6 March 1957
Dr. Reino W. Hakala
310 Benham Avenue
Bridgeport 4, Connecticut
Dear Dr. Hakala:
In answer to your letter of 2 January 1957 I can make the following statements. In the Atomic Energy Commission Report for
1953 there are given values of gamma radiation over a 13-weeks period due to fallout from the atom bomb tests that had been
made, for a number of communities in Nevada and Colorado. For example, the average exposure to radiation of the 4500 inhabitants
of St. George, Utah was 3.5 r for this period, and values around 5 to 9 were reported for other communities. I conclude that
a number of inhabitants in this region, perhaps around 10,000, have received average exposures of 5 roentgen to 10 roentgen
as a result of bomb tests.
Professor Harden Jones of the Bonner Laboratory of the University of California in Berkeley has concluded from the analysis
of mortality rates for Hiroshima and Nagasaki survivors and for people who have received radiation treatments for various
diseases, as well as from a consideration of animal experiments, that human beings probably have a decrease in life expectancy
of 2 weeks per roentgen of radiation.
Accepting this figure, I calculate that the approximately 13,000 people in Nevada and Colorado have a decrease in life expectancy
of 10 to 20 weeks.
The calculation of the number of defective children that can be expected to be born can be made with the use of some reasonable
assumptions about mutations. At the present time about 2 million seriously defective children are born out of every hundred
million children, because of bad genes. If we attribute all of these bad genes to natural radioactivity, principally cosmic
rays, we have a basis for making a calculation. The amount of cosmic radiation received by people during the first 50 years
of their life, when half their children have been born, is about 4 r. A possibility is that artificial radiation exposure
of 4 r on top of this would double the number of mutations, and that the number of defectives would accordingly be doubled.
It may be that mutations are caused also by something other than radiation, in which case the number of defective children
caused by fallout radiation would be less than that given by this calculation. There is considerable uncertainty about estimated
values in this field, but I think that we should consider the worst possible case, rather than the best possible case.