Electronics and Telecommunications Research Institute (ETRI) said on the 3rd that, after conducting a large-scale animal experiment with Japanese researchers to determine whether long-term exposure to radio frequency (RF) electromagnetic waves generated during mobile phone use increases cancer, it found no statistically significant association between RF exposure and the occurrence of brain or heart tumors.
RF electromagnetic waves are the radio waves used when a mobile phone exchanges signals with a base station, and this study examined how long-term exposure at specific frequencies and intensities affects tumor development.
The study was carried out to check carcinogenic potential at exposure levels that underpin human safety standards for mobile phone electromagnetic waves and to re-verify the 2018 report by the National Toxicology Program (NTP) under the U.S. National Institutes of Health (NIH), which observed increases in brain, heart and adrenal tumors when male rats were exposed for life to 900 MHz CDMA electromagnetic waves. The researchers said they began a long-term animal study in 2019 as a Korea-Japan joint project and aligned experimental conditions to integrate, compare and analyze data across the two countries.
The research applied the same system as the NTP and was conducted under a joint protocol based on the Organisation for Economic Co-operation and Development (OECD) toxicology test guidelines. A key feature was standardizing the laboratory animals, feed, equipment and RF exposure environment in Korea and Japan. To ensure consistent exposure, an RF exposure chamber based on a reverberation room designed by ETRI was installed in both countries, and exposure quantification and simulations were conducted in parallel. A reverberation room is structured so that radio waves spread relatively uniformly in the space and is used to keep exposure conditions for animals consistent.
The experiment consisted of three groups: an RF exposure group, a sham exposure group and a cage control group. The sham group was placed in the same experimental environment but was not actually exposed to RF, allowing the effect of RF itself to be isolated. In each group, 70 male rats were exposed to 900 MHz CDMA RF at an intensity of 4 W/kg for 104 weeks, spanning from early gestation through the entire postnatal lifespan. W/kg is an indicator of the amount of RF energy absorbed per kilogram of body weight, and the researchers said this intensity was at the level referenced in setting human safety standards.
Observations showed that patterns of changes in body temperature, body weight and feed intake due to RF exposure were generally similar in both Korea and Japan. However, the RF exposure group tended to have slightly lower feed intake than the sham group. The researchers said survival rates showed no significant differences between groups in Korea, while in Japan the RF exposure group had relatively higher survival.
In the tumor incidence analysis, all groups in Korea had tumor rates within the range of spontaneous occurrence, and no statistically significant differences were identified between the RF exposure and sham groups in major organs such as the heart, brain and adrenal glands. Japan also reported no differences between groups in tumor incidence or timing, and tumors in major target organs showed low incidence.
Based on these results, the researchers concluded there was no significant association between long-term exposure to CDMA mobile phone RF and the occurrence of brain, heart or adrenal tumors.
Ahn Young-hwan, a neurosurgery professor at Ajou University School of Medicine, said, "The NTP-reported increases in tumors were not reproduced at exposure levels that underpin human protection standards," and added, "This can serve as a reference to alleviate excessive concerns about mobile phone electromagnetic waves."
ETRI said it will pursue follow-up research to determine carcinogenic associations in complex radio environments where 4G and 5G coexist.