Environment and Breast Cancer: Science Review

Evidence From Humans
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Cancer mortality among workers in chemical plant contaminated with dioxin
Manz, A., Berger, J., Dwyer, J. H., Flesch-Janys, D., Nagel, S., Waltsgott, H. Lancet. 1991. 338:8773, 959-64.
Topic area
Environmental pollutant - dioxin (TCDD), occupation
Study design
Other: Retrospective mortality follow-up in cohort of workers
Study Participants
Number of Cases
9 breast cancer deaths
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number of Controls
399 female workers
Cohort participation rate
Greater than 70%
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Workers hired between 1952 and 1984 at a German herbicide production chemical plant, "including processes contaminated with TCDD," who worked there for more than 3 months, identified from company and union records.
Comment about participation selection
For men, a worker cohort was available for comparison, mitigating the "healthy worker" effect. For women, this was not an option, reducing comparability of the comparison cohort.
Exposures investigated
TCDD primarily from production of trichlorophenol (TCP) and 2,4,5-T. Exposure was reduced after a change in production process in 1954. High, medium, or low exposure based on production department. Production department classifications were assigned bas
Statistical Analysis
Breast cancer outcome investigated
Mortality from breast cancer
Ethnic groups with separate analysis
If this study provided a separate analysis by ethnic or racial group, the groups are listed here.
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.
Not controlled
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Description of major analysis
Standardized mortality ratio comparison with West Germany
Strength of associations reported
Standardized mortality ratio = 2.15 (95% CI 0.98-4.09)
Results Comments
Few women (6.9%) were in "high" exposed occupations. Comparison to a national population that includes nonworkers may underestimate worker risks due to "healthy worker" effect.
Author address
Centre for Chemical Workers' Health, Department of Health, Hamburg, Germany.