Radioactive substances

Radioactivity has always been a part of our environment. The substances in the world around us all contain unstable atoms that emit energy as radiation when they decay to more stable atoms. Such radioactive atoms are also called radionuclides. The air that we breathe, the water we drink, the food we eat, and our own bodies all contain radionuclides. Many radionuclides were formed long before our own solar system came into existence, while some are continually being created in the Earth's atmosphere by the action of cosmic rays.

Around 85% of our average annual radiation dose comes from natural sources, with 14% from medical procedures. The remaining 1% comes from a combination of man-made sources, eg weapons test fallout, Chernobyl fallout and radioactive discharges.

SEPA's main responsibility is to ensure that public exposure to sources of radioactivity in food and the environment from authorised discharges (eg from nuclear power stations) does not go above international limits.

SEPA is not responsible for public exposure to radiation from natural sources or medical treatment.

SEPA's approach to this is two-fold:

  • we monitor levels of radioactivity in food and the environment
  • we identify people who are most likely to come into contact with radioactivity from discharges.

Regulation

Sources of radiation to members of the public from nuclear sites are regulated. There are three main sources:

  • discharges to water
  • discharges to air
  • direct radiation.

SEPA regulates discharges to water and air under the Radioactive Substances Act 1993. We aim to protect the environment and the public, by encouraging users to minimise the production of radioactive waste, and by setting limits on the quantities of radionuclides that may be discharged from authorised premises.

The Health and Safety Executive regulates sources of direct radiation. It is also responsible for the exposure of workers to radiation (eg staff at nuclear power stations).

The Food Standards Agency is responsible for protecting the public from radioactivity in food.

SEPA works closely with all of these organisations to protect the public.