Study type: Epidemiological study (observational study)

Occupational exposures and Parkinson's disease mortality in a prospective Dutch cohort. epidem.

Published in: Occup Environ Med 2015; 72 (6): 448-455

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 Parkinson disease mortality was investigated in the Netherlands Cohort Study. Furthermore, the effects of combined exposure to these occupational risk factors were studied.

Further details

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

Endpoint/type of risk estimation

Type of risk estimation: (hazard ratio)

Exposure

Assessment

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 cumulative exposure: background
Group 5 cumulative exposure: 1st terzile
Group 6 cumulative exposure: 2nd terzile
Group 7 cumulative exposure: 3rd terzile
Reference group 8 electric shock risk: background
Group 9 electric shock risk: low
Group 10 electric shock risk: high
Reference group 11 electric shock; cumulative exposure: 1st terzile
Group 12 electric shock; cumulative exposure: 2nd terzile
Group 13 electric shock; cumulative exposure: 3rd terzile

Population

Study size

Type Value
Total 120,852
Other:

17.3 years of follow-up

Statistical analysis method: ( adjustment: )

Conclusion (acc. to author)

Among men, an elevated hazard ratio was observed for high exposure to occupational extremely low-frequency magnetic fields (HR 1.54, CI 1.00-2.36) but neither association with exposure duration nor a trend in cumulative exposure were observed. No association between Parkinson disease mortality and occupational exposure to electric shocks was found. No significant associations between Parkinson disease mortality and occupational exposure to extremely low-frequency magnetic fields as well as electric shocks were observed among women.
When the analysis of exposure to extremely low-frequency magnetic fields was adjusted for risk of electric shocks, the association between high exposure to extremely low-frequency magnetic fields and Parkinson disease mortality became stronger (HR 1.81, CI 1.15-2.85). This suggests that, if the observed association between high exposure to extremely low-frequency magnetic fields and Parkinson disease risk is true, this is likely not driven by electric shocks.
The authors conclude that there are some suggestions for an association between Parkinson disease mortality and occupational exposure to extremely low-frequency magnetic fields. However, the weight given to these findings is limited by the absence of a monotonic trend with duration of exposure or cumulative exposure. No evidence for association between Parkinson disease mortality and occupational exposure to the risk of electric shocks was found.

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