Environment and Breast Cancer: Science Review

Evidence From Humans
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Cancer incidence and work place exposure among Swedish biomedical research personnel
Wennborg, H., Yuen, J., Nise, G., Sasco, A. J., Vainio, H., Gustavsson, P. International Archives of Occupational and Environ. 2001. 74:8, 558-64.
Topic area
Environmental pollutant - Occupation, organic solvents
Study design
Cohort Nested case-control
Funding agency
Swedish Medical Research Council, Swedish Cancer S
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Not reported
Number in Cohort
Cohort: 3,277 laboratory workers (1173 women), 2,011 non-laboratory department workers (721 women), compared to national cancer rates
Cohort participation rate
Few lost to follow-up
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Employed at least one year in laboratory and non-laboratory departments at the Kaolinska Insitutte and universities of Lund, Gothenburg, and Lokoping. Certain departments, such as organic chemistry and physics, with other occupational exposures were excluded.
Comment about participation selection
Most laboratory workers were age 40 or younger at entry. The laboratory personnel were slightly younger than the non-laboratory personnel at entrance into the cohort. Both weigh against finding an effect in a breast cancer study.
Exposure Investigated
Exposures investigated
Work in laboratory and non-laboratory departments. Use of specific chemicals assessed by questionnaire administered to research group leaders.
Exposure assessment comment
The inference that workers in certain departments have substantial exposure is unvalidated. Many workers exposed for short periods of time. Workplace safety regulations reduce hazardous exposures.
Statistical Analysis
Breast cancer outcome investigated
Primary breast cancer from 1970-1994
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 incidence ratio
Strength of associations reported
Deficit of breast cancers in non-laboratory female workers: SIR 0.66 (0.26-1.35) 7 cases
Work with solvents: SIR 1.13 (0.66-1.81) 17 cases
Work with radioisotopes (known breast carcinogen): SIR 0.95 (0.43)1.79) 8 cases
Work with DNA, RNA, which involves extraction with organic solvents, was associated with nonsignificantly elevated breast cancer risk, based on small numbers.
Results Comments
Deficit of breast cancers in the non-exposed cohort and women classified as exposed to radioisotopes, which are known, breast carcinogens, makes the nonsignificant elevation in risk for women categorized as exposed to solvents difficult to interpret. The cohort is somewhat young for breast cancer diagnosis.
Author address
Department of Biosciences, Karolinska Institute, Huddinge, Sweden. helena.wennborg@biosci.ki.se