where P is the population density in people/mi2. A sample evaluation of this formula for Class D weather, which is the most probable set Population doses corresponding to several population densities which follow from these calculations for all weathers are given below. The total area considered in this analysis is 77 square miles. Since the isopleth areas are roughly shaped as a sector of a circle, the total area corresponds roughly to a sector of angle 22.5 degrees extending from a small radius, say 50 meters, to a radius of about 20 miles. For weathers E and F, the individual at 50 meters is within the isopleth for which the concentration equals or exceeds 10-2scc/m3. For all other weathers, the individual at 50 meters is within the isopleth for which the concentration equals or exceeds 10-3 sec/m3. As seen above, 10-2 sec/m3 corresponds to about 12 rem and 10-3 sec/m3 corresponds to about 1 rem. The expected health effects from these doses are small. The NCRP recommended limits for routine exposure of radiation workers are 15 rem to the lungs and 30 rem to the thyroid. The threshold for noticeable physiological effects from whole-body radiation is 50 rem to the whole body. The conclusion of the BEIR Report is that the fatality rate from such an incident is 1.8x10-4 cancer fatalities/ This rate is applicable to single large exposures as person-remn. 10,000 persons/mi2, the number of fatalities is less than one for this postulated incident: (1.8x104 cancer fatalities/person-rem) (200 person-rem) = 0.036 cancer fatality 1 3 "Environmental Survey of Transportation of Radioactive BEIR Report, 1972, National Academy of Sciences National Research Council, "The Effects on Populations of Cohen, B. L. "Conclusions of the BEIR and UNSCEAR Reports on Radiation Effects per Man-Rem," Health Physics 30, 351 (1976). |