Assessment of the Magnetic Field Exposure Due to the Battery Current of Digital Mobile Phones

Abstract

Hand-held digital mobile phones generate pulsed magnetic fields associated with the battery current. The peak value and the waveform of the battery current were measured for seven different models of digital mobile phones, and the results were applied to compute approximately the magnetic flux density and induced currents in the phone-user's head. A simple circular loop model was used for the magnetic field source and a homogeneous sphere consisting of average brain tissue equivalent material simulated the head. The broadband magnetic flux density and the maximal induced current density were compared with the guidelines of ICNIRP using two various approaches. In the first approach the relative exposure was determined separately at each frequency and the exposure ratios were summed to obtain the total exposure (multiple-frequency rule). In the second approach the waveform was weighted in the time domain with a simple low-pass RC filter and the peak value was divided by a peak limit, both derived from the guidelines (weighted peak approach). With the maximum transmitting power (2 W) the measured peak current varied from 1 to 2.7 A. The ICNIRP exposure ratio based on the current density varied from 0.04 to 0.14 for the weighted peak approach and from 0.08 to 0.27 for the multiple-frequency rule. The latter values are considerably greater than the corresponding exposure ratios 0.005 (min) to 0.013 (max) obtained by applying the evaluation based on frequency components presented by the new IEEE standard. Hence, the exposure does not seem to exceed the guidelines. The computed peak magnetic flux density exceeded substantially the derived peak reference level of ICNIRP, but it should be noted that in a near-field exposure the external field strengths are not valid indicators of exposure. Currently, no biological data exist to give a reason for concern about the health effects of magnetic field pulses from mobile phones.

Neurophysiological effects of mobile phone electromagnetic fields on humans: A comprehensive review

“…Moreover, together with the DTX component, it would be interesting to investigate the impact of three different battery voltages, corresponding to three different powers of emission (e.g., 2, .25, .125 W). As regards battery voltage, Jokela et al [2004] claimed that, in a case of real absorption, through small variations of current density measured with a simplified model of a human skull, the current density peaks may actually exceed the average density postulated by ICNIRP Guidelines [1998]. The characteristic pulsed aspect together with signal modulation operated by low frequencies emitted by the battery have been pointed out as disturbing factors possibly due to effects on the body's bioelectrical signals [e.g., Repacholi, 1998;Hamblin and Wood, 2002;Huber et al, 2002].…”

Numerical assessment of induced ELF Currents in the human head due to the battery current of a digital mobile phone

“…Some studies on other non-uniform sources, including a hair dryer and hair clipper [Gandhi et al, 2001], have been published. This study is a continuation of a recent work [Jokela et al, 2004], where fields from seven different GSM phones were measured and the exposure was approximated with a simple spherical model.…”

Environmental Electromagnetic Field and Female Fertility

“…Both types of field would induce biological effects, but magnetic field is more damaging because it penetrates living tissue more easily. Magnetic fields as low as around one microtesla can produce biological effects ( Goldsworthy 2007;Sage et al 2007;Jokela et al 2004 ). The effect of EMF on human health vary widely depending on the frequency and intensity of the fields.…”