Biological Aspects of Mobile Communication Fields

1. Biological Aspects of Mobile Communication Fields Presentation by Parag Tengshe under the guidance of Dr. Yeong Kim

2. Introduction • Wireless communication service is the two way radio communication using RF • Exposure to RF and microwave energy emitted by telecommunication devices • Continuous but very low exposure from base station to the whole body • Intermittent and more intense exposure from the handset to the head • Need to understand the biological effects of RF electromagnetic field

3. Electromagnetic Radiation (EMR) • Consists of electric and magnetic field • Interaction of these fields with matter determining the effects of EMR • Mobile phone system operating at about 900 and 1800 MHz for GSM and 800 MHz for CDMA can be referred as both microwave radiation and radio frequency radiation.

5. Base Station • Different cells using different frequencies to prevent interference • Large number of antennas does not mean greater RF exposure as maximum power will be transmitted when all users operating at the same time

6. The Mobile Phone • CDMA phone average transmission power 200mW while GSM digital phone average transmission power is 250mW • Lower exposure of CDMA compared to GSM

7. Interaction of RFR with Matter • RF radiation absorption causing molecules to vibrate, resulting in heating • Thermal effect –basis for determining health hazard from RF exposure • Distance within a wavelength from a RF transmitter is known as near field • GSM(900 MHz) near field region is 30cm • User’s head disturbs the field and alters the manner in which RFR interacts with tissues • This interaction causes complicates the absorption of RF energy and makes calculations difficult

8. Absorption Of RFR From Mobile Phone • RF absorption in the head from a mobile phone held next to the left ear • Green region represents peak absorption and corresponds to peak SAR of 2-3W/kg • SAR of 4W/kg associating with 1 degree temperature rise

9. Exposure to RFR By Base Station • RFR power emitted from a base station varies from one site to another • Graph about variation of power density with distance from base station • Peak value is 0.1µW/cm. Maximum allowed exposure is 500µW/cm

10. Biological Effects of RFR • Cancer induction and promotion • Nervous system effects--blood-brain barrier (BBB) permeability changes • Nervous system effects-the microwave auditory effect • Cataractogenic and other effects on ocular system • Epidemiology and human studies

11. Cancer Induction And Promotion • Exposure to 915 and 2450 MHz promoting tumor growth in animals only if tumor is first initiated by other means • Modest changes in proliferation of human glioma cells following 2-hr of exposure to 2450 MHz at 5 W/kg • Acute(2-hr) whole body exposure to 2450 MHz microwaves, causing DNA damage in brain cells of rats. • An increase in single and double strand DNA breaks after exposure to either pulsed or CW radiation for 4 hours and SAR was 1-2 W/kg

12. Continued… • Relatively high SARs used for the experiments (6-12 W/kg) that were known to cause appreciable temperature increase • In another experiment, pulsed microwave exposure for 25 months caused significant malignancies in rats • Continuous exposure did not reveal any significant effects on general health in rats

13. Continued… • Frequencies and modulations specific to mobile phone(915 MHz RF fields) did not show any significant difference in tumor growth between microwave and sham exposed rats • Prolonged exposure to mobile phone microwave fields did not promote growth of either the faster or slower growing gliomas beyond their normal course.

14. BBB Permeability Changes • Several experiments using high and low levels of microwave exposures showing microwave-induced increase in BBB permeability • Other studies not finding any microwave-induced disruption of BBB • Effect of microwave radiation on BBB permeability remains controversial

15. Continued… • Barrier permeation appears to have been observed at all levels of RF including those at extremely low level (0.016 W/kg) • Possibility of increase in temperature of brain to 42˚C or higher at high SAR (165 W/kg) • Above conclusion is supported by heating of the rat’s brain by conventional means causes disruption of the BBB

16. The Microwave Auditory Effect • Pertains to the auditory sensation of radar-like pulses by humans and laboratory animals • The effect occurring at power density threshold of 400mJ/m for a single microsecond wide pulse of 2450 MHz • Microwave exposure across a wide range of frequencies (1245-3000 MHz) causing the effect

17. Continued... • Little data regarding the effect on the middle and inner ears hearing apparatus or central nervous system from exposure to microwave pulses • No proper investigation of any health effect regarding exposure to pulsed microwave radiation • Current research using RF radiation from mobile phone operations may provide some insight

18. Cataractogenic And Other Effects On Ocular System • Concern regarding formation of cataracts due to microwave • Production of lens opacities in the eyes of laboratory animals following acute microwave exposure • Subject of debate regarding the conditions under which higher levels of CW radiation causes lens opacification

19. Continued… • One of the most intensively investigated frequency is 2450 MHz, used for WLANs • Lens opacities found in rabbits when exposed to near field of 2450 Mhz CW microwaves with SAR of 138 W/kg • No cataract found in rhesus monkeys when exposed to different SAR level. • Isolated rat lenses produced histopathological damages at the lens equator with high power 918 MHz pulses of 10-microsecond width • 4.7 times greater damage than CW radiation

20. Continued… • Ultrastructural degeneration of retinal neurons observed in rabbits at power level of 55 mW/cm • Corneal lesions found in juvenile monkeys kept under anesthesia after 4-hr/day exposure to 2450 MHz microwaves (pulsed and CW) • No corneal abnormalities reported when monkeys were not anesthetized

21. Epidemiology And Human Studies • Epidemiology offers a valuable investigation tool to access the potential association between cancer and exposure to electromagnetic energy • Case reports of cataracts in humans following accidental exposure to microwave radiation • No association found between military microwave operation and cataract • No effect of microwave exposure on growth and development of children

22. Continued… • No evidence of higher mortality in the Moscow Embassy personnel who were exposed to microwave radiation • High exposure cohorts and low exposure cohorts from US Navy personnel did not reveal any difference in the mortality rate • Difficulty in above studies is the uncertainty in accessing actual exposure to large numbers of people

23. Continued…(Brain Tumor Risk) • Relative risk for brain tumor elevated to (RR=1.6) among all males exposed to RF and microwave radiation • Excess risk of (RR=2.3) for RFR associated with jobs involving design, installation, maintenance or manufacture of electrical or electronic equipment • No increase in brain tumor risk who have never worked in electrical or electronic jobs

24. Continued… • Increased mortality reported for certain cancers like brain tumor(1.4), leukemia(1.8) and cancer in some lymphatic tissues(1.6) when exposed to stronger RF field • Relative risks of children for some cancers were not elevated if they lived within 3.5 km of a microwave tower in San Francisco • The case study regarding the relation between RF exposure and brain tumor risk of males in US Air Force between 1970-89 is weakened by small numbers and lack of exposure assessment i.e. dosimetry data

25. Further Epidemiological Studies • Difficult to demonstrate conclusively that RFR exposure is not a health hazard • What is happening in the human brain remains an absolute enigma • No direct relation between a biological effect in cells in the lab and a health effect

26. Conclusion • Agreement in studies about induction of higher SARs by microwave exposure • Rising of brain temperature to 42ºC or higher at sufficiently high SAR • Increase of BBB permeability • Only small number of case reports of cataracts in humans following accidental exposure • Microwave auditory effect is a high power phenomenon occurring at low average power

27. Continued… • Lack of investigation corresponding exposure to pulsed microwave radiation over prolonged time • Controversy on the effects of RFR on BBB permeability and lens ultrastructure at low SAR levels • Many reports suffering from a lack of realistic measures of RFR results in reducing usefulness for risk analysis • Urgent need for epidemiological studies of RF effects on mobile phone users

28. Continued… • Well established fact that RFR can produce deleterious biological effects at sufficiently high power levels • Available data does not suggest any immediate cause for concern of an impending threat to the health of humans • Need for answering specific questions before dependable scientific conclusions • Investigation to answer some of the questions has already begun • Quantitative information required for extrapolation from animal experimentation to human response

29. How can the Potential Risks Be Reduced? • Limiting the use of mobile phones both in terms of number of calls and call duration • Avoiding the use of mobile phones in enclosed spaces • Holding phone away from your ear • Using ‘hands free’ mobile phone kits and RFR shielding devices • Purchasing mobile phones with lower power outputs

30. References • Biological aspects of mobile communication fields – James C. Lin • www.arpansa.gov.au – The Mobile Phone System and Health Effects • www.globalchange.com

31. Thank You