Answer to Question #1834 Submitted to "Ask the Experts"

Q

After 40 years in aviation and being aloft more than 20,000 hours, most of which was at very high altitudes of 37,000 feet or above, I have probably been exposed to hundreds, if not thousands, of "x rays." I am nearing age 70. Is there any history of airline pilots having cancer-related illnesses as a result of this much radiation exposure?

A

The radiation dose to flight crews of the Concorde has been measured at 6-7 microsievert per hour. This is probably the upper limit for all flying personnel. Crews of other types of aircraft should receive less. At this rate one could fly some 8,300 hours per year before reaching the occupational dose limit of 50 millisievert per year established by the US National Council on Radiation Protection and Measurements. Since there are only 8,760 hours in a year, it seems impossible that anyone could approach the dose limit. To get an upper-limit estimate of your dose, multiply the above hourly rate by the number of hours you fly per year. Remember that 1 millisievert = 1,000 microsievert. No epidemiologic studies have been found that show increased risk of cancer in airline pilots that could be attributed to radiation.

S. Julian Gibbs, DDS, PhD