Cash is no 'dirtier' than your plastic
Updated: May 22
Just when you thought ditching cash for the card was safer . . .
Cash isn’t the only payment method covered in bacteria. Credit cards, payment tablets and ATM keypads all carry them. That’s the finding of a study by CreditCards.com and the University of Texas.
The study analysed samples from payment methods that were swabbed by 30 data collectors across the US from March to May 2018. Contrary to the popular perception that money was ‘dirty’ and cards were less so, the study found cards had more types of bacteria on them than cash and coins. Those bacteria include both Staphylococcus aureus — responsible for staph infections, which can lead to impetigo, blood poisoning, septic arthritis and MRSA infections — and Salmonella enterica, a common source of food poisoning.
The study also found that staph-causing bugs are all over our wallets. All payment methods have a strong likelihood of carrying Staphylococcus aureus; all plastic and metal credit cards had detectable amounts on their surfaces. Credit cards are nearly three times as likely to carry Salmonella enterica than payment tablets. Coins and notes are only slightly more likely than payment tablets to carry it. And tablets are the payment method most likely to carry Streptococcus pneumonia, which can cause pneumonia and meningitis.
“Bacteria live on all surfaces of our bodies and all surfaces of the earth,” says Amesh Adalja, a medical doctor and senior scholar at the Johns Hopkins University Centre for Health Security. “In general, things that are touched more frequently are going to have more bacteria on them.”
Nevertheless, the average healthy person is unlikely to get sick just by swiping or tapping plastic. While credit cards and other payment methods can have more than 3,000 different types of bacteria, there’s likely not enough of it to make most of us sick. According to David Westenberg, associate professor of biological sciences at Missouri University of Science and Technology, while cash, cards and tablets can pick up bacteria from human skin, the microbes can’t thrive there because there’s no food source.
“It takes quite a few microbes to be ingested before you actually get sick, so it’s not something I would equate with being ‘dirty’,” Westenberg says. “It’s just that they are good surfaces that will pick up microbes because they’re handled frequently.” He suggests you could periodically clean your card if you want a little extra protection. “[The bacteria are] just kind of hanging out, and they can be easily wiped off,” he notes. “They haven’t attached and grown on those surfaces.”
Westenberg also suggests even someone with a weak immune system — due to old age, disease or chemotherapy, for instance — can avoid bacteria-related illnesses through good hygiene. In other words, wash your hands after handling cash or cards, especially before you prepare food with your hands.
Putting things in perspective
So, how do cards and cash stack up against other everyday objects? Well, another study found that while credit cards were not as ‘dirty’ as park benches and rental-bike handles, for example, they were 'dirtier' than toilet flush buttons and hand poles on trains. The 41 payment cards tested had an average germ score of 285, compared with 160 for various notes and 136 for coins. The toilet flush button scored 163. The dirtiest payment card examined had scored above a whopping 1,200!
"When you think about all the places your cash has been and how many times it has changed hands, you realise that bills become germ-transporting vessels," reports researcher Michael Brown. Same for payment cards, which are "getting swiped or inserted, changing hands or sitting on bar tops," he adds.
Brown says he was surprised by the higher germ counts for payment cards over cash. "One might expect cash to be the filthiest since cash stays in circulation a lot longer and can travel across the country by changing hands," he writes. However, debit and credit cards are now being used more often and in an increasing number of places.
If you’re still grossed out . . .
If the thought of coming into contact with bacteria on your card makes you queasy, there’s a simple solution. “Alcohol-based sanitisers are effective — they do reduce contamination,” says Miryam Wahrman, a biology professor at William Paterson University and author of The Hand Book: Surviving in a Germ-Filled World. “But they’re not as good as trusty old soap and water, which research has shown to reduce bacterial contamination.”
No matter, there’s little reason to panic about paying with plastic. If you’re healthy and you wash your hands after use, you can tap or swipe without fear.
What might be worse, though, is your mobile phone
While there’s less risk from cards because more of us are paying by tap-and-go rather than typing in a pin, you might still be more at risk when you take out your mobile phone to pay. But it does depend on where you take out your phone. “I think cellphones may pose a unique risk because a lot of people use their phones in the bathroom,” Wahrman says. “Those cellphones have seen germs that you don’t want to be exposed to.” Just saying.