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Two recent studies provide fuel for both camps: They both find the association between brain cancer and cell phone use is dubious. Does this mean they found no associations? Hardly.
The debate about whether cell phones cause brain tumors continues as two new studies appear to illustrate that brain cancers do not rise as a result to increased cell phone use – at least until the data is looked at more closely.
In the first of the two – from the University of Oxford's International Agency for Research on Cancer (IARC) – followed 791,710 middle aged-women for seven years – after they reported their cell phone use in 1999, 2005 and 2009.
The research discovered 51,680 invasive cancers and 1,261 central nervous system cancers during the period.
The research found that there was no increase in any cancers – including brain cancers – for those women who used cell phones versus those who did not.
However, when non-cell phone users were compared with cell users who had used cell-phones for more than ten years, there was a 10% increase in meningioma risk. While the results were clear, the researchers did not consider the finding as significant enough.
In addition to this, compared to non-cell phone users, the long-term (10+ years) use of cell phones increased the risk of acoustic neuroma by two-and-a-half times. Perhaps they didn't think this was significant because acoustic neuromas are considered non-malignant, and thus not a true cancer. That may be true, but this is not a reason to ignore the increased risk.
According to the research, these risks also increased as cell phone use increased – making the risk "dose-dependent."
When a risk is dose-dependent, it validates the causation element of the study. It means that the longer a person uses the cell phone, the greater the risk.
Study tracks meningioma cases...
With regards to meningioma, a more recent study from Swedish researchers, published in this July's Environmental Health Journal, also found minimal increased risk from increased cell phone use.
This study tracked 709 meningioma patients and compared them with 1,368 control subject subjects. They compared mobile phone usage among both groups, and analyzed the data using a latency period – the amount of time from tracked usage - of 25 years.
Here the researchers found, once again, little increased risk – but some. And the risk appeared to increase with increased cell phone use.
Two periods of use – between one and five years and over twenty-five years, showed an increased risk of meningioma by 30% among those who used wireless phones over a 25 year period.
In the highest-use quartile, wireless and mobile phone use resulted in a higher risk of meningioma, by 30% for mobile phones and 40% for wireless phones, and 80% increased risk for cordless phone use.
The increased risks was found to be related primarily to those who used their phones equivalent to about 40 minutes a day for 10 years, equated to 2,376 hours of cumulative use.
The researchers stated that:
"There was a statistically significant trend for increasing cumulative use of 3G mobile phones, cordless phones, phones of the digital type (2G, 3G and/or cordless phone), and wireless phones in total."
They also noted that there was more than a seven times increased risk for high-use 3G cell phone use. But this was considered not significant because it was based on only five users.
"No Conclusive Evidence"
It should be noted that in both of these studies, the researchers clearly stated that they found no conclusive evidence of a link between cell phones and brain cancer.
"No conclusive evidence" is a tricky concept, and yes, to establish a "conclusive" result, there must no doubt. Is there ever no doubt in scientific research? Both of these studies presented enough evidence that the brain cancers may have not come from cell phone use to utilize these terms.
This doesn't mean they proved there is no association, however. Quite the contrary.
The fact that in both studies, risk levels did increase with more use does provide some indication that there could be a link. But there is still more evidence needed. Time perhaps?
In the latest study, for example, one of the problems presented by the researchers was the fact that the use of cell phones and wireless phones are ubiquitous.
And previous studies have also exposed this risk among long-time users. As stated in a 2013 recent review in the Journal of Pathophysiology:
"Studies carried out in Sweden indicate that those who begin using either cordless or mobile phones regularly before age 20 have greater than a fourfold increased risk of ipsilateral glioma."
It only makes sense to consider a wired headset or using the speaker system available on most new cell phones. What's the difficulty with that? I personally prefer not feeling my ear heat up (which has also been studied and found to cause other issues). Maybe it doesn't look as cool as walking around with a phone stuck to the head, but hey, when has being healthy ever looked cool?
Benson VS, Pirie K, Schüz J, Reeves GK, Beral V, Green J; Million Women Study Collaborators. Mobile phone use and risk of brain neoplasms and other cancers: prospective study. Int J Epidemiol. 2013 Jun;42(3):792-802. doi:10.1093/ije/dyt072.
Carlberg M, Söderqvist F, Hansson Mild K, Hardell L. Meningioma patients diagnosed 2007--2009 and the association with use of mobile and cordless phones: a case--control study. Environ Health. 2013 Jul 19;12(1):60.
Davis DL, Kesari S, Soskolne CL, Miller AB, Stein Y. Swedish review strengthens grounds for concluding that radiation from cellular and cordless phones is a probable human carcinogen. Pathophysiology. 2013 Apr;20(2):123-9. doi: 10.1016/j.pathophys.2013.03.001.