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Radiation exposure from natural radionuclides in food

The measure of the effect of radiation on human organs and tissues when meals and drinks are consumed is referred to as the effective dose. It is given in the unit sievert. The different types and energies of radiation have different effects on human organs and tissues.

The expected radiation exposure is estimated by multiplying the activity of a radionuclide ingested with food with the respective dose coefficient of the radionuclide. These dose coefficients indicate the effective dose in the body per becquerel of ingested activity as a function of the person’s age (unit: sievert/becquerels).

One exception is the radionuclide potassium-40, which is naturally present in potassium (0.0117%). Because potassium is an essential mineral, the potassium content in the body is regulated. The human body also indirectly regulates its potassium-40 content via the total potassium content.

Activity per year ingested with food

The activity per year ingested with foodstuffs can be calculated using the specific activities in the individual foods and the average consumption rates of various foods per year (in kilograms per year) or from the corresponding values in the total diet.

Average consumption rates in kilogram per year*
foodage group in years
     ≤ 1> 1-2> 2-7> 7-12> 12-17< 17
* from Federal Law Gazette Volume 2018 Part I Number 41, issued at Bonn on 5 December 2018, page 2034, 2036
1) Quantities in litres per year.
160 l per year are added to an infant’s annual drinking water quantity (55 l per year) if it is assumed that the infant is not breastfed but rather receives only ready-made formula that is produced supraregionally and assumed to be non-contaminated. It is assumed that 0.2 kg of concentrate (equivalent to 1 l of milk) are dissolved in 0.8 l of water.
2) Depending on the nuclide composition, the most unfavourable nutritional variant is to be used as a basis.
3) The proportion of freshwater fish in total fish consumption is about 17% on average and must be adapted to regional specifics.
drinking water55 1)100100150200350
breast milk, Ready-to-use milk product with drinking water200 1,2)
milk, dairy products45160160170170130
fish 3)0,5334,557,5
Meat, sausage, eggs51350658090
grain products12308095110110
fruit, juices254565656035
potatoes, root vegetables, juices304045555555
leafy vegetables36791113
vegetables, vegetable products, juices51730353540

Dietary radiation exposure for different age groups of the German population

Based on the examination results of the Federal Office for Radiation Protection on the total diet, the following table shows the diet-related radiation exposure for different age groups of the German population:

Mean effective ingestion dose by radionuclide of the natural decay series and potassium-40 in areas with average natural radioactivity in millisievert per year
foodage group in years
     ≤ 1> 1-2 > 2-7 > 7-12 > 12-17 > 17
* including drinking water, ** according to the UNSCEAR-Report 2000
drinking water0,0110,0080,0100,0130,009
total diet (without drinking water)0,336*0,1810,1410,1380,1600,041
effective dose (without potassium-40)0,3360,1920,1490,1480,1730,050
effective dose by potassium-40-activity in humans **0,1850,1850,1850,1850,1850,165
effective dose - sum0,5210,3770,3340,3330,3580,215

Depending on age, the contributions from the uranium decay series and the thorium decay series to the effective dose can differ significantly – from 0.04 to 0.27 millisieverts per year. According to the international guidelines on the average distribution of population groups (adults: 65%, children: 30%, infants: 5%) indicated in the Report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000, an age-weighted average value of 0.10 millisieverts per year can be calculated from this. When potassium-40, which provides an age-weighted contribution of about 0.17 millisieverts per year, is included, the natural radiation exposure of the population through the diet is about 0.27 millisieverts per year – assuming average dietary habits.

Age-weighted mean effective ingestion dose from radionuclides of the natural decay series and potassium40, taking into account the mean age proportions according to UNSCEAR 2000, in millisievert per year
age group in years
     ≤ 1 > 1-2 > 2-7 > 7-12 > 12-17 > 17
mean age share according to UNSCEAR 2000 (%)0,0500,3000,650
effective dose values for food (in millisievert per year)

without
potassium-40

effective dose total food and drinking water0,3360,1920,1490,1480,1730,050
age-weighted mean effective dose0,0130,0470,033
age-weighted effective dose0,093

potassium-40

effective dose potassium-400,1850,165
age-weighted mean effective dose potassium-400,0650,107
age-weighted effective dose potassium-400,172
age-weighted dose sum of the total population0,265

These data are in good agreement with the data in the UNSCEAR Report 2008: In this study, the authors estimate the dietary contribution from potassium-40 at 0.17 millisieverts per year and the contribution from the uranium decay series and the thorium decay series at 0.12 millisieverts per year. This results in a total value of 0.29 millisieverts per year.

For comparison: In Germany, the total natural radiation exposure averages 2.1 millisieverts per year. External exposure amounts to about 0.7 millisieverts per year, and the inhalation of radioactive radon and its by-products leads to an average radiation exposure of 1.1 millisieverts per year.

Radiation exposure through the diet is naturally determined by the characteristics of the soils on which agricultural products are produced. The food properties differ only slightly from region to region and do not change.

State of 2023.02.16

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