Epidemiological study (observational study)

Occupational exposures and risk of dementia-related mortality in the prospective Netherlands Cohort Study epidem.

By: Koeman T, Schouten LJ, van den Brandt PA, Slottje P, Huss A, Peters S, Kromhout H, Vermeulen R

Published in: Am J Ind Med 2015; 58 (6): 625-635

Aim of study (acc. to author)

The association between the occupational exposure to extremely low-frequency magnetic fields, electrical shocks as well as other risk factors and the risk of dementia-related mortality was investigated in the Netherlands Cohort Study. Furthermore, the effects of combined exposure to these occupational agents were studied.

Further details

Following a case-cohort approach, a randomly selected subcohort (n=5000) was drawn.

Endpoint/type of risk estimation

neurodegenerative diseases: non-vascular dementia including Alzheimer disease

Type of risk estimation:

mortality

(hazard ratio)

Exposure

- 50/60 Hz
- magnetic field
- touch current
- also other exposures without EMF
- electric injuries/electrocution
- occupational

Assessment

job exposure matrix

Exposure groups

Group	Description
Reference group 1	magnetic field exposure: background
Group 2	magnetic field exposure: low
Group 3	magnetic field exposure: high
Reference group 4	magnetic field exposure: background
Group 5	magnetic field exposure: 1st terzile
Group 6	magnetic field exposure: 2nd terzile
Group 7	magnetic field exposure: 3rd terzile
Reference group 8	electric shock risk: background
Group 9	electric shock risk: low
Group 10	electric shock risk: high

Population

Group:
- men
- women
Age: ≥ 55 years
Characteristics: participants of the Netherlands Cohort Study on diet and cancer
Observation period: 1986 - 2003
Study location: the Netherlands
Data source: Dutch Bureau of Genealogy, the Municipal Personal Records Database, Statistics Netherlands

Study size

Type	Value
Total	120,852

Other:

17.3 years of follow-up

Statistical analysis method:

Cox proportional regressions analysis

(adjustment:

age
sex
education
smoking, BMI, physical activity

)

Results (acc. to author)

A statistically non-significant association between high occupational exposure to extremely low-frequency magnetic fields and dementia-related mortality was observed in men (OR 1.40, CI 0.92-2.14), but not with cumulative occupational exposure.
A significant association between electrical shocks and dementia-related mortality in women was found (OR 11.11, CI 3.84-32.16). However, this association was only observed among women, and the number of high exposed female cases was very low (approximately 1 % of all female cases). Hence this observation should be interpreted with caution.
The authors conclude that there is only limited support for a possible association between occupational exposure to extremely low-frequency magnetic fields and non-vascular dementia.

Study funded by

ZonMw, The Netherlands

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