Environment and Breast Cancer: Science Review

Evidence From Humans
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Cancer incidence among Icelandic nurses
Gunnarsdottir, H., Rafnsson, V. J Occup Environ Med. 1995. 37:3, 307-12.
Topic area
Environmental pollutant - Occupation
Funding agency
Not reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Pre menopausal
Post menopausal
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
2159 female nurses during 1920-1979 identified from the Books of Nurses. Men, nuns, nurses educated abroad excluded. Compared with Icelandic rate.
Comment about participation selection
58% graduated in or after 1970. Fertility rate and age at first birth similar to national statistics.
Exposure Investigated
Exposures investigated
Work in nursing
Exposure assessment comment
Chemicals associated with exposure are not identified.
Breast cancer outcome investigated
Primary breast cancer from 1955-1989
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 adequately 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
Risk is elevated for no and all lag times and statistically significantly elevated for lag time of 20 years or more.
20 years lag time SIR 1.53 (1.06-2.16)
30 years lag time SIR 1.70 (1.05-2.59)
40 years lag time SIR 1.97 (1.02-3.44)
50 years lag time SIR 3.30 (1.12-7.18)
at least 20 years employment SIR 1.52 (0.96-2.28)
Author address
Department of Occupational Medicine, Administration of Occupational Safety and Health, Reykjavik, Iceland.