hand, with some evidence to support lower levels. Like I said, I think anti-microbial soaps work. If you think they don’t, show me the data.

[1]: No, not that Montville, his daughter.
[2]: Does that make me an industry shill? Please. Like anyone can tell me what to say.