Epidemiological study (observational study)

Association between exposure to pulsed electromagnetic fields and cancer in electric utility workers in Quebec, Canada, and France epidem.

By: Armstrong B, Theriault G, Guenel P, Deadman JE, Goldberg M, Heroux P

Published in: Am J Epidemiol 1994; 140 (9): 805-820

Aim of study (acc. to author)

A nested case-control study of electric utility workers was conducted in Quebec, Canada, and France to investigate the association between exposure to pulsed electromagnetic fields (PEMFs) and cancer.

Endpoint/type of risk estimation

leukemia and lymphoma
brain tumor
melanoma, colon, stomach, lung, bone, prostate cancer and other cancer types
all cancer

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

- signals/pulses
- electrical substation
- occupational

Assessment

job exposure matrix: based on level of exposure to each job category estimated from weeklong measurements of 1295 workers in 1991-1992
measurement: PEMFs measurement using meter with PEMF channel compiling the proportion of the time (in parts per billion, ppb) during which the electric field is greater than 200 V/m in the 5- to 20-MHz frequency band
calculation: PEMFs were summarized in each job group as the proportion of subjects measured who had weekly mean PEMFs greater than 100 ppb (equivalent to 14.4 ms per 40-hour work week). Weighted years of cumulative exposure for each subject's working life were calculated as the product of mean exposure (proportion greater than 100 ppb) and duration of employment (years), in units of "(proportion > 100 ppb)-years"

Exposure groups

Group	Description
Reference group 1	cumulative exposure to pulsed electromagnetic fields: < median
Group 2	cumulative exposure to pulsed electromagnetic fields: ≥ median
Group 3	cumulative exposure to pulsed electromagnetic fields: ≥ 90th percentile

Population

Group:
- men
Observation period: 1970 - 1988 (Canada), 1978 - 1989 (France)
Study location: Canada (province of Quebec) and France

Case group

Characteristics: electric utility workers who worked at least 1 year at one of the two electric utilities
Data source: electric utilities Hydro-Quebec and Électricité de France-Gaz de France

Control group

randomly chosen from risk sets of cohort members
Matching:
- age
- utiliy company

Study size

	Cases	Controls
Participants	2,679	-

Other:

cohort comprises 21,479 men in Canada and about 170,000 men in France

Statistical analysis method:

conditional logistic regression

(adjustment:

socioeconomic status

)

Results (acc. to author)

No association was found between exposure to pulsed electromagnetic fields and cancer types previously suspected of association with magnetic fields (leukemia, other hematopoietic cancers, brain cancer, or melanoma). However, there was a clear association between cumulative exposure to PEMFs and lung cancer in the highest exposure group (OR 3.1; CI 1.6-6.0; 84 cases). This association was largely confined to electric utility workers in Quebec, where there was a clear dose-response relationship with an odds ratio of 6.7 (CI 2.7-16.6) in the highest exposure group (32 cases). The association is substantial and was not explained by smoking or other occupational exposures.

Limitations (acc. to author)

However, several factors limit the strength of the evidence for a causal relation: lack of precision of the measurements; little previous evidence for this association; and no elevated risk for lung cancer in the utility workers overall in comparison with the general population.

Study funded by

Electricité de France (EDF)
Hydro-Québec, Canada

Comments on this article

Maisch D (2006): Conflict of Interest and Bias in Health Advisory Committees: A Case Study of the WHO's EMF Task Group
Henshaw DL (1997): Reply: Electromagnetic field exposure and lung cancer
Erren TC (1996): Reply: "Association between exposure to pulsed electromagnetic fields and cancer in electric utility workers in Quebec, Canada, and France"

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