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Ionising radiation

Environmental Radioactivity - Medicine - Occupational Radiation Protection - Nuclear Hazards Defence

Ionisierende Strahlung

Natural radionuclides in mineral waters

  • Natural waters like groundwater and spring water always contain natural radioactive substances alongside traces of other minerals. This applies to drinking water and to mineral water, which is often taken from very low-lying water resources and therefore has a higher degree of mineralisation.
  • In its study "Radiation exposure from natural radionuclides in drinking water in the Federal Republic of Germany", the BfS investigated 401 mineral waters. 366 of these were produced in Germany - the remaining 35 mineral water brands were imported from ten European countries.
  • The results of the BfS investigation and the WHO dose reference value were taken into account in the amendments to the Mineral and Drinking Water Ordinance.

Natural waters like groundwater and spring water always contain natural radioactive substances alongside traces of other minerals. This applies to drinking water and to mineral water, which is often taken from very low-lying water resources and therefore has a higher degree of mineralisation.

Activity concentrations vary

Depending on the local hydrogeological circumstances and the differing content of uranium and thorium in the bedrock, the activity concentrations of natural radionuclides in mineral water from uranium and thorium radioactive decay chains, such as

  • Uranium-238, Uranium-235, Uranium-234,
  • Radium-226, Radium-228,
  • Lead-210, Polonium-210 und Actinium-227,

vary greatly.

This means that the bandwidth of measurement values for different mineral waters is typically very wide. Higher radioactivity values often occur in waters from granite areas, for example in Erzgebirge, Vogtland, Fichtelgebirge, the Bavarian forest and the Black Forest.

Mineral waters are subject to the Mineral and Table Water Ordinance

Natural mineral waters are the subject of official recognition under the 1990 Mineral and Table Water Ordinance (Mineral Water Ordinance); they must be of natural purity and may not be altered in their significant component parts.

For a long time, the natural radioactivity has not been regularly investigated as it is naturally present. Accordingly, no limit or reference values have been stipulated.

Growth of mineral water consumption in Germany

Per capita consumption of mineral and curative water has increased since 1970 from 12,5 litres to 143,6 litres (2014) Per capita consumption of mineral and curative water 1970-2014Development of mineral water consumption in Germany in the period 1970 to 2014

Over the last 40 years, mineral water consumption in Germany has increased continually. The consumer can select from around 500 officially recognised German mineral waters. In addition, mineral waters are available on the market from other countries including France, Italy, Austria and Switzerland.

On average, each German citizen drinks around 143.6 litres of natural mineral water and around 42.2 litres of mineral water-based soft drinks each year. The consequence of this is that a significant proportion of the drinking water requirement of the German population is covered by the consumption of mineral water.

BfS study: Radiation exposure from natural radionuclides in drinking water in the Federal Republic of Germany

Until the year 2000, there was no information about the radiation exposure of the population as a consequence of the consumption of mineral water. However, public awareness has been raised through reports in the media about the increased content of natural radionuclides in mineral waters from certain sources. This made the implementation of a study a matter of urgency, both to determine the content of natural radionuclides in mineral waters and to calculate the radiation dose resulting from the consumption of mineral waters required for its assessment. The objectives of the investigation were

  • to determine the activity concentrations of the natural radionuclides Radium-226, Radium-228, Uranium-234, Uraiumn-235, Uranium-238, Polonium-210, Lead-210 and Actinium-227,
  • to calculate the radiation exposure from the consumption of mineral water
  • to draft proposals for the permitted concentrations of natural radionuclides in the context of the revised Mineral Water Ordinance.

Procedure

In the period from September 2000 to November 2001, a total of 401 mineral waters were purchased randomly from over 150 drinks stores and branches of well-known retail chains throughout the Federal Republic of Germany and the activity concentrations of the aforementioned radionuclides were determined in laboratories of the Federal Office for Radiation Protection (BfS).

366 of these were produced in Germany - the remaining 35 mineral water brands were imported from ten European countries.

Radiation dose from natural radionuclides in mineral waters

By ingesting foodstuffs, the human organism is penetrated by the natural radionuclides it contains and this causes radiation exposure for the consumer. This “internal” radiation exposure (ingestion dose) depends on the radiation properties of the radionuclides, the activity concentrations of the foodstuffs, the quantity of foodstuff consumed and the age of the consumer. In Germany it amounts on average to 0.3 millisieverts per year. The proportion of natural radiation exposure induced by drinking mineral water is low.

The radiation dose caused by the consumption of mineral water (ingestion dose) has been calculated for children and adults on the basis of the activity concentration (Results Table - only in German) under the assumption that the annual drinking water requirement is covered exclusively by the consumption of mineral water.

Considered here were persons aged 0 to 1, 1 to 2, 2 to 7, 7 to 12, 12 to 17 and adults for whom under Appendix VII Part B of the Radiation Protection Ordinance an average annual mineral water consumption of 170, 100, 100, 150, 200 and 350 litres was assumed.

The values calculated in this way were compared with the dose reference value of the World Health Organisation (WHO) for drinking water, which amounts to 0.1 millisieverts per year.

None of the mineral waters investigated exceeded the WHO dose reference value for adults. Only two foreign waters gave higher values.

Radiation dose for infants

Mineral water infants Mineral water infants until 2006Distribution of ingestion dose for infants as a result of the consumption of mineral water as drinking water and for the preparation of infant formula

The highest dose values were calculated for infants aged up to one year, for whom mineral water was used as drinking water and for the preparation of infant formula. The statistical distribution of the ingestion dose value for infants (aged 0 to 1) is presented graphically in the illustration. Shown here is the percentage proportion of mineral waters with a class width of 0.005 and 0.05 millisieverts per year in the dose range beneath and/or above 0.2 millisieverts per year.

At 0.046 millisieverts per year, the median dose amounts to around 50 per cent of the WHO dose reference value for drinking water of 0.1 millisieverts per year. The median corresponds to the dose for which half of the mineral waters had a dose value above this value and half had a dose value beneath it.

The consideration of the ingestion dose for infants was interesting insofar as several mineral waters under Paragraph 9 Para 3 of the Mineral Water Ordinance carry the endorsement "Suitable for the preparation of infant formula". Until 2003, this endorsement was used regardless of the content of natural radionuclides in the mineral water.

For around 20 per cent of the mineral waters investigated, dose values over 0.1 millisieverts per year arose for small children with an assumed annual consumption of 170 litres. The maximum value of 6.5 millisieverts per year was found in a Portuguese product.

Because of its high radiotoxicity, the radionuclide Radium-228 is a determinant for dose. Other natural nuclides such as Radium-226, Uranium-234, Uranium-235, Uranium-238, Polonium-210, Lead-210 and Actinium-227 play a lesser role.

Changes to the Mineral and Table Water Ordinance

The WHO dose reference value and the results of the BfS investigation were taken into account in the amendment to the Mineral and Drinking Water Ordinance. Under "2. Ordinance for the amendment to the Mineral and Table Water Ordinance" the statement "Suitable for the preparation of infant formula" remains permissible only when the following conditions are fulfilled:

"When delivered to the consumer, the activity concentration of Radium-226 may not exceed a value of 125 millibecquerels per litre and Radium-228 may not exceed a value of 125 millibecquerels per litre of natural mineral water. If both radionuclides are present, the sum of the activity concentrations expressed as a percentage of the permissible highest concentration may not exceed 100."

Adherence to this condition ensures that for a drinking water quantity of 170 litres per year, a consequential ingestion dose for infants of 0.1 millisieverts per year from the radionuclides Radium-226 and Radium-228 is not exceeded.

Mineral water producers informed

The BfS has informed producers of mineral waters of the findings from each of their products. A range of mineral water producers have adopted measures to reduce the radioactive content and have made available more recent measurement values from independent measurement laboratories. These values have been taken into account by the BfS after plausibility checks.

State of 2018.09.18

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