Environment and Breast Cancer: Science Review

Evidence From Humans
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New Zealand Malayan war veterans' exposure to dibutylphthalate is associated with an increased incidence of cryptorchidism, hypospadias and breast cancer in their children
Carran, M., Shaw, I. C. N Z Med J. 2012. 125:1358, 52-63.
Topic area
Environmental pollutant - Consumer product chemicals Phthalates
Study design
Retrospective cohort
Funding agency
University of Canterbury
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Number in Cohort
Cohort: 76 female offspring from 85 New Zealand Army veterans
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
New Zealand veterans of the Malayan Emergency from 1948-1960, who were exposed to dibutyl phthalate (DBP) and lived in the Canterbury province of NZ in 2009 were recruited through their membership of the Canterbury branch of the Malayan Veterans Association. Breast cancer incidence in the veterans' children was obtained through questionnaires.
Comment about participation selection
Because participants were recruited based on membership with an organization that requires an application, there are likely many veterans who were not captured from the study population. Also, because only veterans who were members of the Canterbury branch Malayan Veterans Association were recruited, there are many other veterans affiliated with other regions who were not invited to participate, who also applied DBP to their uniform. Study authors state the low response rate to the questionnaire is likely due to the age of veterans, and because men of this age are often reluctant to discuss matters of a personal sexual nature included in the questionnaire, such as genital defects or reduced fertility in their children.
Exposure Investigated
Exposures investigated
Veterans filled out questionnaires that included dates they were stationed in Malaysia, whether or not they used DBP, whether they had children during their time in Malaysia or after returning to NZ, whether they, their children or grandchildren bad breas
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Exposure to DBP was ascertained by asking veterans about application history of DBP to uniforms during military operations. The authors state they met with several NZ Malayan veterans, who indicated that DBP application was a memorable event, and thus an appropriate method to determine DBP exposure. To determine an approximate exposure, the authors obtained army uniforms from the Malayan Emergency, and applied DBP using the same method used during the Malayan Emergency (painted the seams with a liquid concentrate). The resulting amount of DBP absorbed across the uniform was used to estimate the absorbed dose of DBP in soldiers (using absorption rates found in animal models), and is estimated to be 64 mg/kg/day.
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.
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
Of the 76 female offspring, 3 (4.0%) had developed breast cancer. This is higher than the estimated general population breast cancer incidence of 0.48% (p<0.05) (based of U.S. estimates).
Results Comments
The small number of breast cancer cases and study population is not sufficient for creating a statistically powerful conclusion about breast cancer trends in this cohort.
Author address
Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, New Zealand.
Reviewers Comments
Authors state there were no published data available for New Zealand's incidence of breast cancer, so U.S. population breast cancer incidence served as the reference group. This may lead to inconsistent or inaccurate incidence rates of breast cancer in the country. No known breast cancer risk factors, or any potential confounders, were considered in this study. The age of offspring should have been considered; they likely fall into pre- and postmenopausal categories, ranging from 39 to 61 years of age, since they were all born after their fathers returned to New Zealand (1948-1960).