Helen H. McDuffie

Female-male differences in patients with primary lung cancer

This report is based on responses to a mailed questionnaire from 927 patients with lung cancer (730 men, 197 women), or their next of kin, and information obtained from the Saskatchewan Cancer Foundation Tumour Registry. Women were diagnosed at an earlier mean age than males (± ± SE, 63.5 ± 0.85 years versus 67.6 ± 0.37 years, P lt; 0.001), a finding which was consistent for each major histologic type. Women were more frequently diagnosed before age 60 years (42.0%) than were men (25.6%) (P < 0.001). Female patients were significantly more likely to be lifetime nonsmokers of cigaretters than male patients (23% versus 3.7%, P < 0.001). Among current smokers, women started smoking at an older age (19.3 ± 0.69 versus 16.5 ± 0.21 years, P < 0.001), smoked for fewer years (41.0 ± 1.2 years versus 47.4 ± 0.57 years, P < 0.001) and smoked slightly fewer cigarettes per day than male patients (23.6 ± 1.0 versus 26.7 ± 0.63, P < 0.05). Similar results were found for the duration of the smoking habit and number of cigarettes smoked among exsmokers. When current smokers and exsmokers were combined, the distribution of pack years by gender was significantly different. A higher percentage than expected of women as compared to men, are clustered in the lower pack‐year categories (P < 0.0003). No occupational exposure or familial factors which might act in synergism with cigarette smoking were identified. Thus, women developed primary lung cancer at an earlier age while smoking for fewer years than men.

Women at work: agriculture and pesticides.

Numerous occupational studies of cancer risks related to agriculture, agricultural practices, and agricultural exposures have been conducted among male farmers and farmworkers. Relatively few studies of female farmers and farmworkers have been conducted. Excesses of non-Hodgkins lymphoma, leukemia, multiple myeloma, soft tissue sarcoma, and cancers of the breast, ovary, lung, bladder, cervix, and sinonasal cavities have been observed in women in agriculture or with agricultural exposures. Agents that contribute to ill health in exposed men may also affect exposed women, sometimes in unexpected ways.

Prevalence of antinuclear antibodies in a rural population.

Exposure to environmentally and occupationally encountered toxicants can be associated with the development of certain autoimmune diseases and with the induction of antinuclear antibodies (ANA). Some chemicals used in the agricultural industry are known to affect immune function but their roles in the induction of autoimmunity in general, and ANA in particular, have not been reported previously. This study was undertaken to establish the prevalence of ANA in a rural population and to determine environmental and occupational exposures with which they are associated. This cross-sectional study represented one component of an interdisciplinary project (Prairie Ecosystem Study [PECOS], Eco-Research Program, Tri-Council Secretariat of Canada) designed to explore, in a rural population, the roles of environmental exposures as determinants of human health status. Information regarding lifetime, current, and main occupational exposures in the rural-dwelling study population was derived from a self-administered questionnaire. Sera from consenting subjects, collected during the months of February and March 1996, were assayed for ANA by indirect immunofluorescence on HEp-2 cells. The study population comprised 322 adult subjects (mean age 49.3+/-14.7 yr; range 16-87 yr). Statistical analyses adjusted for age and sex revealed that the presence of ANA among the participants was associated with a current agricultural occupation that included oilseed production, hog production, or poultry production. There was a significant association between ANA positivity and a current main farming operation of crop production. There was also an association among individual participants between lifetime exposure to the insecticide class of pesticides and the presence of ANA. In this rural study population, ANA positivity was significantly associated with lifetime exposure specifically to carbamate, organochlorine (including aldrin, chlordane, dieldrin, endrin, heptachlor, and lindane, but excluding DDT and methoxychlor), and pyrethroid insecticides and to phenoxyacetic acid herbicides, including 2,4-D. After adjustment for age, sex, and other insecticide exposures, multivariate analyses indicated that ANA positivity was associated with current oilseed production and with lifetime exposure to pyrethroid insecticides. In a rural population, ANA were associated with production of certain crops and certain animals and exposure to specific pesticides. The data indicate that some occupational exposures related to the agricultural industry are associated with the presence of ANA, a serologic expression of autoimmunity.

Exposure to animals and selected risk factors among Canadian farm residents with Hodgkin's disease, multiple myeloma, or soft tissue sarcoma

Exposures to farm animals has been associated with certain rare cancers. Simultaneously, using the same methodology and control group, we conducted a six-province incident, population-based study of Hodgkin’s disease (HD), multiple myeloma (MM), and soft tissue sarcoma (STS). Farm residence or work was reported by 38% (n = 119) of HD, 45% (n = 178) of MM, 43% (n = 156) of STS cases and 45% (n = 673) of controls. We conducted conditional logistic regression analyses and report odds ratios (ORadj) and 95% confidence intervals. After adjustment for covariates, exposure to farm animals had minimal effect on risk. The independent risk factors after adjustment for covariates were a family history of cancer (MM, STS), occupational uranium exposure (HD), professional driving (MM), and personal previous cancer (MM) or shingles (HD, MM).

Regional variations in risk factors for asthma in school children

BACKGROUND The authors have previously reported an increased prevalence of asthma in Estevan, Saskatchewan (21.4%) compared with Swift Current, Saskatchewan (16.2%). OBJECTIVE To determine the association between asthma and personal and indoor environmental risk factors in these communities. METHODS A population-based cross-sectional study was conducted in January 2000. A questionnaire was distributed to school children in grades 1 to 6 for completion by a parent. Multivariate logistic regression was used to examine associations between various risk factors and physician-diagnosed asthma. RESULTS Asthma was associated with respiratory allergy (adjusted OR [adjOR]=8.85, 95% CI 6.79 to 11.54), early respiratory illness (adjOR=2.81, 95% CI 1.96 to 4.03) and family history of asthma (adjOR=2.37, 95% CI 1.67 to 3.36). Several environmental factors varied with asthma by town. In Estevan, asthma was associated with home mould or dampness (adjOR=1.82, 95% CI 1.23 to 2.69) and was inversely associated with air conditioning (adjOR=0.56, 95% CI 0.37 to 0.85). The risk of asthma was increased if the child had previous exposure to environmental tobacco smoke from the mother in both communities (Swift Current: OR=1.87, 95% CI 1.06 to 3.30; Estevan: OR=2.00, 95% CI 1.17 to 3.43), and there was an inverse association with current exposure to environmental tobacco smoke from the mother in Estevan (OR=0.64, 95% CI 0.40 to 1.00). When multivariate analyses were stratified by sex, the relationship between home mould or dampness and asthma was most prominent in girls in Estevan. CONCLUSIONS Despite a similar regional location, different risk factors for asthma were identified in each community. Local environmental factors are important to consider when interpreting findings and planning asthma care.

Differences in respiratory symptoms and pulmonary function in children in 2 Saskatchewan communities

BACKGROUND Asthma prevalence is known to vary among different geographical regions both nationally and internationally. However, there is limited understanding of the nature of differences within geographical regions. OBJECTIVE To evaluate the prevalence of asthma in 2 prairie communities and differences in the patterns of respiratory symptoms between the communities. METHODS A cross-sectional questionnaire survey was sent through schools in Estevan and Swift Current, Saskatchewan, to parents of 2,231 children in grades 1 to 6. Asthma prevalence was determined by questionnaire report of physician-diagnosed asthma. Pulmonary function tests (PFTs) using spirometry were conducted in children in grades 1 to 4. To evaluate respiratory morbidity without the use of a diagnostic label, similar comparisons were made between communities for respiratory symptoms. RESULTS The overall response rate to the survey questionnaire was 91.3%. The prevalence of ever asthma in Estevan was 21.4% (95% confidence interval [CI], 20.1%-22.7%) compared with 16.2% (95% CI, 15.1%-17.3%) in Swift Current. A higher proportion of girls in Estevan (19.7%; 95% CI, 17.9%-21.5%) compared with girls in Swift Current (12.5%; 95% CI, 11.1%-13.9%) reported a history of asthma. There was no difference found between towns for boys. These findings were supported by findings for respiratory symptoms, including wheeze and cough. For both boys and girls, the forced expiratory flow at 25% to 75% of forced vital capacity and the ratio of forced expiratory volume in 1 second to forced vital capacity were lower in Estevan compared with Swift Current. CONCLUSIONS Differences in the distribution of childhood asthma can be found within regions. These results are strengthened by PFTs and cannot be fully explained by diagnostic biases.

Reduced risk of atopic sensitization among farmers: the Humboldt study.

Background: 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. Methods: 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. Results: 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. Conclusions: The prevalence of atopy was lower in adult farmers than in non-farmers.

Health and environment of rural families: results of a Community Canvass survey in the Prairie Ecosystem Study (PECOS).

This cross-sectional survey was conducted as Phase I of the Prairie Ecosystem Study (PECOS): Environmental Pesticide Exposure and Human Health. In November of 1995, community volunteers delivered a self-administered household questionnaire to 1185 rural households in southern Saskatchewan, Canada. The survey provided a broad description of the general health and the physical environment of 511 men, 499 women, and 393 children (< 18 years of age) residing in 549 respondent households in the rural study area (population density of about one person/km2). Families in the respondent households resided on a farm, in town or both. Of the 369 households that operated a farm, 25.2% of the households did not list the farm as their primary household. Residents of both farming and non-farming households reported contact with pesticides and fertilizers through home or garden use. History of smoking was greater among men and women from non-farming households. The most commonly reported health problems among the children were a history of bronchitis, asthma, skin allergies, pneumonia, and hay fever. The most frequently reported health problems among the men were a history of high blood pressure, bronchitis, pneumonia, hearing problems, and stress; and among the women were a history of bronchitis, high blood pressure, shortness of breath, and pneumonia. Compared to farming households, more members of non-farming households reported a history of respiratory problems, particularly bronchitis among the women and children. Overall, there were important differences in the smoking history, the occupational use of pesticides and fertilizers, and the general health status between the farming and non-farming households and individuals in this rural population.

Factors Associated with Detection of Bromoxynil in a Sample of Rural Residents

In regions of intensive crop production residents may be exposed to herbicides through direct contact or environmental sources. The environmental herbicide exposures of rural populations and resultant potential health effects are not well understood. Epidemiologic studies of herbicides have focused on occupational exposures using, primarily, self-reported data (e.g., information on occupational and nonoccupational herbicide use, agricultural practices and exposures, farm residence). Herbicide exposure characterization in epidemiologic research would be strengthened by the use of self-reported data and biological monitoring (e.g., measuring the herbicide parent compound or its metabolites in blood or urine specimens) to classify individual exposures, identify factors associated with exposure, and obtain integrated estimates of exposure. As both exposure metrics are susceptible to measurement error and some self-reported and biological monitoring data might not be correlated, a worthwhile first step is to identify self-reported data that are statistically associated with biological measures of exposure. This study used gas chromatography/mass spectrometry analysis to measure blood plasma concentrations of target herbicides in a sample of rural residents (men, women, and youths) of Saskatchewan, Canada, and identified factors, based on self-reported data, associated with detection. The questionnaire data and blood specimens were collected in February/March 1996 during winter (frozen soil and water and snow cover) conditions. Sixty-four of the 332 study participants (19.3%) had detectable levels of the herbicide bromoxynil although herbicide application in the region had not occurred for approximately 5mo and bromoxynil has a relatively short environmental half-life. The prevalence of detection of other target herbicides (2,4-D, triallate, trifluralin, dicamba, fenoxaprop, MCPA, and ethalfluralin) varied from 0.3% to 2.7%. Self-reported factors identified in the multiple-variable analysis as statistically significant predictors of bromoxynil detection included recent exposure to grain production as the main farming operation (statistically significant for producers and for nonfarming family members of producers), a history of bromoxynil use, a history of having felt ill with a pesticide exposure, and a history of a pesticide spill on skin or clothing, with apparent gender differences in the relative importance of these factors. Detection of bromoxynil in this rural sample, 3-4mo after freeze-up and winter snow cover, suggests either that bromoxynil is very slowly metabolized/excreted from the body or study participants were environmentally or occupationally exposed to the herbicide during this period. Further research is needed to elucidate the pathways of exposure, biological half-life, and potential human health effects of bromoxynil.

Hodgkin Lymphoma and Pesticides Exposure in Men: A Canadian Case-Control Study

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 statisticalmodels. 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.