A study of cell phone use and brain health has finally been released, but the data are raising more questions than answers. The report is called Interphone, a 13-country study that amounts to the largest and longest study of whether extensive cell phone use increases risk for brain cancer.
The study results, published in The International Journal of Epidemiology, were delayed by four years, reportedly after researchers disagreed over how to present the results.
The final paper states that overall there is no link between cell phone use and brain cancer. However, the investigators report that study participants with the highest level of cell phone use had a 40 percent higher risk for a type of brain tumor called a glioma. That risk, though, is discounted because of potential “biases and errors” that “prevent a causal interpretation,” the investigators wrote.
An increased risk of brain cancer is not established from the data from Interphone. However, observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied by Interphone, particularly in young people, mean that further investigation of mobile phone use and brain cancer risk is merited.
To study the relationship between cell phones and brain cancer, the Interphone researchers gathered data on 2,708 cases of glioma and 2,409 of meningioma, another type of brain tumor, and matched them against about 5,600 controls.
They tracked the cell phone habits and health of all the people in the study in an effort to ascertain whether cell phone use was associated with a higher risk for brain cancer. The $25 million study, which began in 2000, was funded primarily by the European Commission and the cell phone industry.
Although earlier studies have found no link between cell phones and brain cancer that research has been criticized for being too short in duration to detect any trends. The brain tumor-cell phone link has been dismissed by a number of health groups, including the Food and Drug Administration and the American Cancer Society.
Cell phones emit non-ionizing radiation, waves of energy that are too weak to break chemical bonds or to set off the DNA damage known to cause cancer. There is no known biological mechanism to explain how non-ionizing radiation might lead to cancer.
But researchers who have raised concerns have focused on the heat generated by cell phones and the fact that the radio frequencies are absorbed mostly by the head and neck. In observational studies that suggest a risk, the cancer tend to occur on the same side of the head where the patient typically holds the phone.
