An International Collaborative Animal Study of the Carcinogenicity of Mobile Phone Radiofrequency Radiation: Considerations for Preparation of a Global Project.

Radiofrequency radiation (RFR) was classified as a "possible" human carcinogen in 2011, which caused great public concern. A carcinogenicity study by the National Toxicology Program (NTP) found Code Division Multiple Access-and Global System for Mobile Communications-modulated mobile phone RFR to be carcinogenic to the brain and heart of male rats. As part of an investigation of mobile phone carcinogenesis, and to verify the NTP study results, a 5-year collaborative animal project was started in Korea and Japan in 2019. An international animal study of this type has two prerequisites: use of the same study protocol and the same RF-exposure system. This article discusses our experience in the design of this global study on radiofrequency electromagnetic fields (RF-EMFs).© 2022 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.

Mobile Phone Use and Time Trend of Brain Cancer Incidence Rate in Korea.

This study evaluated the time trends in mobile phone subscriber number by mobile network generation (G) and brain cancer incidence by type in Korea. We obtained data from the Information Technology Statistics of Korea (1984-2017) and Korea Central Cancer Registry (1999-2017). The average annual percent change was estimated using Joinpoint regression analysis. We evaluated 29,721 brain cancer cases with an age-standardized incidence rate (ASR) of 2.89/100,000 persons. The glioma and glioblastoma annual ASR significantly increased in 2.6% and 3.9% of males and 3.0% and 3.8% of females, respectively. The ASR for frontal lobe involvement was the highest. The ASR of gliomas of unspecified grade annually increased by 7.8%; those for unspecified topology and histology decreased. The incidence of glioma, glioblastoma, frontal, temporal, and high-grade glioma increased among those aged ≥60 years. No association was observed between the mobile phone subscriber number and brain cancer incidence in Korea. Furthermore, long-term research is warranted because of the latency period of brain cancer. © 2021 Bioelectromagnetics Society.

Biological Effects of Exposure to a Radiofrequency Electromagnetic Field on the Placental Barrier in Pregnant Rats.

The placenta protects the fetus against excessive stress-associated maternal cortisol during pregnancy. We studied whether exposure to radiofrequency electromagnetic field (RF-EMF) radiation during pregnancy can cause changes in dams and their placentas. Pregnant Sprague-Dawley rats were divided into cage-control, sham-exposed, and RF-exposed groups. They were exposed to RF-EMF signals at a whole-body specific absorption rate of 4 W/kg for 8 h/day from gestational Day 1 to 19. Levels of cortisol in the blood, adrenal gland, and placenta were measured by enzyme-linked immunosorbent assay. Levels of adrenocorticotropic hormone and corticotropin-releasing hormone were monitored in maternal blood. Expression levels of placental 11ß-hydroxysteroid dehydrogenase type 2 (11ß-HSD2) messenger RNA (mRNA) were measured by reverse transcription polymerase chain reaction. Morphological changes in the placenta were analyzed using hematoxylin and eosin staining. Fetal parts of the placenta were measured using Zen 2.3 blue edition software. Maternal cortisol in circulating blood (RF: 230 ± 24.6 ng/ml and Sham: 156 ± 8.3 ng/ml) and the adrenal gland (RF: 58.3 ± 4.5 ng/ml and Sham: 30 ± 3.8 ng/ml) was significantly increased in the RF-exposed group (P < 0.05). Placental cortisol was stably maintained, and the level of placental 11ß-HSD2 mRNA expression was not changed in the RF-exposed group. RF-EMF exposure during pregnancy caused a significant elevation of cortisol levels in circulating blood; however, no changes in the placental barrier were observed in pregnant rats. Bioelectromagnetics. © 2021 Bioelectromagnetics Society.

Effect of Exposure to a Radiofrequency Electromagnetic Field on Body Temperature in Anesthetized and Non-Anesthetized Rats.

Exposure to a radiofrequency (RF) signal at a specific absorption rate (SAR) of 4 W/kg can increase the body temperature by more than 1 °C. In this study, we investigated the effect of anesthesia on the body temperature of rats after exposure to an RF electromagnetic field at 4 W/kg SAR. We also evaluated the influence of body mass on rats' body temperature. Rats weighing 225 and 339 g were divided into sham- and RF-exposure groups. Each of the resulting four groups was subdivided into anesthetized and non-anesthetized groups. The free-moving rats in the four RF-exposure groups were subjected to a 915 MHz RF identification signal at 4 W/kg whole-body SAR for 8 h. The rectal temperature was measured at 1-h intervals during RF exposure using a small-animal temperature probe. The body temperatures of non-anesthetized, mobile 225 and 339 g rats were not significantly affected by exposure to an RF signal. However, the body temperatures of anesthetized 225 and 339 g rats increased by 1.9 °C and 3.3 °C from baseline at 5 and 6 h of RF exposure, respectively. Three of the five 339 g anesthetized and exposed rats died after 6 h of RF exposure. Thus, anesthesia and body mass influenced RF exposure-induced changes in the body temperature of rats. Bioelectromagnetics. 2020;41:104-112. © 2019 Bioelectromagnetics Society.

Effects of exposure to electromagnetic field from 915 MHz radiofrequency identification system on circulating blood cells in the healthy adult rat.

We investigated whether exposure to the 915 MHz radiofrequency identification (RFID) signal affected circulating blood cells in rats. Sprague-Dawley rats were exposed to RFID at a whole-body specific absorption rate of 2 W/kg for 8 h per day, 5 days per week, for 2 weeks. Complete blood counts were performed after RFID exposure, and the CD4+ /CD8+ ratio was determined by flow cytometry. The number of red blood cells (RBCs) and the values of hemoglobin, hematocrit, and RBC indices were increased in the RFID-exposed group compared with those in the cage-control and sham-exposed groups (P < 0.05). However, the RBCs and platelet numbers were within normal physiologic response ranges. The number of white blood cells, including lymphocytes, was decreased in RFID-exposed rats. However, there was no statistically significant difference between the sham-exposed and RFID-exposed groups in terms of T-cell counts or CD4+ /CD8+ ratio (P > 0.05). Although the number of circulating blood cells was significantly altered by RFID exposure at a whole-body specific absorption rate of 2 W/kg for 2 weeks, these changes do not necessarily indicate that RFID exposure is harmful, as they were within the normal physiological response range. Bioelectromagnetics. 39:68-76, 2018. © 2017 Wiley Periodicals, Inc.