• 25 JUL 07
    • 0

    #773: Australia considers increasing its ELF exposure limits and to include new “precautionary measures”!

    Following is the latest progress report from the Australian Government’s Radiation Health Committee on its proposed new exposure standard for extremely low frequency (ELF) magnetic and electric fields. Although the standard will apparently contain a precautionary element, as I understand it, advising people how to reduce their exposures if they are concerned, the most notable feature of this standard is an increase in the overall allowable exposure levels ( for 50 Hz powerfrequency) by a factor of three. Thus:

    * The old NH&MRC residential guidelines (read ICNIRP) of 1000mG ( 100uT) become 3,000mG (300uT)

    * The occupational limit increases from 5,000mG (500uT) to 15,000mG (1,500uT)

    From my discussion with one of the members of the ELF standard working party these new limits only apply to “instantaneous exposures” and not chronic exposures. However in the real world, the new limits will inevitably come to be quoted as a reference point to somehow infer safe limits. This was the case with the NH&MRC/ICNIRP limits in the surveys done for RMIT Building 108, ABC Toowong, TYCO Electronics and other similar cases in Australia.

    Worried about the politically incorrect issue of breast cancer and occupational exposure to ELF (ABC Toowong)? Or what about the embarrassing issue of childhood leukaemia and the “heavy exposure (as referred to by NRPB) of a mere 0.4 mG? Why worry about exposures around 4mG/12mG when the benchmark exposure limit is a whopping 3000mG for your home or 15,000mG for your workplace?

    I would at least hope that the RHC will spell out plainly in an introduction to the standard (and as an integral part of it) what exactly these new limits apply to, and what they do not apply to,

    Why such a radical departure from ICNIRP’s hegemony which has long been claimed to represent the pinnacle in expert EMF science? Is it now better science or more likely the implications of one of the European Union’s Physicial Agent Directives (PAD), specifically Directive 2004/40/EC?

    This Directive, designed to protect the health and safety of workers from “established health risks” from exposure to electromagnetic fields, by law must be incorporated within the legislation of all member states by 2008.

    Based on the ICNIRP limits, the EC directive has become a major concern for the Magnetic Resonance Imaging (MRI) medical community because, to quote from the a community source, “there are a number of situations in which MRI workers exceed the proposed exposure-limit values for low-frequency, time-varying magnetic fields set out in the PAD”.

    In other words, both the 2004 EC directive and the ICNIRP rationale used in establishing its exposure limits have created an “enormous detrimental effect” on MRI with a flow-on for the healthcare industry that routinely uses MRI in diagnosis. References:

    http://medicalphysicsweb.org/cws/article/opinion/25661
    http://www.hpa.org.uk/radiation/understand/information_sheets/mri_ec
    _directive_2004_40_ec.htm
    http://www.myesr.org/html/img/pool/Alliance%20for%20MRI%20July%202007.pdf

    A previous concern for the MRI manufacturers was that the proposed limit for static magnetic fields of 2T (Tesla) in the Directive would have halted the development and use of new high-field MRI scanners, especially considering that some now operate up to 3T. Last minute lobbying by the MRI community had this provision deleted from the final Directive.

    Now the MRI community concern is that, as mentioned above, there are MRI workplace practices that place the operator within the gradient coil magnetic field, specially when the operator frequently needs to be able to reach the patient. To quote again from the MRI community source: “Put simply, the PAD [EC Directive] will kill off interventional MRI in Europe, at an early stage of its development and before its value has been properly established.”

    To argue for the elimination of MRI technology because employees could be receiving excessive EMF exposures is totally out of the question. The “catch-22” situation is that enforcement of the ELF limits in the European Directive (and ICNIRP) could result in the return to the use of ionising radiation technology in its place. And that would obviously not be advisable.

    MRI is an indispensable tool in today’s society but why not take a precautionary measure here and take action to protect workers against being exposed to EMF levels in excess of EC Directive or ICNIRP limits? Such precautionary measures could include shielding work areas and writing up safe work practices to keep employees outside of high field areas during MRI operation. Are such measures possible? From my reading of the issue they may difficult but this needs to be determined.

    While the MRI controversy goes on, what is lost in the discussion is what are the ‘health based’ standards supposed to be for anyway? It seems that the only thing that shifts entrenched views on EMF standards, such as ICNIRP, is not biological science but when their limits becomes a barrier to the deployment of new technology.

    So what about the problem of 4mG (0.4uT) increasing the risk of childhood leukaemia? Well, unfortunately, when you weigh up the risk of increased numbers of children exposed to 4 mG getting cancer when compared to the enormous financial investment in MRI technology by the medical fraternity, and the unquestionable benefits of MRI to society as a diagnostic tool, unfortunately the kids lose out. In risk assessment cost/benefit analysis, the benefits of setting a ‘health based’ standard to protect children from an increased incidence of leukaemia pale in comparison to the potential enormous cost to the MRI medical community.

    This is the uncomfortable “catch-22” dilemma facing our standard setters and exposes what the current proposed Australian ELF standard is all about. This is why a “health based” EMF exposure standard based on anything other than economic considerations is virtually impossible under the current regulatory regime.

    The other issue lost in the MRI /standards controversy is what about the possible hazards to people working with MRI machines? Not only the operators but the technicians who routinely service the scanners, even apparently climbing in them, with the magnets energised to save on “costly ramp-downs of the magnets”. Considering that they can be exposed to both static and time-varying magnetic fields in excess of the ICNIRP limits, does simply increasing the limits automatically make them safe from these chronic exposures?

    I wonder what an epidemiological study of workers occupationally exposed to MRI magnetic fields would find?

    Note in the below progress report that when mentioning the new limits they are in relation to “Magnetic Field Reference Levels for the head”. This apparently does mean a full body exposure but mentioning of the head is interesting as that is a concern with MRI workers if they move their heads to rapidly when working close to the scanner – Further suggesting that the MRI controversy is behind the increase in exposure limits.

    Don

    ********************************************************************Notice from the Australian Government Radiation Health Committee

    18 July 2007

    Agenda Item 2.4: Standard for Exposure Limits for Electric and Magnetic Fields (0Hz – 3kHz)

    Decision

    The Radiation Health Committee:

    • Considered the report of the ELF Standard Working Group and reviewed progress in development of the draft Standard.

    • Noted that a public consultation period had been held and that 64 submissions had been received and were being reviewed by the Working Group, and that this work would continue over several months.

    • Supported the changes proposed at this stage by the Working Group, including:

    * Changing the Title to “Limits and Precautionary Measures for Reducing Exposure to Electric and Magnetic Fields – 0Hz to 3kHz”.

    * Removing the “controlled activity” provisions for magnetic field exposure from the draft.

    * Amending Table 3 to provide that the Magnetic Field Reference Levels for the head become 1,500 μT (occupational) and 300 μT (general public). These figures are supported by the science and modelling to protect from established effects.

    * Amending Table 4 to provide that the Reference Levels for Controlled Circumstances become 20kV/m (occupational) and 10 kV/m (public) in situations where the possibility of indirect hazard has been removed and signage is placed in appropriate locations.

    * Strengthening precautionary statements in the Standard.

    • Noted that the next Working Group meeting was to be held on 13 August, where the main items to be discussed included the submissions on MRI, reviewing the statements on epidemiology, and strengthening the precautionary statements in the Standard.

    • Agreed that the Working Group will report again on further progress to the November meeting of the Committee.

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