2007, Piran, Slovenia

Environmental Ergonomics XII
Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007
548
CHANGES IN TYMPANIC TEMPERATURE DURING THE
EXPOSURE TO ELECTROMAGNETIC FIELDS EMITTED BY
MOBILE PHONE
Alicja Bortkiewicz 1 , Elzbieta Gadzicka 1 , Wieslaw Szymczak 2
1 Department of Work Physiology and Ergonomics,
2 Department of Environmental Epidemiology,
Nofer Institute of Occupational Medicine, Lodz, Poland
Contact person: alab@sunlib.p.lodz.pl
INTRODUCTION
Mobile phones generate microwave radiation in the 450-1800 MHz frequency range. The
electromagnetic fields at these frequencies penetrate exposed tissues which absorb EMF energy.
This energy is converted thereafter into heat. The parameter used for assessment of the
absorbed EMF energy is the specific absorption rate (SAR) that can be averaged over the
whole body or a particular organ or tissue. For hand-held radiotelephones used by the general
public, International Commission on Non-Ionizing Radiation Protection (ICNIRP)
recommends that the localized SAR in the head be limited to 2 W/kg averaged to 10 g tissue
(ICNIRP 1998). This limit should protect telephone users from the thermal effect of radiation,
but it is worth noting that those limits have been based on phantom studies, while human
results are not available. Although the exposure due to mobile phone use is below the
admissible maximum values specified in the relevant standards, a lot of mobile phone users
complain about heating and sensation of warmth around the ear (Oftedal et. al., 2000). Also skin
temperature measurements over the phone use area revealed elevated temperature. Experimental
studies show that skin temperature in the area of the ear of a person using mobile phone
increases by 2.3 degrees C to 4.5 degrees C (depending on mobile phone type) (Anderson and
Rowley, 2007, Straume et al. 2005). It remains to be seen whether the use of mobile phones may
lead to changes in the brain temperature. The studies on SAR and temperature in the head have
so far been carried out only as phantom experiments. They revealed temperature increase
ranging from 0.08 0 – 0.16 0 C. However, these studies did not consider the role of the
thermoregulatory system which may significantly affect the actual temperature of the brain
(Bernardi et al. 2000, Weinwright 2000). The aim of our experiment was to assess the core
temperature during exposure to EMF emitted by mobile phone in different exposure
conditions. This problem has not been satisfactory clarified yet.
METHODS
The volunteers taking part in the study were 10 young, healthy men aged 19-29 ys, mean age
22.1 ±4.7 y. Their mean height was 179.5 ±5.8 cm, mean weight 69.5 ±7.6 kg and body mass
index (BMI) 21.5 ±1.53 kg. The subjects gave their written informed consent to take part in
the study and had a medical examination performed before the experiment. This has not
revealed any abnormal findings. The study protocol was approved by the regional Biomedical
Ethics Committee. During the experiment, performed in wintertime, the subjects were
wearing a normalized, cotton clothes (long-sleeved shirt and trousers). The experiment was
performed in laboratory, under strictly controlled climatic conditions: ambient temperature
and relative humidity were maintained at 24 0 C and 70%, respectively. The study was doubleblind,
randomized design. Each subject underwent three sessions: (1) on a day without
exposure (control conditions), (2) on a day with continuous exposure (60 min exposure from
mobile phone), and (3) on a day with intermittent exposure (4x15 min “on” and 4x15 min
“off”). The subjects had not used a mobile phone for at least a week before each experimental
day. Since it was necessary to eliminate the influence of the possible stress caused by talking