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 ( 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 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
– The Mobile Phone System and Health Effects

31. Thank You