Bruno,

It might be interesting to consider the levels of allowable occupational exposure to radiation here in the U.S of A. I did Nuclear Medicine and Health Physics for some 20 years. We wore dosimeters and were allowed to be exposed to a maximum of 5000 millirem (mRem) per year not to exceed 3000 mRem in any one quarter. Your lifetime allowable exposure was calculated at 5 rem (5000mRem) x N (your age) -18. In short, you were allowed 5Rem of occupational exposure for each year after 18 years of age. It would be interesting to see the levels of cancer and cancer deaths among those who have been occupationally exposed. By now we should have some good statistics as at least one generation has retired from this industry.

The conversion to Sieverts would be as follows.

1uSv (1 micro Sievert) = .1 mRem (milli rem)
Therefore 10 uSv would = 1 mRem
50,000 uSv's would = 5000 mRem/ year, the allowable yearly exposure
level for those working in the industry.

Interestingly enough it has been measured that the exposure to an astronaut on the space station would be 1mSv (millsievert) per DAY, which is the equivalent to one year on the Earth's surface. They consider this an acceptable level of risk.

I believe Alan Shepherd died of Leukemia at 74, it would be interesting to research the cause of death among all astronauts/cosmonauts over the years.

Keep flying high, it beats the alternative of dying of boredom.

Walt