European Union legislation designed to limit workers' exposure to electromagnetic radiation will seriously hinder research involving the use of magnetic resonance imaging (MRI), leading investigators warned the British government on Tuesday (September 20).
The Physical Agents (Electromagnetic Fields) Directive sets legal limits on electromagnetic radiation exposure across a range of frequencies, including those used in MRI. In a letter to Patricia Hewitt, Britain's secretary of state for health, twelve scientists and clinicians argue those limits "are huge extrapolations from largely hypothetical possible conditions and are an over-cautious interpretation of very limited experimental data."
The result will limit the use of MRI in diagnosis, treatment and research, which could have potentially disastrous impacts on both the lab and the clinic, they say. "This has implications across all applications of MRI, right through from clinical ones to clinical research and basic research," said Stephen Keevil, a signatory to the letter and head of magnetic resonance physics at Guy's and St Thomas' Hospitals London.
For example, the exposure levels permitted for time-varying gradient fields under the EU law would prevent investigators being close to the scanner while it is gathering data, he explained. "In a research setting you quite often want to make adjustments to the machine and so on without interrupting the imaging," Keevil told
The directive as it stands does not include limits for exposure to static magnetic fields, but UK authorities are considering implementing the law with static field limits, he said. "We think that when the regulations are implemented in the UK, they will include it," Keevil said. "Certainly the Health and Safety Executive are minded to do that." If passed, this would impact the use of high-field MR systems in clinical imaging and research in the UK, and would preclude cleaning inside such scanners or servicing them, Keevil said.
The new directive was passed last year by the European Parliament and Council, and must be enacted into law by countries in the EU by 2008. Keevil and the other signatories are led by Ian Young of Imperial College London.
Other signatories to the letter include the presidents of the Royal College of Radiologists, the Institute of Physics and Engineering in Medicine, and the British Institute of Radiology, as well as Peter Mansfield from the University of Nottingham, winner of the 2003 Nobel Prize for Physiology or Medicine. They call on the UK government to push for an amendment to the directive that avoids the impact on MRI, and in the meantime to postpone its implementation.
A two year delay in implementing the law in the UK would give time for researchers to gather the data to provide full justification for relaxing the limits set out in the directive, according to the signatories.
A spokesman for the Health and Safety Executive, the government agency responsible for putting the directive into action in the UK, said the executive had already begun a process of consulting on how to implement the EU rules. "The HSE is entering into a dialogue with a number of other government departments about the directive," he told
Michael Clark, from the UK's Health Protection Agency, told
"They have to agree that there isn't any evidence of harm at these levels, but we are talking about relatively new technology and have to be cautious," he said. The National Radiological Protection Board, now part of the HPA, had given advice as part of the drafting of the directive.