logo
episode-header-image
Oct 2024
28m 48s

The 5 Second Rule

Bbc Radio 4
About this episode

Would you eat food that fell on the floor? That’s the question Hannah and Dara are getting their teeth into this week as they put the so-called ‘5 second rule’ through its paces.

For some people it’s 3 seconds, and for others its 10 – especially if it involves a dropped ice cream and a screaming child. But microbiologist Don Schaffner says there’s no safe amount of time to leave food on the floor if you’re planning to eat it. And while you might think buttered toast would pick up the biggest number of bugs, it may surprise you to hear that wet foods like watermelon are actually the worst when it comes to attracting harmful bacteria. If all this is putting you off your dinner, the bad news is that the rest of your kitchen is also a microbiological minefield. Research shows nearly 70% of us keep our fridges are the wrong temperature, which sparks a lively discussion about whether it’s ever safe to reheat rice.

For home hygiene guru Sally Bloomfield it’s all a question of being a bit more clever about the kind of germs we expose ourselves to and weighing up risks.

Contributors:

Dr Don Schaffner: Rutgers University Dr Ellen Evans: Cardiff Metropolitan University Professor Sally Bloomfield: International Scientific Forum on Home Hygiene

Producer: Marijke Peters Executive Producer: Alexandra Feachem A BBC Studios Audio Production

Up next
Jan 2026
Frosty Fractals
One winter morning, listener Jane opened her curtains to find her car roof covered in breathtaking, fern-like frost so intricate it looked like a William Morris print. But how does something as ordinary as ice create patterns so beautifully complex?Hannah and Dara explore this cr ... Show More
29m 10s
Dec 2025
Mining for Gold (GOLD!)
From pharaohs' tombs in Ancient Egypt and medieval currency, to priceless royal jewellery and Spandau Ballet songs - gold has been prized for millennia. But it's only really in the last century or so that we've started uncovering its usefulness in less decorative applications.Tod ... Show More
27m 51s
Dec 2025
Phantom Pain
What exactly is 'phantom pain' and how does it work? Hannah and Dara investigate a medical phenomenon that's been known about for centuries but is often misunderstood; and involves masses of unanswered questions.The condition 'phantom pain' is when someone gets a sensation of pai ... Show More
28m 29s
Recommended Episodes
Dec 2020
Do animals exercise?
<p>At Christmas, is there a better gift than knowledge? CrowdScience has cooked up its own version of 'secret Santa', with members of the team setting one another the challenge of answering surprising questions from all over the world. </p><p>Are humans the only animals to exerci ... Show More
37m 44s
Mar 2024
Science Unlocks The Power Of Flavor In ‘Flavorama’
<p>Think about the best meal you’ve ever eaten: Maybe it was in a restaurant in a far-off city, or perhaps it was a home-cooked meal made by someone you love. No matter where or what it was, odds are what made it so memorable was the flavor.</p><p>Flavor is arguably the most impo ... Show More
17m 30s
Sep 2024
Il ne faut pas se baigner juste après avoir mangé, vrai ou faux ?
<p>Est-ce que c’est vrai qu’il vaut mieux ne pas se baigner juste après avoir mangé ?</p><p>On entend souvent ce conseil, car il est lié à une inquiétude fréquente : celle de crampes ou de noyade en se baignant après un repas. Mais cette précaution est-elle vraiment justifiée ? D ... Show More
5m 11s
Jun 2024
Top 10 Interviews 2024 #8: Thinking Way Outside the Box! Adventures in Microwave and Aseptic Processing (S4:E5)
Send us Fan MailKeith, Eliza, and Paige are scheduled to travel with family, go to conferences and engage in science nerdiness, and do some hardcore development whether it’s manuscripts or courses. So while we are otherwise engaged, we thought you would like to hear the top 10 WD ... Show More
1h 1m
Sep 2024
Ask a Chemist: Does raw milk have more bacteria? (and other questions)
tail spinning
29m 55s
Nov 2024
The truth about expiry dates, freezing food and vegetable scraps | Carleigh Bodrug and Dr. Will Bulsiewicz
We waste a shocking 40% of the food we buy. We throw away foods like carrot tops, beet greens, and spent coffee grounds. These ‘food scraps’ stuff our landfills and drain our pockets. But we can eat these foods and many of them offer tons of healthy nutrients. Today’s guest is Ca ... Show More
1h 2m
Oct 2024
Scurvy, Bird Flu and a Big Old Meteorite
An enormous meteorite’s impact 3.26 billion years ago may have made conditions on Earth more hospitable for life in the long run. Washington State is the sixth state to report cases of bird flu in humans. Weight-loss procedures and treatments could lead to an uptick in scurvy cas ... Show More
9m 27s