Study type: Epidemiological study (observational study)

Case-control study on occupational exposure to extremely low-frequency electromagnetic fields and glioma risk. epidem.

Published in: Am J Ind Med 2017; 60 (5): 494-503

Aim of study (acc. to author)

The association between occupational exposure to extremely low-frequency magnetic fields and glioma risk was investigated in a case-control study in Sweden.

Endpoint/type of risk estimation

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

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 cumulative exposure: < 2.33 µT-years
Group 2 cumulative exposure: 2.33 - < 3.79 µT-years
Group 3 cumulative exposure: 3.79 - < 5.55 µT-years
Group 4 cumulative exposure: 5.55 - < 8.52 µT-years
Group 5 cumulative exposure: ≥ 8.52 µT-years
Reference group 6 average exposure: < 0.11 μT
Group 7 average exposure: 0.11 - < 0.13 μT
Group 8 average exposure: 0.13 - < 0.18 μT
Group 9 average exposure: 0.18 - < 0.27 μT
Group 10 average exposure: ≥ 0.27 μT
Reference group 11 maximum exposed job: < 0.13 μT
Group 12 maximum exposed job: 0.13 - < 0.16 μT
Group 13 maximum exposed job: 0.16 - < 0.24 μT
Group 14 maximum exposed job: 0.24 - < 0.60 μT
Group 15 maximum exposed job: ≥ 0.60 μT

Population

Case group

Control group

Study size

Cases Controls
Participants 1,346 3,485
Participation rate 86 % 86 %
Statistical analysis method: (adjustment: )

Conclusion (acc. to author)

Overall, no significant increased risk for glioma was observed in the groups with occupational exposure to extremely low frequency magnetic fields (groups 2-5, 7-10, 12-15) in comparison with the respective reference groups. However, a significant increased risk for the glioma subtype astrocytoma grade IV (glioblastoma multiforme) was observed with cumulative exposure in the time window 1-14 years before diagnosis (highest cumulative exposure category (≥ 2.75 µT): OR 1.9, CI 1.4-2.6), but not in the time window of 15 years and longer (highest cumulative exposure category (≥ 6.59 µT): OR 0.9, CI 0.6-1.3).
No statistically significant interaction between occupational exposure to extremely low frequency magnetic fields and mobile phone and cordless phone use was found.
The authors conclude that an increased risk in late stage (promotion/progression) of astrocytoma grade IV for occupational exposure to extremely low frequency magnetic fields was found.

Study funded by

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