Wednesday, February 03, 2010

EU Disturbs The Magnetic Force

When we're done here, I want you to sign THIS petition.  You'll see why momentarily. 

The European Union, perhaps the prototype for a world-government that some in our country seem to desire, is about to do radiology, and thus humanity, a disservice.  It seems that the folks over there in charge of such things issued a Phyical Agents (Electromagnetic Field) Directive in 2004, which was to take effect in 2008, but has now been postponed to 2012.  Feel free to read the entire Directive at your leisure, but here are some of the salient Whereases

(1) Under the Treaty (creating the European Union) the Council may, by means of directives, adopt minimum requirements for encouraging improvements, especially in the working environment, to guarantee a better level of protection of the health and safety of workers. Such directives are to avoid imposing administrative, financial and legal constraints in a way which would hold back the creation and development of small and medium-sized undertakings. . .

(4) It is now considered necessary to introduce measures protecting workers from the risks associated with electromagnetic fields, owing to their effects on the health and safety of workers. However, the long-term effects, including possible carcinogenic effects due to exposure to time-varying electric, magnetic and electromagnetic fields for which there is no conclusive scientific evidence establishing a causal relationship, are not addressed in this Directive. These measures are intended not only to ensure the health and safety of each worker on an individual basis, but also to create a minimum basis of protection for all Community workers, in order to avoid possible distortions of competition.

And then, the commandments:
Article 1
 Aim and scope

1. This Directive, which is the 18th individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC, lays down minimum requirements for the protection of workers from risks to their health and safety arising or likely to arise from exposure to electromagnetic fields (0 Hz to 300 GHz) during their work.

2. This Directive refers to the risk to the health and safety of workers due to known short-term adverse effects in the human body caused by the circulation of induced currents and by energy absorption as well as by contact currents.

3. This Directive does not address suggested long-term effects.

4. This Directive does not address the risks resulting from contact with live conductors.

5. Directive 89/391/EEC shall apply fully to the whole area referred to in paragraph 1, without prejudice to more stringent and/or more specific provisions contained in this Directive.

Article 5

Provisions aimed at avoiding or reducing risks

1. Taking account of technical progress and of the availability of measures to control the risk at source, the risks arising from exposure to electromagnetic fields shall be eliminated or reduced to a minimum.
.and in the Annex (I think we Yanks call that an Appendix):


Depending on frequency, the following physical quantities are used to specify the exposure limit values of electromagnetic fields:

— exposure limit values are provided for current density for time-varying fields up to 1 Hz, to prevent effects on the cardiovascular and central nervous system,

— between 1 Hz and 10 MHz exposure limit values are provided on current density to prevent effects on central nervous system functions,

— between 100 kHz and 10 GHz exposure limit values on SAR are provided to prevent whole-body heat stress and

excessive localised heating of tissues. In the range 100 kHz to 10 MHz, exposure limit values on both current density and SAR are provided,

— between 10 GHz and 300 GHz an exposure limit value on power density is provided to prevent excessive tissue heating at or near the body surface.
Well, I, for one, don't approve of any nasty effects upon my cardiovascular or central nervous system, and we certainly don't want any whole-body heat stress.  But, the protective action of the EU might have some unforseen consequences.  From S. F. Keevil, writing in the British Journal of Radiology in 2005: 

Not that I mind US researchers getting the upper hand in something, but you know very well that if the limits go into effect in Europe, they will eventually find their way across the Pond, given our admiration for all things European. 
In the absence of a static field limit, the gradient field limit poses the greatest problem. It will exclude staff from the vicinity of the bore during imaging, with the extent of the exclusion zone depending on magnet and gradient system design and choice of sequence. Since the limits are absolute, without scope for time averaging or relaxation for brief exposure, it will become illegal for an anaesthetist to lean into the bore even for a moment to check a patient, or for a radiographer or nurse to hold an anxious patient’s hand.

Incorporation of these limits into law will make many interventional MR procedures illegal in Europe, closing off development of a field with tremendous clinical potential. It will make it more difficult to provide appropriate care for anaesthetised, monitored and anxious patients. It will affect manufacture of MR equipment, particularly if a static field limit is adopted, and hence threaten the UK’s global position in this sector. It will give US researchers a significant advantage over European competitors, both in th development of MR methodology itself and in the growing exploitation of these techniques, for example in the pharmaceutical industry. Most importantly, it will mean that current and future MR techniques may be denied to patients, in many cases necessitating an examination with X-rays instead, with the resulting dose of ionizing radiation to both patient and staff.
But Keevil then reveals the basis for the proposed limits: 
What are the known short-term adverse effects that the Directive seeks to avoid? A recent paper [4] has considered ICNIRP and NRPB documents [2, 5] in more detail than is possible here. In the gradient frequency range, peripheral nerve stimulation (PNS), due to induction of electric currents by time varying magnetic fields, is an adverse effect that forms the basis for limitation of patient exposure [6, 7]. PNS occurs at a threshold current density of around 1 A m22 – 100 times higher that the limit set in the Directive. The difference arises because ICNIRP occupational exposure guidelines rely on less well-established phenomena, such as alteration of visual evoked potentials and subtle cognitive effects. Evidence for most of these effects is sparse, often dating from the 1980s, in some cases presented in preliminary form at conferences rather than in full papers, and in other cases reported only in the 10–100 Hz frequency range but extrapolated to higher frequencies in the absence of more appropriate data.

ICNIRP concludes from these data that thresholds for acute CNS effects are exceeded above 100 mA m22, but in view of the sparse evidence, applies a safety factor of 10, resulting in the 10 mA m22 limit. In supporting the same limit, the NRPB acknowledges adoption of ‘‘a cautious approach… to indicate thresholds for adverse health effects that are scientifically plausible’’ [3]. Many things are scientifically plausible, but the exposure limits are supposed to be based not on hypothetical possibilities but on ‘‘known adverse health effects’’ causing ‘‘detectable impairment of… health’’, as opposed to biological effects that may or may not be harmful [2] if they exist at all. There is no substantial evidence for any such effects in the gradient frequency range below the PNS threshold.
Could it be that the EU overreacted?  Keevil hammers the point home in in a report prepared for the Institute of Physics in London: 

Keevil goes on to outline the actions taken by the MRI community, as well as possible outcomes and alternatives.  The Directive is, as noted above, currently on hold until 2012. 
The members of ICNIRP are internationally acknowledged experts in their fields, but the guidelines that they produced are based on the cautious interpretation of sparse data and are essentially precautionary in nature. It has since come to light that the possibility of the directive causing problems with MRI was raised by some MEPs at an early stage. However, it was dismissed because the European Commission received assurances from ICNIRP that the ELVs would not be exceeded by MRI workers. It has not been possible to determine the precise nature, timing and basis of this erroneous advice. . .

For practical reasons, when an MR scan is performed the operator normally leaves the room and operates the scanner from a separate control room. However, there are instances in which a member of staff remains in the examination room and close to the scanner while it is operating. Examples of these situations include:

● interventional MRI, where a radiologist or other clinician may be reaching inside the bore of the magnet to carry out invasive procedures during scanning;

● some types of functional MRI, such as research studies on deaf-blind subjects where a member of staff touches the palm of the patient’s hand during scanning;

● imaging of children, where the close presence of a nurse or radiographer may avoid the need for anaesthesia to obtain satisfactory images;

● imaging of patients who are anaesthetised or require monitoring, where it is common for an anaesthetist to remain in the room and visually assess the patient during scanning;

● research applications, where a researcher may need to adjust experimental equipment during imaging.

Initial estimates showed that for workers remaining close to the magnet bore in these situations, when the switched gradients are operating, the exposure is likely to exceed the AV for 500–1000 Hz magnetic fields by a factor of around 504,5 and the ELV by an order of magnitude. . .

(I)t is difficult to avoid the conclusion that a range of current and emerging MRI procedures would be rendered illegal by the directive. Some of these techniques simply cannot be performed in other ways, and in other cases the only possible option would expose both the patient and workers to ionising radiation. So, far from protecting worker health and safety, in the context of medical imaging the directive might have quite the opposite effect: a recent study found that almost 40% of interventional radiologists who perform X-ray-guided procedures have signs of radiation damage to their eyes.

Electromagnetic radiation is scary to the public, be it X-rays, gamma rays, or even magnetic and electric fields.  In its zeal to protect EMF workers, the EU appears to have used questionable science and just a tincture of panic, without complete understanding of the consequences of its actions.  I am sorely tempted to compare this to the Cap and Trade/Global Climate Warming Change fiasco, but at least in this case, the data was probably misunderstood and not falsified.  That counts for something. 

I would urge all of my readers to go HERE and sign the petition that reads in part:

I urge decision-makers at all levels in Europe to endorse the position of the Alliance for MRI requesting an EU-wide exemption for the medical use of MRI and related research from any exposure limit values set in the Physical Agents 2004/40/EC (EMF) Directive and the implementation of user guidelines.
Please sign, even if it helps our European friends get ahead of us in research.  While politics may be local, science is global, and there needs to be no unnecessary restriction on this aspect of imaging.

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