section_path: Safety concerns/Environmental hazards/Medical issues
section_name: Medical issues
paragraph_text: Medical issues
  
  Astronauts may not be able to quickly return to Earth or receive medical supplies, equipment, or personnel if a medical emergency occurs. The astronauts may have to rely for long periods on limited resources and medical advice from the ground.
  
  The possibility of blindness and of bone loss have been associated with human space flight.
  
  On 31 December 2012, a NASA -supported study reported that spaceflight may harm the brains of astronauts and accelerate the onset of Alzheimer's disease.
  
  In October 2015, the NASA Office of Inspector General issued a health hazards report related to space exploration, which included the potential hazards of a human mission to Mars.
  
  On 2 November 2017, scientists reported, based on MRI studies, that significant changes in the position and structure of the brain have been found in astronauts who have taken trips in space. Astronauts on longer space trips were affected by greater brain changes.
  
  Researchers in 2018 reported, after detecting the presence on the International Space Station (ISS) of five Enterobacter bugandensis bacterial strains, none pathogenic to humans, that microorganisms on ISS should be carefully monitored to assure a healthy environment for astronauts.
  
  In March 2019, NASA reported that latent viruses in humans may be activated during space missions, possibly adding more risk to astronauts in future deep-space missions.
  
  On 25 September 2021, CNN reported that an alarm had sounded during the Inspiration4 Earth-orbital journey on the SpaceX Dragon 2. The alarm signal was found to be associated with an apparent toilet malfunction.