Absorption of wireless radiation in the child versus adult brain and eye from cell phone conversation or virtual reality

Abstract

Children’s brains are more susceptible to hazardous exposures, and are thought to absorb higher doses of radiation from cell phones in some regions of the brain. Globally the numbers and applications of wireless devices are increasing rapidly, but since 1997 safety testing has relied on a large, homogenous, adult male head phantom to simulate exposures; the “Standard Anthropomorphic Mannequin” (SAM) is used to estimate only whether tissue temperature will be increased by more than 1 Celsius degree in the periphery. The present work employs anatomically based modeling currently used to set standards for surgical and medical devices, that incorporates heterogeneous characteristics of age and anatomy. Modeling of a cell phone held to the ear, or of virtual reality devices in front of the eyes, reveals that young eyes and brains absorb substantially higher local radiation doses than adults’. Age-specific simulations indicate the need to apply refined methods for regulatory compliance testing; and for public education regarding manufacturers’ advice to keep phones off the body, and prudent use to limit exposures, particularly to protect the young.

Introduction

With many nations having more mobile phones than people, and the rapidly increasing use of wireless transmitting devices by infants, toddlers and young children, it is important to consider children’s unique absorption of radiofrequency (RF), also called microwave (MW) non-ionizing radiation (Gandhi et al., 1996, de Salles et al., 2006, Wiart et al., 2008, Christ et al., 2010) and potential health impacts.

Standards for wireless devices have not changed since 1997, and are based on the assumption that the only adverse effect to be avoided is heat (Gandhi et al., 2012). Mobile phones are certified to be within RF radiation regulatory limits using robot-assisted determination of peak spatial Specific Absorption Rate (psSAR) – i.e. maximum dose rate – within a phantom of a large, adult male head and body, the Standard Anthropometric Mannequin (SAM). The plastic SAM head mold, filled with a homogeneous liquid to simulate dielectric characteristics of soft tissues at the frequency of the device being tested, is assumed to be valid for those with younger and smaller heads (U.S. Federal Communications Commission (FCC) Office of Engineering and Technology, 1997; IEEE International Committee on Electromagnetic Safety (SCC39), 2005), to test compliance with outdated standards set for exposure to the entire head. This ignores human anatomy, and the fact that the brain and eyes are target tissues where such radiation can be especially biologically important. Studies have consistently indicated that children’s brains absorb substantially higher peak doses than adults (Morris et al., 2015, Foster and Chou, 2016).

Anatomically-based, age-appropriate mathematical models of younger heads with thinner skulls and higher water content were used to examine specifics of psSAR averaging volume and dielectric constants within specific regions of the head. Specific regions include the eye and brain, to aid interpretation of international standards (Institute of Electrical and Electronics Engineers, 2013, Gosselin et al., 2014, Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz). International Commission on Non-Ionizing Radiation Protection, 1998, Peyman et al., 2009). Age-appropriate simulations are used to advance the understanding of the exposure of critical parts of the brain to RF radiation using models over a broad range of ages (from 3 to 34 years) (Fernandez-Rodriguez et al., 2015) from cell phones used against the ear, as well as in front of the face to view virtual reality (Google, n.d.).