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Epidemiological study (observational study)

Occupational exposure to magnetic fields and electric shocks and risk of ALS: The Swiss National Cohort.

Published in: Amyotroph Lateral Scler Frontotemporal Degener 2015; 16 (1-2): 80-85

Aim of study (acc. to author)

The association between occupational exposure to magnetic fields and electric shocks and mortality of amyotrophic lateral sclerosis was investigated in the Swiss National Cohort.

Further details

Occupational exposure was assessed by applying job exposure matrices for occupations at censuses 1990 and 2000. Furthermore, the job titles were classified into electrical occupations according to Deapen et al. (1988) und Feychting et al. (2013).

Endpoint/type of risk estimation

Type of risk estimation:
  • mortality
(hazard ratio)

Exposure

Assessment

Exposure groups

Reference group 1 magnetic field exposure (job-exposure matrix): low
Group 2 magnetic field exposure (job-exposure matrix): medium
Group 3 magnetic field exposure (job-exposure matrix): high
Reference group 4 electrical shocks (job-exposure matrix): low
Group 5 electrical shocks (job-exposure matrix): medium
Group 6 electrical shocks (job-exposure matrix): high
Reference group 7 electrical occupations (according to Deapen et al., 1988): no
Group 8 electrical occupations (according to Deapen et al., 1988): yes
Reference group 9 electrical occupations (according to Feychting et al., 2003): no
Group 10 electrical occupations (according to Feychting et al., 2003): yes

Population

  • Group:
    • men
    • women
  • Age: ≥ 30 years
  • Characteristics: participants of the Swiss National Cohort
  • Observation period: 1990 - 2000
  • Study location: Switzerland
  • Data source: death registry, Swiss National Cohort
  • Exclusion criteria: pensioners

Study size

Total 2,167,046
Statistical analysis method:
  • Cox proportional regressions analysis
( adjustment:
  • sex
  • nationality
)

Conclusion (acc. to author)

A total of 278 persons of the study population died from amyotrophic lateral sclerosis.
When analyzed separately for each census data, mortality from amyotrophic lateral sclerosis was not increased for workers exposed to extremely low frequency magnetic fields, for workers at risk of electrical shocks, or employed in electrical occupations in either 1990 or 2000. Mortality was higher in workers who had medium or high magnetic field exposure in both censuses (HR 1.55, CI 1.11-2.15), but closer to unity for electrical shocks (HR 1.17, CI 0.83-1.65). When both exposures were included in the same model, the hazard ratio for extremely low frequency magnetic fields changed little (HR 1.56, CI 1.09-2.25), but the hazard ratio for electric shocks was attenuated to 0.97 (CI 0.66-1.42).
The authors concluded that there was an association between exposure to extremely low frequency magnetic fields and mortality from amyotrophic lateral sclerosis among workers with a higher likelihood of long-term exposure.

Study funded by

  • Swiss National Science Foundation (SNF)
  • ZonMw, The Netherlands

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  • Hug K et al. (2006): Magnetic field exposure and neurodegenerative diseases--recent epidemiological studies.
  • Park RM et al. (2005): Potential occupational risks for neurodegenerative diseases.
  • Qiu C et al. (2004): Occupational exposure to electromagnetic fields and risk of Alzheimer's disease.
  • Harmanci H et al. (2003): Risk factors for Alzheimer disease: a population-based case-control study in Istanbul, Turkey.
  • Feychting M et al. (2003): Occupational Magnetic Field Exposure and Neurodegenerative Disease.
  • Hakansson N et al. (2003): Neurodegenerative diseases in welders and other workers exposed to high levels of magnetic fields.
  • Noonan CW et al. (2002): Occupational exposure to magnetic fields in case-referent studies of neurodegenerative diseases.
  • Johansen C (2000): Exposure to electromagnetic fields and risk of central nervous system disease in utility workers.
  • Graves AB et al. (1999): Occupational exposure to electromagnetic fields and Alzheimer disease.
  • Savitz DA et al. (1998): Electrical occupations and neurodegenerative disease: analysis of U.S. mortality data.
  • Savitz DA et al. (1998): Magnetic field exposure and neurodegenerative disease mortality among electric utility workers.
  • Feychting M et al. (1998): Dementia and occupational exposure to magnetic fields.
  • Sobel E et al. (1996): Elevated risk of Alzheimer's disease among workers with likely electromagnetic field exposure.
  • Schulte PA et al. (1996): Neurodegenerative diseases: occupational occurrence and potential risk factors, 1982 through 1991.
  • Sobel E et al. (1995): Occupations with exposure to electromagnetic fields: a possible risk factor for Alzheimer's disease.
  • Gunnarsson LG et al. (1992): A case-control study of motor neurone disease: its relation to heritability, and occupational exposures, particularly to solvents.