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Epidemiological study (observational study)

Neurodegenerative disease and magnetic field exposure in UK electricity supply workers.

Published in: Occup Med (Lond) 2014; 64 (6): 454-460

Aim of study (acc. to author)

A cohort study was conducted in UK to investigate whether risks of Alzheimer disease, motor neuron disease or Parkinson disease are related to occupational exposure to extremely low-frequency magnetic fields. The present study is an update of the publication by Sorahan and Kheifets (2007).

Further details

The cohort included in the present publication was further analysed for brain tumor risk (Sorahan, 2014) and for leukemia risk (Sorahan, 2014).
Cumulative occupational lifetime exposure together with exposures received more than 10 years ago (lagged exposures) and those received less than 10 years ago (lugged exposures) were developed for each study participant. The analyses were performed for the whole cohort and a sub-cohort consisting of 48,768 employees first employed in power stations because the exposure assessments are more detailed for power station workers than for other groups of workers.

Endpoint/type of risk estimation

Type of risk estimation:
  • incidence
(relative risk (RR))

Exposure

Assessment

Exposure groups

Reference group 1 occupational cumulative lifetime exposure to magnetic field: 0 - < 2.5 µT
Group 2 occupational cumulative lifetime exposure to magnetic field:2.5 - < 5.0 µT
Group 3 occupational cumulative lifetime exposure to magnetic field:5.0 - < 10.0 µT
Group 4 occupational cumulative lifetime exposure to magnetic field: 10.0 - < 20.0 µT
Group 5 occupational cumulative lifetime exposure to magnetic field: ≥ 20 µT
Reference group 6 occupational exposure to magnetic fields received >10 years ago (lagged exposure): 0 - < 2.5 µT
Group 7 occupational exposure to magnetic fields received >10 years ago (lagged exposure): 2.5 - < 5.0 µT
Group 8 occupational exposure to magnetic fields received >10 years ago (lagged exposure): 5.0 - < 10.0 µT
Group 9 occupational exposure to magnetic fields received >10 years ago (lagged exposure): 10.0 - < 20.0 µT
Group 10 occupational exposure to magnetic fields received >10 years ago (lagged exposure): ≥ 20 µT
Reference group 11 occupational exposure to magnetic fields received <10 years ago (lugged exposure): 0 - < 2.5 µT
Group 12 occupational exposure to magnetic fields received <10 years ago (lugged exposure): 2.5 - < 5.0 µT
Group 13 occupational exposure to magnetic fields received <10 years ago (lugged exposure): 5.0 - < 10.0 µT
Group 14 occupational exposure to magnetic fields received <10 years ago (lugged exposure): 10.0 - < 20.0 µT
Group 15 occupational exposure to magnetic fields received <10 years ago (lugged exposure): ≥ 20 µT

Population

  • Group:
    • men
    • women
  • Age: 18–95 years
  • Characteristics: employees of the former Central Electricity Generating Board (CEGB) of England and Wales hired in the period 1952-1982 with a minimum of 6 month employment and some employment after 1 January 1973
  • Observation period: 1973 - 2010
  • Study location: UK
  • Data source: death certificates

Study size

Total 73,051
Statistical analysis method:
  • Poisson regression model
( adjustment:
  • age
  • sex
  • socioeconomic status
  • calender period
)

Conclusion (acc. to author)

No statistically significant trends were shown for risks of Alzheimer disease, motor neuron disease or Parkinson disease to increase with estimates of lifetime, recent or distant occupational exposure to magnetic fields.
The authors conclude that there is no convincing evidence that UK electricity generation and transmission workers have suffered elevated risks from neurodegenerative diseases as a consequence of exposure to extremely low-frequency magnetic fields.

Study funded by

  • Energy Networks Association (ENA), UK

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