Epidemiological study (observational study)

Occupational exposure to magnetic fields and breast cancer among Canadian men epidem.

By: Grundy A, Harris SA, Demers PA, Johnson KC, Agnew DA, Villeneuve PJ

Published in: Cancer Med 2016; 5 (3): 586-596

Aim of study (acc. to author)

A case-control study was conducted in Canada to investigate the association between occupational exposure to magnetic fields and the risk for breast cancer in men.

Endpoint/type of risk estimation

breast cancer: male breast cancer

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

- 50/60 Hz
- magnetic field
- occupational

Assessment

questionnaire: occupational history of all jobs ever had for at least 12 months (including seasonal and part-time work), for each job: start and stop dates, the type of industry or business and main job duties
calculation: cumulative exposure calculated as product of intensity of exposure, duration and full-time status

Exposure groups

Group	Description
Reference group 1	highest average exposure: none
Group 2	highest average exposure: 0.3 - < 0.6 µT
Group 3	highest average exposure: ≥ 0.6 µT
Reference group 4	cumulative magnetic field exposure: none
Group 5	cumulative magnetic field exposure: 0 - < 0.8 µT
Group 6	cumulative magnetic field exposure: ≥ 0.8 µT
Reference group 7	time since last exposure: never exposed
Group 8	time since last exposure: < 10 years
Group 9	time since last exposure: 10 - 19 years
Group 10	time since last exposure: 20 - 29 years
Group 11	time since last exposure: ≥ 30 years
Reference group 12	time since first exposure: never exposed
Group 13	time since first exposure: < 10 years
Group 14	time since first exposure: 10 - 19 years
Group 15	time since first exposure: 20 - 29 years
Group 16	time since first exposure: ≥ 30 years
Reference group 17	age at first exposure: < 20 years
Group 18	age at first exposure: 20 - 34 years
Group 19	age at first exposure: ≥ 35 years
Reference group 20	duration of exposure: never exposed
Group 21	duration of exposure: < 15 years
Group 22	duration of exposure: 15 - 29 years
Group 23	duration of exposure: ≥ 30 years

Population

Group:
- men
Age: ≥ 18 years
Observation period: 1994 - 1998
Study location: Canada (Alberta, British Columbia, Manitoba, Newfoundland and Labrador, Nova Scotia, Ontario, Prince Edward Island, and Saskatchewan)

Case group

Characteristics: men with breast cancer
Data source: Canadian National Enhanced Cancer Surveillance System

Control group

Selection:
- population-based
Matching:
- sex
- age
- area

Study size

	Cases	Controls
Evaluable	115	570

Statistical analysis method:

unconditional logistic regression

(adjustment:

age
BMI, leisure-time physical activity

)

Results (acc. to author)

A non-statistically significant increased risk of breast cancer was observed in men who were exposed to occupational magnetic flux densities ≥ 0.6 µT (group 3: OR 1.80, CI 0.82-3.95) when compared to those with exposures < 0.3 µT. Those exposed to occupational magnetic fields for at least 30 years had a nearly threefold increase in risk of breast cancer (group 23: OR 2.77, CI 0.98-7.82) when compared to the reference group. Findings for the other time-related magnetic field variables were inconsistent.
The authors conclude that their analysis provides limited support for the hypothesis that occupational exposure to magnetic fields increases the risk breast cancer in men.

Study funded by

Cancer Care Ontario (CCO), Canada

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