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.