Study type: Epidemiological study

Electric Shock and Extremely Low-Frequency Magnetic Field Exposure and the Risk of ALS: Euro-MOTOR. epidem.

Published in: Am J Epidemiol 2019 [in press]

Aim of study (acc. to author)

A pooled analysis of population-based case-control studies from 3 European countries was conducted to investigate the association of amyotrophic lateral sclerosis (ALS) with lifetime occupational exposure to extremely low-frequency magnetic fields and electric shocks in the Euro-MOTOR project.

Endpoint/type of risk estimation

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 extremely low frequency magnetic fields: never exposed above background level
Group 2 extremely low frequency magnetic fields: ever exposed above background level
Reference group 3 duration of exposure to extremely low frequency magnetic fields: background level
Group 4 duration of exposure to extremely low frequency magnetic fields: < 5 years
Group 5 duration of exposure to extremely low frequency magnetic fields: 5 - 11 years
Group 6 duration of exposure to extremely low frequency magnetic fields: 12 - 30 years
Group 7 duration of exposure to extremely low frequency magnetic fields: > 30 years
Reference group 8 cumulative exposure to extremely low frequency magnetic fields: background level
Group 9 cumulative exposure to extremely low frequency magnetic fields: < 5 unit-years
Group 10 cumulative exposure to extremely low frequency magnetic fields: 15 - 33 unit-years
Group 11 cumulative exposure to extremely low frequency magnetic fields: > 33 unit-years
Reference group 12 time since last exposure to extremely low frequency magnetic fields: background level
Group 13 time since last exposure to extremely low frequency magnetic fields: 3 - 4 years
Group 14 time since last exposure to extremely low frequency magnetic fields: 5 - 17 years
Group 15 time since last exposure to extremely low frequency magnetic fields: 18 - 38 years
Group 16 time since last exposure to extremely low frequency magnetic fields: > 38 years
Reference group 17 electric shocks: never exposed above background level
Group 18 electric shocks: ever exposed above background level
Reference group 19 electric shocks, duration of exposure: background level
Group 20 electric shocks, duration of exposure: < 6 years
Group 21 electric shocks, duration of exposure: 6 - 16 years
Group 22 electric shocks, duration of exposure: 17 - 37 years
Group 23 electric shocks, duration of exposure: > 37 years
Reference group 24 electric shocks, cumulative exposure: background level
Group 25 electric shocks, cumulative exposure: < 9 unit-years
Group 26 electric shocks, cumulative exposure: 9 - 29 unit-years
Group 27 electric shocks, cumulative exposure: 30 - 70 unit-years
Group 28 electric shocks, cumulative exposure: > 70 unit-years
Reference group 29 electric shocks, time since last exposure: background level
Group 30 electric shocks, time since last exposure: 3 - 4 years
Group 31 electric shocks, time since last exposure: 5 - 16 years
Group 32 electric shocks, time since last exposure: 17 - 34 years
Group 33 electric shocks, time since last exposure: > 34 years

Population

Case group

Control group

Study size

Cases Controls
Evaluable 1,323 2,704
Statistical analysis method: (adjustment: )

Conclusion (acc. to author)

Both ever having had exposure to extremely low-frequency magnetic fields above the background level (group 2: OR 1.16, CI 1.01-1.33) and ever having had potential exposure above background for electric shocks (group 4: OR 1.23, CI 1.05-1.43) were associated with amyotrophic lateral sclerosis in comparison to the reference groups 1 resp. 3. Adjustment for the respective other exposure resulted in similar risk estimates. Heterogeneity in risks across study centers was significant for both exposures.
The authors conclude that the findings support possible independent associations of occupational exposure to extremely low-frequency magnetic fields and electric shocks with the risk of amyotrophic lateral sclerosis.

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