The U.S. National Toxicology Program (NTP) has released draft results from its long study of cell phone radiation in rats and mice. The findings came out on February 2, 2018, as two technical reports, one for rats and one for mice. They do not settle the brain cancer question, though they do flag a clear signal in the heart.
Male rats exposed to high levels of radiofrequency radiation (RFR) developed tumors in the tissue around nerves in the heart. These were malignant schwannomas, and they became more common as exposure rose. Female rats did not show the effect, and neither did mice.
Exposed rats of both sexes also showed more of an unusual kind of heart tissue damage, called cardiomyopathy. Mice, by contrast, showed little sign of health problems linked to RFR.
What about the brain?
The researchers did see statistically significant tumor increases in some organs at one or more exposure levels. The list included the brain, prostate, pituitary gland, adrenal gland, liver and pancreas. However, NTP called these results equivocal, which means it is unclear whether the radiation caused them.
The doses were high. Rats received 1.5 to 6 watts per kilogram, and mice received 2.5 to 10. The lowest rat dose matched the highest level allowed for local tissue exposure from a phone, while phones usually emit less. The animals lived in special chambers that exposed their whole bodies for up to two years. Exposure ran in 10-minute on, 10-minute off cycles, for just over nine hours a day.
The studies used 2G and 3G signals. They did not test 4G, 4G-LTE or 5G networks.
John Bucher, an NTP senior scientist, said the exposure levels and length were far beyond what people get from normal phone use. For that reason, he said, the results should not be applied directly to humans. He also noted that the tumors looked like those reported in some studies of frequent phone users. In his view, the work is the most complete look so far at RFR and health in rats and mice.
Newborn rats and their mothers also weighed less, mostly after high exposure during pregnancy and nursing. Later, the young rats grew to normal size.
The U.S. Food and Drug Administration asked NTP to take on the study because cell phones are so widely used. The FDA and the Federal Communications Commission share oversight of wireless devices. Before any final conclusions, outside experts were set to review the full findings on March 26 to 28, 2018.
