Tetra masts and MND - what is the evidence?

30 January 2006

The following statement has been issued by the MND Association following the broadcast of the BBC programme Judge John Deed on Friday 27 January, which featured a successful damages claim from someone with MND living near a Tetra mast.

There is some evidence that occupational exposure to extremely low magnetic fields (EMFs) may be linked to MND. However, at worst, these data suggest that this may be a contributory risk factor in developing MND, rather than the single cause of the disease.

It is difficult to know how the levels of occupational exposure measured in these studies would compare to the estimated levels of exposure from phone or Tetra masts.

Evidence linking EMFs and MND
A small number of studies have shown that people who have worked in the electrical industry have an overall slightly higher risk of developing MND, however, only one of these studies investigated EMF exposure in this profession.

Exposure to EMFs is an occupational hazard of electrical workers and so it has been suggested that this could be a relevant factor. However, there is no consistent evidence demonstrating a link between EMFs and MND in electricians, or anyone with MND. With electricians, the more likely explanation is down to an increased likelihood of electric shock, as it is known that electric shocks (and lightning strikes) can cause irreparable damage to nerve cells.

Causes of MND
The single most commonly asked question from people living with MND is ‘Why me’ or 'I worked in this industry/did this as a hobby etc, did this cause my MND?'. Unfortunately it is also the most difficult question to answer. Researchers believe that MND is likely to be due to many small contributory risk factors that in combination may tip the balance towards someone developing MND. Research to identify such factors is notoriously difficult, particularly in rare diseases such as MND. It has been an area of MND research for many years.

Generally, epidemiology research is approached from two points of view, firstly where a possible risk factor has been identified, a larger, more rigorous study would be conducted to explore this risk. The second point of view is looking at a distinct group of people or population where a higher than expected number of people developed MND than could be accounted for by chance. In the second type of study, it is necessary to establish that the numbers of people affected really are higher than can be accounted for by chance, before explanations can be explored. It is also important to be sure that there are no confounders in either type of analysis. As the cause of motor neurone disease is unknown, it is difficult to account for any confounding factors, as we don’t know what they are.

Richard Green, Director of Communications
01604 611837. Mobile 07960 941070
richard.green@mndassociation.org