1. Protons for Breakfast
Are Mobile Phones Safe?
Week 5
March 2013

2. In the event of…In the event of a new ice age…

3. This evening…
0. The Media!
1. How do mobile phones work?
What is the hazard?
2. How do electromagnetic waves interact
with matter?
3. SAR
• Microwave Ovens
• Mobile Phone
4. Are mobile phones safe?

4. The word ‘radiation’
• The word ‗radiation‘ means
Anything which ‘radiates’ on ray-like paths
• Could be
Sound
Radio
Light
Infra-red light
Particles or waves emitted from the nuclei of atoms
Nuclear Radiation

5. Media

6. Media

7. Sunday, 20 January 2008
It also complements other recent research.
A massive study, following 1,656 Belgian
teenagers for a year, found most of them
used their phones after going to bed. It
concluded that those who did this once a
week were more than three times – and
those who used them more often more than
five times – as likely to be "very tired".

8. 1. How do mobile phones work?

9. Magic?
Any sufficiently advanced technology
is indistinguishable from magic
Arthur C. Clarke

10. Not magic
• Mobile Phones are ‗radio‘
phones
• Operating at microwave
frequencies
• Handset power minimised
by having a network of
local transmitters and
receivers
• 52,500 base stations in UK
Roughly
hexagonal cells
Mast
• Each colour represents a
base station operating at a
slightly different frequency

11. Mobile Phones (3)
Recognise the masts?
• Each cell has a transmitter and receiver mast
• Notice the typical three way structure

12. 3G Masts
Photo Credit Brighton and Hove Green Party

13. Linking to base stations
• Mast power between
60 watts and 120 watts
• Handset power
less than 1 watt
• Handset sends signals
every few minutes to
establish which is the
nearest mast
• A central computer
• keeps track of all the telephones that are switched on
• remembers which cell they are in

14. Making a mobile-to-mobile call
Its complicated!
Network Control
Knows in which cell
every telephone is
Originating
Telephone
Receiving
Telephone

15. 2G or GSM phone
Hello! How are you?
Sound
217 pulses of encoded sound every second
No sound: No signal
Encoding to Radio Signal
Hello! How are you?
Peak Power
2 W Maximum
Average power is
0.25 W Maximum
Global System for
Mobile Communications

16. 2G or GSM phone
Base station
Transmitter
Frequencies
(MHz)
Handset
Transmitter
Frequencies
(MHz)
Peak
Handset
Power
(Watts)
Originally
licensed to
GSM900 935 - 960 890-915 2
O2 (Tesco)
Vodafone (Asda)
GSM1800 1805-1880 1710-1785 1
Orange
T Mobile (Virgin)

17. Anatomy of a GSM Signal

18. 2G or GSM phone
217 Pulses per second per telephone call
217 Pulses per second
Each frequency channel can carry 7 calls

19. Safety
• The safety issues surrounding mobile phones
concern…
• the interactions of the microwaves emitted by
mobile phones
base stations
with human tissue 6 degrees
50 m to 200 m

20. And its not just mobile phones!
• ‗WiFi‘ Wireless Networking
• Bluetooth devices
• Wireless keyboards and mice
• DECT cordless phones
• Baby Monitors
• ‗Walkie Talkie‘
• All involve electromagnetic
waves in the radio and
microwave part of the
spectrum

21. 2. How do electromagnetic waves
interact with matter?
?

22. Electromagnetic spectrum
1 101 102 103 104 105 106 107 108 109 1010 1011
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022
Radio & TV
Infra Red
Microwaves
Gamma-
Rays
X-Rays
Ultra
Violet
Microwaves
0.8 GHz
to
1000 GHz
Non-ionising
Radiation
(generally not so bad)
Ionising
Radiation
(generally bad)
Frequency (Hertz)

23. Waves & Matter
• When an electromagnetic wave interacts with matter…
Some absorption
Some reflection
Some transmission

24. Summary
• Electromagnetic waves interacting with matter can be
Reflected, absorbed or transmitted
• What happens depends on
the frequency of the electric field
the natural frequencies of the atoms and molecules
• Microwaves emitted by mobile phone systems
Are absorbed by human tissue

25. 1 101 102 103 104 105 106 107 108 109 1010 1011
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022
Radio & TV
Frequency (Hertz)
Microwaves
Infra Red
Ultra
Violet
X-rays
Gamma
Rays
Electrons in Atoms
Protons in
nucleus
Atoms in
solids or
molecules
Entire molecules or
parts of molecules
Lighter particles
Stronger forces
Waves
What vibrates?

26. Absorption demo
Frequency
•Well below the natural frequency
•Not much absorption
•Well above the natural frequency
•Not much absorption
•Near the natural frequency
•Absorption

27. Waves & Matter
• When electromagnetic waves are ‘absorbed’ …
• Atoms jiggle faster:
i.e. increase their temperature.
Heat
Electricity
Electromagnetic waves
Atoms

28. 3. How much energy gets absorbed?
S.A.R.
Specific Energy Absorption Rate

29. Terminology
• Power
watts
• Intensity
watts per square metre
• Specific energy Absorption Rate (SAR)
watts per kilogram

30. • 1 cm from 20 W source
20 W absorbed in hand
Intensity 8000 watts per square metre
SAR 200 watts per kilogram
• 10 cm from 20 W source
2 W absorbed in hand
Intensity 200 watts per square metre
SAR 20 watts per kilogram
• 1 metre from 20 W source
0.02 W absorbed in hand
Intensity 5 watts per square metre
SAR 0.2 watts per kilogram
SAR: Example using light
rather than microwaves

31. Microwave Hazard
The potential hazard from mobile phones and other
wireless devices arises from
the absorption of microwave radiation
Mobile phones
• only emit a watt or two
• so little power it makes
experiments difficult
Microwave ovens
• emit a few hundred watts
• makes experiments easy

32. Microwave Ovens
3a. Microwave ovens

33. Electromagnetic spectrum
1 101 102 103 104 105 106 107 108 109 1010 1011
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022
Radio & TV
Infra Red
Microwaves
Gamma-
Rays
X-Rays
Ultra
Violet
Microwaves
Conventional Oven
200 °C
Microwave Oven
2.45 GHz

34. 0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.01 0.1 1 10 100
Absorbtion
Frequency
Absorption of microwaves by liquid water
• Well below the natural
frequency
• Not much absorption
• Well above the
natural frequency
• Not much
absorption
• Near the natural
frequency
• Absorption
2.45 GHz

35. Absorption (1)
Too strong
• If power were absorbed too strongly,
Microwaves would only penetrate a short distance
Surface would be heated
Inside would remain uncooked
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.01 0.1 1 10 100
Lossofenergyinwaterat0C
Frequency (GHz)
Microwave ovens
operate at
2.45 GHz

36. Absorption (2)
Too weak
• If power were absorbed too weakly,
Microwaves would go right through
No cooking
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.01 0.1 1 10 100
Lossofenergyinwaterat0C
Frequency (GHz)
Microwave ovens
operate at
2.45 GHz

37. Absorption (3)
• If power is absorbed just right,
Microwaves penetrate about 5 cm (2 inches)
Cooks the outer 5 cm of the food
Good enough for most cases
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.01 0.1 1 10 100
Lossofenergyinwaterat0C
Frequency (GHz)
Microwave ovens
operate at
2.45 GHz

38. Microwave Ovens
Summary
• A microwave oven cooks food by heating it
• The heating comes from
• intense waves at 2.45 GHz
• (Instead of a wide spectrum of waves at infra red frequencies)
Frequency chosen because of absorption properties of water
molecules at that frequency.

39. Microwave Ovens
Inside a microwave oven

40. Microwave Power
• Power
– This is a 700 watt oven
– Think of 7 x 100 watt light bulbs

41. Microwave Electric field
• 700 watts
– Around 140 000 volts per metre
– Look what happens to a CD

42. Microwave Intensity
– Between 104 to 105 watts per square metre
– (Most intense sunlight around 103 watts per square metre)
– Very Dangerous
Could I have a
stupid volunteer
please?

43. Microwave Oven
SAR inside oven
• 700 watts absorbed in 1 kg of water:
– SAR = 700 watts per kg
• Question: After 1 minute, how hot would your
brain become if subject to an SAR of 700 watts
per kg?

44. Experiment

45. Microwave Ovens
Comparison with handsets
SAR Watts
per kilogram
Temperature
Rise in 1 kg of
‘Brain Fluid’
Microwave 700 8 ºC (ish)
Mobile Phone 1 Can‘t be measured directly
Expect 1/700 of microwave temperature rise
The effects of blood flow reduce this further
0.01 °C (ish)

46. Back to Mobile Phones
3b. Mobile Phone SAR

47. New StyleOld StyleMobile Phones (14)
SAR and Safety

48. Mobile Phones (8)
Your telephone
• Look in the small print!

49. Typical SAR with phone near the head
• SAR Averaged over 10 grams
• By law must be less than 2 watts per kilogram
Power Intensity Maximum
SAR
Watts Watts per
square metre
Watts
per kilogram
1 200 1
• Typical figures

50. Base Station SAR

51. Base Stations
• Power
6 degrees
50 m to 200 m

52. Base Station Information
http://www.sitefinder.ofcom.org.uk/

53. EIRO
Equivalent
isotropic
Radiated
Output
Actual Pattern of
Emitted Radiation
60 W
How this is specified

54. Mast near my children’s old school
Power
• 30 dBW
• 1000 W
• Equivalent isotropic
Radiated Output
• 60 W to 120 W in
actual power
1000 W
EiRO
Actual Pattern of
Emitted Radiation
0.3
Watts per square metre
0.01
Watts per square metre
SAR 0.001
Watts per kilogram

55. Comparison of handsets
and base stations
• Base station SAR is extremely low
but you can‘t choose whether you want it or not!
Power Intensity Maximum
SAR
Watts Watts per
square metre
Watts
per kilogram
Handset 1 200 About 1
Base Station 60 0.01 About 0.001

56. Wireless Networking
• WiFi
802.11(b), 802.11(g), 802.11(n)
• Operates at 2.4 GHz
Power Intensity
(at 1 metre)
SAR
(at 1 metre)
Watts Watts per square
metre
Watts
per kilogram
0.1 Less than 0.01 About 0.0001

57. Comparison of handsets
and base stations and wi-fi
Power Intensity Maximum
SAR
Watts Watts per
square metre
Watts
per kilogram
Handset 1 200 About 1
Base Station 60 0.01 About 0.001
Wi Fi 0.1 < 0.01 About 0.0001

58. 4. Are Mobile Phones Safe?

59. SAR and Safety
Health Protection Agency
• Based on ICNIRP guidelines
http://www.icnirp.de/documents/emfgdl.pdf
International Commission on Non-Ionising Radiation Protection
determines what we believe is safe
• How do they do that?
• They determine a borderline safe level
• Divide by 10 for occupational exposure
• Divide by another factor 5 for general public exposure

60. What are the risks?
• Basic safety assumption is that the main effect of
exposure to microwaves is thermal
• Are there ‘non-thermal’ effects?
If so are they harmful?
Normal thermal vibrations are much larger than
vibrations induced by microwaves emitted by
mobile phones.
• Question of safety must be resolved by experiment
Experiments are very hard

61. Are mobile phones safe?
Stewart Report
• A group of non-industry related experts
Gave rise to MTHR
Mobile Telecommunications and Health Research
• ONGOING Research Program
• Funded 50:50 government & industry

62. Stewart Report
Mobile Phones and their
networks are ‘pretty’ safe
There may
be ‘effects’
Precautionary
Approach:
More research
please
Children Driving

63. Mobile Phones
Suppose we discovered ‘an effect’:
What might it look like?
Nora D. Volkow, Dardo Tomasi, Gene-Jack Wang, Paul Vaska, Joanna S.
Fowler, Frank Telang, Dave Alexoff, Jean Logan, Christopher Wong,
Effects of Cell Phone Radiofrequency Signal Exposure
on Brain Glucose Metabolism
Journal of the American Medical Association, February 23, 2011—Vol 305, No. 8

64. PET Scan
This device can see you think!
Glucose metabolism in this area appears
to have been affected

65. What could we do?
What should we do?
In smaller groups
• Please come up with some
questions, and suggestions
• We will gather these together and
then ask the experts
You decide!

66. On-line
Resources
• www.protonsforbreakfast.org
This PowerPoint ™ presentation.
Handouts as a pdf file
• blog.protonsforbreakfast.org
Links to other sites & resources
Me going on about things

67. See you next week to
discuss Nuclear
Power
Goodnight

68. Mobile Phones
Unused Slides

69. Perception of risk
Risk is expressed mathematically,
but our judgement of risk is not mathematical
More willing
to take risk
Less willing
to take risk
Example
Benefits Direct Indirect
Base Stations/
Mobile Phones
Technology Familiar Unfamiliar
Cars/
Mobile Phones
Exposure Voluntary Involuntary
Base Stations/
Mobile Phones
Exposure Fair Unfair
Poverty/
Wealth
Exposure Personal Control
No Personal
Control
Driver/
Pedestrian
Consequence Not Dreaded Dreaded
Cancer/
Broken bone

70. Electromagnetic
waves
Electricity
Heat
How it all fits together…
Atoms

71. A Cautionary Tale
Don’t try this at home!
August 14, 2002 I don't want to sound like I know everything in the world or
even like I know quite a lot. But you had a question regarding ―If a microwave
oven door were to open while it was still on, what would happen? Could it hurt
you?- JP‖ Well ..Having the thought process that I have, kinda how should I put
it? ...Stupid? or inventive or even in-between. Well, my microwave door did
happen to come off. Magic Chef 900-watt microwave. Well, I did my best to try to
fix it but the hinge on one side did not attach properly, therefore having a gap
between the door and the appliance. Being me (stupid) I wondered if it would
burn fast or would it gradually warm up. I slid my finger between...You probably
dying to hear what happened... But it didn't gradually warm up at all. It was
instant heat! It didn't scar me or anything like that, but sure scared the H*** out of
me to find out it got so hot so quick. I didn't get any blisters either. But it just
burned like touching something hot on the tip of my finger being that is the only
thing I put in. Well you know the old adage, "You learn from your
mistakes", stands true. lol -

72. Mobile Phones
Suppose we discovered ‘an effect’:
What might it look like?
R Luria, I Eliyahu, R Hareuveny, M Margaliot, N, Meiran
Cognitive Effects of Radiation Emitted by Cellular Phones:
The influence of exposure side and time
Biolectromagnetics 30: 198-204 (2009)
Possibility#1

73. No Match
Click with Left Hand


 

74. Match
Click with Right Hand
 


75. Task Completed with
Phone
On LEFT
On RIGHT
OFF

76. RESULTS
700
750
800
850
900
950
1000
1050
1100
1 2 3 4 5 6 7 8 9 10 11 12
SHAM
LEFT EXPOSURE
RIGHT EXPOSURE
ResponseTime:milliseconds
Block
LEFT HAND RESPONSE
'No Match' RESPONSE
700
750
800
850
900
950
1000
1050
1100
1 2 3 4 5 6 7 8 9 10 11 12
SHAM
LEFT EXPOSURE
RIGHT EXPOSURE
ResponseTime:milliseconds
Block
RIGHT HAND RESPONSE
Match RESPONSE
1 hour 1 hour

77. RESULTS
With Uncertainty
700
750
800
850
900
950
1000
1050
1100
1 2 3 4 5 6 7 8 9 10 11 12
SHAM
LEFT EXPOSURE
RIGHT EXPOSURE
ResponseTime:milliseconds
Block
LEFT HAND RESPONSE
'No Match' RESPONSE
700
750
800
850
900
950
1000
1050
1100
1 2 3 4 5 6 7 8 9 10 11 12
SHAM
LEFT EXPOSURE
RIGHT EXPOSURE
ResponseTime:milliseconds
Block
RIGHT HAND RESPONSE
'Match' RESPONSE
Only these two points have statistical significance

78. What could we do?
• Ban mobile phones ?
The ‗Precautionary principle‘
Could there be some harm caused?
How many lives are saved by mobile phones?
• Reduce mobile phone power ?
Increase the number of mobile phone masts
• Reduce mast power ?
Increase the mobile phone handset power
Increase the number of masts
• Ban mobile phone use while driving ?
Done: has it been effective?
• Nothing ?