Environment and Breast Cancer: Science Review

Evidence From Humans
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Female breast cancer and electrical manufacturing: results of a nested case-control study
Oddone, E., Edefonti, V., Scaburri, A., Vai, T., Bai, E., Modonesi, C., Crosignani, P., Imbriani, M. J Occup Health. 2014. 56:5, 369-78.
Topic area
Environmental pollutant - Occupation
Study design
Other: registry-based case-control
Funding agency
INAIL, Italian National Occupational Insurance Ins
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Cohort participation rate
Not applicable. This study was records-based.
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Parent study, Occupational Cancer Monitoring (OCCAM) project: 44,486 women residing in Lombardy, Italy and diagnosed with breast cancer 2002-2009 between the ages 35-69 were identified through hospital discharge records. Women diagnosed during the period 1999-2001 were excluded. 53,095 controls were randomly sampled, with matching to cases by province of residence and 5-year age groups, from the regional list of citizens registered with the National Health Service as of December 31, 2015. "Blue collar" workers were then identified from this group based on linkage to occupational history from National Institute for Social Security (INPS) database. Among the blue collar workers, this analysis was further limited to women employed at a particular electrical manufacturing plant near Milan for ≥ 1 year between 1974-2005. All cases (108) were eligible, and 216 controls were selected (2 per case). However women for whom occupational data was not available from the plant were excluded, as reflected in the numbers listed above. Authors note that women included in this study had not been exposed to night work or shift work.
Comment about participation selection
A substantial portion of cases (30%) and controls (35%) were excluded from analysis because of missing data.
Exposure Investigated
Exposures investigated
The electrical manufacturing plant provided occupational files, which included job titles and exposure status (ever/never) to several agents: lead and lead alloys, chlorinated solvents, lubricant oils, non-ionizing radiation, and epoxy resins. Exposure st
Exposure assessment comment
The reference group comprised blue collar workers (i.e. not administrative clerks or managers) who worked at the plant for at least one year but were classified as "never" exposed to the chemical of interest.
Breast cancer outcome investigated
Primary incident breast cancer
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
Age at enrollment, age at hire, age at menarche, smoking habits (never, former/current), alcohol consumption (never, low/medium consumer), number of children, age at first child (<30 or ≥30 years), BMI (<25, ≥25), education, calendar year of hire, and
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked Yes. No, if not.
Strength of associations reported
Among all female workers:
Ever vs. never exposed to lead and lead alloys: aOR 0.46 (95% CI 0.19-1.21)
Ever vs. never exposed to chlorinated solvents: aOR 1.65 (95% CI 1.04-2.62)
Ever vs. never exposed to lubricant oils (3 exposed cases and 6 exposed controls): aOR 0.96 (95% CI 0.56-1.66)
Ever vs. never exposed to non-ionizing radiation (4 exposed cases and 3 exposed controls)): aOR 1.40 (95% CI 0.87-2.72)
Ever vs. never exposed to epoxy resins (6 exposed cases): aOR 1.11 (95% CI 0.90-1.37)

Among female workers employed >=10 years:
Ever vs. never exposed to lead and lead alloys: aOR 0.51 (95% CI 0.19-1.38)
Ever vs. never exposed to chlorinated solvents: aOR 2.10 (95% CI 1.21-3.66)
Ever vs. never exposed to lubricant oils (2 exposed cases and 4 exposed controls): aOR 0.96 (95% CI 0.48-1.92)
Ever vs. never exposed to non-ionizing radiation (3 exposed cases and 1 exposed control): aOR 1.83 (95% CI 0.90-3.71)
Ever vs. never exposed to epoxy resins (5 exposed cases and 8 exposed controls): aOR 1.12 (95% CI 0.88-1.43)
Results Comments
Analyses were also performed considering job title of longest duration, with administrative clerks/managers as a reference group, but based on very small numbers within job categories.
Author address
Department of Public Health, Experimental and Forensic Medicine, Occupational Medicine Unit, University of Pavia.
Reviewers Comments
This was one of the only studies of occupational solvent exposure to use unexposed blue collar workers as a reference group, which may be a more appropriate comparison than white collar workers or the general population.