Panagopoulos DJ, Margaritis LH. 2010. The effect of exposure duration on the biological activity of mobile telephony radiation. Mut. Res. 699:17-22.
The biological and health effects of pulsed radio-frequency (RF) electromagnetic radiation emitted by digital mobile telephony are well documented however; few studies have been conducted on the effects of the duration of exposure to this type of radiation, and the results of the studies that have been conducted are conflicting. The duration of exposure to any kind of external stimulus is an important parameter in determining whether the biological effects related to this stimulus are cumulative or not.
The objective of this study was to find out whether short-term exposure to digital mobile telephony radiation is cumulative or not and if it is, to what extent.
Drosophila melanogaster were used to explore the effects of different durations of a single (continuous) daily exposure to the two established systems of digital mobile telephony radiation that are commonly used in Europe, GSM 900MHz (Global System for Mobile telecommunications) and GSM 1800MHz. Twelve replicate experiments were conducted, six with GSM 900MHz radiation and six with GSM 1800MHz radiation. The insects were exposed to each type of radiation at an intensity of 10µW/cm2, corresponding to a distance of 20 or 30 cm from the antenna of a mobile phone handset. In each experiment, the insects were separated into six groups, each consisting of ten females and ten males, and were exposed to no radiation (sham group), 1, 6, 11, 16 or 21 minutes of RF radiation. Insects in each group were then mated and the effect on reproductive capacity (number of F1 pupae per maternal fly) was compared between groups.
The reproductive capacity of all the exposed groups was significantly decreased compared with the sham-exposed groups, for both radiation types and for all the exposure periods from 1 to 21 min (P<10-5). Reproductive capacity decreased almost proportionally as the exposure duration increased, for both types of mobile telephony radiation. The average decrease for the six experiments of each series compared with the sham groups, was 36.4% for 1 min exposure, 42.5% for 6 min, 49.2% for 11 min, 56.1% for 16 min, and 63.0% for 21 min for the for GSM 900 MHz exposure. Correspondingly, for GSM 1800 MHz, it was 35.8%, 41.8%, 49.0%, 55.8% and 62.4%.
Interpretation and Limitations
Both types of mobile telephone radiation decreased considerably the reproductive capacity of D. melanogaster, for all the periods of daily exposure and duration tested, although the intensity of radiation was only 10µW/cm2, which is much lower than the established ICNIRP limits of 450µW/cm2 and 900µW/cm2 for 900 and 1800 MHz, respectively. Reproductive capacity decreased almost linearly with increasing exposure duration suggesting that short-term exposures have cumulative effects on living organisms. It is unknown if longer-term exposures would result in an even higher decrease of reproductive capacity, or whether the effect would saturate after a longer duration of exposure. Future experiments are needed to explore this. Also, since insects are relatively less sensitive to radiation than other organisms such as mammals, future experiments should be conducted using other animal models.
This study suggests that exposure to mobile telephone radiation may have adverse health effects and it should be restricted by more rigorous exposure criteria. Since the radiation intensity in the present experiments was 45 and 90 times lower than the current exposure limits for 900 and 1800 MHz, respectively, the present results suggest a significant reduction of the current exposure limits are needed.