Is there really such a thing as “too clean”? When it comes to keeping one’s house looking presentable, “too clean” probably isn’t something that most of us have to worry about—it’s hard enough keeping up with vacuuming carpets, scrubbing floors, and washing windows. Unless you're extremely serious about air filters and disinfectants, there’s little chance of completely removing the microorganisms living all around us.
The International Space Station, though, is a different matter. In the sealed, sterile environment of the ISS, astronauts are surrounded by a much more limited selection of microbes than they would on Earth. They aren't coming into contact with any part of the natural world except for other astronauts, and this isn’t necessarily a good thing. According to a new study, the lack of microbial diversity on the ISS could be responsible for certain health issues that astronauts sometimes experience while in orbit, including rashes, allergies, and infections.
Spending time outside doing activities like gardening is known to benefit the immune system due to exposure to healthy soil microbes. This has been the norm for humans for millennia and stands in stark contrast to the artificial living conditions aboard space shuttles and space stations.
To study which microbes are found on the ISS, astronauts swabbed over 800 surfaces in their living and working quarters. Researchers from the University of California, San Diego (UCSD) used the samples to create 3D maps of which microbes were found at which locations. They also noted the presence of disinfecting chemicals on surfaces around the space station.
Unsurprisingly, most of the microbes had come from human skin rather than soil or water, similar to what you would find in a hospital or a quarantine room. The researchers also noted that residue from cleaning chemicals remained on various surfaces for multiple days after being used.
Although it’s widely accepted that regular exposure to “good microbes” is beneficial, putting that into practice in an extreme environment like the International Space Station would undoubtedly be a delicate and controversial prospect. It’s well known that factors relating to the space environment, including microgravity and radiation, mean that the human immune system has to work harder than it does on Earth. In space, astronauts might not respond to certain microbes the same way they would back home.
Keep it clean, but not too clean:
- Some potential solutions to safely increase microbial diversity on the ISS could include providing astronauts with fermented foods, bringing certain animals to the space station, or using probiotic-based cleaners instead of chemical ones.
- This type of research has been undertaken before, but never on this scale, with hundreds more samples taken than previous surveys. The surface swabs were collected from areas including the bathroom, kitchen, and dining area.
- The study, entitled The International Space Station Has a Unique and Extreme Microbial and Chemical Environment Driven by Use Patterns was published last week in the journal Cell.
