The main neurodegenerative disorders are Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis (ALS, known in the USA as Lou Gehrig's disease). For Alzheimer's disease, see also a compilation of the abstracts of the epidemiological studies dealing with this and information on a new study in 2008 by Huss et al further down this page.
Conclusions of review bodies on neurodegenrative disorders generally
View of NRPB
In November 2001 the NRPB’s Advisory Group published a Report on electromagnetic fields and neurodegenerative disease. The conclusion was:
“There is no good ground for thinking that exposure to extremely low frequency electromagnetic fields can cause Parkinson’s disease and only very weak evidence to suggest it could cause Alzheimer’s disease. The evidence that people employed in electrical occupations have an increased risk of developing amyotrophic lateral sclerosis is substantially stronger, but this could be because they run an increased risk of having an electric shock rather than any effect of long-term exposure to the fields per se.” More on NRPB
In its new advice on exposure guidelines in 2004, the NRPB stated:
“Studies of occupational exposure to ELF EMFs do not provide strong evidence of associations with neurodegenerative diseases. The only possible exception concerns people employed in electrical occupations who appear to have an increased risk of developing amyotrophic lateral sclerosis; however, this may be due to effects of electric shocks rather than any effect of long-term exposure to the fields per se.” More on NRPB
View of ICNIRP
A major review published by ICNIRP in 2002 concluded:
"For reasons discussed in the preceding sections, the ALS [amyotrophic Lateral sclerosis] results are intriguing and point toward a possible risk increase in subjects with EMF exposure. However, confirmatory studies are needed, as is an appropriate consideration of confounding, for example, from electric shocks, as a conceivable explanation. As for AD [Alzheimer’s disease], it appears the excess risk is constrained to studies with weaker designs; thus support for the hypothesis of a link between EMF and AD is weak." More on ICNIRP
View of SCENIHR
SCENIHR is the European Commission's Scientific Committee on Emerging and Newly Identified Health Risks. In their opinion on EMFs in 2007 they stated:
"For several of the other outcomes the support was never strong. Nevertheless, several neurodegenerative diseases are still considered worthy of study in this respect, and this refers particularly to ALS (amyotrophic lateral sclerosis) and Alzheimer disease."
In a 2009 update they said:
"New epidemiological studies indicate a possible increase in Alzheimer's disease arising from exposure to ELF. Further epidemiological and laboratory investigations of this observation are needed." More on SCENIHR
View of WHO
The WHO Environmental Helath Criteria Monograph published in 2007 concluded:
"It has been hypothesized that exposure to ELF fields is associated with several neurodegenerative diseases. For Parkinson's disease and multiple sclerosis the number of studies has been small and there is no evidence for an association with these diseases. For Alzheimer's disease and amyotrophic lateral sclerosis (ALS) more studies have been published. Some of these reports suggest that people employed in electrical occupations might have an increased risk of ALS. So far, no biological mechanism has been established which can explain this association, although it could have arisen because of confounders related to electrical occupations, such as electric shocks. Overall, the evidence for the association between ELF exposure and ALS is considered to be inadequate.
The few studies investigating the association between ELF exposure and Alzheimer's disease are inconsistent. However, the higher quality studies that focused on Alzheimer morbidity rather than mortality do not indicate an association. Altogether, the evidence for an association between ELF exposure and Alzheimer's disease is inadequate."
The Huss et al study from Switzerland
We give here more information on one important study that was published in the American Journal of Epidemiology in 2008, of neurodegenerative disorders in Switzerland in relation to proximity to power lines. See the press release by the university concerned.
It reports an association between living within 50 m of a power line (particularly for longer periods) and Alzheimer's disease but not ALS, Parkinson's disease or multiple sclerosis.
Results for Alzheimer's disease
The relative risks for subjects living at various distances from the power lines are shown here (for the subjects who had lived there at least 15 years):
And the relative risks for various durations of residence are shown here, for subjects living within 50 m:
|Am J Epidemiol. 2008 Nov 5. [Epub ahead of print] |
Residence Near Power Lines and Mortality From Neurodegenerative Diseases: Longitudinal Study of the Swiss Population.
Huss A, Spoerri A, Egger M, Röösli M; for the Swiss National Cohort Study.
The relation between residential magnetic field exposure from power lines and mortality from neurodegenerative conditions was analyzed among 4.7 million persons of the Swiss National Cohort (linking mortality and census data), covering the period 2000-2005. Cox proportional hazard models were used to analyze the relation of living in the proximity of 220-380 kV power lines and the risk of death from neurodegenerative diseases, with adjustment for a range of potential confounders. Overall, the adjusted hazard ratio for Alzheimer's disease in persons living within 50 m of a 220-380 kV power line was 1.24 (95% confidence interval (CI): 0.80, 1.92) compared with persons who lived at a distance of 600 m or more. There was a dose-response relation with respect to years of residence in the immediate vicinity of power lines and Alzheimer's disease: Persons living at least 5 years within 50 m had an adjusted hazard ratio of 1.51 (95% CI: 0.91, 2.51), increasing to 1.78 (95% CI: 1.07, 2.96) with at least 10 years and to 2.00 (95% CI: 1.21, 3.33) with at least 15 years. The pattern was similar for senile dementia. There was little evidence for an increased risk of amyotrophic lateral sclerosis, Parkinson's disease, or multiple sclerosis.
Multiple sclerosis has not been looked at as much as the other neurodegenrative disorders. We are aware of just one paper which concludes it found “no support” for an association with EMFs.
Neurology. 1999 Apr 12;52(6):1279-82.
Multiple sclerosis among utility workers
Johansen C, Koch-Henriksen N, Rasmussen S, Olsen JH.
Institute of Cancer Epidemiology, The Danish Cancer Society, Copenhagen. firstname.lastname@example.org
The incidence of MS was assessed in a nationwide cohort study of 31,990 employees of Danish utility companies between 1900 and 1993. Overall, 32 cases of MS were diagnosed, as compared with 23.7 expected from national incidence rates, to yield a standardized incidence ratio of 1.35 (95% confidence interval, 0.92 to 1.91). We found no support for the hypothesis of an association between occupational exposure to electromagnetic fields and the risk of MS.