Studies attempting to determine whether or not cellphones can cause cancer have been going on for decades. Now, an experiment conducted by the National Toxicology Program found that there is modest evidence that radio waves from some types of cellphones are linked to an increased risk of cancer for male rats. The study involved about 3,000 rodents and cost $30 million.
The study involved radio frequencies long out of routine use. It focused on 900 megahertz, a frequency typical of the second generation of cellphones. This early generation of cellphone technology was used mainly in the 1990s. The 2G networks remain in use for calls and texts.
The study found that 2 to 3 percent of the exposed male rats developed malignant gliomas, a deadly brain cancer. No malignant gliomas developed in the control group. Roughly 5 to 7 percent of the male rats exposed to the highest level of radiation developed a specific type of heart tumors, while the control group didn’t develop any. The studies also found evidence that the radiation was linked to tumors in male rats’ adrenal glands.
The exposure levels and durations were far greater than what people typically encounter. The lowest level of radiation used was the maximum exposure allowed for cellphone users by federal regulations. The highest exposure level was four times greater than the maximum power level allowed. The radiation exposure occurred for nine hours a day, starting before birth and continuing for two years.
Current cellphones are considered a fourth generation, known as 4G. The higher frequencies used by current cellphones cannot penetrate the tissues of humans and rats as easily as the previously used frequencies. Still, even a small rise in cancer risk could have significant implications for the general public. Billions of people around the world now use cellphones on a near daily basis.