Apr 4, 2018

Effect of cell phone radiofrequency radiation on body temperature in rodents: Pilot studies of the National Toxicology Program's reverberation chamber exposure system

Michael E. Wyde, Thomas L. Horn, Myles H. Capstick, John M. Ladbury, Galen Koepke, Perry F. Wilson, Grace E. Kissling, Matthew D. Stout, Niels Kuster, Ronald L. Melnick, James Gauger, John R. Bucher, and David L. McCormick, Bioelectromagnetics, Volume 39, Issue 3, pp. 190–199, April 2018, Online: 22 December 2017; doi: 10.1002/bem.22116.

Radiofrequency radiation (RFR) causes heating, which can lead to detrimental biological effects. To characterize the effects of RFR exposure on body temperature in relation to animal size and pregnancy, a series of short‐term toxicity studies was conducted in a unique RFR exposure system. Young and old B6C3F1 mice and young, old, and pregnant Harlan Sprague‐Dawley rats were exposed to Global System for Mobile Communication (GSM) or Code Division Multiple Access (CDMA) RFR (rats = 900 MHz, mice = 1,900 MHz) at specific absorption rates (SARs) up to 12 W/kg for approximately 9 h a day for 5 days. In general, fewer and less severe increases in body temperature were observed in young than in older rats. SAR‐dependent increases in subcutaneous body temperatures were observed at exposures ≥6 W/kg in both modulations. Exposures of  ≥10 W/kg GSM or CDMA RFR induced excessive increases in body temperature, leading to mortality. There was also a significant increase in the number of resorptions in pregnant rats at 12 W/kg GSM RFR. In mice, only sporadic increases in body temperature were observed regardless of sex or age when exposed to GSM or CDMA RFR up to 12 W/kg. These results identified SARs at which measurable RFR‐mediated thermal effects occur, and were used in the selection of exposures for subsequent toxicology and carcinogenicity studies.

The scientific and technical impact of the study can be summarized as:

  • Young and aged rats and mice and pregnant rats were exposed to determine the effects of animal size and pregnancy status on the thermal response to RFR
  • The extent of heating effects depends on the age, size, species, and strain of the animal as well as the power level, frequency, and the modulation parameters of the RF signal
  • Rats are more sensitive than mice to RFR‐induced increases in body temperature; larger rats are more sensitive than smaller rats of the same strain; and male rats are more sensitive than female rats, which are smaller than males
  • Differences are likely to be due to factors such as mass, surface area, species‐specific differences in thermoregulation, and differences in the frequencies at which the animals were exposed