Management of Commercially Generated Radioactive Waste - U.S. ...

3.29
surfaces, and 25 mrem/yr to bone marrow. The dose to women from internally deposited
radionuclides is about 25% lower than that to men, because of their smaller potassium con-
tent per unit body weight.
Dose to Lung from Inhaled Radionuclides. Dose to the lung from natural airborne
radionuclides results principally from the alpha-emitting daughters of 222 Rn. The short
range of alpha radiation means that the doses are delivered locally to the lung tissue,
particularly to the bronchial epithelium. The average dose rate to the total lung is about
90 mrem/yr, while the bronchi epithelium receives about 450 mrem/yr.
Variability in dose rate to the lung is dependent on local concentrations of 222Rn.
There is some increase in areas with elevated levels of 238 U and 226 Ra in soil and a
decrease in coastal regions during periods of onshore winds. Levels of 222Rn indoors are
dependent on the building's structural materials and ventilation rates. Dose rates to the
lungs of smokers from the long-lived decay products lead-210 ( 210 Pb) and 2 1 0 Po from 222Rn
may be up to three times higher than for nonsmokers.
3.3.1.3 Summary of Whole-Body Dose
From the foregoing, the combined whole-body dose rates from terrestrial radioactivity
received by groups at 1) sea level for the Atlantic and Gulf Coastal Plains, 2) for the
majority of the United States, and 3) for an undetermined area along the Rocky Mountains is
15, 30, and 55 mrem/yr, respectively. The internal and cosmic ray dose rate to the whole
body adds about 50 mrem/yr, which results in totals of 65, 80, and 105 mrem/yr as shown in
Table 3.3.1.
The whole-body dose rate for groups living at an altitude of 1500 m would be increased
by about 20 mrem/yr from the increased cosmic ray radiation. A total whole-body dose rate
of 125 mrem/yr from all sources essentially represents the situation for the city of Den-
ver, where both cosmic and terrestrial components are higher than average.
In this Statement, doses calculated as resulting from various waste management activi-
ties are often compared with the dose received from naturally occurring sources. To avoid
use of ranges of naturally produced doses and to suggest the lack of certainty in the value
for any individual, a well-rounded 100 mrem/yr dose rate has been used for illustration.
On that basis, the doses used in this report for the population and time periods cited are
as given in Table 3.3.2.
TABLE 3.3.1. Summary of Average Whole-Body Dose-Equivalent Rates
from Naturally Occurring Radiation, mrem/yr
Cosmic Rays Terrestrial Radiation
(Sea Level) External Internal Total
Atlantic and Gulf
Coastal Plains 28 15 22 65
Majority of U.S. 28 30 22 80
Rock Mtn. Area 28 55 22 105