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Brazil nuts are often on the plate, especially at Christmas time


Zacharie Scheurer / dpa

They are considered a healthy snack, especially during the Christmas season, nuts are increasingly on the table. But the Federal Office for Radiation Protection (BfS) is now warning against one particular nut: children, pregnant women and breastfeeding women should not eat Brazil nuts. These could contain high amounts of radioactive radium, the Federal Office said. Other, especially native nut species, are not affected.

Brazil nuts, like all foods, contain natural radioactive substances – but some to a higher degree. Brazil nut trees grow in tropical rainforests of South America. According to the BfS, there are soils there that naturally contain large amounts of radium. The radioactive element is absorbed through the roots and transported in the tree to the nuts.

It is generally safe for adults to consume Brazil nuts in moderation. The radiation dose that is generated for them as a result is low, according to the Federal Office. In children, however, the same amount can lead to a significantly higher radiation dose: Radium is deposited in teeth and bones like calcium – and these are still in the process of building up in children. Unborn children and infants absorb the radioactive substance through the placenta and breast milk.

"If children only eat Brazil nuts occasionally, they are also concerned with comparatively small doses of radiation. That is why the advice to be cautious may sound exaggerated. But children need special protection, including from unnecessary radiation," it says.

Just two nuts a day can significantly increase the radiation dose

In general, according to the BfS, a person in Germany absorbs a comparatively low annual radiation dose of around 300 microsieverts with food. "Even the regular consumption of small amounts of Brazil nuts can noticeably increase this value," it said. "For example, an adult who eats an average of two Brazil nuts a day for a year receives an additional radiation dose of around 160 microsieverts." According to the BfS, if a child were to consume the same amount of Brazil nuts in the second year of life, the additional radiation dose would be around 1,000 microsieverts – i.e. about six times as high, partly because of the significantly different physique and metabolism.