To conduct analyses of a Canadian population-based case-control dataset to evaluate:
- the effects of multiple pesticides in combination on cancer risk
- the potential for immunologic complications such as asthma to act as effect modifiers in this relationship (i.e. to determine whether the link between pesticide exposure and cancer risk is altered by the presence of immunologic conditions)
- the cancer risks from exposure to combinations of pesticides based on their carcinogenic potential
Over the past several decades, incidence rates of non-Hodgkin’s lymphoma (NHL) have been increasing in countries worldwide, including in Canada. Although the reasons for this increase are not clearly understood, lymphomas, multiple myeloma, and soft-tissues sarcomas have been associated with farming and some specific farm exposures. A Canadian population-based case-control study in six provinces was designed to evaluate specific agricultural exposures that might be involved (McDuffie et al., 2001; Pahwa et al., 2006). This important study found a number of interesting associations including links between NHL and the pesticides dicamba, mecoprop, malathion, carbaryl, and 2,4-D (McDuffie et al., 2001). This dataset was used for further analyses in this study.
The dataset was analyzed using logistic regression to evaluate the associations of interest. In addition to information on pesticide use, the study also obtained information on demographic factors, medical history, family history of cancer, lifetime job history, occupational exposure to pesticides, use of personal protective equipment, and tobacco use that was included in the models to control for possible confounding.
The findings of this project contributed to our understanding of the role that agricultural exposures and other factors play in the development of NHL, Hodgkin lymphoma, multiple myeloma, and soft tissue sarcoma — cancers that have been linked to farming in the past. These new analyses provided further information on the carcinogenicity of pesticides, which has relevance for both occupational and non-occupational settings.
- Journal article: The effect of multiple pesticides on the risk of non-Hodgkin lymphoma
- Plain language summary: The effect of multiple pesticides on the risk of non-Hodgkin lympoma
- Journal article: The effect of multiple pesticides on the risk of Hodgkin lymphoma
- Journal article: The effect of multiple pesticides and the risk of multiple myeloma
- Journal article: The effect of immunological conditions on the association between pesticide exposures and the risk of non-Hodgkin lymphoma
- Plain language summary: The effect of immunological conditions on the association between pesticide exposures and the risk of non-Hodgkin lymphoma
In addition, researchers from the U.S. National Cancer Institute and the OCRC have joined the CCSPH dataset with three other datasets of similar case-control studies that were conducted in four American states during the 1980s. More information about this initiative, called the North American Pooled Project, can be found here.
McDuffie HH, Pahwa P, McLaughlin JR, Spinelli JJ, Fincham S, Dosman JA, Robson D, Skinnider LF, and Choi NW. Non-Hodgkin’s lymphoma and specific pesticide exposures in men: Cross-Canada study of pesticides and health. Cancer Epidemiol Biomarkers Prev 2001; 10: 1155-1163.
Pahwa P, McDuffie HH, Dosman JA, McLaughlin JR, Spinelli JJ, Robson D, Fincham S. Hodgkin lymphoma, multiple myeloma, soft tissue sarcomas, insect repellents, and phenoxyherbicides. J Occup Environ Med 2006; 48: 264-274.
Aaron Blair (Occupational Cancer Research Centre) (PI)
Shelley Harris (Occupational Cancer Research Centre and Cancer Care Ontario)
Paul Demers (Occupational Cancer Research Centre and Cancer Care Ontario)
John McLaughlin (Samuel Lunenfeld Research Institute and Occupational Cancer Research Centre)
Karin Hohenadel (Public Health Ontario)
Manisha Pahwa (Occupational Cancer Research Centre)
Garthika Navaranjan (Occupational Cancer Research Centre)
Linda Kachuri (Occupational Cancer Research Centre)
John Spinelli (BC Cancer Agency)
Punam Pahwa (University of Saskatchewan)
James Dosman (University of Saskatchewan)