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Gross Study Reminds Us Why We Wash Our Hands, Not Our Chicken, When We Cook


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

raw chicken

Mmm, delicious salmonella. Image credit: AlexeiLogvinovich/

Humans, as a species, eat so many chickens every day that it’s literally leaving a mark on the geological record. The birds outnumber us about three to one worldwide, making a chicken uprising worryingly possible if they ever figured out the kind of things we subject them to, and the average American eats the equivalent of around 24 individual chickens every year. So you’d expect we knew how to cook them by now.

Unfortunately, as social media has proven time and time again, that is not always the case. You don’t have to look very far to find people purporting to eat the meat “rare” or even straight-up raw – both preferences you will (hopefully) recognize as carrying a serious risk of food poisoning.


But a new study, recently published in the Journal of Food Protection, suggests that maybe we shouldn’t judge those e-E. coli connoisseurs too harshly. After all, it turns out there's a surprising proportion of people who don’t know one of the most basic pieces of cooking advice when it comes to preparing chicken: wash your hands, not the meat.

“We wanted to know what effect an educational intervention would have on getting people to stop washing poultry before cooking, and what effect any resulting change in behavior might have on reducing contamination in the kitchen,” explained Ellen Shumaker, corresponding author of the study and an extension associate at North Carolina State University. “We also wanted to get a better idea of how, if at all, washing poultry actually led to increased contamination in the kitchen.”

So the researchers recruited 300 home cooks and set them a task: make a chicken salad. They were set up in special test kitchens, equipped with cameras that monitored their preparation techniques, and halfway through – after the cooks had prepared the chicken, but before they put them in the oven and got started on the salad – they were asked to step away and take a short interview.

But here’s the thing: not all the test subjects had been given the same information going in. Slightly fewer than half of the 300 had been sent an email ahead of time reminding them of standard food safety recommendations – including the recommendation, echoed by the CDC and USDA alike, to not wash raw poultry during food preparation.


Of those home chefs who received the reminder, more than nine out of every ten remembered not to wash the chicken before cooking it. In the group who didn’t get the email, more than six out of every ten did wash the chicken.

So why is this important? Isn’t washing things good? Well, yes, generally – but when it comes to raw meat, and chicken especially, you have to look at the bigger picture.

“A minimum of 25 percent of chicken carcasses come in contaminated with salmonella, and there are about 2,600 species of salmonella,” explained Rick Holley, a food microbiology professor at the University of Manitoba, back when the “medium-rare chicken” meme first took off.

“If you look at the US baseline data on carcass contamination with campylobacter, and you're looking at anywhere from 30 to 90 percent of carcasses that are contaminated,” added Holley, who was not involved in the new study. “Foodborne illness costs two-thirds of the money that diabetes costs, so it's not insignificant.”


While that might sound like more of a reason to wash the meat before you cook and eat it, the reverse is actually true. See, the germs in, on, and around your chicken carcass are easily neutralized in the cooking process – assuming you cook it properly, that is. Washing it, on the other hand, only spreads those germs around, contaminating your sink and countertops.

At least, that’s what the conventional wisdom said. The truth, Shumaker and her colleagues found, is a little more complicated.

Unbeknownst to the test subjects, the chicken used in the experiment had been contaminated with a harmless strain of E. coli, and while the cooks were distracted with half-time interviews, a team of researchers was sent into the kitchens armed with swabs. What they expected to find was that the sinks and countertops of chicken-washing cooks would be contaminated by splashes from the tap water – but what they actually found was more surprising.

“Regardless of whether people washed their chicken, the kitchen sinks became contaminated by the raw chicken, while there was relatively little contamination of nearby counters,” said Shumaker. “This was a little surprising, since the conventional wisdom had been that the risk associated with washing chicken was because water would splash off of the chicken and contaminate surrounding surfaces. Instead, the sink itself was becoming contaminated, even when the chicken wasn’t being washed.”


When partcipants weren’t given the reminder not to wash chicken, the incidence of contamination in the salads was similar for the cooks who had washed the chicken and those who hadn’t. But when they were reminded, those who washed the chicken ended up with around twice as much contamination on their salads.

So what’s going on? The answer is fairly simple, said Shumaker: “We think the salad contamination stems from people doing a poor job of washing their hands after handling the raw chicken, and/or doing a poor job of sanitizing the sink and surrounding surfaces before rinsing or handling the salad,” she explained.

Now, if there’s anything we’ve learned from living through two years of a pandemic, it’s that the importance of properly washing your hands can’t be overstated. That’s not just true for COVID-19, though – it’s also crucial for maintaining good food hygiene.

And that’s a lesson Shumaker thinks we may need reminding of.


“Washing the chicken is still not a good idea,” she said, “but this study demonstrates the need to focus on preventing contamination of sinks and emphasizing the importance of hand-washing and cleaning and sanitizing surfaces.”


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