Department of Environmental Medicine, Kurume University School of Medicine, Fukuoka, Japan;
Advanced Wireless and Communication Research Center (AWCC), The University of Electro-Communications, Tokyo, Japan.
In Vivo. 2023 Sep-Oct;37(5):2092-2099. doi: 10.21873/invivo.13306.
BACKGROUND/AIM: The widespread use of fifth-generation 5G millimeter-waves (MMW) generates concern about potential adverse health effects. The latest international guidelines for MMW exposure adopt an absorbed power density (APD) of 200 W/m to avoid a local temperature rise of 5°C in human tissues as an operational adverse health effect threshold. However, because APD is estimated by simulations using human tissue models, it is unknown whether a similar value can be confirmed for living tissues. The aim of this study was to investigate the relationship between APD and skin temperature rise in vivo, and to validate the estimated values.
The rat dorsal skin was locally exposed to a 26.5 GHz quasi-MMW (qMMW) for 18 min using a patch antenna. The qMMW exposure intensities estimated by dosimetry were set to 0-500 W/m of APD. The temperatures in the dorsal skin and rectum were simultaneously measured during exposure.
The qMMW-induced local temperature increase at different sites. The dorsal skin temperature increased by approximately 11.3°C at a maximum intensity of 500 W/m, but the rectal temperature increased by only 0.6°C, indicating highly localized effects of exposure to rats. A significant correlation was observed between APD and skin temperature rise. The relationship provided a linear regression model, and a temperature rise of less than 5°C was estimated in the skin exposed to 200 W/m of APD.
These results suggest that the operational threshold for the MMW exposure guidelines is valid under the present experimental conditions using rats.
背景/目的：第五代 5G 毫米波（MMW）的广泛应用引发了人们对潜在健康影响的担忧。最新的国际 MMW 暴露指南采用 200 W/m 的吸收功率密度（APD）作为操作不良健康效应阈值，以避免人体组织局部温升 5°C。然而，由于 APD 是通过使用人体组织模型进行模拟估计的，因此尚不清楚对于活体组织是否可以确认类似的值。本研究旨在研究体内 APD 与皮肤温升之间的关系，并验证估计值。
使用贴片天线对大鼠背部皮肤进行局部暴露于 26.5 GHz 准毫米波（qMMW），暴露时间为 18 分钟。通过剂量测定估计 qMMW 暴露强度设定为 0-500 W/m 的 APD。在暴露过程中同时测量背部皮肤和直肠的温度。
qMMW 诱导了不同部位的局部温升。在最大强度为 500 W/m 时，背部皮肤温度升高约 11.3°C，而直肠温度仅升高 0.6°C，表明对大鼠的暴露具有高度的局部效应。APD 与皮肤温升之间存在显著相关性。该关系提供了一个线性回归模型，估计在 200 W/m 的 APD 下暴露的皮肤温升低于 5°C。
这些结果表明，在目前使用大鼠的实验条件下，MMW 暴露指南的操作阈值是有效的。
