With a scientist and some swabs, we uncover ‘The Dirty Truth’ about the surfaces you touch every day

JACKSONVILLE, Fla. – It’s The Dirty Truth! Things you touch all day -- every day -- are covered in it. From the bottom of your purse to buttons on an ATM, they are all swimming with bacteria.

To find out just how much is growing and where News4JAX turned to an expert at the University of North Florida to test common items.

With everything in hand needed for microbial sampling -- like sterile swabs and Petri dishes -- we joined UNF Biology Professor Dr. Dale Casamatta on our journey into the microscopic and gross.

UNF Biology Professor Dr. Dale Casamatta led us on our journey into the microscopic and gross. (WJXT)

We made our way around UNF’s campus for a lot of swabbing and testing of more than a dozen items and took those samples back to the lab where they needed to sit in Petri dishes for 48 hours.

When we returned two days later with Casamatta, we saw a lot of blobs inside those dishes.

“Those are the different organisms,” Casamatta explained as we looked at each Petri dish. “Some organisms like to grow in large sheets, and those can be significant because those organisms can cause problems for us -- form biofilms and stuff.”

We were honestly shocked by the amount of bacteria growing. Here were the items we tested and the results for each one in alphabetical order:

  • ATM buttons: The buttons we swabbed on the ATM were bad. They had a considerable amount of fungus growing.
  • Cellphone: The cellphone was pretty clean -- something Casamatta said was unusual because they are typically pretty dirty. “That’s the cleanest cellphone I have seen in several years,” he said. “I’m shocked by this.”
  • Computer keyboard: We all know how much we rely on our computer keyboards, so yes, we tested them. As expected, it had a lot of growth. And Casamatta noted that accountants’ keyboards are notoriously dirty.
  • Door handle: The door handle we swabbed was pretty disgusting. “Door handle looks pretty bad,” we said looking at the Petri dish. “Door handle is terrible,” Casamatta agreed. It had some of the most bacteria we saw in all the things we tested.
  • Drinking fountain buttons: The drinking fountain buttons we swabbed had good growth but not as much as others. Casamatta said metal buttons don’t give bacteria a lot of room to grow.
  • Food menu screen: We took samples from the screen of the food menu kiosk in the cafeteria where customers place their orders. It had considerable growth of fungus.
  • House key: The house key we swabbed was relatively clean -- which Casamatta also said was unusual as keys and coins are often covered with bacteria.
  • Hairbrush: The hairbrush we tested had a lot of growth as well. And this was interesting: Casamatta said typically, men’s hair is dirtier than women’s hair. “Something like 90% of all adult males will have dandruff at some time. And it is a very rich microbial community on our scalps. Oddly enough women have much less microbial activity on their hair than men do,” he said. “Males have a lot more materials living in their hair. A lot more fungi.”
  • Makeup applicators: Makeup applicators had a lot of growth in the Petri dish -- both from the makeup particles and dead skin.
  • Purse: The samples we took after swabbing the bottom of a student’s purse were one of the dirtiest things we found during our experiment. “This is the bottom of a purse, and this is a great illustration of why you should never leave your purses on bathroom floors and stuff,” Casamatta said as we looked at the overflowing results inside the Petri dish. “Purses are horribly dirty kinds of places.”
  • Shoe: With even more growth than the bottom of the purse was the bottom of the shoe we swabbed. Not a surprise, but definitely worth noting.
  • Vending machine buttons: Also not unexpected, but the buttons we swabbed from the vending machine dispensing food and drinks had a lot of bacteria.
  • WJXT-TV microphone: Very unexpected for us were the results from swabbing the very top of our microphone. Bacteria covered the entire Petri dish. “There’s not even space for anything on that plate anymore,” Casamatta said in disbelief. It’s good information for us to know so we can regularly clean the microphones as we do with other equipment.

What’s also good information is what Casamatta revealed about our cash. He honestly grossed us out a bit when he went into detail about what typically lives on American currency.

“Pinworms are these little, tiny worms that live in your butt. Kids get them a lot,” he said.

We made our way around UNF’s campus for a lot of swabbing and testing of more than a dozen items. (WJXT)

Casamatta pointed to the fiber that’s used to make dollar bills. He said they are a good place for those tiny worms to lay eggs. So where did they come from? Well, he said, those worms live in a lot of peoples’ intestines and are nocturnal. They come out when someone’s body temperature cools and they touch their own backside. The worms end up under fingernails and transfer to money.

As disturbing as these findings can be, Casamatta said, people shouldn’t be too concerned.

“I had moments when I first took microbiology as an undergrad. I was paranoid about going out to eat. Paranoid about doing anything,” he said, noting most bacteria we come in contact with are not pathogenic. “I’m always amazed in our population of 330 million Americans, so few people die of pathogens every year. It is rather remarkable.”

Casamatta said most alcohol-based sanitizers will kill nearly everything we care about, so keep that sanitizer handy and use it.

About the Authors:

Scott is a multi-Emmy Award Winning Anchor and Reporter, who also hosts the “Going Ringside With The Local Station” Podcast. Scott has been a journalist for 25 years, covering stories including six presidential elections, multiple space shuttle launches and dozens of high-profile murder trials.