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Epidemiological study (observational study)

Psychological effects of chronic exposure to 50 Hz magnetic fields in humans living near extra-high-voltage transmission lines.

Published in: Bioelectromagnetics 1997; 18 (8): 584-594

Exposure

Exposure Parameters
Exposure 1: 50–60 Hz
Exposure duration: at least 6 months
General information
epidemic study
Exposure 1
Main characteristics
Frequency 50–60 Hz
Exposure duration at least 6 months
Additional info 50 or 60 Hz transmission line
Exposure setup
Exposure source
Additional info Residence in the vicinity of the transmission lines.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 674 nT mean measured - in the rooms where the subject spent most of his/her time
Additional parameter details
B = 54.4 µT local geomagnetic field

Aim of study (acc. to author)

A cross-sectional study was conducted in New Zealand to investigate the association between the exposure to magnetic fields of power lines and psychological and mental health.

Further details

The participants completed following neuropsychological tests: digit span test, trail making tests, digit symbol test, symbol-digit modality test, d2 cancellation test, selective reminding test, visual memory test. Furthermore they filled in the life changes questionnaire and the general health questionnaire-28.

Endpoint/type of risk estimation

Exposure

Assessment

  • measurement: magnetic flux densities at three places in each room where the participant spent one hour or more per day at average
  • calculation: average exposure: arithmetic mean of all readings taken in the two or three rooms in which the participant spent one hour or more per day on average. Time-integrated exposure: multiplying the average estimated hours spent in each room by the mean of the readings taken in the room, and summing across the rooms in which the participant spent one or more hours per day on average

Exposure groups

Reference group 1 1st quintil, mean average exposure: 0.057 µT; mean time integrated exposure: 0.640 µT-hour
Group 2 2nd quintil, mean average exposure: 0.209 µT; mean time integrated exposure: 2.756 µT-hour
Group 3 3rd quintil, mean average exposure: 0.392 µT; mean time integrated exposure: 5.333 µT-hour
Group 4 4th quintil, mean average exposure: 0.766 µT; mean time integrated exposure: 10.579 µT-hour
Group 5 5th quintil, mean average exposure: 1.944 µT; mean time integrated exposure: 30.761 µT-hour

Population

  • Group:
    • men
    • women
  • Age: 18–70 years
  • Characteristics: residents of houses in streets running beneath overhead transmission lines
  • Observation period: not stated
  • Study location: New Zealand (Auckland)

Study size

Evaluable 540
Statistical analysis method:
  • multiple linear regression analysis
( adjustment:
  • age
  • sex
  • socioeconomic status
  • life changes, self-rated health and perceived effect of powerlines on personal health
)

Conclusion (acc. to author)

Performance on most memory and attention measures of the participants living close to power lines was unrelated to magnetic field exposure, but significant linear dose-response relationships were found between exposure and some psychological and mental health variables. In particular, higher time-integrated exposure was associated with poorer coding-test performance and more adverse health effects (anxiety, somatic symptoms, depression) . These associations were found to be independent of participants' beliefs about effects of electromagnetic fields.

Study funded by

  • not stated/no funding

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