Analysis of RF exposure in the head tissues of children and adults

Abstract

This paper analyzes the radio frequencies (RF) exposure in the head tissues of children using a cellular handset or RF sources (a dipole and a generic handset) at 900, 1800, 2100 and 2400 MHz. Based on magnetic resonance imaging, child head models have been developed. The maximum specific absorption rate (SAR) over 10 g in the head has been analyzed in seven child and six adult heterogeneous head models. The influence of the variability in the same age class is carried out using models based on a morphing technique. The SAR over 1 g in specific tissues has also been assessed in the different types of child and adult head models. Comparisons are performed but nevertheless need to be confirmed since they have been derived from data sets of limited size. The simulations that have been performed show that the differences between the maximum SAR over 10 g estimated in the head models of the adults and the ones of the children are small compared to the standard deviations. But they indicate that the maximum SAR in 1 g of peripheral brain tissues of the child models aged between 5 and 8 years is about two times higher than in adult models. This difference is not observed for the child models of children above 8 years old: the maximum SAR in 1 g of peripheral brain tissues is about the same as the one in adult models. Such differences can be explained by the lower thicknesses of pinna, skin and skull of the younger child models.

Specific absorption rate in neonates undergoing magnetic resonance procedures at 1.5 T and 3 T

“…Since local SAR 10g is more dependent on local geometry than the global average, these values are subject to greater uncertainty, especially when attempting to represent a population using a small number of models. It is difficult to assess this uncertainty; a 30% estimate is given in the mobile communications literature 28 (in the GHz range); however, the lower frequencies used in MRI will lead to deviations closer to 10% 29. Our own SAR 10g estimate for an adult model at 3 T was very close to the scanner's prediction (10.1 W kg −1 compared with 10 W kg −1 ), though this may be coincidental given that the model used by the scanner's own software is unknown.…”

Prenatal cell phone use and developmental milestone delays among infants

“…When modeling specific absorption rates of RF to the womb of pregnant mothers, research suggests that exposures are likely low and not high enough to elevate the body temperature (26)(27)(28). But this modeling is based on numerous assumptions and extrapolations.…”

Children's Mobile Phone Use and Dosimetry

“…Several studies have measured electromagnetic absorption in realistic child and adult head models that were developed based on medical images and compared this to absorption in the SAM phantom exposed to radiation from a mobile phone antenna [12,[16][17][18][19][20]. Some studies comparing the peak local SAR in the MRI-based head models from adults and children have found either no significant difference or a statistically higher peak SAR in the larger (adult) head [12,16,17].…”

“…Wiart et al [18] reported that the peak 1-g SAR in the brain tissues of models of children aged between 8 and 15 years is comparable to that of adult models, while it is about two times higher for models of children aged between 5 and 8 years, due to the smaller thicknesses of the pinna, skin, and skull.…”