1. SYDNEY SCHOOL OF PUBLIC HEALTH
Interphone and beyond: Evidence
for harm or safety
(and managing mobile phone
fears)
Bruce Armstrong
Sydney School of Public Health

2. SYDNEY SCHOOL OF PUBLIC HEALTH
Principal objectives of Interphone
To investigate whether
• mobile phone use increases the risk of
tumours and
• whether RF fields emitted by mobile
phones are tumourigenic
INTERPHONE Study Group. Brain tumour risk in relation to mobile telephone use: results of the
INTERPHONE international case-control study. International Journal of Epidemiology 2010; 39: 675-94

3. SYDNEY SCHOOL OF PUBLIC HEALTH
A case-control study
• Cases – people aged 30-59 years in
defined populations with confirmed
– Cerebral glioma or meningioma
– Vestibular schwannoma
– (Parotid gland cancer)
• Controls – people of the same age
representative of those populations and
not cases

4. SYDNEY SCHOOL OF PUBLIC HEALTH
Mobile phone data collection
• Face to face or telephone interview,
occasionally by proxy
• Based on a mobile phone use “biography”

5. SYDNEY SCHOOL OF PUBLIC HEALTH
Dimensions
• 16 centres in 13 countries (excluding USA
and including Japan)
• Cases diagnosed between 2000 and 2004

6. SYDNEY SCHOOL OF PUBLIC HEALTH
Dimensions
Ascertained Participated Participation
%
Glioma 4,301 2,765 64
Meningioma 3,115 2,425 78
Vestibular
Schwannoma
1,361 1,121 82
Parotid gland
cancer
146 109 75
Controls 14,354 7,658 53
Total 23,277 14,078 60

7. SYDNEY SCHOOL OF PUBLIC HEALTH
Results for meningioma and glioma
Based on analyses of estimates of
cumulative use that exclude periods during
which a hands-free device was used.

8. SYDNEY SCHOOL OF PUBLIC HEALTH
Regular use
Any 1+ years before vs Never

9. SYDNEY SCHOOL OF PUBLIC HEALTH
Time since first use
10+ years vs Never regular use

10. SYDNEY SCHOOL OF PUBLIC HEALTH
Cumulative call time (hours)
1,640+ hours vs Never regular use

11. SYDNEY SCHOOL OF PUBLIC HEALTH
Cumulative number of calls (‘000s)
27,000+ calls vs Never regular use

12. SYDNEY SCHOOL OF PUBLIC HEALTH
1,640+ hours of call time
by side of use relative to tumour

13. SYDNEY SCHOOL OF PUBLIC HEALTH
1,640+ hours of call time
by lobe of tumour
Meningioma Glioma

14. SYDNEY SCHOOL OF PUBLIC HEALTH
Possible explanations for an
association
• Chance
• Bias
• Confounding
• A causal relationship

15. SYDNEY SCHOOL OF PUBLIC HEALTH
Evidence of bias
• Participation bias
• Recall bias
– Amount of use
• Implausible values
• Retrospective validation study
– Side of use
• Inconsistencies in results

16. SYDNEY SCHOOL OF PUBLIC HEALTH
Reasons for non-participation
Participation
outcome
Controls Glioma Meningioma
Participated 53% 64% 78%
Not
contacted
13% 4% 3%
Refused 31% 16% 13%
Other 3% 17% 5%
Vrijheid et al Annals of Epidemiology 2009; 19:33-42

17. SYDNEY SCHOOL OF PUBLIC HEALTH
Effect of non-participation on mobile
phone use
• 12 centres asked refusers some questions
• 57% of control and 41% of case refusers
answered
Ever regular mobile phone use
Refusers Participants
Controls 56% 69%
Cases 50% 66%

18. SYDNEY SCHOOL OF PUBLIC HEALTH
Effect of non-participation on RR for
brain tumours with mobile phone use
• Greater non-participation in controls
– leads to
• A greater proportion of mobile phone
users in controls
– leads to
• Downward bias in the RR for any regular
use of a mobile phone

19. SYDNEY SCHOOL OF PUBLIC HEALTH
An approach to bias correction
“One means of correcting, at least crudely,
for downward bias in the risk estimates for
mobile phone use might be to undertake
analyses using the lowest category of
users as the reference category for risk
estimates in higher categories.”

20. SYDNEY SCHOOL OF PUBLIC HEALTH
Adjusted relative risks of glioma by
cumulative call time
Appendix 2 in: INTERPHONE Study Group. International Journal of Epidemiology 2010; 39: 675-94

21. SYDNEY SCHOOL OF PUBLIC HEALTH
Bias in recall of amount of use
• Implausible values for accumulated call
time
– 38 glioma cases and 22 glioma controls
reported >5 hours of calls a day in any period
– Their exclusion caused a fall in the RR for
1,640+ hours accumulated call time
• Included 1.40 (95% CI 1.03–1.89)
• Excluded 1.27 (95% CI 0.92–1.75)

22. SYDNEY SCHOOL OF PUBLIC HEALTH
Biased recall in longer term users
• Recall compared with corresponding
billing records in
– 212 cases and 296 controls in
– 6 centres in 3 countries
• Mean ratios of recalled to recorded calls
(~0.8) and call time (~1.4) were similar in
cases and controls
• Ratios increased with recall interval, more
in cases than controls
Vrijheid et al JES&EE 2009; 19:369-81

23. SYDNEY SCHOOL OF PUBLIC HEALTH
Mean ratio of recalled to recorded
number of calls by recall interval
Cases
Controls

24. SYDNEY SCHOOL OF PUBLIC HEALTH
Mean ratio of recalled to recorded
duration of calls by recall interval
Cases
Controls

25. SYDNEY SCHOOL OF PUBLIC HEALTH
Bias in recall of side of use
• Sub-study in 3 centres
– 332 cases and 340 controls asked to put a
phone to their ear as if answering it
– Side of use recorded
• Side concordance
– Meningioma 66%, Glioma 72%
– Controls 95%
• Direction of error in cases
– 48% ipsilateral, 52% contralateral

26. SYDNEY SCHOOL OF PUBLIC HEALTH
Ratios of relative risk of ipsilateral use
to relative risk of contralateral use

27. SYDNEY SCHOOL OF PUBLIC HEALTH
Conclusion
“There were suggestions of an increased
risk of glioma at the highest exposure
levels, but biases and errors limit the
strength of the conclusions we can draw
from these analyses and prevent a causal
interpretation.”

28. SYDNEY SCHOOL OF PUBLIC HEALTH
How do Interphone’s results compare
with results of similar studies?
• One other study has examined the
relationship of mobile phone use with risk
of recently diagnosed brain tumours; that
of Hardell and colleagues from Sweden.
• It’s results are rather different, as can be
seen in context in a recent meta-analysis

29. SYDNEY SCHOOL OF PUBLIC HEALTH
Mobile phone use and risk of
tumors: A meta-analysis
• Selection criteria
– Case-control studies
– Association of mobile/cell phones or cordless
phones & malignant of benign tumours
– Reported outcome measures with odds ratios
and 95% CIs or data from which they could be
calculated
Myung et al Journal of Clinical Oncology 2009; 27: 5565-72

30. SYDNEY SCHOOL OF PUBLIC HEALTH
Mobile phone use and risk of
tumors: A meta-analysis
• 23 studies included
– Brain tumours (glioma, meningioma,
vestibular schwannoma, pituitary) (14)
– Ocular melanoma (1)
– Salivary gland tumours (4)
– Intratemporal facial nerve (1)
– Non-Hodgkin lymphoma (2)
– Testicular cancer (1)
Myung et al Journal of Clinical Oncology 2009; 27: 5565-72

31. Any mobile phone use vs never or rarely used a mobile phone

32. Mobile phone use of 10 years of longer vs never or rarely used

33. SYDNEY SCHOOL OF PUBLIC HEALTH
Is there something wrong with
Hardell’s study?
• Not obviously
• Features
– Population-based – 729 cases and 692 controls
– Histopathologically confirmed cases
– Self completed questionnaire and telephone interview
– Interviewers blind to case/control status
– Case participation 67% (18% died)
– Control participation 84% (full accounting not given)
– Matching broken in analysis but adjusted for matching
variables (age, sex, reference year)

34. SYDNEY SCHOOL OF PUBLIC HEALTH
Summary of Hardell’s results
Hardell et al. Neuroepidemiology 2005; 25: 120-8
Hardell et al. Environmental Research 2006; 100: 232-41

35. SYDNEY SCHOOL OF PUBLIC HEALTH
Summary of Hardell’s results
Hardell et al. Neuroepidemiology 2005; 25: 120-8
Hardell et al. Environmental Research 2006; 100: 232-41

36. SYDNEY SCHOOL OF PUBLIC HEALTH
Future directions for Interphone
• Report on results for vestibular
schwannoma
• Report on parotid gland tumours
• Report on risk by estimated RFE exposure
to the site of the tumour (case only
analyses)
• Report on analyses using more
sophisticated methods for bias correction

37. SYDNEY SCHOOL OF PUBLIC HEALTH
Other directions
• Case-control studies of mobile phone use
and brain tumours in children, adolescents
and young adults
• Cohort studies of health effects of mobile
phone use
• Studies of effects of base station exposure
• Monitoring trends in brain tumour
incidence
• IARC monograph

38. SYDNEY SCHOOL OF PUBLIC HEALTH
COSMOS
• Collaborative cohort study in UK, Denmark,
Sweden, Finland, The Netherlands
• Recruitment through mobile phone service providers
• 30-45 minute questionnaire covering mobile phone
use, health and lifestyle
• ~250,000 participants & 25+ years follow-up
• Initial and ongoing monitoring of use through mobile
phone service provider
• Updating service provider details annually
• Outcomes through cancer registers, hospital data &
follow-up questionnaires

39. SYDNEY SCHOOL OF PUBLIC HEALTH
COSMOS participation rates
Schuz et al. Cancer Epidemiology 2010 –
doi:10.1016/j.canep.2010.08.001

40. SYDNEY SCHOOL OF PUBLIC HEALTH
Base stations and childhood cancer
• Case-control study
• 72% of all brain tumours, leukaemia and
NHL in children 0-4 years of age in UK in
1999-2001 – 1,397 cases
• 5,588 controls from birth register,
individually matched 4:1 by sex and birth
date
Elliott P et al. BMJ 2010; 340: c3077

41. SYDNEY SCHOOL OF PUBLIC HEALTH
Base stations and childhood cancer
• Exposure assessed using GIS information
for residence at birth and macrocell base
stations
• Three exposure metrics
– Distance from nearest base station tower
– Total power output of all base stations within
700 metres
– Modelled power density from all base stations
within 1,400 metres

42. SYDNEY SCHOOL OF PUBLIC HEALTH
Base stations and childhood cancer
• Modelled power density validated
empirically – Spearman’s r 0.66
• Three metrics reasonably highly correlated
– Total power with modelled density r 0.62
– Total power with distance r 0.82
– Modelled density with distance r 0.74
• Estimated power density for controls
– Median 0.32 mW/m2 Maximum 8.6 mW/m2

43. SYDNEY SCHOOL OF PUBLIC HEALTH
Base stations and childhood cancer
Adjustments:
Education and SES
+ population density and population mixing

44. SYDNEY SCHOOL OF PUBLIC HEALTH
Global trends in mobile phone use
Khurana et al. Surgical Neurology 72 (2009) 205–215

45. SYDNEY SCHOOL OF PUBLIC HEALTH
Brain cancer incidence in men Australia 1982-2006
http://www.aihw.gov.au/cancer/data/acim_books/index.cfm

46. SYDNEY SCHOOL OF PUBLIC HEALTH
Brain cancer incidence in women Australia 1982-2006
http://www.aihw.gov.au/cancer/data/acim_books/index.cfm

47. SYDNEY SCHOOL OF PUBLIC HEALTH
What should people do?
http://www.arpansa.gov.au/news/MediaReleases/mr1_170510.cfm

48. SYDNEY SCHOOL OF PUBLIC HEALTH
What should mobile phone
manufacturers do?
• Continue to reduce SAR values by innovation
in mobile phone design
• Make comparative SAR data easily and
usefully available online and at the point of
sale

49. SYDNEY SCHOOL OF PUBLIC HEALTH
What should mobile phone service
providers do?
• Make available easily accessible and
understandable information on exposure from
base stations at postal address level
• Support independent and expert modelling
that would help to identify optimum cell sizes
and base station distributions considering:
– Exposure in use
– Exposure from base stations
– Impact of base stations on amenity

50. SYDNEY SCHOOL OF PUBLIC HEALTH
What should we all do?
• Be honest about the present uncertainty
regarding health effects of personal use of
a mobile phone