Early-Life Exposure to Pulsed LTE Radiofrequency Fields Causes Persistent Changes in Activity and Behavior in C57BL/6 J Mice

Abstract

Despite much research, gaps remain in knowledge about the potential health effects of exposure to radiofrequency (RF) fields. This study investigated the effects of early-life exposure to pulsed long term evolution (LTE) 1,846 MHz downlink signals on innate mouse behavior. Animals were exposed for 30 min/day, 5 days/week at a whole-body average specific energy absorption rate (SAR) of 0.5 or 1 W/kg from late pregnancy (gestation day 13.5) to weaning (postnatal day 21). A behavioral tracking system measured locomotor, drinking, and feeding behavior in the home cage from 12 to 28 weeks of age. The exposure caused significant effects on both appetitive behaviors and activity of offspring that depended on the SAR. Compared with sham-exposed controls, exposure at 0.5 W/kg significantly decreased drinking frequency (P ≤ 0.000) and significantly decreased distance moved (P ≤ 0.001). In contrast, exposure at 1 W/kg significantly increased drinking frequency (P ≤ 0.001) and significantly increased moving duration (P ≤ 0.005). In the absence of other plausible explanations, it is concluded that repeated exposure to low-level RF fields in early life may have a persistent and long-term effect on adult behavior. Bioelectromagnetics. 2019;40:498-511. © 2019 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.

Keywords: activity; brain; electromagnetic fields; locomotion; rodent.

Figure 1

Experimental design. Animals were exposed to pulsed 1,846 MHz radiofrequency (RF) fields for 30 min/day, 5 days/week from gestation days 13.5–18.5 and from postnatal days 3 to day 21 (weaning) at a whole‐body averaged specific energy absorption rate (SAR) of 0.5 or 1 W/kg using a Gigahertz transmission electromagnetic cell (GTEM). Sham exposures consisted of the same procedures except that the electric field strength in the GTEM was reduced to 0. Two weeks were allowed for habitation to the home cages before data collection from 13 to 28 weeks of age.

Figure 2

Appetitive behavior after prenatal and early‐life exposure to radiofrequency (RF) fields. (a) Animal body mass (n = 3 per experimental group), (b) number of licks made against the spout of the water bottle, and (c) number of visits to the food hopper. See Table 2 for significant differences between groups. For all experimental groups n = 5 or 6 except for weeks 14, 21, and 28 where n = 3. All data are presented as mean ± standard error of the mean.

Figure 3

Locomotor behavior after prenatal and early‐life exposure to radiofrequency (RF) fields. (a) Number of revolutions of the PhenoWheel, (b) overall distance moved (cm), and (c) cumulative moving duration (seconds). See Table 2 for significant differences between groups. For all experimental groups n = 5 or 6 except for weeks 14, 21, and 28 where n = 3 due to data loss. All data are presented as mean ± standard error of the mean.

Figure 4

Rest behavior after prenatal exposure to radiofrequency (RF) fields. (a) Number of non‐active episodes, (b) number of visits to the shelter, and (c) cumulative duration in shelter. See Table 2 for significant differences between groups. For all experimental groups n = 5 or 6 except for weeks 14, 21, and 28 where n = 3 due to data loss. All data are presented as mean ± standard error of the mean.

Figure 5

Anatomical and specific energy absorption rate (SAR) distribution images for axial slices of the pregnant mouse model. The incident field is to the left side of the mouse and horizontally polarized. Slices 65 (a) and 105 (b) are shown, providing cross‐sections of the six fetuses.

Figure 6

Experimental setup. (a) Block diagram for long term evolution (LTE) signal generation and monitoring. (b) Photograph showing position of the polystyrene mouse cages during exposure. Foam blocks under the cages are made of a low dielectric constant material. (c) Screengrab of a digitally demodulated LTE downlink signal as used in this study. It was obtained using a Keysight N9080A LTE‐FDD measurement application, on an Agilent N9020A MXA Signal Analyzer.

Figure 7

Photograph of the inside of a home cage showing features and analysis zones. A mouse was housed in a home cage for 13 weeks to collect behavioral data. The feeder zone and shelter zone were used for analysis but the other zones are for illustrative purposes only.