Epidemiological study

Motor neuron disease risk and magnetic field exposures epidem.

By: Sorahan T, Nichols L

Published in: Occup Med 2022; 72 (3): 184-190

Aim of study (acc. to author)

The risk of motor neuron disease and occupational exposure to magnetic fields was investigated in a large UK cohort study.

Further details

The present study is an update of the publications by Sorahan and Kheifets (2007) and Sorahan and Mohammed (2014).
Cumulative occupational lifetime exposure together with exposures received more than 10 years ago (distant) and those received less than 10 years ago (recent) were developed for each study participant.

Endpoint/type of risk estimation

neurodegenerative diseases: motor neuron disease (including amyotrophic lateral sclerosis)
mortality: all causes

Type of risk estimation:

mortality

(standardized mortality rate (SMR))

Exposure

- 50/60 Hz
- magnetic field
- power transmission line
- electrical substation
- occupational

Assessment

calculation: cumulative occupational exposure separately for each study participant (based on Renew et al. (2003))

Exposure groups

Group	Description
Reference group 1	occupational cumulative lifetime exposure to magnetic fields: 0 - 2.4 µT-years
Group 2	occupational cumulative lifetime exposure to magnetic fields: 2.5 - 4.9 µT-years
Group 3	occupational cumulative lifetime exposure to magnetic fields: 5.0 - 9.9 µT-years
Group 4	occupational cumulative lifetime exposure to magnetic fields: 10.0 - 19.9 µT-years
Group 5	occupational cumulative lifetime exposure to magnetic fields: ≥ 20.0 µT-years
Reference group 6	occupational exposure to magnetic fields received >10 years ago: 0 - 2.4 µT-years
Group 7	occupational exposure to magnetic fields received >10 years ago: 2.5 - 4.9 µT-years
Group 8	occupational exposure to magnetic fields received >10 years ago: 5.0 - 9.9 µT-years
Group 9	occupational exposure to magnetic fields received >10 years ago: 10.0 - 19.9 µT-years
Group 10	occupational exposure to magnetic fields received >10 years ago: ≥ 20.0 µT-years
Reference group 11	occupational exposure to magnetic fields received < 10 years ago: 0 µT-years
Group 12	occupational exposure to magnetic fields received < 10 years ago: 0.01 - 0.4 µT-years
Group 13	occupational exposure to magnetic fields received < 10 years ago: 0.5 - 1.9 µT-years
Group 14	occupational exposure to magnetic fields received < 10 years ago: ≥ 2.0 µT-years

Population

Group:
- men
- women
Characteristics: employees of the former Central Electricity Generating Board of England and Wales first employed in the period 1942–82 and still in employment on 1 November, 1987
Observation period: 1987 - 2018
Study location: UK
Data source: death certificates

Study size

Type	Value
Total	37,986

Statistical analysis method:

Poisson regression model

(adjustment:

5-year age group
sex
socioeconomic status
calender period

)

Results (acc. to author)

Mortality from motor neuron disease in the cohort was similar to national mortality (observed number of deaths 69, expected 71.3, SMR 97, CI 76–122). There were no statistically significant trends of risks increasing with cumulative lifetime, recent or distant magnetic field exposure, although positive associations were observed for some categories of recent exposure.
The authors concluded that the study did not find elevated risks of motor neuron disease as a consequence of occupational lifetime exposure to magnetic fields. However, a possible role for recent exposures could be investigated in other datasets.

Study funded by

Energy Networks Association (ENA), UK

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