Irish exposed to higher radiation levels. RPII publishes detailed assessment of radiation doses

Date released: Jul 28 2008

The most recent estimate of the radiation dose received by the Irish population shows a 9 per cent increase over previous estimates. This is according to a report “Radiation Doses Received by the Irish Population” published today by the Radiological Protection Institute of Ireland (RPII). The report details results of a three-year baseline study of the various sources of ionising radiation to which the Irish population is exposed.

The report summarises the most comprehensive study of its kind undertaken in Ireland, bringing together data on exposure of the Irish population to all sources of radiation, both natural and artificial. Natural sources of radiation include radon, thoron (a radioactive gas similar to radon) and cosmic radiation from outer space. Artificial sources of radiation include medical exposure of patients, fallout from nuclear weapons testing, the accident at Chernobyl as well as discharges from Sellafield. 

According to the report’s principal author, Dr Tony Colgan, Director of Advisory Services at the RPII, “the evaluation undertaken clearly identifies radon as the primary source of radiation dose in Ireland. Radon is a cancer causing gas and is the second most important cause of lung cancer in the country. It is also one of the few sources which can be controlled through measurement and remediation, both of which are relatively inexpensive to undertake. For these reasons, the RPII has always highlighted radon as a key radiation protection issue.” 

The report identifies medical (patient) exposure to radiation as a matter of potential concern. According to Dr Colgan, “in recent years several countries have experienced a very significant increase in the radiation exposure of patients. Many of the new diagnostic techniques now available routinely deliver relatively high radiation doses and it is important that, at the individual level and in consultation with expert medical advice, each exposure is fully justified.” 

The report notes that radiation doses in Ireland attributable to discharges from the Sellafield reprocessing plant are low compared to other sources of radiation exposure. On-going monitoring has shown that these discharges and the associated radiation doses in Ireland have been continuously reduced since the 1970s and early 1980s. Dr Colgan notes that “for those who eat fish and shellfish sourced from the Irish Sea, their radiation doses are of negligible health significance and the RPII does not recommend any restrictions on the consumption of seafood landed at east coast ports.” 

The Irish population is exposed to higher levels of radiation than many other European countries. The report’s findings show that the average annual radiation dose in Ireland from all sources of radiation is 3950 microsievert (µSv). This may be compared, for instance, to 2600 µSv in the UK, 4200 µSv in Germany and a worldwide average of 2800 µSv. In Germany, the dose due to medical (patient) exposures is more than three times higher than in Ireland. 

Some of the principal conclusions of the report are: 

  • Approximately 86 per cent of the average radiation dose in Ireland comes from natural sources of radiation
  • Medical (patient) exposures account for the bulk of the exposure from artificial sources of radiation
  • Radiation doses attributable to the routine discharges of radioactivity from Sellafield contribute very much less than 1 per cent of the average radiation dose in Ireland
  • Over 95 per cent of all radiation exposure in the workplace is due to radon 

distribution of readiation doses in Ireland

The report is available under publications.

ENDS 

Note to Editors:

Radiation can be considered to fall into two broad groups: naturally occurring and man-made radiation. Natural radiation sources include radon, thoron, cosmic rays, gamma radiation from the ground and natural radionuclides in food and water. Man-made radiation is used in medicine and industry. It also comes from the generation of nuclear power and the reprocessing of nuclear fuel in facilities such as Sellafield. For the same radiation dose, there is no difference between the harm caused by naturally occurring and man-made radiation. 

On average, a person in Ireland receives an annual dose of 3950 µSv (microsieverts) from all sources of radiation. This is equivalent to about 200 chest X-rays per person per year. The pie-chart above shows the contribution by each source of radiation to the average annual dose of a member of the Irish population. By far the largest contribution of approximately 86% (3395 µSv) comes from natural sources. Man-made radiation contributes approximately 14% (555 µSv) and is dominated by the beneficial use of radiation in medicine (540 µSv). Doses from other man-made sources account for less than 1% (15 µSv). These are average values and there will be considerable variability between individuals. 

The estimated average dose in Ireland from all sources of radiation is 3950 µSv. The increase from 3620 µSv in 2004 to the present value of 3950 µSv is due to the fact that, because of the absence of national data, previous estimates of the doses from medical procedures and from thoron were based on international average values. In addition, the contribution from cosmic radiation to the total dose is now better understood. Previously this was estimated as 300 µSv but has now increased to 345 µSv as a result of the recent growth in air travel. 

The Sievert (Sv) is the unit of radiation dose and is a measure of the amount of harm radiation causes when it hits the human body. The Sievert is a large unit and in practice it is more usual to use the microsievert (µSv), which is one-millionth of a Sievert.