- What are electromagnetic fields?
- Static and low-frequency fields
- What are static and low-frequency electric and magnetic fields?
- Direct and alternating voltage
- Effects of static and low-frequency fields
- Reports & Evaluations
- Radiation protection relating to the expansion of the national grid
- Basics transfer of electrical power
- High-frequency fields
- What are high-frequency fields?
- Applications high-frequency fields
- Radiation protection in mobile communication
- What is mobile communication?
- Reports and evaluations
- What is optical radiation?
- UV radiation
- What is UV radiation?
- Sun but safe!
- Effects of UV radiation
- Protection against UV radiation
- UV index
- Infrared radiation
- What is ionising radiation?
- Radioactivity in the environment
- Where does radioactivity occur in the environment?
- What is the level of natural radiation exposure in Germany?
- Air, soil and water
- Building materials
- Natural radionuclides in building materials
- Clay as building material
- Granite plates used in households
- Industrial residues (NORM)
- BfS laboratories
- Applications in medicine
- Radiation protection in medicine: international activities
- Applications in daily life and in technology
- Radioactive radiation sources in Germany
- Register high-level radioactive radiation sources
- Type approval procedure
- Cabin luggage security checks
- Radioactive materials in watches
- Ionisation smoke detectors (ISM)
- What are the effects of radiation?
- Effects of selected radioactive materials
- Consequences of a radiation accident
- Cancer and leukaemia
- Genetic radiation effects
- Individual radiosensitivity
- Epidemiology of radiation-induced diseases
- Ionising radiation: positive effects?
- Risk estimation and assessment
- Radiation protection
- Basic information
- Occupational radiation protection
- Nuclear accident management
- What is an emergency?
- What happens in an emergency?
- Federal and state tasks
- In the event of an emergency
- Measuring networks
- Exercises for emergency situations
- Defence against nuclear hazards
- Service offers
- Radon measurements
- Incorporation monitoring
- Biological dosimetry
- Online library
- About us
- Science and research
- Research concept
- Scientific collaborations
- EU research framework programme
- BfS research programme
- Third-party funded research
- Departmental research
- Selected research projects
- Selected research results
- Professional opinions
- Science Council
- Laws and regulations
- BfS Topics in the Bundestag
Granite plates used in households
- Natural stone and other building materials contain the natural radionuclides uranium-238, thorium-232 and their decay products as well as potassium-40.
- As an intermediate of the uranium-238 decay chain, the radioactive noble gas radon-222 originates from radium-226.
- However, in most instances the proportion of radon from building materials and natural stone in homes is small compared to the amount of radon emitted from soil.
- If you are interested in granite for your home and would like to take account of radiation exposure, please ask the distributor or manufacturer for information on the radionuclide concentrations.
In the past, newspapers reported about granite in homes as a source of potential radiation exposure. Natural stone and other building materials contain the natural radionuclides uranium-238, thorium-232 and their decay products as well as potassium-40.
As an intermediate of the uranium-238 decay chain, the radioactive noble gas radon (radon-222, half life 3.8 days) originates from radium-226. However, in most instances the proportion of radon from building materials and natural stone in homes is small compared to the amount of radon emitted from soil.
Granite countertops in homes
Granite is the name of stones that have solidified underground in greater depth from fluid magma.
Granites frequently show enhanced concentrations of the nuclides from the uranium and thorium series and of potassium-40, compared to other building materials. Although mainly consisting of quartz, feldspar and dark, ferrous or magnesian minerals, their composition may vary broadly, depending on their geology and origin, which is recognisable by different colour and structure.
However, the correct name of stone is not always used in trade, based on considerations geared to the specific utilisations, processing and maintenance of materials. Thus, "granite" need not necessarily signify granite stone but this term is also used for gneiss, diorite, granodiorite, and other stones.
Radon: Cause of lung cancer
Radon is part of the natural decay chain of uranium-238 and is known to cause lung cancer. The risk to contract lung cancer on account of radon in indoor air depends on the long-time indoor concentration.
However, comprehensive studies in Germany have clearly shown that enhanced indoor concentrations in the predominant number of cases are not due to radon escaping from building materials but to radon entering the house from the soil via the cellar. There are only very rare cases where enhanced indoor concentrations are being caused by the building materials used.
This has been confirmed by recent studies on the radon release from building materials and natural stone (also including granite) conducted by the BfS during the last few years.
How ist the radionuclide content assessed?
The new Radiation Protection Law requires for certain granites that the manufacturer or importer has to measure the concentrations of the natural radionuclides and must prove that the legal reference value for the exposure of the users of buildings is not exceeded by the building material. The Radiation Protection Ordinance describes how the manufacturer can prove this.
At the same time, the European Standards Institute CEN is developing standards for the measurement and evaluation of building materials within the framework of the Construction Products Regulation. Ultimately, the CE mark on a building material will also prove that the European radiation protection requirements have been met.
If you are interested in granite for your home and would like to take account of radiation exposure, please ask the distributor or manufacturer for information on the radionuclide concentrations. These are mostly known to the manufacturers, either in consequence of licensing procedures and import directives of third countries, or because they want to stand out from competitors.
Arrange for measurements of the radon concentration in your home. An increased radon concentration in homes represents a health risk to the inhabitants, independent of its origin. Laboratories for measurements, which are subjected to quality assurance in Germany, are participating in the annual comparative measurements for passive radon detectors of the BfS.
State of 2019.01.14