UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation), Sources and Effects of Atomic Radiation, New York, 1982.


Conversion Coefficients from Air Kerma to Effective Dose for Terrestrial Gamma Rays

Conversion Coefficient (Sv per Gy)
Radionuclides Adults Children Infants
K-40 0.74 0.81 0.95
Th-232 series 0.72 0.81 0.92
U-238 series 0.69 0.78 0.91
Overall 0.72 0.80 0.93

National Estimates of the Average Annual Effective Dose for Terrestrial Gamma Rays

Country Effective Dose (mSv)
Bulgaria 0.45
Canada 0.23
China 0.55
Denmark 0.36
Finland 0.49
Germany 0.41
Japan 0.32
Norway 0.48
Spain 0.40
Sweden 0.65
United Kingdom 0.35
United States 0.28
USSR 0.32
Population-weighted world average 0.45

Reference Annual Intake of Food and Air

Food Consumption (kg per year)
Intake Adults Children Infants
Milk products 105 110 120
Meat products 50 35 15
Grain products 140 90 45
Leafy vegetables 60 40 20
Roots and fruits 170 110 60
Fish products 25 10 5
Water and beverages 500 350 150
Breathing Rate (m3per year)
Intake Adults Children Infants
Air 8,000 5,500 1,400

Reference Activity Concentrations of Natural Radionuclides in Food and Air

Activity Concentration (mBq/kg)
Intake 238U-234U 230Th 226Rn 210Pb 210Po 232Th 228Ra 228Th 235U
Milk products 1 0.5 5.0 40 60 0.30 5.0 0.30 0.05
Meat products 2 2.0 15.0 80 60 1.00 10.0 1.00 0.05
Grain products 20 10.0 30.0 100 100 3.00 60.0 3.00 1.00
Leafy vegetables 20 20.0 50.0 30 30 15.00 40.0 1.50 1.00
Roots and fruits 3 0.5 30.0 25 30 0.50 20.0 0.50 0.10
Fish products 30 NA 100.0 200 2,000 NA NA NA NA
Water supplies 1 0.1 0.5 10 5 0.05 0.5 0.05 0.04
Activity Concentration (µBq/m3)
Intake 238U-234U 230Th 226Rn 210Pb 210Po 232Th 228Ra 228Th 235U
Air 1 0.5 0.5 500 50 1 1 1 0.05

Committed Effective Dose per Unit Activity Intake of Natural Radionuclides for Adults

Ingestion Inhalation
Radionuclide Fractional Transfer in Blood Dose Coefficient(µSv/Bq) Class of Solubility Dose Coefficient(µSv/Bq)
U-238 0.0500 0.025 Y 30
U-234 0.0500 0.030 Y 30
Th-230 0.0002 0.070 Y 50
Ra-226 0.2000 0.200 W 2
Pb-210 0.2000 1.000 D 2
Po-210 0.1000 0.200 D 1
Th-232 0.0002 0.400 Y 200
Ra-228 0.2000 0.300 W 1
Th-228 0.0002 0.070 Y 100
U-235 0.0500 0.030 Y 30
Pa-231 0.0010 2.000 W 200
Ac-227 0.0010 2.000 W 300

Average Age-Weighted Annual Intakes of Natural Radionuclides and Associated Effective Doses

Ingestion Inhalation
Radionuclide Intake (Bq) Dose (µSv) Intake (mBq) Dose (µSv)
U-238 4.90 0.12 6.9 0.21
U-234 4.90 0.15 6.9 0.21
Th-230 2.50 0.18 3.5 0.18
Ra-226 19.00 3.80 3.5 0.01
Pb-210 32.00 32.00 3,500.0 7.00
Po-210 55.00 11.00 350.0 0.35
Th-232 1.30 0.52 6.9 1.40
Ra-228 13.00 3.90 6.9 0.01
Th-228 2.30 0.09 6.9 0.69
U-235 0.21 0.01 0.4 0.01
Total 146.60 52.00 3,291.9 10.00