If an astronaut had been on the Moon at the time, they might have received a 400 rem (Roentgen Equivalent Man) radiation dose.
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2.
The part of this line above 10 rem (0.1 Sv) certainly supports this idea, although doubling the dose does not double the effect like is commonly thought.
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3.
Doses between 50 and 100 rem (0.5 and 1 Sv) resulted in a 29% increase in cancers over doses between 0.5 and 10 rem (0.005 and 0.1 Sv) even though there was a 1000% increase in dose.
FORBES: Fear Of Radiation -- It's All In The Noise