Jul 15, 2011

Children and Adults Exposed to Electromagnetic Fields at the ICNIRP Reference Levels: Theoretical Assessment of the Induced Peak Temperature Increase

Jurriaan F. Bakker, Margarethus M. Paulides, Esra Neufeld, Andreas Christ, Niels Kuster, Gerard C. van Rhoon, Physics in Medicine and Biology, Volume 56, Number 15, pp. 4967–4990, August, 2011, online July 19

To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels. Restrictions on induced whole-body averaged specific absorption rate (SARwb) are provided to keep the whole-body temperature increase under 1◦C. Additional restrictions on the peak 10 g spatial-averaged SAR (SAR10g) are provided to prevent excessive localized tissue heating. In this study the localized peak temperature increase in children upon exposure at the reference levels has been assessed using simulations of multiple anatomical models. A peak temperature increase as high as 1◦C can occur for worst-case scenarios at the ICNIRP reference levels. It is recommended to use peak temperature increase as a better metric to prevent excessive localized tissue heating instead of localized peak SAR and to consider the exposure duration.

The scientific and technical impact of the study can be summarized as:

  • The rationale behind exposure guidelines is generally based on temperature increase. We investigated extensively and systematically the relationship between peak averaged SAR and peak temperature increase for many frequencies and exposures using multiple anatomical models of children and adults.
  • A detailed sensitivity study and Monte Carlo analysis have been performed to assess the uncertainty of the results.
  • The correlation between peak temperature increase and SAR, SAR1g or SAR10g was shown to depend on the frequency and the peak location is not necessarily identical to the peak SAR, SAR1g or SAR10g location.
  • The study demonstrates that despite the built in safety margins, exposure at the SAR reference levels can result in local temperature increases of larger than 1◦C.