Epidemiological study (observational study)

Occupational exposure to extremely low-frequency magnetic fields and electrical shocks and acute myeloid leukemia in four Nordic countries epidem.

By: Talibov M, Guxens M, Pukkala E, Huss A, Kromhout H, Slottje P, Martinsen JI, Kjaerheim K, Sparen P, Weiderpass E, Tryggvadottir L, Uuksulainen S, Vermeulen R

Published in: Cancer Causes Control 2015; 26 (8): 1079-1085

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Aim of study (acc. to author)

A case-control study was conducted in four Nordic countries to investigate the association between occupational exposure to extremely low-frequency magnetic fields as well as electrical shocks and acute myeloid leukemia.

Endpoint/type of risk estimation

leukemia and lymphoma: acute myeloid leukemia

Type of risk estimation:

incidence

(hazard ratio)

Exposure

- electric injuries/electrocution
- occupational

Assessment

job exposure matrix: data on occupations at censuses 1960, 1970, 1980 and/or 1990
calculation: cumulative exposure was calculated by multiplying the duration of the job with a weight to the exposure and expressed in unit-years

Exposure groups

Group	Description
Reference group 1	magnetic field exposure: no
Group 2	magnetic field exposure: low
Group 3	magnetic field exposure: high
Reference group 4	magnetic field cumulative exposure: 0 unit-years
Group 5	magnetic field cumulative exposure: 1 - 16.2 unit-years
Group 6	magnetic field cumulative exposure: 16.2 - 29.9 unit-years
Group 7	magnetic field cumulative exposure: 29.9 - 159.9 unit-years
Reference group 8	electrical shocks: no risk
Group 9	electrical shocks: low risk
Group 10	electrical shocks: high risk
Reference group 11	electrical shocks, cumulative exposure: 0 unit-years
Group 12	electrical shocks, cumulative exposure: 1 - 19.9 unit-years
Group 13	electrical shocks, cumulative exposure: 19.9 - 45.7 unit-years
Group 14	electrical shocks, cumulative exposure: 45.7 - 159.9 unit-years
Reference group 15	electric/electronic occupations (according to Deapen et al., 1988): no
Group 16	electric/electronic occupations (according to Deapen et al., 1988): yes
Reference group 17	electric/electronic occupations (according to Feychting et al., 2003): no
Group 18	electric/electronic occupations (according to Feychting et al., 2003): yes

Population

Group:
- men
- women
Age: ≥ 20 years
Observation period: 1961 - 2005
Study location: Finland, Iceland, Norway and Sweden

Case group

Characteristics: patients with acute myeloid leukemia
Data source: Nordic Occupational Cancer cohort (NOCCA), census
Exclusion criteria: starting employment before 1945

Control group

Matching:
- sex
- year of birth, country
- case:control = 1:5

Study size

	Cases	Controls
Evaluable	5,049	27,045

Statistical analysis method:

conditional logistic regression

Results (acc. to author)

Approximately 40 % of the subjects were ever occupationally exposed to low levels and 7 % to high levels of extremely low-frequency magnetic fields, whereas 18 % were ever at low risk and 15 % at high risk of electrical shocks.
The authors did not observe an association between occupational exposure to neither extremely low-frequency magnetic fields nor electrical shocks and acute myeloid leukemia. The hazard ratio was 0.88 (CI 0.77-1.01) for subjects with exposure to high levels of extremely low-frequency magnetic field and 0.94 (CI 0.85-1.05) for subjects with high risk of electrical shocks in comparison to the reference groups.
The authors conclude that there is no evidence for an association between occupational extremely low-frequency magnetic fields or electric shock exposure and acute myeloid leukemia.

Study funded by

Doctoral Programs for Public Health (DPPH), Finland
Finnish Cultural Foundation, Finland
Yrjö Jahnsson Foundation, Finland
ZonMw, The Netherlands

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