Interphone and beyond evidence for harm or safety armstrong

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Interphone and beyond evidence for harm or safety armstrong

  1. 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. 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. 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. 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. 5. SYDNEY SCHOOL OF PUBLIC HEALTH Dimensions • 16 centres in 13 countries (excluding USA and including Japan) • Cases diagnosed between 2000 and 2004
  6. 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. 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. 8. SYDNEY SCHOOL OF PUBLIC HEALTH Regular use Any 1+ years before vs Never
  9. 9. SYDNEY SCHOOL OF PUBLIC HEALTH Time since first use 10+ years vs Never regular use
  10. 10. SYDNEY SCHOOL OF PUBLIC HEALTH Cumulative call time (hours) 1,640+ hours vs Never regular use
  11. 11. SYDNEY SCHOOL OF PUBLIC HEALTH Cumulative number of calls (‘000s) 27,000+ calls vs Never regular use
  12. 12. SYDNEY SCHOOL OF PUBLIC HEALTH 1,640+ hours of call time by side of use relative to tumour
  13. 13. SYDNEY SCHOOL OF PUBLIC HEALTH 1,640+ hours of call time by lobe of tumour Meningioma Glioma
  14. 14. SYDNEY SCHOOL OF PUBLIC HEALTH Possible explanations for an association • Chance • Bias • Confounding • A causal relationship
  15. 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. 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. 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. 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. 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. 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. 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. 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. 23. SYDNEY SCHOOL OF PUBLIC HEALTH Mean ratio of recalled to recorded number of calls by recall interval Cases Controls
  24. 24. SYDNEY SCHOOL OF PUBLIC HEALTH Mean ratio of recalled to recorded duration of calls by recall interval Cases Controls
  25. 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. 26. SYDNEY SCHOOL OF PUBLIC HEALTH Ratios of relative risk of ipsilateral use to relative risk of contralateral use
  27. 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. 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. 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. 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. 31. Any mobile phone use vs never or rarely used a mobile phone
  32. 32. Mobile phone use of 10 years of longer vs never or rarely used
  33. 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. 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. 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. 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. 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. 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. 39. SYDNEY SCHOOL OF PUBLIC HEALTH COSMOS participation rates Schuz et al. Cancer Epidemiology 2010 – doi:10.1016/j.canep.2010.08.001
  40. 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. 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. 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. 43. SYDNEY SCHOOL OF PUBLIC HEALTH Base stations and childhood cancer Adjustments: Education and SES + population density and population mixing
  44. 44. SYDNEY SCHOOL OF PUBLIC HEALTH Global trends in mobile phone use Khurana et al. Surgical Neurology 72 (2009) 205–215
  45. 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. 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. 47. SYDNEY SCHOOL OF PUBLIC HEALTH What should people do? http://www.arpansa.gov.au/news/MediaReleases/mr1_170510.cfm
  48. 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. 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. 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

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