Occupational exposure standards and guidelines

Pages15-16
6
Occupational exposure standards and guidelines
Many countries have now established RF health protection standards or
guidelines. There have been a number of in-depth reviews of current RF standards
(Czerski, 1985; Stuchly, 1987; Sliney, 1988; Repacholi, 1990). Most of the early
standards addressed the microwave region only (300 MHz-300 GHz) because of the
introduction and proliferation of radar, telecommunications, and radio and TV
broadcasting. Later the vastly expanded use of the electromagnetic spectrum was
recognized, especially at lower frequencies where concerns were raised about RF
exposures from induction heaters, heat sealers and other industrial applications.
RF exposure standards have also been proposed by groups of countries, such as
the European Community and the Council for Mutual Economic Assistance. A proposal
for a Directive of the Council of the European Communities was published in March
1993. The proposal on the minimum health and safety requirements regarding the
exposure of workers to the risks arising from physical agents included electromagnetic
fields and waves. Following the advice of the European Parliament, the Commission
submitted an amended proposal in July 1994, which was adopted in August 1994. The
European Committee for Electrical Standardization (CENELEC) published a
prestandard (ENV 50166 part 2) in January 1995, which will be reviewed for adoption
as a full standard in three years. The Commission of Mutual Economic Assistance
Standard 5801-86, established in 1986, had been incorporated into the regulations of
several Eastern European countries in the following years. The maximum exposure
levels in the various standards can differ by two orders of magnitude. It is speculated
that these differences result from: (a) the physical and biological effects data selected as
the basis for the standards; (b) the interpretation of these data; (c) the different purposes
to be served by the standards; (d) the compromises made between levels of risk and
degrees of conservatism; and (e) the influence of preceding standards in each particular
nation. In recent years, an increasing number of countries have adopted limits identical
or very close to those recommended by INIRC/IRPA.
6.1. ICNIRP guidelines
The INIRC/IRPA guidelines for frequencies between 100 kHz and 300 GHz were
published in 1988 and were based on a whole-body average SAR of 0.4 W/kg (IRPA,
1988). Under conditions where the whole-body average SAR might not exceed the
whole-body average limit, several reports (Conover et al., 1992; Dimbylow, 1988;
Gandhi et al., 1985, 1986; Chou and Guy, 1985; Stuchly et al., 1985, 1986a, 1986b;
Williams and Mild, 1991; Erickson and Mild, 1985) indicate that under certain
conditions peak values of local SAR in the extremities (particularly the wrists and
ankles) can exceed the whole-body limit value by a factor of 300 at certain frequencies.
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