Abstract

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 recently. 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," says 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