Epidemiological study (observational study)

Cardiovascular mortality and exposure to extremely low frequency magnetic fields: a cohort study of Swiss railway workers epidem.

By: Röösli M, Egger M, Pfluger D, Minder C

Published in: Environ Health 2008; 7: 35

Aim of study (acc. to author)

A cohort study was conducted in Switzerland to examine the cardiovascular mortality and the occupational exposure to intermittent 16.7 Hz magnetic fields.

Further details

Exposure to magnetic fields was determined by measurement and modeling for each occupational group. Cumulative exposure for each individual was achieved by adding up annual workplace specific exposures during his work life.

Endpoint/type of risk estimation

cardiovascular diseases: arrhythmia related disease, acute myocardial infarction, atherosclerosis related mortality, subacute and chronic coronary heart disease

Type of risk estimation:

mortality

(unspecified)

Exposure

- 16 2/3 Hz (train)
- magnetic field
- occupational

Assessment

measurement: measurements of extreme low frequency magnetic fields in train engines, passenger coaches and workplace of station masters in 1993-1994 and 2003-2004
calculation: annual exposure for each occupational group and cumulative exposure by adding up annual workplace specific exposures according to start and end date of employment

Exposure groups

Group	Description
Group 1	station master: average exposure in 1980: 0.7 µT
Group 2	train attendant: average exposure in 1980: 1.8 µT
Group 3	shunting yard engineer: average exposure in 1980: 5.5 µT
Group 4	train driver: average exposure in 1980: 21.4 µT
Group 5	station master: average exposure in 2000: 1.0 µT
Group 6	train attendant: average exposure in 2000: 4.2 µT
Group 7	shunting yard engineer: average exposure in 2000: 6.0 µT
Group 8	train driver: average exposure in 2000: 21.0 µT
Group 9	station master: median cumulative lifetime expsoure: 5.7 µT-years
Group 10	train attendant: median cumulative lifetime expsoure: 13.3 µT-years
Group 11	shunting yard engineer: median cumulative lifetime expsoure: 42.1 µT-years
Group 12	train driver: median cumulative lifetime expsoure: 120.5 µT-years

Population

Group:
- men
Characteristics: Swiss Railway Cohort includes all men who were registered as train driver, shunting yard engineer, train attendant or station master in the personnel or pension records of the Swiss Federal Railways between 1972 - 2002
Observation period: 1972 - 2002
Study location: Switzerland
Data source: Swiss Federal Railways

Study size

Type	Value
Total	20,141

Other:

follow-up of 464,129 person-years

Statistical analysis method:

Cox proportional regressions analysis

(adjustment:

5-year age group
periode before and after 1995 due to change in coding for cause of death

)

Results (acc. to author)

5,413 deaths were observed in the cohort, 3,594 deaths were attributed to cardiovascular diseases. The hazard ratios for all cardiovascular mortality and for the subgroups were not elevated in the separate analysis for train drivers, shunting yard engineers, train attendants or station masters. For cumulative exposure the hazard ratio was not increased.
The results provide evidence against an association between long-term exposure to 16.7 Hz magnetic fields and cardiovascular mortality.

Study funded by

Federal Office of Public Health (FOPH; Bundesamt für Gesundheit), Switzerland
Federal Office of Transport (FOT; Bundesamt für Verkehr), Switzerland

Koeman T et al. (2013): Occupational exposure to extremely low-frequency magnetic fields and cardiovascular disease mortality in a prospective cohort study
Lednev VV et al. (2008): Modulation of cardiac rhythm in the humans exposed to extremely weak alternating magnetic fields
Röösli M et al. (2007): Leukaemia, brain tumours and exposure to extremely low frequency magnetic fields: cohort study of Swiss railway employees
Kheifets L et al. (2007): Extremely low-frequency magnetic fields and heart disease
Röösli M et al. (2007): Mortality from neurodegenerative disease and exposure to extremely low-frequency magnetic fields: 31 years of observations on Swiss railway employees
Santangelo L et al. (2005): Magnetic field exposure and arrythmic risk: evaluation in railway drivers
Minder CE et al. (2001): Leukemia, brain tumors, and exposure to extremely low frequency electromagnetic fields in Swiss railway employees
Savitz DA et al. (1999): Magnetic field exposure and cardiovascular disease mortality among electric utility workers
Minder CE et al. (1993): Extremely Low Frequency Electromagnetic Field Measurements (ELF-EMF) in Swiss Railway Engines