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.

Keywords:

• electrotherapy
• EMF measurement
• therapeutic diathermy device
• nonionizing radiation
• physical therapists
• physiotherapy workplace

ACKNOWLEDGMENTS

This study is an extended work that was undertaken in a project funded by the Health and Safety Executive (Project No: R47.022); however, the views expressed are entirely those of the authors. The authors wish to declare that this article is an extension of work presented in a published doctoral dissertation entitled “Safety of Medical Device Users: A Study of Physiotherapists’ Practices, Procedures and Risk Perception” by author SGSS at the School of Health Sciences and Social Care, Brunel University, U.K. (2011). The authors gratefully acknowledge input and advice by Alan Esnouf, lecturer in Physiotherapy at Brunel University, in explaining physiotherapists’ intended practice during diathermy device use. The authors gratefully acknowledge that constructive and critical comments and suggestions from anonymous reviewers improved this manuscript.