You might be picking up more than just money when you go to cash machines, if this latest research is anything to go by.
Thousands of grubby fingers trail over the shared buttons on the keypads of ATMs every day and, scientists say, germ traces left on them can reveal quite a lot about the surrounding neighbourhoods.
New York University researchers found keypads were crawling with human skin, mould and food bacteria after testing ATMs across various locations in New York.
They also found traces of a parasite related to the STD trichomoniasis as well as bacteria linked to the flu-like infectious disease Toxoplasmosis.
After scouring cash machines across Manhattan, Queens and Brooklyn, researchers also looked into demographic factors such as ethnicity, population and age in those areas.
One of the team’s most interesting findings focused on the eating trends of certain communities.
For example, keypad swabs taken from Asian areas like Flushing and Chinatown showed higher levels of bony fish and molluscs while chicken was “significantly enriched” in samples from predominantly black Central Harlem South.
A mould associated with “high-sugar foods” like cake was discovered to be more prevalent in areas with a largely white demographic.
The study, carried out in 2014, was published in the mSphere journal.
Lead scientist Holly M Bik and colleagues wrote in their report: “ATM surfaces, potentially retaining microbial signatures of human inhabitants… are interesting from both a biodiversity perspective and a public health perspective.”
The keypads are a “specific and unexplored microhabitat for microbial communities”, the report added.
The research was done to contribute to the “growing body of work focused on the ‘urban microbiome’”.
The project is a massive one because, as the researchers note, the urban surface area of Manhattan is “three times as large as the geographic area of the island itself”.
Until we figure out the health implications of these micro-universes on cash machine keypads – remember to wash your hands.