Environment and Breast Cancer: Science Review

Evidence From Humans
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Ten-year mortality study of the population involved in the Seveso incident in 1976
Bertazzi, P. A., Zocchetti, C., Pesatori, A. C., Guercilena, S., Sanarico, M., Radice, L. American Journal of Epidemiology. 1989. 129:6, 1187-200.
Topic area
Environmental pollutant - Dioxin, TCDD
Study design
Other: Cohort mortality follow up.
Funding agency
Other: Government of the Region of Lombardy, Itali
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Number in Cohort
Cohort: 30,703 males and females in zones A, B, R compared with 167,391 referent cohort in surrounding area
Cohort participation rate
99% vital status ascertainment
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Residence in region surrounding Seveso, Italy, between December 1976 and 1986 and age 20-74 years at follow-up.
Exposure Investigated
Exposures investigated
Residence in zones A, B, R in or near Seveso, Italy, after contamination by 2,3,7,8 tetrachlorodibenzodioxin (TCDD) from an industrial accident July 10, 1076. Residence determined by population registry. Exposure based on residence at the date of the ac
How exposure was measured
GIS/geographic location
Exposure assessment comment
People resident elsewhere who were in accident area at time of accident and those resident in accident area, but elsewhere at the time, were not identified. The zones represent a range of exposure, combining higher and more moderate exposures. The validity of the zones as representing a gradient of exposure has been questioned.
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.
Age, gender
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
Poisson regression
Strength of associations reported
Zone A females: 1 breast cancer death; RR 1.06 (0.1-7.5)
Zone B females: 5 breast cancer deaths; RR 0.87 (0.4-2.1)
Zone R females: 28 breast cancer deaths; RR 0.64 (0.4-0.9)
Results Comments
Because dioxin is anti-estrogenic, reduced breast cancer risk was hypothesized. Mortality is an insensitive indicator for breast cancer.
Author address
Institute of Occupational Health, Clinica L. Devoto, Universita' degli Studi, Milano, Italy.