Saturday, June 18, 2011

Cell phones and brain cancer

The recent news items about the World Health Organization's ruling on the "potential" for cell phones to cause cancer is based on contradictory research results that have been obtained for years. But the lead up to their recent decision really began a little over a year ago with the Interphone study. At that time, news reports stated that the WHO found that cells phones increase cancer risk with 30 minutes of use each day, but they actually said the opposite. The news was so keen on grabbing the headlines they didn't wait for the actual study results when reporting the sensationalistic "potential" headline.

The Interphone study was carried out for 4 years in 13 countries. It found that use of cell phones over 10 years did not conclusively increase cancer risk. But the study had some methodology issues and potential conflicts of interest.

The contradictory results on glioma development is what prompted the WHO to play it safe and advise headset use with cell phones. In light of recent research on the increased energy use of brain regions near cell phone antennas indicates something is happening, even if it isn't an increased cancer risk.


An embargoed press release from the World Health Organization (WHO) on the INTERPHONE study was prematurely released by British media in order to spin the story to sensationalism with some of the more poignant and questionable findings. Despite headlines touting that the agency found 30 minutes of cell phone use a day to increase the risk of brain cancer, the WHO actually made no such conclusion. 


Here's how it unfolded

In January 2010, the journal "Health Research Policy and Systems" published a review about the mobile phone (or cell phone to Americans) radiation controversy. Since its debut, this technology has been a target of suspicion regarding the radio waves it emits so close to the head. Numerous studies have attempted to elucidate whether the cell phones can cause cancer, with little agreement and only limited success at making determinations in vitro. At the time, a severe lack of volunteer human studies led the WHO and other concerned agencies to publicly state there was no known risk of using cell phones in regards to cancer.

On May 17, 2010, the results of the INTERPHONE study were published in the International Journal of Epidemiology. This study was carried out from 2000 to 2004 and included thousands of cell phone users over the age of 30 in 13 countries who had 10 years of exposure to determine if there is any increased risk of brain cancer from cell phone use. It is the largest epidemiological study of its kind to date. The WHO's stance did not change with the publication.

The WHO states that, of the four brain tumor types studied, only an increased risk of glioma was suggested by the results, but not shown for certain. A large problem is that the maximum cell phone use by the participants (and only 10% of participants at that) was 30 min a day, much less than the time spent by current users, particularly young users. Also, newer phones have fewer emissions and the numerous hands-free devices limit the time a phone is against one side of the head. So the associated study centers are continuing their research, focusing on specific cancers and younger age groups.

Some feel the study should have been released four years ago, but one of the funders, the Mobile Manufacturers Forum, is a cell phone manufacturer trade group who some feel held up the study because of the potential for some to make a conclusion of potential for increased cancer risk from using their cell phones. However, that is not the conclusion presented by the WHO, though many media outlets, including the Telegraph, would have readers believe otherwise.

The press release from the International Agency for Research on Cancer, a part of the WHO is available here. The study population and methodology were described in the European Journal of Epidemiology in 2007.

Study details

The INTERPHONE study was carried out from 2000 to 2004 in 13 countries (Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and UK) as the largest epidemiological study of cell phone use investigating a potential association with the occurrence of brain cancer. The study included 2,765 patients with glioma, a tumor arising from glial cells in the central nervous system; 2,425 patients with meningioma, a tumor arising from the meninges, the membrane surrounding tissues in the central nervous system; 1,121 patients with acoustic neurinoma, a benign tumor of the acoustic nerve;  109 patients with malignant parotid gland tumors; and 7,658 controls. In May 2010, the Interphone Study Group published the results of their evaluation of gliomas and meningiomas in the International Journal of Epidemiology (which unfortunately requires a subscription).

Overall, the study has found no conclusive increase in brain tumors associated with cell phone use over 10 years. However, the study has some issues. They only looked at adults (people over 30 years of age), not at the younger people who commonly use cell phones for long periods of time. Also, the study is several years old already. The maximum cell phone use by the 10% of participants using the phone more often was 30 minutes a day, much less than the time spent by current users, particularly young users. Also, newer phones have fewer radio wave emissions targeted at the head, and the numerous hands-free devices and prevalence of texting limit the time a phone is against one side of the head, one factor that was found to influence the malignant effects of cell phone use in the INTERPHONE study.

The associated study centers are continuing their research, focusing on younger cell phone users and specific cancers that had some suggestive results. The WHO felt that the study may have suggested an increased risk of glioma, but not conclusively. This uncertainty has pervaded the field since cell phone radiation became a studied question. A lack of volunteer human studies leads the World Health Organization (WHO) and other concerned agencies to admit that there is no known risk of cancer when using cell phones. That doesn’t appear to have changed with the Interphone results.

However, the study was funded in part by the cell phone manufacturer trade group, Mobile Manufacturers Forum, which supposedly held up the results as the researchers found a way to frame the conclusions from the study.


See also: 

Leszczynski and Xu, Mobile phone radiation health risk controversy: the reliability and sufficiency of science behind the safety standards, Health Research Policy and Systems, 2010. doi: 10.1186/1478-4505-8-2

No comments: