Australia's revised RF standard
EMRAA looks at some of the problems with Australia's draft RF standard.
A year in preparation, the new draft Standard for radiation protection is now available for public review. The Standard, which covers the frequencies from 3 kHz to 300 GHz—including the range used by mobile phones and base stations—has been drafted by a working group convened by Australian Radiation Protection and Nuclear Safety Agency (ARPANSA), with representation from industry, unions, Occupational Health & Safety representatives, and the community which was represented by EMRAA’s Convenor, John Lincoln.
The document was released for public comment without a meeting of the working group to review last-minute changes and before several members of the group had even had a chance to read the final draft. Therefore, it does not necessarily represent a consensus of committee views.
The starting-point for the document was the final draft of the standard begun by the Standards Australia TE7 committee in 1998 and the present document is based upon the 1998 Guidelines of the International Commission on Non-Ionising Radiation Protection (ICNIRP).
The foreword to the draft states that “There is currently a level of concern about RF exposure, which is not fully alleviated by existing scientific data. It is true that data regarding biological effects, at levels below the limits specified in this Standard, are incomplete. The health implications of these data are not known and such data could not be used for setting the levels of the basic restrictions in this Standard. … The Standard, nevertheless, states the principle that it is generally sensible in achieving service or process requirements to minimise unnecessary or incidental RF exposure, provided it does not introduce other risks and can be achieved at modest expense.” (p.i)Differences from the previous standard
- It introduces an instantaneous spatial peak SAR (p 36).
- It specifies types of measuring equipment that must be used to test compliance with the Standard.
- The draft claims that there is no scientific evidence that some groups of the population are more susceptible to RF effects, including children and foetuses (p32-3).
- Because the document claims that pregnant women may not dissipate heat as well, it suggests they should be exposed to public but not occupational exposure levels (p. 33). (See comments on adequacy of occupational/public exposure below.)
- The draft includes information about managing risk in occupational exposures (22-3).
Problems with the Rationale of the Draft Standard
The Rationale of the draft Standard is based upon number of premises that are substantially flawed.Premise 1 Heating is the only health risk.
The Standard is based on the assumption that adverse health effects only occur if radiation heats our bodies by 1º C. At lower (athermal/below-heating) exposures, biological effects are known to occur but the document states that there is some doubt as to how significant these effects are.
Yet some of the effects that have been observed at athermal levels of radiation include effects on the brain, behaviour, performance, learning, sleep, reproduction, cancer, DNA, immunity, hormones, cell proliferation and genes. Because many of these are quite significant effects, there is a need for the Standard to protect the public from athermal levels of exposure.
(This poses a difficulty for regulators as there is no consensus on what levels of athermal radiation are “safe” or what mechanisms might cause effects at these levels of exposure. Moreover, not all the studies that have shown athermal effects have been replicated, a criterion considered important for confirming scientific results.)Premise 2 The body can safely absorb 4 W/kg & parts of it 100 W/kg.
The draft Standard is based on the assumption that the whole body can absorb 4 watts per kilo (W/kg) for about 30 minutes before its average temperature rises by 1º C causing health problems.
Certain parts of the body will absorb 25 times as much radiation (ie up to 100 W/kg) without the overall temperature of the body increasing above the 1º C mark. Therefore, the draft assumes the certain parts of the body can safely be exposed to 25 times as much radiation as the whole body and the body will dissipate the heat.
However, there are some significant problems with these assumptions.
- Can children absorb 25 times as much radiation as adults at the head?
- Do all people respond in the same way, or do we absorb radiation differently?
- Can pregnant women dissipate heat as effectively?
- Do we dissipate heat as well in summer or after exercise?
- How do we know that adverse health effects don’t occur if only parts of the body (particularly the brain) are heated to 100 W/kg?
Just how sensible is the assumption that adverse effects only occur if the whole body temperature is affected? Putting our finger in a candle flame produces obvious ill-effects from localised heating without the whole body temperature rising significantly. Can we be sure that damage from localised heating doesn’t occur inside the brain for example in much the same way?
At the RF Spectrum Conference in Sydney on 22-23 March, Dr Andrew Wood presented information about the different uptake of RF radiation in different types of cells. He referred to studies which showed non-uniform absorption of EMR [Guy et al (BEMS 20, sup 4:21) and Burkhardt (BEMS 17:483)]. One study, by Kotnik and Miklavcic (Bioelectromagnetics 21:385), showed that there can be a 20-fold enhancement of SAR in cell membranes compared with the outside of the body at 900 MHz. Data of this type casts serious doubt on the assumption that parts of the body can safely absorb 25 times more radiation than others.Premise 3 - “Safety factors” provide additional protection.
The draft Standard claims to incorporate safety factors to provide protection for occupational and residential exposures. This is because people in industry can perform risk analysis and risk management and control strategies, whereas “public exposure is less controlled and in many cases members of the pubic are unaware of their exposure to RF fields. Moreover, individual members of the public may be continually exposed and cannot reasonably be expected to take precautions to minimise or avoid exposure.” (p 5)
The baseline is the assumption that it is acceptable for a person to absorb 4 W/kg. (This is an SAR of 4W/kg.) The draft provides a safety factor of 10 for occupational exposure. This allows workers to receive a whole body exposure of 0.4 W/kg averaged over a 40-hour week.
The draft allows the public to be exposed to 0.08 W/kg and claims that this represents a safety factor of 50 (ie 1/5th of 0.04 W/kg). However, in reality, the public is exposed for 24 hours per day, seven days per week, ie 168 hours or almost five times the time of exposure for workers. So this provides no additional safety factor whatsoever.
Given the stated need to provide additional protection for the public, the draft would need to reduce exposure by a factor of at least five.Premise 4 We can average exposure over time
The draft Standard presumes that the amount of radiation to which a person may be exposed can be averaged over six minutes. This assumes that continuous exposure to a “smooth” signal has the same effect on the body as random signals with sharp bursts of radiation. This may not, in fact, be the case as there is evidence that the pulses of radiation may be causing effects.Premise 5 We can average exposure over mass of body tissue
The draft presumes that absorption of 2 W/kg in the body can be averaged over 10 grams of body tissue. The previous Standard (Interim Standard, 1998) averaged absorption of 1.6 W/kg over 1 gram of tissue.
Averaging the absorption over a larger amount of body tissue gives a less reliable result. According to Dr James Lin, “the absorbed energy averaged over a defined tissue volume of 10g is artificially low, compared to a 1g SAR. The 1g SAR is a more precise representation of localized microwave energy absorption, and a better measure of SAR distribution inside the head.” (IEEE Antennas and Propagation Magazine, October, 2000.)
The SAR of 2.0 W/kg in this draft averaged over 10 grams of tissue is the same as an SAR of 4-6 W/kg averaged over 1 gram of tissue. This means that, by averaging the SAR over a larger amount of body mass, the draft is effectively allowing people to be exposed to more radiation.
Other Problems with the Draft1. Mobile phones
Mobile phones or portable transmitting equipment does not have to comply with the Standards if their mean power output does not exceed 100 mW at any frequency (p 47). They are also exempt from the Standard if they have a power output of 7 Watts or less at frequencies between 100 kHz and 450 MHz. However, some mobile phones operating at 7 Watts would produce an SAR greater than 0.4 W/kg which is thought in the rest of the Standard to be unacceptable.
In frequencies between 450 MHz and 2500 MHz, they do not have to comply with the draft if their power output exceeds a level calculated by a given formula. This formula allows a GSM mobile phone to operate at a power output of 3.4 Watts. However, because most mobile phones of this sort operate at just 2W, they would be exempt from the Standard.2. Blood-brain barrier
Research has shown that breaches of the blood-brain barrier occur at extremely low (athermal) levels of exposure to mobile phone radiation, against which the draft Standard does not provide protection. It is, therefore, possible that in a person on medication making a mobile phone call, chemicals could penetrate the blood-brain barrier and enter the brain.
According to New Zealand consultant, Dr David Black, at the recent RF Spectrum Conference in Sydney, this possibility “needs more research”.3. Other mechanisms
The Standard does not allow for the possibility that effects of EMR might occur as a result of mechanisms other than heating. Dr Peter French has recently demonstrated a possible mechanism by which mobile phones may cause cancer without a heating effect by the chronic activation of heat shock proteins (see “EMRAA News” Dec, 2000.) Other mechanisms that may contribute to health problems at athermal levels of exposure include resonance effects (see page 7) and reduction in melatonin.4. Windows of effect
Research has shown that biological effects occur at windows of frequency or power density. In other words, some frequencies or exposures seem to elicit effects, while others do not. As mobile telecommunications moves to new technologies and higher frequencies, which have not yet been fully researched, it is possible that unpredicted effects may occur on human health.5. Amplification of signals in the environment
At the RF Spectrum Conference, Dr David McKenzie discussed measurements he had taken in the vicinity of an RF transmitter. He found that signals were considerably amplified by metal door and window frames. In light of this work, Dr McKenzie recommended that a “factor of 5 in field [strength] and 25 in [power] intensity should be allowed for in the estimating of worst case exposures” in the environment.6. Precautionary approach
The draft includes reference to the precautionary approach only in an appendix. It does not include such a reference in the body of the document, itself, nor does the draft embody a precautionary approach.
EMRAA News June 2001, Vol 6 No 2