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Natural radioactivity in food

  • With the essential elements for nutrition taken up from the soil, also radioactive substances get into the plants and thus into the food chain.
  • Knowledge of the content of natural radioactive substances in food is necessary to estimate the radiation exposure to humans resulting from the ingestion of food.
  • The results show that with regard to the mixed diet, there is no significant difference between the individual German regions.

Various foods, including Brazil nuts Food

The tasks of the Federal Office for Radiation Protection (BfS) also include investigations of radiation from natural sources to which people are exposed.

In addition to radiation from the cosmos and natural radionuclides in soils and rocks, as well as radiation from radon and its short-lived decay products, the radiation to which people are exposed through ingestion of natural radionuclides with food is of interest.

Objective of investigations

The knowledge of the natural level of radioactivity in food is necessary to be able to recognise and evaluate changes resulting from impact of humans. This is e.g. essential for decisions to be taken on the utilisation of areas that have been radioactively contaminated by mining.

bananas, tomatoes, peas Fruit and vegetables2001/2002 mixed diet samples from all over the Federal Republic of Germany were examined

To get a general idea of the content of natural radionuclides in food, mixed diet samples taken from the daily rations of community institutions all over the Federal Republic of Germany were examined in 2001/2002. The programme continued until 2004; the results are summarised here.

Investigation results

Food produced in Germany shows in most cases very low concentrations of long-lived radionuclides of the uranium and thorium decay chains. This also applies to food from areas with geologically caused enhanced natural environmental radioactivity.

The Federal Office for Radiation Protection examined the mixed diet, i.e. the solid and liquid components of the mixed diet provided in different community institutions. The results of these examinations (66 samples of mixed diet for adults, 11 samples of mixed diet for babies aged nine months) are shown in the following table:

Specific activity of natural radionuclides in mixed diet
(in becquerel per kilogram fresh mass [Bq/kg])

Baby food (for nine-month-old babies)Mixed diet of adults
Radionuclide

Mean value

Range of values

Mean value

Range of volues

Uranium-2380.0070.005 - 0.0100.0080.001 - 0.020
Uranium-234 0.008 **0.0120.004 - 0.036
Thorium-2300.003< 0.001 - 0.0040.001< 0.001 - 0.004
Radium-2260.0220.009 - 0.0320.021< 0.006 - 0.042
Lead-2100.0340.017 - 0.0680.0280.010 - 0.115
Thorium-2320.001 **0.001< 0.001 - 0.004
Radium-228 *0.020< 0.013 - 0.0310.032< 0.016 - 0.069
Thorium-228 *0.008 **0.0090.007 - 0.013

* Values on the day of sampling

** Single value

Both in baby food and in total adult food, the specific activities of the radionuclides lead-210, radium-226 and radium-228 dominate.

The values for thorium-232 and thorium-230 in food were very low, because thorium is strongly bound in the soil and therefore hardly being taken up by plants. On average, the food examined so far had specific activities below 0.003 becquerel per kilogram fresh mass. The activity levels were mostly just around the detection limits.

Brazil nuts

Brazil nut fruit (Bertholletia excelsa) with Brazil nuts Source: RHJ/Stock.adobe.com

ArticleNatural radioactivity in Brazil nuts

All foods contain natural radioactive substances that emit radiation. However, Brazil nuts contain some natural radionuclides at higher levels than other foods. When people eat Brazil nuts, they also ingest the radium contained in them, among other things. This radium is then stored in bones and teeth. The BfS gives precautionary recommendations for adults, pregnant and breastfeeding women, adolescents, and children.

New examinations starting in 2016

In cooperation with the Federal Institute for Risk Assessment (BfR) the BfS will examine food in a typical form prepared in households for its content of natural radionuclides. Within the framework of this BfR Total Diet Study (MEAL - meals for the exposure assessment and analysis of foods) food is considered which is mostly consumed by the population in Germany, like grain products, vegetables and potatoes, milk products, meat and fish.

Based on the measuring results of the samples, BfS will assess the dose to the population. This study is carried out on behalf of the Federal Ministry of Food and Agriculture (BMEL). It will last for seven years and include the total German food supply. One of the central objectives of the BfR MEAL Study is to generate data on the levels of different substances in the diet that are representative for the German population.

State of 2023.07.21

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