04/04/2006 - Best evidence yet that mobile phones could be causing brain cancer
* 18/09/2006 -- There is now user feedback and a full response to this article.
Summary:
The latest study [1] on brain tumours and phone use shows the biggest increase of any study so far, and is statistically significant in all areas. The new study on 905 malignant brain tumour cases shows a 1.7 to 5.9-fold increase in risk for long-term mobile phone and cordless phone users.
The current criteria upon which phone exposure is normally assessed is the SAR value. Regarding exposure from cordless phones, the HPA-RPD (ex NRPB) website states:
"Measurements of the SAR values from cordless phones are not generally available, however it is possible to scale the range of typical values reported for mobile phones operating at full power (0.2-1.4 W/kg). Assuming physical factors (such as the antenna types and positions in relation to the head) are similar to those with mobile phones, this suggests that DECT cordless phone SAR values would be expected to be in the range 0.008-0.06 W/kg, at least 30 times below the ICNIRP guidelines."
Drs Lennart Hardell, Michael Carlberg and Kjell Hansson Mild, combined two studies on malignant brain tumours diagnosed during 1997-2003 included answers from 905 (90%) cases and 2,162 (89%) controls aged 20-80 years. The results are shown in the table below. In the multivariate analysis all phone types increased the risk and were statistically significant.
Cumulative lifetime use for > 2,000 hours of use cellular phones |
All malignant tumours |
|
OR |
CI |
Analogue phone |
5.9 |
2.5 - 14.0 |
Digital phones |
3.7 |
1.7 - 7.7 |
Cordless phones |
2.3 |
1.5 - 3.6 |
Ipsilateral (tumour on side of head where phone handset was usually held) |
Analogue phone |
2.1 |
1.5 - 2.9 |
Digital phones |
1.8 |
1.4 - 2.4 |
Cordless phones |
1.7 |
1.3 - 2.2 |
High-grade astrocytoma for more than 10 years mobile / cordless phone use |
Analogue phone |
2.7 |
1.8 - 4.2 |
Digital phones |
3.8 |
1.8 - 8.1 |
Cordless phones |
2.2 |
1.3 - 3.9 |
OR = Odds Ratio (the risk of tumours in users' brains compared with non-users)
The Confidence Interval (CI) ranges given in brackets below represent a 95% confidence level that the actual OR lies between the two numbers given (p=0.05).
Conclusion:
Increased risk was obtained for both cellular and cordless phones, highest in the group with more than 10 years use of mobile or cordless phones.
As we have mentioned before SAR values seem to be a totally inappropriate metric to measure the potential risk of the phone (as cordless phones appear to be having just as pronounced effects as mobile phones despite having about one twentieth (5%) of their SAR value). It seems that some other characteristic (the nature of the pulsing signal perhaps?) is causing the increase in cancer, by a mechanism we have not yet discovered. Now there is so much more evidence such as this study being published, surely it is now time to accept that the risk is now likely and to investigate other factors than simple power absorption that may be responsible for these increases.
References
[1] - Hardell L, Carlberg M, Hansson Mild K, Department of Oncology, University Hospital, 701 85, Orebro, Sweden
Pooled analysis of two case-control studies on use of cellular and cordless telephones and the risk for malignant brain tumours diagnosed in 1997-2003, Int Arch Occup Environ Health. 2006 Mar 16; [Epub]
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