HPA Studies Health Effects Of Magnetic Resonance Imaging
The Chairman of the Health Protection Agency, Sir William Stewart today announced that the Agency's Board had approved in principle the need for an epidemiological study of possible adverse health effects from high static field Magnetic Resonance Imaging (MRI) machines.
Sir William said: "MRI scanning has some undoubted benefits in medicine, especially as an aid to accurate clinical diagnosis. However we need to bear in mind that the magnetic fields produced by the machines are quite substantial and that these fields are increasing in order to achieve improved clarity of image. The exposures to patients and medical staff from the magnetic fields can be high and there is a shortage of information on possible adverse long term health effects. The Agency's Board therefore considers more research is needed in this area."
The announcement follows a report to the Board from the Agency's independent Advisory Group on Non-ionising Radiation (AGNIR) which made a number of recommendations on new areas for research1. This followed a thorough examination of the sources of MRI exposure and the scientific evidence for biological effects and health effects. In particular the Chairman of AGNIR, Professor Anthony Swerdlow, said "There is a pressing need for a well-conducted study of mortality and cancer incidence in workers with high occupational exposures to static magnetic fields, particularly those associated with medical MRI scanners."
The Board also noted that the view that there is a need for more epidemiological research on people exposed to MRI is shared by the World Health Organization2. The WHO points out that an international collaborative study may be the most effective way forward, because it would ensure there are sufficient numbers of exposed cases in the study to draw accurate conclusions. The Agency will now examine the feasibility of such a study with specialists here and abroad, with the aim of launching such a study as soon as possible.
The Agency will be setting up a Working Group under the Chairmanship of Board member Professor Andrew Hall. The Group will undertake a detailed review in order to advise the HPA Board on future research on possible long-term health consequences in people exposed to the static magnetic fields associated with Magnetic Resonance Imaging. Emphasis will be placed on identifying appropriate study groups and their exposures, the diseases of potential concern and the feasibility of future epidemiological investigations. The Group will report to the HPA Board within one year of commencement of the scoping study.
Magnetic Resonance Imaging (MRI) was first developed 30 years ago as an aid to medical diagnosis. It is based on a well established scientific technique, nuclear magnetic resonance, which uses the interaction of magnetic fields with the spin of the nuclei of atoms to provide detailed information on the constituents of chemicals and biological materials. MRI can provide excellent, detailed images of the body's soft tissue and is an alternative to using x-ray techniques such as computed tomography (CT). MRI does not use ionising radiation and this can be a distinct advantage for examinations of children or for abdominal examinations where radiation doses can be high. However, MRI requires large magnetic fields for successful scanning and hence the need for a study of people who work in the fields. People are exposed to high magnetic fields in industry and elsewhere, but MRI produces the highest magnetic fields in use today, and hence the need for a study of people who regularly work with the machines.