Radioactivity: frequently asked questions

Why does SEPA monitor radioactivity?

SEPA is obliged to monitor the environment for radioactivity in order to:

  • check that public exposure to radiation from authorised discharges is less than the statutory limit of one millisievert
  • assess the overall impact of radioactivity on the population
  • assess levels of radioactivity in the environment
  • assist the Food Standards Agency in checking that radioactivity in food does not compromise food safety.

How does SEPA estimate the dose to the public?

SEPA assesses the potential risks from radioactivity by determining the dose to the most exposed individual. For example, someone living near a nuclear site, and who eats local shellfish, may potentially be the most exposed individual.

If the assessed dose is within statutory limits, it follows that the doses to other lesser exposed members of the public will also be within these limits.

How does SEPA identify the most exposed individual?

SEPA employs the Centre for Environment, Fisheries & Aquaculture Science (CEFAS) to carry out a habits survey for the following factors:

  • angling, commercial fishing (netting and creeling) and mollusc collection
  • production, use and destination of local produce
  • types, seasonality and consumption of local wild foods
  • land use and soil types
  • occupancy rates at locations around the site
  • local food consumption rates
  • extraordinary practices

SEPA's researchers use a range of techniques to investigate these factors:

  • interviewing local residents, farmers, gardeners etc
  • interviewing food retailers, fishery managers etc
  • observing habits at particular locations (eg beach use)
  • taking measurements of radioactivity

SEPA staff also directly input into this process by using their knowledge about the locality and the sites they regulate.         

What local knowledge is used in deciding where to do habit surveys?

Habits surveys are undertaken around all nuclear installations in Scotland, as the inhabitants of these areas are likely to be the most exposed to radiation from authorised discharges. In addition, a habits survey is regularly carried out along the Solway Coast, where the effects of Sellafield are at their greatest in Scotland.

How is SEPA certain that the most exposed individual is at the highest risk?

Analyses of samples from across Scotland are taken, in addition to those where the most exposed individual has been identified. If high levels of radioactivity were found outwith a critical area, an investigation would be undertaken to determine if a new most exposed individual existed.

SEPA's monitoring programme – taking samples

SEPA takes samples through its monitoring programme. The samples must comply with the requirements of Article 35 of the Euratom treaty, which stipulates that levels of radioactivity are measured across Scotland to help determine the impact on the population as a whole. The European Commission recommends what samples should be taken to fulfil this requirement.

The SEPA monitoring programme is regularly reviewed, with participation from the Food Standards Agency, the Health Protection Agency, Scottish Natural Heritage and the Scottish Government. For more information, visit the Environmental Radioactivity Monitoring Task Team link:

ERMTT

How does SEPA analyse samples?

Most samples are analysed by gamma spectrometry, which identifies a wide range of radionuclides from the characteristic gamma rays they emit.

However, not all radionuclides emit radiation in the form of gamma rays, so two additional analysis techniques are also used:

  • those that measure alpha and beta particles
  • those that look for specific radionuclides

If high values of alpha and beta particles are measured, specific analysis will be undertaken to determine what the particular radioactive contaminant is.

If a specific radionuclide is released from a nuclear installation, then analysis will be carried out on samples near that location which specifically look for that radionuclide.

Who is responsible for protecting public health?

SEPA works with the Food Standards Agency (FSA) on a monitoring programme that fulfils the needs of both organisations. The FSA is responsible for ensuring that foodstuffs are safe to eat, while SEPA checks that radioactivity in authorised discharges do not compromise public safety or impact on the environment.

Does SEPA monitor non-nuclear sites, eg hospitals and industry?

Some samples are taken from around non-nuclear sites that are also authorised to dispose of radioactive waste.

What precautions does SEPA take to protect children's health?

Dose assessments are carried out for adults, 10-year olds and one-year olds. This is to take account of the biological differences between the age groups.

What is the long-term impact of Chernobyl?

There are still some livestock restrictions in place in England, Scotland and Wales because of the Chernobyl accident. In addition, radionuclides from the accident are widely measurable across the whole of Scotland, though they do not pose any significant risk to the Scottish public.

What happens in the event of an accident or unusual discharge?

SEPA would carry out additional monitoring. In extreme circumstances, restrictions could be applied to certain foodstuffs and public may be evacuated from the affected area.

Do different standards apply between accidents and normal situations?

The one millisievert limit only applies to authorised discharges. In the event of an accidental release, there are international guidelines on the amount of radioactivity acceptable in foods and acceptable levels of dose. No fixed standards have been set for emergencies because different emergency scenarios would require different responses.