The 1949-1951 leukemia and lymphoma mortality rates for the 163 metropolitan areas in the United States were compared to the corresponding elevations of the areas, taken as an approximate measure of the intensity of cosmic radiation. No increase in mortality rates with rise in elevation was apparent. From this it is concluded that at usual habitation levels in the United States variation in cosmic ray intensity either has no effect upon leukemia and lymphoma mortality rates, or has very small effect as compared to other factors.
The same procedure was applied to congenital malformation mortality rates. In this instance, there appears to be a distinct increase in this condition between the lowest elevation zone and all others.
If we assume a positive relationship between the intensity of cosmic radiation and the rate of congenital malformations, it is reasonable to expect a progressive increase in congenital malformations as elevation (and hence cosmic radiation) increases. However, according to table 6, the rate of congenital malformation mortality remains fairly constant over the three highest elevation zones. From this it is concluded that the variation in the intensity of cosmic radiation does not play an important part in the mortality from this disease. It is possible that some factor not considered by us accounts for the difference in congenital malformation mortality between the lowest elevation zone and the other zones.