Pesticide exposure and female breast cancer risk in Canada: a case control study
Date
2001-08
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ORCID
Type
Degree Level
Masters
Abstract
Breast cancer is one of the most common types of cancer among females in
Canada. The importance of personal characteristics such as obesity, diet, age of
menarche, age of menopause, parity, and family history have been implicated.
However, there is only a 30% attributable risk for breast cancer from these factors.
Environmental exposures are being more closely scrutinized and studies have
shown that occupational and residential exposure to pesticides may be associated with
increased risk for breast cancer. This thesis describes a case control study that
investigated the relationship between pesticide exposure and breast cancer using data
from the National Enhanced Cancer Surveillance System. All cases of female breast
cancer and corresponding controls available from the data (2,360 cases and 2,488
controls) were used in the analysis. Potential pesticide exposure was assessed through
self-reported lifetime occupational histories and lifetime residential histories. Known or
suspected covariates were controlled for in the multiple logistic regression models.
Manitoba, Saskatchewan and Alberta, the three provinces that have the highest reported
usage of pesticides, were analyzed as a sub-group.
Results of this study did not find any association between exposure to pesticides
and an increased risk in breast cancer. However, there was a significantly negative
association between women who had lived all their lives in a rural setting and breast
cancer risk [odds ratio (OR) 0.70, 95% confidence interval (CI) 0.474, 0.780].
The strengths and limitations of the study are discussed. While women living in a
rural setting may experience increased exposure to pesticides, women living in urban
settings may be exposed to more sources of environmental toxins. Furthermore, self
reported environmental exposures are difficult to measure, analyze and generalize to the
larger population. Implications for future research are also included.
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Degree
Master of Science (M.Sc.)
Department
Community Health and Epidemiology
Program
Community Health and Epidemiology