Germophobes may dread their morning commute over fears of the potentially harmful bacteria and viruses lurking on turnstiles, railings, and hanging grips.
With the amount of people touching them on a daily basis, there’s at least some reason to be concerned, especially when drug-resistant bacteria are on the rise.
Every day, more than 18 million pairs of hands are touching those surfaces in New York’s subway system, the largest in the nation.
Boston’s T, the United States' fourth busiest mass transit system, sees 569,200 passengers on any given workday. Since each of those people has about 100 trillion microbes in and on their body, there’s ample opportunity for contamination.
But scientists — the people who taught us about germs and what they can do — assure us there’s little to worry about.
No, really. It turns out the bugs in your own gut are much worse than what’s in that mysterious puddle over in the corner.
Examining the bugs
While the bugs are plentiful on the T, they’re mostly those found on human skin and incapable of causing disease, according to research published in the journal mSystems.
In 2013, researchers collected nearly 100 samples from train cars and stations, including poles, seats, seat backs, walls, hanging grips, touchscreens, and ticketing machines.
They then ran those samples through a process called 16S amplicon and shotgun metagenomic sequencing, a process that unravels DNA recovered from the environment.
Curtis Huttenhower, Ph.D., associate professor of computational biology and bioinformatics at the Harvard T.H. Chan School of Public Health, said researchers were surprised how normal the samples were and how similar they were to shaking someone’s hand.
“Even when we looked closely, there was nothing unusual or dangerous about the microbes we found,” Huttenhower said in a press release. “It shows that, in the absence of something like flu season, all of the germs you run into, even in a crowded environment like the T, are normal.”
The type of surface on the train played a major role as well. Researchers found the porous surface of the hanging grips have the most microbes, followed by seats and touch screens.
Researchers found more skin-related microbes and fewer ones normally associated with the human gut or mouth.
Besides what they found, it’s also important to emphasize what researchers didn’t find: high levels of antibiotic-resistant bacteria.
Those are of greatest concern to infectious disease experts as they currently sicken 2 million people a year, 23,000 of who die, according to the latest estimates by the U.S Centers for Disease Control and Prevention (CDC).
“This indicates that the real pathogenic potential detected in the Boston subway is very low,” Huttenhower said.
The snapshot of the Boston subway can help researchers understand what levels of what bugs are considered normal in such a heavily used mass transit system.
This provides a baseline for comparison should an outbreak occur, whether the seasonal flu or something worse.
Crowdsourcing a city’s microbiome
To fully understand what invisible organisms are populating the surfaces so many people touch, researchers at Weill Cornell Medicine in New York and others across the globe have begun collecting samples from major meeting places, including subways, buses, and airports.
In June, they held Global Sampling Day, which synchronized 400 people across six continents —sorry, Antarctica — to swab and photograph the surfaces for the MetaSUB Global Consortium.
Just like in Boston, researchers wanted to know more about the DNA, RNA, and microbes we transmit while in transit. More importantly, they want to know which cells are living, which are dead, and which can be cultured in a lab setting.
Researchers also want to know how major events can change a city’s microbiome.
The team in Rio de Janeiro will collect samples leading up to the Olympic games in August. They hypothesize that changes will be in proportion to the vast number of people visiting from countries across the globe.
“With this work, we'll be able to answer that question, and not just in New York City, but in locations all over the globe. This is truly the fulfillment of a long-sought goal of genetic understanding of the world around us,” the project’s principal investigator, Dr. Christopher Mason, an associate professor of physiology and biophysics and of computational genomics in the HRH Prince Alwaleed Bin Talal Bin Abdulaziz Al-Saud Institute for Computational Biomedicine at Weill Cornell Medicine, said in a press release.