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20 October 2004

COMARE 9th Report: Advice on a report by the Committee Examining Radiation Risks of Internal Emitters (CERRIE)

COMARE welcomes the CERRIE report [1] and endorses its general conclusions on radiation risks and dosimetry. COMARE agrees [2] that available data on radiation risks do not support a speculative hypothesis that the risks from internal emitters are radically underestimated. Furthermore, COMARE agrees with the majority view of CERRIE that presently available biological evidence does not indicate a need for a fundamental change in radiological protection standards. Despite the above, COMARE has reservations about how CERRIE was set up, in particular how its composition was influenced by environmental politics rather than science.

The CERRIE report examines in detail the uncertainties involved in making radiation risk estimates and shows that the uncertainties are greater for internal emitters than for external radiation. Uncertainties in estimating risk from internal emitters are typically within a factor of two or three above and below a central best estimate, but in some cases they can become a factor of ten or more. Current recommendations on radiation risks from the International Commission on Radiological Protection (ICRP) are under review. COMARE hopes that ICRP will address the issue of uncertainties in future recommendations.

COMARE notes the uncertainties in dosimetry for certain radionuclides introduced by observed biological effects such as the bystander effect and genomic instability. COMARE accepts the recommendations of CERRIE on this issue, especially the need for further research. However, although these effects are new scientific observations, they must have been in operation before their discovery. They will therefore already be incorporated in epidemiological observations and in other observed effects of radiation on health.

  • COMARE endorses the view of CERRIE that epidemiological studies will only produce valid results if they are conducted to a high standard and are subject to both ethical and peer review.
  • COMARE recommends that Government reviews resources made available for radiobiological research, especially as this has declined steadily over a decade or more.
  • COMARE recommends that Government also reviews the resources made available for research on radon exposures and for remedial action to reduce radon levels in homes and workplaces, because radon gas and its progeny give the largest exposure of the UK population to internal emitters.

Although COMARE welcomes the CERRIE report, it has reservations about how the Committee was set up, particularly how its composition was influenced by a minister rather than under the guidance of the Office of the Commissioner of Public Appointments (OCPA).

Press enquiries to Professor Bryn Bridges, Chairman (Tel no: 07963 700995)


[1]  Report of the Committee Examining Radiation Risks of Internal Emitters (CERRIE) 2004. Downloads available on and hard copies are available from NRPB.

[2]  COMARE Ninth Report 2004. Advice to Government on the review of the radiation risks from radioactive internal emitters carried out and published by the Committee Examining Radiation Risks of Internal Emitters (CERRIE). Downloads are available on this website (see below) and hard copies are available from NRPB.

Notes for editors

1. The term “internal emitter” refers to radioactive material that has entered the human body by breathing, eating or drinking (inhalation or ingestion). Once in the body, the radioactive material will deposit in various organs, resulting in radiation exposure. Where the material goes in the body depends on its chemical form; for example, strontium isotopes will tend to accumulate in bone whereas caesium isotopes will be more uniformly distributed throughout the body. The radiation exposures caused by various internal emitters (internal dosimetry) has been the subject of international scientific research for over 60 years. An example of an internal emitter is naturally occurring uranium, which is in food and drinking water. We all have uranium in our bodies to an extent that depends on where we live, what we eat and what we drink. Uranium does concentrate in some organs more than others, but is also steadily excreted via bodily functions.

2. External radiation comes from radioactive material outside the body. An example is the radiation from an x-ray machine which enters and then passes through the human body. Once the x-ray machine is switched off, the radiation disappears and none remains in the body. Here the dose to particular organs (external dosimetry) depends on the particular type and energy of the radiation; for example, x-rays or gamma rays of different energies will be able to penetrate the body to different depths. The dose will also depend on how the body is positioned; for example, the dose will be different depending whether you are facing the radiation source or not. External dosimetry has been the subject of international scientific research for about a century.

3. The Committee on Medical Aspects of Radiation in the Environment (COMARE) was established in November 1985 in response to the final recommendation of the report of the Independent Advisory Group chaired by Sir Douglas Black. The terms of reference are
“ to assess and advise Government and the Devolved Administrations on the health effects of natural and man-made radiation in the environment and to assess the adequacy of the available data and the need for further research”.
(Black D (1984). Investigation of the possible increased incidence of cancer in West Cumbria. Report of the Independent Advisory Group. London HMSO).

4. In 2001, the Government requested COMARE to provide up-to-date advice on the risk estimates applied to radiation arising from radioactivity within the body. Consequently, on 31 July 2001, the then Environment Minister, Rt Hon Michael Meacher MP, after consulting COMARE, announced that a working group would be set up with the following remit,
“ to consider present risk models for radiation and health that apply to exposure to radiation from internal radionuclides in the light of recent studies and to identify any further research that may be needed”.

5. The group, later known as CERRIE (the Committee Examining Radiation Risks of Internal Emitters) was therefore set up with the composition as directed by the Minister. CERRIE held its first meeting in December 2001. Although established under the auspices of COMARE, CERRIE functioned independently of COMARE and of the Department for Environment, Food and Rural Affairs (DEFRA) and the Department of Health (DH). It was agreed that, following the publication of its report to COMARE, the Government would seek the views of COMARE on the CERRIE report. The COMARE ninth report referred to here contains that advice.

Download the 9th Report in Portable Document Format  PDF Document



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