The International Space Station Is Too Clean for Astronauts, Which Could Negatively Impact Their Health
The International Space Station (ISS) is kept immaculately clean, but perhaps it’s too clean. According to scientists, the sterile environment might be making astronauts less healthy and can even cause issues like cold sores, skin rashes, and immune dysfunction.
The research team suggests that cultivating communities of microbes in space bases will better support astronauts’ immune systems.
“Sterile environments are not, in fact, the safest environments,” said Rob Knight, the senior author of the study and a microbiologist at the University of California, San Diego (UCSD).
“Exposure to beneficial microbes in the environment is important for maintaining health—this is not surprising, because as humans, we have co-evolved with those environmental microbes for millions of years.”
The team worked with astronauts to gather 803 surface swabs from the bathroom, kitchen, dining area, and other parts of the ISS. Then, they analyzed the samples and compared them to buildings on Earth like homes, offices, and hospitals.
The analysis revealed that the space station did not contain the microbial diversity necessary for benefiting the human immune system.
At the station, the microbes were surprisingly uniform and were mostly related to humans. It was similar to places on Earth that have been industrialized or isolated from the natural environment.
“The ‘home’ on Earth that looks most similar to the [ISS] was an isolation dormitory used during COVID-19,” said Haoqi Nina Zhao, the study co-lead author and an environmental chemist at UCSD.
On the ISS, human skin was the main source of bacteria. The samples also contained very little of the microbes found in soil and water on Earth.
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In addition, the analysis showed high levels of chemicals from cleaning products, even though astronauts had been told not to disinfect surfaces for four days before collecting the samples.
It is unclear exactly how much the lack of microbial diversity is affecting astronauts’ health, but in other environments, its absence has been linked to health problems that resemble those seen in astronauts.
The findings can help lead to the decision of what kinds of bacteria should be added to space habitats.
In the future, space bases could benefit from the cultivation of diverse microbial communities that imitate the natural microbial exposures on Earth.
Scientists still need to test microbes to see if certain ones can become dangerous in a space environment, even if they have health benefits on Earth.
Human immune systems have to work harder to overcome infections in space due to radiation, microgravity, and physiological stress.
Some options to introduce more microbes to the space station include bringing more fermented foods and animals. Or, chemical disinfectants could be swapped out for probiotic-based cleaners.
The details of the study were published in the journal Cell.
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