- Flickr/Andrew Forgrave
Researchers have found a link between cancer and exposure to cellphones in rats.
The National Toxicology Program, an interagency government group that is part of the National Institutes of Health, released a report Thursday looking at what happened when rats and mice were exposed to cellphone radiation over a two-year period.
The $25 million study found that more of the male rats that were exposed to the cellphone radiation developed certain kinds of cancer compared with a control group that wasn’t exposed to the radiation.
The study has some obvious limitations, though. For one thing, it was conducted in rats and mice, not people. Here are a few of the other things to keep in mind when considering the new study and its implications for your cellphone use:
- Cellphones give off a type of radiation called nonionizing radiofrequency radiation. That’s different from ionizing radiation, which is a known carcinogen. Both types of that radiation can be absorbed into the body, but nonionizing radiofrequency radiation can’t cause the DNA damage that can lead to cancer. This study, however, suggests that there might be something else at play, at least in rats, such as perhaps heat damage. The study found that male rats that were exposed to cellphone radiation had higher incidences of heart and brain tumors than the nonexposed male rats – but interestingly it didn’t find the same result in the female rats. Across the board, the control-group rats that weren’t exposed to the cellphone radiation didn’t have any incidences of heart or brain cancer. In pregnant rats, the researchers didn’t see any exposure effects on their litter size or the sex of the babies. There were some small changes in weights for both the mothers and the babies that were exposed to the radiation, however.
What previous studies have found
Previous research has not been able to conclusively show an impact of cellphones on cancer incidence in people. In a statement released earlier this week, the NIH said, “It is important to note that previous human, observational data collected in earlier, large-scale population-based studies have found limited evidence of an increased risk for developing cancer from cellphone use.”
The Federal Communications Commission, which monitors radiofrequency exposure from cellphones and sets limits on it, said in a statement that it knew about the report, adding: “Scientific evidence always informs FCC rules on this matter. We will continue to follow all recommendations from federal health and safety experts including whether the FCC should modify its current policies and RF exposure limits.”
What’s still missing
We asked Dr. Ashley Sumrall, an oncologist who treats brain tumor patients at the Carolinas HealthCare Systems about other limitations to the study. One of the biggest, she pointed out, was that we don’t know exactly how long all of the rats actually lived. It was difficult to tell how long the rats lived, and the researchers that the rats who weren’t exposed to the radiation didn’t live as long as rats in other studies. “The control group didn’t do as well as expected or as well as the rats do in other scenarios, which may be biasing them to being sicker predisposed condition,” she said.
That, and what this means for humans is still rather unknown.
“What’s not clear is how that correlates to what a human would experience using a cell phone,” Sumrall said. For example, is this the same frequency that a human would experience? Also, the definition of a glioma (a brain tumor) used in the report didn’t look like the human definition of glioma.
“For patient care, this wouldn’t impact me,” she said. “We have multiple studies that are large in number and power to detect small changes. They show us that there’s no definitive correlation.”
The researchers said in the report that they had more data on the way, including the results for the mice involved in the study, which could shed even more light on nonrodent implications.