SAR Exposure From UHF RFID Reader in Adult, Child, Pregnant Woman, and Fetus Anatomical Models

Abstract

The spread of radio frequency identification (RFID) devices in ubiquitous applications without their simultaneous exposure assessment could give rise to public concerns about their potential adverse health effects. Among the various RFID system categories, the ultra high frequency (UHF) RFID systems have recently started to be widely used in many applications. This study addresses a computational exposure assessment of the electromagnetic radiation generated by a realistic UHF RFID reader, quantifying the exposure levels in different exposure scenarios and subjects (two adults, four children, and two anatomical models of women 7 and 9 months pregnant). The results of the computations are presented in terms of the whole-body and peak spatial specific absorption rate (SAR) averaged over 10 g of tissue to allow comparison with the basic restrictions of the exposure guidelines. The SAR levels in the adults and children were below 0.02 and 0.8 W/kg in whole-body SAR and maximum peak SAR levels, respectively, for all tested positions of the antenna. On the contrary, exposure of pregnant women and fetuses resulted in maximum peak SAR10 g values close to the values suggested by the guidelines (2 W/kg) in some of the exposure scenarios with the antenna positioned in front of the abdomen and with a 100% duty cycle and 1 W radiated power.

http://onlinelibrary.wiley.com/doi/10.1002/bem.21789/abstract

(My note: the ICNIRP guidelines are weaker than those adopted by the U.S. so the peak values may have exceeded U.S. guidelines.)

Excerpts

Radio frequency identification (RFID) is one of the most pervasive technologies making use of electromagnetic radiation in the RF band. RFID devices are typically used
close to the body

An RFID system is based on the communication between two devices, a reader unit and a tag. In a passive ultra high frequency (UHF) RFID system, investigated in this study, the reader transmits a modulated RF signal to the tag, consisting of an antenna and an integrated circuit chip powered only by the received RF energy. It responds via the modulation of its backscattering aperture (or radar cross section) linked to its input impedance. Thus, the reflection of electromagnetic waves is used for the transmission of data from the reader to the tag and vice versa

North and South America in the frequency band 902–928 MHz

The present work aims at addressing the near-field exposure assessment of the EMF generated by an RFID reader antenna operating in the UHF band in anatomical models of adult, children, and pregnant women at different gestational ages and their respective fetuses, considering various RFID reader exposure scenarios

In this study, the exposure assessment of a UHF RFID system operating in the European UHF RFID frequency range was explored. All the results were normalized to 1 W radiated power and a duty cycle of 100%.

The great variety of RFID applications and the corresponding reader models make extending the results of this study to any RFID exposure situation impossible.

CONCLUSIONS

This article represents the first attempt to address an EMF near-field exposure assessment due to a typical patch antenna of a UHF RFID reader in adults, pregnant women, and children. The great flexibility of these devices allows their diffusion in a great number of general purpose applications and, as a consequence, it involves people diversified in gender and age.

The highest exposure values in terms of the psSAR10 g values were found in the pregnant women, where levels close to the existing exposure guidelines [ICNIRP, 1998] for 1 W antenna radiated power and 100% duty cycle could suggest a deeper investigation.

Leave a Reply