31-34 If a man lives in Denver instead of at sea level, how much does the additional cosmic-ray exposure reduce his life expectancy? (Use the data in Table 31.3, and assume that 10,000 person rems produces one premature cancer death.) TABLE 31.3 Chronic sources of radiation in the United States. All values are approximate or average (1 millirem = 10 rem). Source Cosmic rays Dose (millirems per year except as noted) Sea level 41 Denver (5000 ft) 70 Leadville, Colorado, area (10,500 ft) 160 20,000 ft 400 Commercial jet (35,000 ft) U.S. average from cosmic rays y rays from rocks, soil (Ra, U, Th, K, etc.) Atlantic Coastal Plains Colorado Front Range U.S. average from external radionuclides Calculation of gonadal dose Correction factor due to housing shielding Correction factor due to biological shielding U.S. average gonadal dose from external radionuclides Internal radionuclides 40K 14C, Ra, and decay products Total Total U.S. environmental average gonadal dose (Oakley, 1972) Fallout (1970) 0.7 millirems per hour 22.8 89.7 06 40 0.8 0.8 (40)(0.8)(0.8) 16 62 44 26 26 18 88 11 Nuclear power Medical diagnostic Medical radiopharmaceuticals Occupational 0.003 72 0.8 2 Miscellaneous Sources: Natural Radiation Exposure in the U.S., by D. T. Oakley, U.S. Environmental Pro- tection Agency, June 1972; National Academy of Sciences Committee on Biological Effects of Ionizing Radiation Report. November 1972.