H H McDuffie

University of Saskatchewan, Saskatoon, Saskatchewan, Canada

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Publications (70)173.11 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study was to investigate the putative associations of specific pesticides with Hodgkin lymphoma. A population-based, case-control study of Hodgkin lymphoma was conducted among males in six regions of Canada. Data were collected by a mailed questionnaire followed by a telephone interview to obtain detailed exposures data for those reporting ≥ 10 hours per year of pesticide exposure. Conditional logistic regression was used to fit statistical models. Comparisons of 316 Hodgkin lymphoma cases and 1506 controls identified several factors as predictors for increased Hodgkin lymphoma risk: family history of cancer, exposure to the insecticide chlorpyrifos [OR (95% CI) = 1.19 (1.03, 1.37)], and previous diagnosis of acne or shingles. The increased risk of developing Hodgkin lymphoma detected among Canadian men who used chlorpyrifos must be interpreted cautiously; however the strength of its association indicates that it requires investigation in other populations.
    Journal of Agromedicine 01/2012; 17(1):30-9. · 0.72 Impact Factor
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    ABSTRACT: The objective of this study was to investigate the putative associations of specific pesticides with multiple myeloma. A matched, population-based, case-control study was conducted among men residing in six Canadian provinces (Quebec, Ontario, Manitoba, Saskatchewan, Alberta, and British Columbia). Data were collected on 342 multiple myelome cases and 1506 age and province of residence matched controls. Data were collected by mailed questionnaires to capture demographic characteristics, antecedent medical history, detailed lifetime occupational history, smoking history, family history of cancer, and exposure to broadly characterized pesticides at home, work, and practicing hobbies. Details of pesticide exposures were collected by telephone interview for those who reported 10 hours or more per year of exposure. Exposure to pesticides grouped into major chemical classes resulted in increased risk being detected only for carbamate insecticides [odds ratio (OR) and 95% confidence interval (CI) 1.90 (1.11, 3.27) adjusted for potential confounders]. An exposure to fungicide captan [2.35 (1.03, 5.35)] was positively associated with the incidence of multiple myeloma. While an exposure to carbaryl [1.89 (0.98, 3.67)] was associated with the incidence of multiple myelome with borderline significance. The authors further suggest that certain pesticide exposures may have a role in multiple myeloma etiology, and identify specific factors warranting investigation in other populations.
    Journal of Agromedicine 01/2012; 17(1):40-50. · 0.72 Impact Factor
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    ABSTRACT: The present study aims to identify occupational exposures associated with incidence of multiple myeloma (MM). A population-based case-control study of MM (ICD-9 203) was conducted among Canadian males, with a total of 342 cases and 1506 controls contributing to the final analyses. Conditional logistic regression was used to estimate odds ratios (OR) and confidence intervals (CI), stratifying by age groups and province of residence. Based on the most parsimonious multivariable model, the following variables were significantly associated with an increased incidence of MM: exposure to coal dust (OR 1.7, 95% CI 1.2-2.4), long-held occupations as a carpenter (OR 3.2, 95% CI 1.4-7.1) or a machinist (OR 2.4, 95% CI 1.0-5.8); and immediate family member having been previously diagnosed with certain cancers (OR 1.4, 95% CI 1.1-1.8). In this study of Canadian men, a higher risk of MM may be associated with exposure to coal dust, long-held occupations as a carpenter or machinist, and a positive family history of cancer.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 06/2011; 53(6):641-6. · 1.88 Impact Factor
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    ABSTRACT: Objective: The objective was to study the association between Hodgkin Lymphoma (HL) and occupational exposures related to long-held occupation among males in Canada. Methods: A population-based case–control study of HL was conducted among males stratified by province of residence and age group. Conditional logistic regression was used to fit statistical models. Results: Several factors independently increased the risk of HL. Ever exposure to ionizing radiation from uranium showed a significant association with HL. Men who had smoked cigarettes for 25 years or more were the most likely to develop HL. Exposure to ultraviolet light and diagnosis with measles were negatively associated with HL, whereas diagnosis with shingles increased the risk of HL. Conclusions: The higher risk of developing HL may be associated with exposure to uranium ionizing radiation and years of cigarette smoking.
    Journal of Occupational and Environmental Medicine 11/2009; 51(12):1447-1454. · 1.85 Impact Factor
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    ABSTRACT: Research has shown that ethnicity is a significant predictor of Hodgkin lymphoma (HL). Variations in cancer incidence among ethnic groups in the same country can lead to important information in the search for etiological factors. Other risk factors important in the etiology of HL are medical history and exposure to pesticides. In this report we investigated the association between ethnicity and HL in the presence of medical history, and exposure to pesticides. The data resulting from a matched population-based case-control study conducted in six provinces of Canada (Ontario, Quebec, Manitoba, Saskatchewan, Alberta, and British Columbia) was analyzed to determine whether or not there was any association between ethnicity and incidence of HL when adjusted for personal medical history and pesticide exposure. Information on ethnicity, personal medical history, and pesticide exposure was collected by questionnaires via mail on 316 men diagnosed with HL; and on 1506 controls. A conditional logistic regression was utilized and results were presented as odds ratios and 95% confidence intervals. In our study population, the distribution of ethnic groups was: 38.5% North American, 15% British, 8.4% Western European, 8.2% Eastern European, 1.7% Asian, 1.4% Scandinavian and 27% of other ethnic origin. Compared to North Americans (i) the risk of HL was greater among the Eastern European descendents (Odds Ratio (ORadj): 1.82; 95% confidence interval (CI): 1.02, 3.25) and Western European (ORadj: 1.62; 95% CI: 0.95-2.76) descent population (borderline significance at 5% level); and (ii) the risk of HL was lower in Asian descents. Diagnosis with measles (ORadj: 0.72, 95% C.I.: 0.53-0.98) and/or positive history of allergy desensitization shots (ORadj: 0.55, 95% C.I.: 0.30-0.99) were negatively associated with the incidence of HL, while diagnosis with acne (ORadj: 2.12, 95% C.I.: 1.19-3.78), shingles (ORadj: 2.41, 95% C.I.: 1.38-4.22) and positive family history of cancer (ORadj: 1.93, 95% C.I.: 1.40-2.65) increased the risk of HL. Exposure to individual herbicide dichlorprop showed an increased risk of HL (ORadj: 6.35, 95% C.I.: 1.56-25.92). In Canada, compared to North Americans descendents, the risk of HL was significantly greater among the Eastern European and Western European descent population. Our results related to association between ethnicity and HL support the findings reported by other researchers. Our data showed that subjects who were diagnosed with measles or had allergy desensitization shots negatively associated with the incidence of HL; and other medical conditions, ever diagnosed with acne, and positive family history of cancer were positively associated with the incidence of HL.
    BMC Cancer 06/2009; 9:141. · 3.33 Impact Factor
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    ABSTRACT: A positive family history of chronic diseases including cancer can be used as an index of genetic and shared environmental influences. The tumours studied have several putative risk factors in common including occupational exposure to certain pesticides and a positive family history of cancer. We conducted population-based studies of Hodgkin lymphoma (HL), Multiple Myeloma (MM), non-Hodgkin's Lymphoma (NHL), and Soft Tissue Sarcoma (STS) among male incident case and control subjects in six Canadian provinces. The postal questionnaire was used to collect personal demographic data, a medical history, a lifetime occupational history, smoking pattern, and the information on family history of cancer. The family history of cancer was restricted to first degree relatives and included relationship to the index subjects and the types of tumours diagnosed among relatives. The information was collected on 1528 cases (HL (n = 316), MM (n = 342), NHL (n = 513), STS (n = 357)) and 1506 age +/- 2 years and province of residence matched control subjects. Conditional logistic regression analyses adjusted for the matching variables were conducted. We found that most families were cancer free, and a minority included two or more affected relatives. HL [(OR(adj) (95% CI) 1.79 (1.33, 2.42)], MM (1.38(1.07, 1.78)), NHL (1.43 (1.15, 1.77)), and STS cases (1.30(1.00, 1.68)) had higher incidence of cancer if any first degree relative was affected with cancer compared to control families. Constructing mutually exclusive categories combining "family history of cancer" (yes, no) and "pesticide exposure > or = 10 hours per year" (yes, no) indicated that a positive family history was important for HL (2.25(1.61, 3.15)), and for the combination of the two exposures increased risk for MM (1.69(1.14,2.51)). Also, a positive family history of cancer both with (1.72 (1.21, 2.45)) and without pesticide exposure (1.43(1.12, 1.83)) increased risk of NHL. HL, MM, NHL, and STS cases had higher incidence of cancer if any first degree relative affected with cancer compared to control families. A positive family history of cancer and/or shared environmental exposure to agricultural chemicals play an important role in the development of cancer.
    BMC Cancer 03/2009; 9:70. · 3.33 Impact Factor
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    ABSTRACT: Longitudinal declines in pulmonary function are associated with individuals experiencing occupational exposure to organic dusts in combination with lifestyle factors such as cigarette smoking and with genetic factors, and interactions between these factors. Objective:To investigate the relationship between polymorphism of genes encoding Tumor Necrosis Factor Alpha (TNF-alpha) and longitudinal lung function decline in grain workers exposed to grain dust. Male grain handlers who participated in the Saskatchewan Grain Workers Surveillance Program from 2002 through 2005 provided demographic, occupational, lifestyle, and respiratory symptoms information as well as pulmonary function measurements and DNA for genotyping. Marginal models using the generalized estimating equations approach were fitted by using a SAS PROC GENMOD to predict the annual decline in Forced Expired Volume in one second (FEV(1)) and Forced Vital Capacity (FVC). Smoking intensity contributed to the decline in FEV(1.)Among *1/*1 homozygotes and *1/*2 heterozygotes, grain workers with <10 years in the grain industry had significantly lower FEV(1)declines compared to those of the other two exposure groups (>10 and < or =20 years, and >20 years in the grain industry). The annual declines in FEV(1)for grain workers who were either *1/*1 homozygote or *1/*2 heterozygote and had been in the grain industry for <10 years were lower by comparison to those of grain workers who were *2/*2 genotype and had been in the industry for <10 years. This research demonstrates that years in the grain industry is an effect modifier between TNF-alpha 308 genotype and longitudinal decline in FEV(1)in male subjects exposed to grain dust.
    Journal of Agromedicine 01/2009; 14(2):215-21. · 0.72 Impact Factor
  • Punam Pahwa, James A Dosman, Helen H McDuffie
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    ABSTRACT: To determine longitudinal estimates of pulmonary function decline in Canadian grain elevator workers before and after dust control by analyzing data collected from five regions of Canada over 15 years. Declines in forced expired volume in one second and forced vital capacity before and after dust control were estimated by using a generalized estimating equations approach. For grain workers who were in the grain industry for 20 or more years both before and after dust control: the mean annual loss of forced expired volume in one second was greatest among current smoking grain workers followed by ex-smokers and nonsmokers, respectively. Similar results were obtained for forced vital capacity. Grain dust control was effective in reducing decline in the lung function measurements among grain workers in all smoking and exposure categories.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 01/2009; 50(12):1394-400. · 1.88 Impact Factor
  • Punam Pahwa, Helen H McDuffie
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    ABSTRACT: To investigate what factors contribute to the increased risk of developing cancer among potash mine workers. Data on 1434 male potash workers based on a nested case-control (Cases: potash workers whose personal identifiers matched those of an individual registered with the Saskatchewan Cancer Agency, Controls: all other potash workers) study design were analyzed. An occupational history of farming (RR [95% CI =]: 1.79 [1.26, 2.55]), presence of pleurisy at baseline [1.90 (1.07 to 3.40)], previous hard rock mining experience [1.74 (1.01 to 3.00)], and age statistically significantly elevated the risk of becoming a case. Smoking status was an effect modifier for the relationship between any respiratory disease at baseline and cancer. Age; previous occupational history of farming and rock mining; interaction between any respiratory disease and smoking status were positively associated with the development of cancer.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 10/2008; 50(9):1035-41. · 1.88 Impact Factor
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    ABSTRACT: The activity of the enzymes that metabolize tobacco smoke may affect the susceptibility to chronic obstructive pulmonary disease (COPD). Cytochrome P450 (CYP) 3A5 is expressed selectively over CYP3A4 in human lung, but the association between the CYP3A5 polymorphisms and the airway injury is unknown. Two hundred and six male Saskatchewan grain workers participated in this longitudinal study, and their lung function values of forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC), respiratory symptoms, smoking status, and the occupational history were analyzed. A significant interactive effect was observed between the CYP3A5 genotype and current smoking status on FEV1, and the annual decline rates of FEV1 and FVC in current smokers were greater among CYP3A5*1/*3 carriers than CYP3A5*3/*3 carriers (-48.7+/-16.4 vs. -31.5+/-4.7 ml/years, P=0.02; -27.4+/-18.9 vs. -5.8+/-6.5 ml/years, P=0.04). The incidences of chronic cough and COPD were also higher in current smokers with CYP3A5*1/*3 than in nonsmokers and current smokers with CYP3A5*3/*3. The adjusted odds ratios for chronic cough and COPD current smokers with CYP3A5*1/*3 versus nonsmokers with the CYP3A5*3/*3 genotype were 11.4 (P=0.009) and 4.3 (P=0.13), respectively. The results suggest that CYP3A5*1 may be a novel genetic risk factor for airway injury in smokers, and that CYP3A5 may play a role in airway injury owing to the bioactivation of chemicals in tobacco smoke.
    Pharmacogenetics and Genomics 07/2008; 18(6):487-93. · 3.61 Impact Factor
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    S Ghosh, P Pahwa, D Rennie, H H McDuffie
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    ABSTRACT: The prevalence of asthma is on the rise worldwide, with large variations in prevalence existing between and within countries. Little is known regarding the variation in asthma prevalence in adults living in rural and urban settings. Using questionnaire data from the Canadian National Population Health Survey, the prevalence of asthma at four time periods (1994/1995 [cycle 1], 1996/1997 [cycle 2], 1998/1999 [cycle 3] and 2000/2001 [cycle 4]) was compared between rural and urban populations stratified by sex, smoking status and age group. Asthma was defined as a positive response to the question: "Do you have asthma diagnosed by a health professional?" To account for the complexity of the survey design, the bootstrap method was used to calculate prevalences and 95% CIs. Overall, the prevalence of asthma increased from 7.3% (cycle 1) to 7.5% (cycle 4). After stratifying by sex, the asthma prevalence decreased among men, but in women, there was a steady increase. Asthma prevalence increased for both the rural population and the urban population. After stratifying each cycle by sex and location (rural or urban), both rural and urban men showed a decrease in asthma prevalence. On dividing according to age groups (0 to 14 years, 15 to 34 years, 35 to 64 years, and 65 years and older), the prevalence of asthma was greatest in the 15- to 34-year age group of urban and rural women. Asthma prevalence increased among rural and urban women. The prevalence of asthma was highest among female smokers and male nonsmokers when stratified by smoking status. Based on these findings, the rate of increase in asthma prevalence is different for men and women.
    Canadian respiratory journal: journal of the Canadian Thoracic Society 05/2008; 15(3):146-52. · 1.29 Impact Factor
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    ABSTRACT: This retrospective longitudinal study investigated the association between the Q192R polymorphism of the high-density lipoprotein-associated multifunctional antioxidant enzyme, paraoxonase-1 (PON1), and lung function decline, while taking into account smoking history. The demographic, occupational, and respiratory symptom information and lung function variables were obtained from 216 male Saskatchewan grain workers. An interaction between the PON1 genotypes and smoking status was observed. Current smokers with the 192R allele had a lower forced expiratory volume in the first second (FEV(1)) and FEV(1) per forced vital capacity (FVC). The annual decline rate of FEV(1)/FVC in current smokers was greater among 192R allele carriers than noncarriers (0.58+/-0.05 vs. 0.35+/-0.04 %/yr, p<0.0001). A similar result was observed with FEV(1) (40.9+/-6.4 vs. -33.0+/-7.0 mL/yr, p=0.10). The annual decline rate of FVC was not influenced by the genotypes. These results strengthened the previous findings of our cross-sectional study, suggesting that the 192R allele may be a novel genetic risk factor for airway injury among current smokers.
    Annals of Epidemiology 04/2008; 18(4):330-4. · 2.48 Impact Factor
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    ABSTRACT: The objective was to study the association between Non-Hodgkin's Lymphoma (NHL) and occupational exposures related to long held occupations among males in six provinces of Canada. A population based case-control study was conducted from 1991 to 1994. Males with newly diagnosed NHL (ICD-10) were stratified by province of residence and age group. A total of 513 incident cases and 1506 population based controls were included in the analysis. Conditional logistic regression was conducted to fit statistical models. Based on conditional logistic regression modeling, the following factors independently increased the risk of NHL: farmer and machinist as long held occupations; constant exposure to diesel exhaust fumes; constant exposure to ionizing radiation (radium); and personal history of another cancer. Men who had worked for 20 years or more as farmer and machinist were the most likely to develop NHL. An increased risk of developing NHL is associated with the following: long held occupations of faer and machinist; exposure to diesel fumes; and exposure to ionizing radiation (radium). The risk of NHL increased with the duration of employment as a farmer or machinist.
    Environmental Health 02/2008; 7:44. · 2.71 Impact Factor
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    ABSTRACT: Previous studies reported associations of non-Hodgkin's lymphoma (NHL) with agriculture, agricultural practices, herbicide, and insecticide exposure. McDuffie et al. (McDuffie, H.H., P. Pahwa, and D.F. White. 1995. Saskatchewan women and agricultural exposures: any relationship to tumor incidence? In Agricultural Health and Safety: Workplace, Environment, Sustainability, ed. HH McDuffie, JA Dosman, KM Semchuk, S.A. Olenchock, and A. Senthilselvan, 135-42. Boca Raton, FL: CRC Press, Lewis Publishers) demonstrated a significantly higher risk of NHL associated with drinking water from shallow as compared to deep wells among women in Saskatchewan. Contamination of drinking water derived from groundwater sources may be due to natural sources and/or to the widespread use of pesticides and agricultural chemicals which may contain heavy metals and other elements as active ingredients. A NHL case (n = 88) - control (n = 132) study of drinking water quality was conducted by questionnaire, and by measuring the concentrations of 64 chemical elements simultaneously in drinking water samples utilizing inductively coupled plasma mass spectrometry technology. These data are reported either as geometric means or log-transformed because of skewness. Independent two sample t-test was used to compare the concentrations of each chemical element in samples of drinking water obtained from the homes of cases and controls. The chemical elemental analysis revealed statistically significant case/control differences in concentrations of 15 chemical elements versus three expected based on chance. Elements for which the concentrations in case/control drinking water samples differed were: lithium, boron, aluminum, silicon, phosphorus, titanium, cobalt, arsenic, selenium, yttrium, zirconium, cadmium, cesium, gadolinium, and uranium. The mean aluminum concentration was higher in water taken from the homes of controls compared to case homes, while the reverse occurred for the other 14 elements, with statistically significant differences in concentration.
    Toxicological and Environmental Chemistry 01/2008; 90(6).
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    ABSTRACT: The main objective of this study was to investigate potential association between development of soft-tissue sarcoma (STS) and occupational exposures related to farming and the agricultural industry in Canada. A population-based case-control study of STS was conducted among Canadian men stratified by province of residence and age group. Conditional logistic regression was used to fit multivariable statistical models. The following variables were positively associated with the incidence of STS: machinist, chicken farming, pulp and paper industry worker, and apartment complex worker. Mixed farming and exposure to chlorine were negatively associated with STS. The higher risk of developing STS may be associated with longest-held job as a machinist, short-term jobs as chicken farm worker, pulp and paper industry worker, and apartment complex worker.
    Journal of Occupational and Environmental Medicine 01/2008; 49(12):1386-93. · 1.85 Impact Factor
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    ABSTRACT: Different wheeze phenotypes have been identified, primarily in preschool children. To explore the characteristics of children in primary school without a history of wheeze or asthma and the onset of wheeze during a 3-year follow-up period. Students in grades 1 to 3 participated in a cross-sectional study in 2000 and again in 2003, creating a prospective cohort. Data were collected using questionnaires in both years. Children without a history of asthma or wheeze in or before 2000 were selected for this analysis (n = 212). Associations between baseline characteristics and an outcome of the onset of new wheeze were evaluated. Twenty-two children (10.4%) reported new wheeze by 2003. Significant associations were found between new-onset wheeze and body mass index (odds ratio [OR], 1.33; 95% confidence interval [CI], 1.10-1.62) and history of allergic disease (OR, 7.17; 95% CI, 2.48-20.72); significant inverse associations were found with farming exposures in the first year of life (OR, 0.17; 95% CI, 0.05-0.64) and with having a fireplace in the home (OR, 0.20; 95% CI, 0.05-0.83). After stratification by sex, the associations were typically stronger in girls than in boys. Allergic disease in childhood and early and current exposures affect the development of wheeze. These results support efforts to lead healthy lifestyles and direct continued research into wheeze phenotypes, especially by sex.
    Annals of allergy, asthma & immunology: official publication of the American College of Allergy, Asthma, & Immunology 01/2008; 99(6):502-8. · 3.45 Impact Factor
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    ABSTRACT: Paraoxonase-1 (PON1) is a high-density, lipoprotein-associated, multifunctional antioxidant enzyme that is detected in nonciliated bronchiolar epithelial cells, although its role in the lung has not yet been clarified. We therefore investigated the association between the PON1 Q192R polymorphism and lung function. A total of 216 male Saskatchewan grain handlers provided demographic, occupational and respiratory-symptom information by means of questionnaires, and thereafter underwent PON1 Q192R genotyping and lung-function testing. Mean lung-function values did not differ among the Q192R genotypes. However, current smokers with the Q/Q genotype had a higher mean percent predicted forced expiratory volume in the first second (FEV(1)), and absolute and percent predicted FEV(1) per forced vital capacity (FVC) compared with current smokers with at least one 192R allele (100.9 +/- 11.2% vs 92.0 +/- 15.1%, p = 0.01; 78.0 +/- 5.9% vs 74.1 +/- 6.8%, p = 0.03; and 96.8 +/- 7.1% vs 92.1 +/- 8.3%, p = 0.03; respectively). The incidence of subjects with FEV(1)/FVC less than 70% was significantly higher in current smokers with at least one 192R allele than in nonsmokers with the Q/Q genotype (odds ratio: 5.0; 95% confidence interval: 1.5-17.4). The protective effect of the Q/Q genotype was not found in nonsmokers. The FVC was not influenced by either PON1 genotype or smoking status. The results obtained from grain handlers suggest that PON1 may play some role in the protection of the airways against the toxicity of cigarette smoke, and the 192R allele may be a novel genetic risk factor for airway injury.
    Pharmacogenomics 09/2007; 8(8):901-8. · 3.86 Impact Factor
  • H H McDuffie, J Quail, S Ghosh, P Pahwa
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    ABSTRACT: The incidence rates of testicular cancer are increasing in several countries, especially among younger adults. The role of agricultural exposure in the etiology of testicular cancer is contentious. We extracted information related to the host, lifestyle, and tumor characteristics from the files of the Saskatchewan Cancer Agency for all cases (n = 517) of testicular cancer diagnosed in Saskatchewan between 1979 and 2000. The following questions were the subject of this initial inquiry: (1) Are tumor characteristics similar or different among occupational groups dichotomized into farmer/nonfarmer? (2) Are host characteristics similar or different among occupational groups? (3) Is farming as an occupation one of the independent predictors of tumor stage at diagnosis? Statistical analyses were restricted on 486 cases. The nonfarmers (n = 349) had smaller tumors in length on average, and more of them were diagnosed at stage I compared to farmers (n = 72). Occupation was not recorded for 65 cases. Farmers were older than nonfarmers. In logistic regression analyses with adjustment for relevant variables as cited in the literature, individuals with nonseminomas [OR (95% CI) 1.99 (1.30-3.31)] and < or = 26 years old at diagnosis [2.12 (1.15-3.93)] were significantly more likely to be diagnosed with a stage 2 or higher tumor. Farmers were significantly more likely than nonfarmers to be diagnosed at stage 2 or higher [1.76 (1.00-3.10)]. Based on our data, the significant predictors of being diagnosed with stage 2 and higher are: presence of nonseminoma, < or = 26 years old, and farming as an occupation.
    Journal of agricultural safety and health 07/2007; 13(3):247-58.
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    ABSTRACT: Previous research suggests that farmers may have an increased risk of developing autoimmunity and that exposure to certain pesticides may alter immune function. Little is known, however, about the immunologic effects of farming and pesticide exposures. As part of the Prairie Ecosystem Study, associations between detection of antinuclear antibodies (ANA), an autoimmunity indicator, and exposure to the herbicide bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) were investigated in a cross-sectional study of 208 residents (94 women, 114 men) of a cereal-producing region in Saskatchewan, Canada, during spring herbicide application, 1996. The ANA were assayed in serum by indirect immunofluorescence on HEp-2 cells. Bromoxynil was measured in plasma by gas chromatography/mass spectrometry analysis. Associations were explored between ANA detection and detection of bromoxynil in plasma, self-reported use of bromoxynil and other pesticides, farming exposures, gender, age, body mass index (BMI), and residency. The mean age (SD) of the participants was 50.8 (13.6) yr [women: 49.7 (13.5) yr, men: 51.6 (13.6) yr]. ANA prevalence was 37.5% (women: 39.4%, men: 36%,) at 1:40 serum dilution, 17.3% (women: 20.2%, men: 14.9%) at 1:80, and 10.1% (women: 13.8%, men: 7%) at 1:160. In the multiple-variable Generalized Estimating Equation (GEE) logistic regression analyses, female gender was a positive predictor of ANA detection and gender differences were observed in the relative importance of other study factors. None of the variables examined in the multiple-variable GEE analysis were statistically significant predictors of ANA detection for women. For many of these variables, however, the point estimates for women are similar to those seen in men. For men, with adjustment for age, ANA presence was inversely associated with detection of concentrations of bromoxynil in winter or spring samples and recent occupational use of 2,4-dichlorophenoxyacetic acid, and the positive ANA predictors included having a BMI in the obese (BMI > 30.04 kg/m2) category, recent occupational use of trifluralin or fungicides, and current exposure to oilseed, poultry, or dairy production. The inverse association between ANA detection and bromoxynil exposure observed in farmers in this study is consistent with earlier empirical observations that certain pesticides may suppress immune function. Further research is needed to examine whether these findings are confirmed in other populations and to elucidate the biological mechanisms involved.
    Journal of Toxicology and Environmental Health Part A 05/2007; 70(7):638-57. · 1.73 Impact Factor
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    ABSTRACT: It needs to be clarified whether farming is associated with a reduced risk of atopy or allergic condition. There is a lack of consistent evidence for prevalences of atopy, respiratory allergy and asthma in adult farmers. A cross-sectional study of adults (n = 2,081) was conducted in the town of Humboldt, Sask. Allergy skin prick tests were conducted to determine atopic sensitization. Respiratory allergy and physician-diagnosed asthma were based on self-reporting. Logistic regression was used to assess the associations of atopy, respiratory allergy and asthma with farming practices, adjusting for other important variables. Of 2,081 participants, 27.8% were farmers. Reduced risks of atopic sensitization, respiratory allergy and asthma were observed among farmers compared to non-farmers. After adjustment for sex and age, which are major confounders, the odds ratio for atopic sensitization was 0.79 (95% confidence interval: 0.65, 0.97) for farmers versus non-farmers. Asthma showed a similar trend; however, there was no statistically significant difference in either respiratory allergy or asthma rates observed between farmers and non-farmers. The prevalence of atopy was lower in adult farmers than in non-farmers.
    International Archives of Allergy and Immunology 02/2007; 144(4):338-42. · 2.25 Impact Factor

Publication Stats

900 Citations
173.11 Total Impact Points

Institutions

  • 1988–2012
    • University of Saskatchewan
      • • Canadian Centre for Health and Safety in Agriculture
      • • Department of Community Health and Epidemiology
      • • Department of Medicine
      • • Department of Pediatrics
      Saskatoon, Saskatchewan, Canada
  • 2007–2008
    • Kumamoto University
      • Department of Pharmacology and Therapeutics
      Kumamoto, Kumamoto Prefecture, Japan