A cohort study on adult hematological malignancies and brain tumors in relation to magnetic fields from indoor transformer stations.
Published in: Int J Hyg Environ Health 2021; 233: 113712
Aim of study (acc. to author)
Endpoint/type of risk estimation
- leukemia and lymphoma: any hematological neoplasms, all types of leukemia, lymphoid leukemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, myeloid leukemia, acute myeloid leukemia, chronic myeloid leukemia, Lymphoma, Hodgkin lymphoma, Non-Hodgkin lymphoma, multiple myeloma
- brain tumor: glioma and meningioma
- list: categorization of all apartments in the buildings included in the Database of Finnish Buildings with Indoor Transformer Stations (DaFBITS) according to their location in relation to the transformer room (located on ground floor or basement) (see Khan et al., 2020)
Reference group 1
apartment located on any other floor than the first or ground floors of the building
apartment located above the transformer station or sharing a wall with the transformer station
≥ 18 years
adults living in buildings with indoor transformer stations for at least 1 month
1967 - 2016
Finnish Cancer Registry
9,636 individuals in the exposed group and 194,027 individuals had been living in reference apartment;
total person-years of follow-up were 165,240 for the exposed residents and 3,323,413 for the referents and 877,994 for the first or ground floor residents
Statistical analysis method:
- Cox proportional regressions analysis
- sensitivity analyses
Conclusion (acc. to author)
The risk of most hematological neoplasms seemed to be decreased by residential exposure to extremely low frequency magnetic fields (HR for any hematological neoplasm: 0.75, CI 0.54-1.03), and decreased with increasing duration of exposure (HR for exposure ≥ 10 years: 0.47, CI 0.22-0.99). However, an increased risk was observed for acute lymphocytic leukemia (HR 2.86, CI 1.00-8.15, based on 4 exposed cases); the risk increased with duration of exposure (HR for exposure ≥ 3 years: 3.61, CI: 1.05–12.4) and was particularly associated with childhood exposure (, HR for exposure during the first 2 years of life: 11.5, CI 1.92-68.9, 2 exposed cases).
The risk for meningioma was decreased (HR 0.46, CI 0.19-1.11), with no evidence of exposure-response gradient with increasing duration of exposure. The risk for glioma was increased (HR 1.47, CI 0.84-2.57).
The authors concluded that the hypothesis of a positive association between exposure to extremely low frequency magnetic fields and adult hematological malignancies was supported only for acute lymphocytic leukemia. The results suggested decreased rather than increased risk of most hematological neoplasms. The slightly increased risk for glioma does not provide clear evidence for malignant brain tumor risk associated with exposure to extremely low frequency magnetic fields.
Limitations (acc. to author)
A limitation of the study was low number of cases, especially when different cancer subtypes were studied individually.
Study funded by
Alfred Kordelin Foundation, Finland
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