John Metcalfe was CityLab’s Bay Area bureau chief, covering climate change and the science of cities.
Skin bacteria, mold, and parasites on ATM keypads can tell us a lot about New York’s habits and communities.
When you withdraw money from a New York ATM, you’re sticking your fingers into a microbiome as diverse as the city itself. Traces of human skin, mollusks and fish, rotten baked goods, and household surfaces like TVs, bathroom counters, and pillows—these are all things scientists have found lurking on the buttons of New York’s cash machines.
Much gross stuff has been written about the microorganisms splashed all over the city’s subway system. Researchers from New York University wanted to perform a similar investigation into ATMs, because—with all the grubby fingers jabbing them—they evolve similarly fascinating worlds of microbes.
“ATM surfaces... are interesting from both a biodiversity perspective and a public-health perspective,” the researchers write in the journal mSphere. They focused on machines in neighborhoods with distinct demographic groups in order to learn more about the diversity of microbes in those areas, “thus making a unique contribution to the growing body of work focused on the ‘urban microbiome.’”
So they swabbed ATMs in Manhattan, Brooklyn, and Queens, and sequenced the samples. Unsurprisingly, the most prevalent thing they noted were bacteria that live on human skin. To a lesser degree they found fungal communities, organisms “generally associated with the intestinal tract,” and a species related to the parasite Trichomonas vaginalis (which can cause trichomoniasis, a common sexually transmitted disease). On one ATM near Brighton Beach, they detected Toxoplasma, the culprit in the infectious disease Toxoplasmosis, which sometimes has flu-like symptoms. (Don’t panic just yet: The research didn’t determine how many of these microbes were still active when collected, and it’s possible that many were in such small amounts that they wouldn’t be harmful.)
Though no huge patterns emerged, the researchers registered some “molecular echoes” possibly related to food geography. Microorganisms associated with mollusks and bony fish predominated in Asian neighborhoods in Flushing and Manhattan’s Chinatown. Traces of microbes linked with chicken appeared more in a largely black community in Harlem. And ATMs in predominantly white neighborhoods were festooned with Xeromyces bisporus, a mold associated with the “spoilage of high-sugar foods such as cakes and confectionaries.”
Still, the diversity of microbes among different locations was relatively small, a finding that the American Society for Microbiology says could result from “periodic cleaning of the machines, which would wipe out some of the microbes, as well as usage of ATMs by tourists, commuters from other locations,” and other factors.