Study type: Epidemiological study (observational study)

Risk of birth defects by parental occupational exposure to 50 Hz electromagnetic fields: a population based study. epidem.

Published in: Occup Environ Med 2002; 59 (7): 92-97

Aim of study (acc. to author)

To evaluate the risk of birth defects by parental occupational exposure to 50 Hz magnetic fields, a population based study was conducted in Norway.

Further details

The Medical Birth Registry of Norway including information about birth defects was linked with census data on parental occupation. Exposure to 50 Hz magnetic fields was estimated by combining occupation and branch of industry into less than 4 hours, 4 to 24 hours and more than 24 hours per week above 0.1 µT.

Endpoint/type of risk estimation

Type of risk estimation: (odds ratio (OR))

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 maternal occupational exposure > 0.1 µT: < 4 hours/week
Group 2 maternal occupational exposure > 0.1 µT: 4 - 24 hours/week
Group 3 maternal occupational exposure > 0.1 µT: > 24 hours/week
Reference group 4 paternal occupational exposure > 0.1 µT: < 4 hours/week
Group 5 paternal occupational exposure > 0.1 µT: 4 - 24 hours/week
Group 6 paternal occupational exposure > 0.1 µT: > 24 hours/week

Population

Study size

Type Value
Total 1,688,263
Other:

occupational information on 836 475 mothers and 1 290 298 fathers; births with birth defects: 23 888 with occupational information of the mother and 32 856 of the father

Statistical analysis method:

Conclusion (acc. to author)

The total risk of birth defects was not associated with parental occupational exposure to 50 Hz magnetic fields. Maternal exposure was associated with increased risk of spina bifida and clubfoot however after adjustment for chemical exposure the risk of spina bifida was no longer significantly increased. An increased risk of anencephaly was found for offsprings with paternal exposure. The study gives an indication of an association between selected disorders of the central nervous system and parental occupational exposure to 50 Hz magnetic fields.

Limitations (acc. to author)

The results should be interpreted with caution due to the crude exposure assessment and the lack of information on residential exposure.

Study funded by

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