The origin of the discussion
December 4, 2011 2 Comments
Many studies have been carried out trying to confirm or refute a relation between cell phone usage and brain cancer. Most studies are done by means of case-control. People diagnosed with brain cancer are asked for their cell phone use in the previous years which is compared by the cell phone use of people without brain cancer. The largest case-control study has been carried out in 13 countries under the name of INTERPHONE. The researchers compared the cell phone usage of more than 5000 people who developed brain tumors with a similar group of people without tumors. This study did not found a link between brain tumor risk and the frequency of calls or the duration of calls or cell phone use for 10 years or more. But the findings were difficult to interpret because of some people reporting implausibly high cell phone use. Therefore the researchers noted that due the shortcomings of the study it prevented them from drawing any firm conclusions.
Another type of study has been performed in Denmark between 1982 and 1995. More than 420000 people were followed in time regarding their cell phone use. The benefit of this type of study is that it does not rely on peoples memories and therefore is thought to be stronger than a case-control study. The results of this study are similar to those found in the INTERPHONE study but there are still limits as to how well this study might apply to people using cell phones today. At that time cell phones tended to require more power but people also probably used the phones less than they do today.
So although these studies cannot find a link between cell phone use and brain tumors it is unlikely that they will end the controversy due some limitations. Since cell phones are in widespread use for less than 20 years in most countries, it is not possible to rule out future health effects. Secondly, cell phones from 10 years ago are very different from the ones which are being used today. Additional studies have focused on adults rather than children and today cell phone use is widespread, even among young children. Finally, the measurements on cell phone use is mostly based on case-control studies which has known limitations.
On the other hand, several studies published by the Hardell group in Sweden report increased risk of tumors, particularly with 10 or more years of cell phone use. These results could not be found in other studies. Since there is no overall increase in brain cancer in Sweden during the years that correspond to these reports it is hard to know what to make of these results.
Christoffer Johansen et al., Cellular telephones and cancer-a nationwide cohort study in Denmark, 2001, Journal of the National Cancer Institute, Vol. 93, No. 3, 203-207
Vini G. Khurana et al., Cell phones and brain tumors-a review including the long-term epidemiologic data, 2009, Surgical Neurology, 72, 205–215
Lennart Hardell and Michael Carlberg, Mobile phones, cordless phones and the risk for brain tumours, 2009, International Journal of oncology, 35, 5-17
American Cancer society, 4/12/2011, http://www.cancer.org/Cancer/CancerCauses/OtherCarcinogens/AtHome/cellular-phones