Biggest ever study shows no link between mobile phone use and tumors

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ScienceDaily (Oct. 20, 2011) — There is no link between long-term use of mobile phones and tumours of the brain or central nervous system, finds new research published online in the British Medical Journal.

In what is described as the largest study on the subject to date, Danish researchers found no evidence that the risk of brain tumours was raised among 358,403 mobile phone subscribers over an 18-year period.

The number of people using mobile phones is constantly rising with more than five billion subscriptions worldwide in 2010. This has led to concerns about potential adverse health effects, particularly tumours of the central nervous system.

Previous studies on a possible link between phone use and tumours have been inconclusive particularly on long-term use of mobile phones. Some of this earlier work took the form of case control studies involving small numbers of long-term users and were shown to be prone to error and bias. The International Agency for Research on Cancer (IARC) recently classified radio frequency electromagnetic fields, as emitted by mobile phones, as possibly carcinogenic to humans.

The only cohort study investigating mobile phone use and cancer to date is a Danish nationwide study comparing cancer risk of all 420,095 Danish mobile phone subscribers from 1982 until 1995, with the corresponding risk in the rest of the adult population with follow-up to 1996 and then 2002. This study found no evidence of any increased risk of brain or nervous system tumours or any cancer among mobile phone subscribers.

So researchers, led by the Institute of Cancer Epidemiology in Copenhagen, continued this study up to 2007.

They studied data on the whole Danish population aged 30 and over and born in Denmark after 1925, subdivided into subscribers and non-subscribers of mobile phones before 1995. Information was gathered from the Danish phone network operators and from the Danish Cancer Register.

Overall, 10,729 central nervous system tumours occurred in the study period 1990-2007.

When the figures were restricted to people with the longest mobile phone use -- 13 years or more -- cancer rates were almost the same in both long-term users and non-subscribers of mobile phones.

The researchers say they observed no overall increased risk for tumours of the central nervous system or for all cancers combined in mobile phone users.

They conclude: "The extended follow-up allowed us to investigate effects in people who had used mobile phones for 10 years or more, and this long-term use was not associated with higher risks of cancer.

"However, as a small to moderate increase in risk for subgroups of heavy users or after even longer induction periods than 10-15 years cannot be ruled out, further studies with large study populations, where the potential for misclassification of exposure and selection bias is minimised, are warranted."

In an accompanying editorial, Professors Anders Ahlbom and Maria Feychting at the Karolinska Institutet in Sweden say this new evidence is reassuring, but continued monitoring of health registers and prospective cohorts is still warranted.

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The above story is reprinted from materials provided by BMJ-British Medical Journal.

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Journal References:

P. Frei, A. H. Poulsen, C. Johansen, J. H. Olsen, M. Steding-Jessen, J. Schuz. Use of mobile phones and risk of brain tumours: update of Danish cohort study. BMJ, 2011; 343 (oct19 4): d6387 DOI: 10.1136/bmj.d6387A. Ahlbom, M. Feychting. Mobile telephones and brain tumours. BMJ, 2011; 343 (oct19 4): d6605 DOI: 10.1136/bmj.d6605

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

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Aggregating bandwidth for faster mobile networks

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ScienceDaily (Oct. 21, 2011) — Smart phones, tablet computers and mobile broadband have begun to shift the mobile communications industry into a new phase especially as global mobile data traffic had already exceed voice traffic by the end of 2009.

A new study published in the Int. J. Management and Network Economics reveals that the value of mobile spectrum, the capacity to transfer data across mobile networks, is only likely to increase as the demand for data transfer increases. However, it is only those telecommunications companies that bought up in government auctions the inexpensive licences to operate at particularly frequencies of the spectrum that will be in strong position to dominate in the consumer and enterprise markets as well as being in a position to lease bandwidth to their competitors at a high profit.

Jan Markendahl of the Royal Institute of Technology and Bengt G. Mölleryd of the Swedish Post and Telecom Agency in Stockholm have demonstrated that operators that are able to obtain more spectrum than their competitors, and pursue network sharing and spectrum aggregation have a competitive advantage as they have the lowest production cost, highest margin and highest capacity when usage takes off. Spectrum is much cheaper than the construction of new base stations, network towers, power, and site leases.

With the emergence of new radio technology that allows otherwise separate blocks of frequencies to be used as if they were a single block of bandwidth means will allow those operators who enable the so-called 3GPP standard to profit from the separate chunks of bandwidth they own. Similarly, the evolution of 4G technology and devices will also allow aggregation. Indeed, the mobile equipment manufacturers have already launched flexible radio equipment capable of handling all relevant frequencies and access technologies.

Data traffic across mobile networks in Sweden alone increased by more than 90% during 2010 compared to 2009, from 27,800 to 53,100 terabytes (TB). Similar increases are being experienced elsewhere. The figures are likely to rise even faster in coming years as more people opt for smartphones and the use of tablet computers becomes more widespread. Such operators are likely to benefit considerably from this growth.

The researchers point out that the level of data rates a company can offer will be pivotal for its marketing success in mobile broadband services. Even minor differences will be exploited to gain brand advantage and those operators who can best use the entire spectrum available to them will be able to beat their competitors on data speeds. As the technology evolves, the companies that bought up lots of separate chunks of spectrum in the cheap government sell-offs of bandwidth could gain the upper hand.

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