Assessment of Physiotherapists’ Occupational Exposure to Radiofrequency Electromagnetic Fields from Shortwave and Microwave Diathermy Devices: A Literature Review

Abstract

We reviewed studies reporting the strength of radiofrequency (RF) electromagnetic fields (EMF) in physiotherapists’ occupational environment. Studies from academic journals published from January 1990 to June 2010 were identified in nine online bibliographic databases. EMF strength was compared with occupational exposure limits (OELs) recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). In the reviewed studies, EMFs were measured at different distances (range 0.2 m to 6 m) from the console of diathermy devices, electrodes, and cables. For continuous shortwave diathermy (CSWD) (27.12 megahertz, MHz), measurements of EMFs at < 1 m, 1 m, 1.1–1.5 m, and 2 m reported the maximum E field strength as 8197%, 1639%, 295%, and 69%, respectively, and the maximum H field strength as 6250%, 681%, 213%, and 56%, respectively, of the ICNIRP limits for E and H fields for occupational exposure. For pulsed shortwave diathermy (PSWD) (27.12 MHz), EMF measurements at < 1 m, 1 m, and, 1.1–1.5 m showed the maximum E field intensity as 1639%, 175%, and 32%, and the maximum H field strength as 1175%, 968%, and 28%, respectively, of the ICNIRP limits for E and H fields for occupational exposure. For microwave diathermy (MWD) (2.45 gigahertz, GHz), the maximum power density measured at < 1 m, 1 m, 1.1–1.5 m, and 2 m was 200%, <30%, 0.76%, and 0.82%, respectively, of the ICNIRP limit for occupational exposure. RF EMF emissions measured from continuous and pulsed electrotherapeutic diathermy devices may well be higher than OELs at specific distances, i.e., at 1 m, which is currently designated to be a safe distance for physiotherapists. The minimum safe distance for physiotherapists should be revised to at least 2 m for CSWD and 1.5 m for PSWD. The reviewed studies did not provide evidence of exceeding the ICNIRP's reference levels for occupational exposure at 1 m from MWD devices.