Researchers compared nearly 60 years of data on U.S. male astronauts
and a group of men who are similarly extra-fit, affluent and receive
elite healthcare - pro athletes. They found that neither group has
higher rates than the other of death overall or of early deaths.
Both groups do tend to outlast the rest of us, however.
Astronauts are generally well-educated, more affluent and more
physically fit than the typical American, and some previous research
has linked this career to a lower risk of premature death, the study
team notes in Occupational & Environmental Medicine.
But much of the previous research on mortality rates in astronauts
hasn't accounted for the mental and physical demands of this career,
or the so-called "healthy worker effect" that leads people with
employment of any kind to typically have fewer medical issues than
individuals who are unable to work, said study co-author Robert
Reynolds of Mortality Research & Consulting, Inc. in City of
Industry, California.
"The challenge has always been to understand if astronauts are as
healthy as they would be had they been otherwise comparably employed
but had never gone to space at all," Reynolds said by email. "To do
this, we needed to find a group that is comparable on several
important factors, but has never been to space."
The researchers compared mortality rates for male U.S. astronauts to
professional athletes from Major League Baseball (MLB) and the
National Basketball Association (NBA) between 1960 and mid-2018.
Both athletes and astronauts had a lower risk of premature death
than the general population, the study found. And there was no
meaningful mortality difference between NBA and MLB players.
Astronauts were more likely to die of accidents and other external
causes, and less likely to die from heart disease and all other
natural causes, the study also found.
"We cannot be sure from the data we have, but we speculate that
cardiovascular fitness in particular is the most important factor in
astronaut longevity," Reynolds said.
The results suggest that radiation exposure in space might not lead
to a premature death for astronauts due to heart problems or certain
cancers, the study authors conclude. In fact, astronauts had a lower
rate of death from heart disease than the NBA and MLB players, and
had cancer mortality similar to the athletes' rates.
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The study wasn't designed to prove whether or how space travel may
directly impact human health. It also didn't examine mortality among
female astronauts or athletes.
Radiation exposure may also have been much lower during early
missions to the moon and not reflect what would happen with the
current generation of astronauts, said Francis Cucinotta, a
researcher at the University of Nevada, Las Vegas, who wasn't
involved in the study.
"The missions in the past were low dose, while in the future the
dose would be 50 to 100 times higher for a Mars mission," Cucinotta
said by email.
Astronauts have typically never smoked, leading to a lower risk of
heart disease than the general population, Cucinotta added.
Diet and exercise also set astronauts and professional athletes
apart from the rest of the population, said Michael Delp, a
researcher at Florida State University in Tallahassee who wasn't
involved in the study.
"When physical fitness is a requisite part of a job, such as with
astronauts and professional athletes, this is a major determinant of
the healthy worker effect," Delp said by email.
Even for the rest of us, "remaining or becoming physically active
and maintaining a well-balanced diet greatly improves overall health
and wellbeing, and can enhance successful aging," Delp advised.
SOURCE: https://bit.ly/2rXx28i Occupational & Environmental
Medicine, online December 4, 2018.
(This story was refiled to clarify study groups in paragraph 2
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