The technique, called "quasistatic zooming," will help researchers calculate the amount of radiation from mobile phones absorbed by human tissue on scales of less than one millimeter.

The work is published today in the UK's Institute of Physics journal, Physics in Medicine and Biology.

Concern about the potentially hazardous effects of mobile phones on human tissue has led to a great deal of research on the subject. Using computer models of the head, the amount of electromagnetic radiation absorbed and the resulting increases in the temperature in the head have been calculated.

One drawback of this research is that these computer models are very complicated and take a long time to do the calculations, so the models have to be simplified to make the experiments practical. To keep the experiment time down, the computer calculates the amount of radiation absorbed on two millimeter sections of the head, but Jeroen Van de Kamer and colleagues from the University of Utrecht are concerned that this resolution is too limiting.

"A resolution of two millimetres is adequate for studying the brain as it does not have small-scale intricate features, but this is not high enough to test how mobile phones affect the inner ear and eye," said Dr. Van de Kamer. "To find out what is going on here, high-resolution simulations are needed," he added.

To make higher-resolution simulations, Dr. Van de Kamer and Dr. Lagendijk have developed a new technique that calculates the distribution of the absorbed radiation on a sub-millimeter scale from the conventionally computed, low-resolution distribution of the electric field.

This "quasistatic zooming" allows the researchers to find the power distribution in the head, at a scale as low as 0.4mm, due to a radiating phone held next to the ear.

Comparing their results with conventional calculations, they found that the main part of the brain has the same power distribution due to the mobile phone, but the more intricate structures in the head absorbed the power of the mobile phone in a different way than had been seen before.

For example, a thin sheet of cerebral spinal fluid around the brain was seen to absorb more radiation at the surface of the brain than had been seen with the 2 millimeter resolution computer model.

"It is clear from this that, for small scale structures, high-resolution electromagnetic modeling is a necessity," said Dr. Van de Kamer.

Although the maximum increase in temperature found in the head is less than 0.2 degrees centrigrade, as it was with lower resolution computer models, research must now be done with this higher resolution technique to check the impact of mobile phones on the inner ear and eye and other small-scale parts of the head.

The Institute of Physics is a leading international professional body and learned society with over 36,000 members, which promotes the advancement and dissemination of a knowledge of and education in the science of physics, pure and applied. It has a world-wide membership.

The Institute is a member of the UK's Science Council and a nominated body of the Engineering Council. The Institute works in collaboration with national physical societies and plays an important role in transnational societies such as the European Physical Society, and represents British and Irish physicists in international organizations.

In Great Britain and Ireland, the Institute is active in providing support for physicists in all professions and careers, encouraging physics research and its applications, providing support for physics in schools, colleges and universities, influencing government and informing public debate.

(Reference: Physics in Medicine and Biology, Vol 47, Issue 10.)

Related websites:

Physics in Medicine and Biology

University of Utrecht


[Contact: Dr. Jeroen Van de Kamer, Alice Bows]

02-May-2002