SOP Bulletin No. 79

Decision Support Unit

3 — rd Floor AMP Place, 10 Eagle St Brisbane  3 — rd Floor Blackburn House, 199 Grenfell St Adelaide

Intranet site:  http://intranet/nat/comp/dp/Nop/dsu/dsudefault.htm

16 December 2003

THE FOLLOWING RMA SOP IS TO BE GAZETTED ON 17 DECEMBER, 2003

New SOPs	Nil
Revocations & Replacements	Nil
Amendments	Chronic lymphoid leukaemia

IMPORTANT OPERATIONAL FEATURES

Chronic lymphoid leukaemia

Amendment – 59 of '03 Amends 67 of '01

Under direction from the Specialist Medical Review Council (SMRC), the RMA has added a new factor to the RH CLL SOP only, for exposure to extremely low frequency magnetic fields.

Note that in accordance with the SMRC decision, this amendment is effective from 1 October 2003.

The factor and associated definitions specify a requirement for > 25.0 microtesla-years of cumulative exposure to magnetic fields generated at frequencies in the range of 50 Hz to 60 Hz.

This bulletin is intended to help decision makers make some sense of that requirement.

Magnetic fields at 50 to 60 Hz are produced by electric power transmission and distribution lines, electrical wiring, and electrical equipment and appliances.  In Australia and much of Europe electric power is supplied at a frequency of 50 Hz.  In the United States power is supplied at 60 Hz.

Other sources of technologically generated electromagnetic radiation (EMR) produce magnetic fields at frequencies much higher than 50 to 60 Hz.  Exposure to magnetic fields from these sources are therefore not covered by this factor.  Sources of EMR that are NOT covered by this factor include the following:

• Radar
• Navigation systems
• Communications equipment
• Two way radio
• Microwave
• Satellite
• Mobile phones
• TV and radio transmissions

The effects of exposure to higher frequency EMR from these types of sources, in relation to CLL, is being further investigated by the RMA.

Magnetic fields are produced by the flow of current through wires or electrical devices and increase in strength as the current increases.  Magnetic fields are measured in units of tesla (T) or gauss (G) (1 T = 10,000 G).  Electrical equipment usually has to be turned on for a magnetic field to be produced (current may flow through some devices even when not “on”).

Exposure to magnetic fields depends on the strength of the sources, the distance from those sources, and the time spent in the field.  The strength of the field decreases very rapidly with distance from the source.

A microtesla (T) is one millionth of a tesla.  A microtesla year means the equivalent of being exposed to 1 T all day, every day, for a year.

25 T-years is a very high dose.

Typical background levels of 50 to 60 Hz magnetic fields in the home and environment are of the order of 0.1 T.  However, considerably higher levels are experienced when a person is in close proximity to an active electrical appliance or power line.  The following tables gives some examples.

Typical magnetic field strength of household appliances at various distances

Source: Federal Office for Radiation Safety, Germany 1999

Typical magnetic field strengths from EMF sources

Source	Magnetic field strength (T)
275,000 volt transmission line
- directly underneath	0.5 to 2.5
- edge of easement	0.1 to 0.5
66,000 volt distribution line
- directly underneath	0.5 to 2.0
- edge of easement	0.1 to 0.3

Source: National Health and Medical Research Council (NHMRC): 'Interim Guidelines on Limits of Exposure to 50/60 Hz Electric and Magnetic Fields (1989)'.

Occupational exposure to 50 to 60 Hz magnetic fields is highest in electric utility workers such as linesmen and substation operators, and in workers who work in close proximity to electrical devices such as electricians, welders and sewing machine operators.  Workers in occupations of this type could achieve 25 T-years cumulative exposure, but generally would require decades of employment to reach that level.

Typical exposure to 50 to 60 Hz magnetic fields in most occupations amounts to considerably less that 0.1 T-years for each year of employment.

Accurate assessment of an individual's cumulative 50 to 60 Hz magnetic field exposure is  essentially impossible.  Data collected using personal dosimetry monitoring devices are needed to arrive at even a rough estimate.  This is because there are so many sources of 50 to 60 Hz magnetic fields in the modern environment and because exposure varies so dramatically with distance from the source.

No specific information is yet available about exposures to 50 to 60 Hz magnetic fields that may occur in a military setting.   If any claims are received for CLL where magnetic field exposure is contended as being causal, then detailed work exposure information should be sought from the applicant.  If that information points to high level exposure then further advice should be sought from the DSU.

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