Autores

Budak GG, Muluk NB, Budak B, Oztürk GG, Apan A, Seyhan N. Effects of intrauterine exposure to GSM-like radiofrequency on distortion product otoacoustic emissions in infant male rabbits. Int J Pediatr Otorhinolaryngol Ahead of print Dec 22, 2008

Background
Possible adverse health effects of exposure to electromagnetic radiation, especially the question of whether there exists a special vulnerability of children, have been a subject of debate during the last two decades. Potential hazardous effects of 1800 MHz radiofrequency radiation (RFR) similar to that emitted by GSM mobile phones on cochlear functions of infants is a very important issue, which has not been thoroughly investigated to date.

Objective
The aim of the study was to investigate potential hazardous effects of intrauterine (IU) and/or extrauterine (EU) exposure to 1800 MHz GSM-like radiofrequency radiation on cochlear functions of infant rabbits by distortion product otoacoustic emission (DPOAE) recordings.

Methods
Thirty-six 1-month old white male New Zealand rabbits were randomly divided into four groups: Group 1: 9 infant rabbits were not exposed to 1800 MHz GSM-like RFR (Control – C); Group 2: 9 infant rabbits were exposed to 1800 MHz GSM-like RFR, 15 minutes daily/14 days after they reached 1 month of age (Extrauterine - EU); Group 3: 9 infant rabbits were exposed to 1800 MHz GSM-like RFR, 15 min daily/7 days in the intrauterine period (between 15th and 22nd days of the gestational period) (Intrauterine-IU); Group 4: 9 infant rabbits were exposed to 1800 MHz GSM-like RFR, 15 min daily/7 days in the intrauterine period (between 15th and 22nd days of the gestational period) and 15 min daily/14 days after they reached 1 month of age (IU+EU). The cochlear functions were assessed by measuring distortion product otoacoustic emission (DPOAE). At each DPOAE frequency (1.0; 1.5; 2.0; 3.0; 4.0; 6.0; 8.0 kHz) the difference between the DPOAE amplitudes (decibel, dB) of groups 1, 2, 3 and 4 was analyzed.

Results
DPOAE amplitudes for the frequencies 1.0 – 8.0 kHz of groups 1-4.

Groups

DPOAE results (dB)

 

1.0 kHz

1.5 kHz

2.0 kHz

3.0 kHz

4.0 kHz

6.0 kHz

8.0 kHz

Group 1 (C)

4.51

10.01

19.66

28.15

33.24

32.69

33.12

Group 2 (EU)

4.82

11.91

17.77

24.17

27.40

27.50

29.35

Group 3 (IU)

9.41

19.15

21.70

32.28

36.92

32.41

32.50

Group 4 (IU+EU)

10.31

20.22

23.28

32.28

38.60

33.13

31.01

p

0.062

0.000

0.004

0.000

0.000

0.002

0.125

Statistically significant differences between the groups in DPOAE amplitudes were present at all frequencies except 1.0 and 8.0 kHz. The p-values for the inter-group differences at frequencies 1.5 – 6.0 kHz are presented by the authors in the following table:
Wilcoxon Signed-Ranks with Bonferroni correction results at 1.5-6.0 kHz.


Groups

p value

 

 

 

 

 

1.5 kHz

2.0 kHz

3.0 kHz

4.0 kHz

6.0 kHz

Groups 1 and 2

0.157

0.499

0.016

0.003

0.001

Groups 1-3

0.004

0.327

0.028

0.028

0.210

Groups 1-4

0.006

0.055

0.012

0.005

0.068

Groups 2-3

0.010

0.074

0.020

0.022

0.039

Groups 2-4

0.004

0.003

0.001

0.000

0.000

Groups 3 and 4

0.760

0.472

0.145

0.433

0.570

Interpretation and conclusion
The results of this study indicate that exposure to 1800 MHz GSM-like RF during intrauterine period increases the DPOAE amplitudes. If the exposure occurs during the extrauterine period, it decreases the DPOAE amplitudes. Research has suggested that exposure to mobile phones (900 MHz or 1800 MHz) with their maximum allowed antenna powers increases the temperature in the air canal as a consequence of mobile phone battery warming during maximum antenna power use. There has been no indication in earlier studies of any significant contribution of RF fields emitted by mobile phones into the temperature rising in the ear canal. The authors have concluded that prolonged exposure and hyperthermia related to the power density of applied RF, increasing the temperature in the air canal, may affect DPOAE amplitudes. Harmful effects of RF are mainly observed as a decrease in DPOAE amplitudes at 4.0-6.0 kHz during extrauterine exposure in infancy. During the intrauterine period, the water content of the middle and inner ear and amnion fluid may play a protective role. Therefore, children must be protected from RF exposure. The use of mobile phones at short distances from the ear of infants should be avoided because of the lower thickness of the anatomical structure in infancy.



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