MTHR - Mobile Telecommunications and Health Research

Dosimetry Workshop

Chair: Professor L J Challis

Following a joint session with the Human Volunteer Group to discuss progress on the Standard Human Exposure System, the Workshop moved on to consider progress with the dosimetry studies funded under the Programme. There are four projects supported by the programme to try and refine current understanding of the interaction between mobile phone emissions and people.

One of the most common approaches to assessing the deposition of radiofrequency energy within the body is to use numerical modelling and much of the work supported by MTHR in this area includes at least an element of this. However, the key to obtaining a true assessment by this means is accurately defining the dieletric properties of tissue. One area that has been little explored in the past is how these properties may vary with age. This could be particularly important in assessing how exposures of children may differ from those of adults. The project being undertaken by MCL in conjunction with Dstl, Porton Down, had been using contact probes to obtain data on conductivity and permittivity in vivo. Standard approaches previously developed for in vitro work have been applied to in vivo experimental models and appear promising.

Two projects are assessing the deposition of energy from new communications technologies. Both projects are using a combination of numerical modelling and physical measurements to assess energy deposition in people using the devices. The project assessing energy deposited in the head from the handsets being issued to the emergency services for use with the new TETRA communications systems is finding good agreement between calculated and measured values. The second project, which is using a combination of numerical modelling and measurements to assess exposures from a variety of new communications applications, is considering not just the types of devices likely to come into use in the future, but also how the devices will be used.

The NPL team reported on progress with their wide-ranging project. The fixed-term component of the project, assessing low frequency magnetic fields produced by mobile phones, and developing traceable SAR standards was on schedule for completion. NPL also provide a dosimetry consultancy service across the programme and demand for this is inevitably linked to the progress and needs of other projects in the programme.

Several projects are funded directly by DTI as an adjunct to the programme. The EMF dosimetry handbook is a project to update an established reference work in the field. As an innovation the handbook will be available to download free from the internet (www.emfdosimetry.org). It is planned that four chapters per year will be produced. The second project funded directly by DTI is measuring power densities in publically accessible locations close to a randomly selected sample of microcell base stations. The third project is designed to be a definitive study to resolve the outstanding issue of energy deposition in the head during the use of hands free kits. All three project teams reported good progress and were on schedule.

Summaries of the closed sessions of the MTHR Research Seminar - 11th of November 2002