ISLAMABAD: High exposure to radiofrequency radiation resulted in tumors in tissue around the nerves in the hearts of male rats, but not of female rats or male or female mice, according to preliminary conclusions of two studies.
Draft reports on the two studies by the National Toxicology Program (NTP), which is part of the National Institutes of Health (NIH) in the United States, were released recently, pending a review by external experts that is scheduled to take place March 26–28. Members of the public may also submit comments.
The reports contain the remaining results of two large "toxicology and carcinogenesis" studies — one conducted in rats and the other in mice — of the effects of radiofrequency radiation (RFR) emitted by cell phones.
"The levels and duration of exposure," explains Dr. John Bucher, a senior scientist with the NTP, "to RFR were much greater than what people experience with even the highest level of cell phone use, and exposed the rodents' whole bodies."
High frequency radiation — like X-rays and gamma rays — and some higher energy ultraviolet radiation are known as ionizing radiation because they can knock out electrons and other charged particles from within atoms. They carry enough energy to damage DNA inside cells, which can give rise to cancer.
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However, RFR is at the lower energy end of the spectrum and is not able to knock out charged particles and alter atomic structure, but it can cause atoms and molecules to vibrate. It generates heat if absorbed in large amounts by food, tissues, and other materials that hold water.
Thus, although RFR is not the type of radiation that can cause cancer by damaging DNA, there have been concerns that it might alter tissue in other ways that could lead to cancer.
Rats, mice exposed to different RFR levels.
The NTP researchers note that the "predominant source of human exposure to RFR occurs through the use of cellular phone handsets."
For their studies, they constructed special chambers, in which they exposed the rats and mice to different levels of RFR.
Exposure occurred in a pattern of 10 minutes on, 10 minutes off, for a total of just over 9 hours per day and went on for 2 years.
Dr. Bucher says that 2 years of age in a rat or mouse is about 70 years of age in a human.
The RFR exposure levels ranged from around the maximum that is legally allowed for cell phones in the U.S. to around four times that level.
The animals were exposed to the same "frequencies and modulations" as those of 2G and 3G signals that are used to make voice calls and send texts in the U.S. Later generations of RFR — such as 4G, 4G-LTE, and 5G — use different frequencies and modulations.