Study: Longterm cellphone use does raise brain tumor risk

Researchers at the Swedish National Institute for Working Life examined mobile phone use with 905 people between age 20 and 80 who have malignant brain tumors, and observed a connection.

"A total 85 of these 905 cases were so-called high users of mobile phones, that is they began early to use mobile and/or wireless telephones and used them a lot," the study said. "The study also shows that the rise in risk is noticeable for tumors on the side of the head where the phone was said to be used."

Kjell Mild, who led the study, said the figures meant that heavy users of mobile phones, for instance of who make mobile phone calls for 2,000 hours or more in their life, had a 240 percent increased risk for a malignant tumor on the side of the head the phone is used.

"The way to get the risk down is to use hands-free," he told Reuters.

Link to Reuters item, via CNET.

Here's the website for the institute, and here's an English PDF summary of the study from the Institute's website: "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." Here's a related PDF from the institute, in Swedish. (Thanks, resonantorder)

Reader Comment: Mike B says,

This most recent Swedish study by Hardell, which claims to have found a connection between cell phones and cancer incidence, is in direct conflict with a very large Danish study that didn't find any connection at all: Link.

I skimmed the Swedish paper, and Hardell et al. seem to be claiming that the Danes might not have done their interviews correctly, or something. Which brings up a big issue: the methodology in both studies is to determine people's cell phone use by interviewing them after diagnosis, which must surely be inaccurate. And it must be hard to get proper controls: I suspect that people recently diagnosed with brain cancer probably remember their cell phone usage rather differently than healthy people do... precisely because the media has spent a decade or more printing scary articles suggesting that cell phones cause cancer. I'd like to see more evidence that the Swedes' statistical techniques have completely eliminated this obvious source of bias.

Note also that the highest reported risk ratios here are on the order of 2 or 2.5, which is awfully hard to detect.

I think a better headline would have been "Cancer researchers continue argument over cell phones and cancer; panic over press release ensures continued research funding for another twenty years."

Reader comment: Avi Solomon says,

This study is the most important previous evidence against using cellphones. More here. You be the judge!