In our glasses and on our plates …
Editorial revision 2026
A publicity stunt that has gone out of fashion…
There is no escaping radioactivity. Granite rocks are slightly radioactive due to the presence of thorium, uranium, and their decay products. A famous thermal spring once proudly advertised this fact, back when radioactivity was viewed favorably. Seventy years later, another spring in the region preferred to rely on the smile of a popular footballer, set against the backdrop of the Auvergne volcanoes, to promote the excellence of its water. All waters currently sold commercially have fairly low levels of radioactivity, similar to those found in food.
© ANDRA
The very acts of breathing and walking around make it impossible for us to escape radioactivity. We also regularly come into contact with radiations when we eat: all foodstuffs are slightly radioactive due to their content of carbon 14 and potassium 40 – radioisotopes that are present wherever regular carbon and potassium can be found.
Food is naturally radioactive !
The food we eat is lightly radioactive, as we can see from the levels measured in various different foodstuffs. Activities of several hundred becquerels (Bq) per kilogram or litre may seem high, but the bequerel is a very small unit : the body of a 70kg man has a natural activity of 8000 Bq.
© IN2P3
The spring water that we drink is also radioactive. Before bursting out of the ground it has dissolved various mineral salts from its underground path, including a large variety of radioisotopes. The most radioactive waters come from areas with granite or volcanic rocks, where uranium, thorium and their descendants are present in the ground. The exposure levels here, however, vary wildly.
Radioactivity of spring water:
Water contains small amounts of radioactivity owing to radioactive rocks. As an example, the above graph displays the annual dose one would receive from a granitic spring water, supposing that one drinks a litre of this water every day for a whole year. This study shows that the contribution to the annual dose would be a fraction of millisievert (mSv) to be compared to the 2,4 mSv average dose due to natural radioactiviry.
IN2P3
After the Chernobyl accident, French radiation protection authorities were criticized for allowing food products with radioactivity levels exceeding the permitted standards to remain available for consumption. These exceedances were probably too limited and short-lived to have had any significant effects, but the lack of transparency and the impression that the risks were being concealed undermined public trust in experts—a psychological disaster whose consequences are still being felt today.
Another example of these fears is the concern surrounding the irradiation of certain foods using radioactive sources, an effective technique used to sterilize them without altering their taste. Irradiation does not leave behind any residual radioactivity and has no harmful effects, as confirmed by WHO documents. Until recently, irradiation was used for pepper and spices, which pose significant health risks due to bacterial contamination when they are not sterilized. A regulation made it mandatory to indicate that they had been “sterilized by ionization.” Fearing rejection from their customers, some manufacturers abandoned the practice and now use less effective methods.
Sterilized by ionization symbol
Upper limits
The graph shows the maximum dose allowed in the European Community for different radioactive elements in three different food categories. The limits are given in terms of activity (becquerels) per kilogram. The more radiotoxic the radioelement is (the most dangerous being alpha emitters such as plutonium), the weaker the activity has to be. This is especially true in the case of baby food, where limits are particularly strict. When it comes to food which is consumed in small quantities (under 10 kilograms a year), activities up to ten times greater than those shown above can be allowed.
© IN2P3
As with blood alcohol limits for drivers, the permissible levels of radioactivity in various substances have been lowered over the past fifteen years or so. Increasing safety margins effectively means overestimating the risks. This approach, intended to reassure the public and applied mainly to the consumption of contaminated food, has actually had the opposite effect, increasing anxiety surrounding the effects of radioactivity and ionizing radiation.
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