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Biomedical subjects

J A Dosman

Publications and source records attributed to J A Dosman.

At least 19 recordsLinked to original sources
PubMed1992

Decline in spirometric variables in grain workers from start of employment: differential effect of duration of follow up.

Prospective study of 164 young men from the start of employment in grain elevators showed that of those seen at the initial evaluation of respiratory state only 30% were available for a complete four year follow up. The drop out of subjects could represent a health related selection leading to the underestimation of respiratory effects of exposure to grain dust as assessed in the survivor group. This hypothesis was examined by comparisons of longitudinal changes in lung function in four groups defined by the duration of follow up involving the initial examination and periodic evaluations after one, two, and four years of work. Sixty four men were tested only on the initial examination (group I), 18 underwent two (group II), 31 underwent three (group III), and 51 (group IV) all four examinations. The groups had similar mean ages (range: 19.4-20.1 years), mean duration of previous exposure to grain dust (range: 8-13 weeks), smoking habits, lung function, and prevalences of respiratory symptoms evaluated on the initial occasion. The average decline in lung function over the first year was associated with duration of follow up. The annual decline in FVC (ml) was 58 in group II, 41 in group III and -55 (increase) in group IV; the decline in FEV1 (ml) was 224, 130, and 70 respectively. The differences for the annual declines of FEV1, FEF25-759 Vmax509 and Vmax25 were significant between groups II and IV, and the FEF25-759 Vmax509 and Vmax25 differed significantly between groups II and III. The results show that the restriction of analysis to the survivors may underestimate the relation between work and respiratory impairment.

Adolescent↗
PubMed1992

Association of asthma with use of pesticides. Results of a cross-sectional survey of farmers.

We investigated the association of self-reported asthma and pesticide use in 1,939 male farmers. Regardless of age, smoking pack-years, and nasal allergic reactions, the prevalence of asthma was significantly associated with the use of carbamate insecticides (prevalence odds ratio = 1.8, 95% confidence interval: 1.1 to 3.1, p = 0.02). Self-reported asthmatics, in comparison with nonasthmatics, had significantly lower mean values for lung function test variables after adjusting for age and height and a higher prevalence of respiratory symptoms. These findings raise the possibility that exposure to agriculture chemicals could be related to lung dysfunction in exposed farmers.

Adult↗
PubMed1992

Risk factors for reduced pulmonary function in women. A possible relationship between Pi phenotype, number of children, and pulmonary function.

Smoking and severe deficiency of protease inhibitor (Pi Z phenotype) both contribute significantly to the development of chronic obstructive pulmonary disease (COPD). The role of moderate Pi deficiency (Pi MZ phenotype) remains controversial. During a community-wide study of respiratory health which included 1,633 individuals, of whom 897 were women, we measured forced vital capacity (FVC), forced expired flow in 1 s (FEV1), midmaximum expired flow rate (MMFR), flow rate at 50 percent of FVC (Vmax50%) and flow rate at 25 percent of FVC above residual volume (Vmax25%). We carried out Pi phenotyping on 544 of these women, including 22 who were Pi MZ or FZ phenotypes. There were no statistically significant differences in mean pulmonary function (pf) values between the Pi MZ and Pi M women. Examination of residual pf values (difference between observed and expected) by means of multiple multivariate regression analysis revealed that in Pi MZ women, FEV1/FVC%, MMFR, Vmax50%, and Vmax25% had significantly greater values with increasing numbers of children, whereas there was no relationship in the Pi M women. These results suggest that some factors may interact differently in individuals with Pi M and MZ phenotypes. In addition, the results suggest that pregnancy or pregnancy-induced increased Pi levels may have significant effects on the pulmonary health of Pi MZ women.

Adult↗
PubMed1991

Respiratory health status of 3098 Canadian grain workers studied longitudinally.

Analyses of data on 3098 male individuals surveyed twice by the Labour Canada Medical Surveillance Program for the Grain Industry are presented. The program collects information on respiratory symptoms, job description, and smoking habits of these workers. In addition, each worker performs pulmonary function tests obtainable through spirometry. Chronic sputum production and chronic wheezing were more prevalent during the latest testing period (rising to 17 percent and 13%, respectively), while the prevalence of chronic cough (16%) and dyspnea (10%) did not change significantly. Eighty-two percent of these workers, in each time cycle, had normal pulmonary function despite an additional 3 years of work exposure. In each cycle, obstructive dysfunction (less than or equal to 12% of workers) was more prevalent than restrictive dysfunction (less than or equal to 5%) or combined obstructive/restrictive dysfunction (less than or equal to 2.4%). It is unknown unknown whether this demonstrated dysfunction is due to previous workplace exposure, as Labour Canada and the Canadian grain industry have cooperated in lowering the grain dust levels found in grain elevators and terminals. In addition, the prevalence of current cigarette smoking has declined. (decreases 5%) among these grain handlers, and there is suggestive evidence that those continuing to smoke have reduced their consumption (mean pack-years changed only from 15.3 to 17.4). Knowledge of environmental dangers and educational programs have contributed to these encouraging results.

Adult↗
PubMed1991

Men, women and primary lung cancer--a Saskatchewan personal interview study.

In a previous study conducted by mail questionnaire and with a large proportion of surrogate responders, we found differences in smoking habits, age at diagnosis, tumour cell type distribution and occupational exposures between men and women who developed primary lung cancer. This study was designed to confirm those findings by conducting personal case interviews and extend them by examining the impact of certain biological factors. We have investigated demographic, smoking, occupational and medical history sex differences in cases with primary lung cancer by interviewing 273 male and 103 female cases diagnosed between November 1983 and July 1986. The females were significantly younger at diagnosis, a pattern consistent for all cell types. Squamous cell (40%), small cell anaplastic (20%) and adenocarcinomas (16%) were the most prevalent cell types in men. In women, similar frequencies of adenocarcinomas (32%) and squamous cell carcinomas (29%) occurred. Despite a higher prevalence of physician diagnosed allergy and asthma among women, minimal sex differences in the prevalence of atopy as measured by prick skin test were found. Female cases were more likely to be lifetime non-smokers (15% vs 3%), to have started smoking on average 3 years older and to smoke 6 fewer cigarettes per day. The mean pack years of female cases was significantly lower than males' for squamous, adenocarcinoma and small cell anaplastic tumours. The majority of these women had not been occupationally exposed to any substance known to be carcinogenic or to damage the lung. However, in a small subset of cases pulmonary function variables were as depressed in women as in men with significantly higher mean pack years.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1991

Combined effect of grain farming and smoking on lung function and the prevalence of chronic bronchitis.

The combined effect of grain farming and smoking on lung function and the prevalence of chronic bronchitis was examined in 1633 residents 20 to 65 years of age from the town of Humboldt, Saskatchewan. Multiple multivariate analysis indicated that in women grain farming and smoking had a significant synergistic effect on the values of forced expired volume in one second/forced vital capacity (FEV1/FVC), mid-expiratory flow rate (MMFR), flow rate at 50% and 25% of total volume (Vmax50 and Vmax25) after adjustment for covariates including age and height. No other factors were found to change the results. The combined effect of grain farming and smoking on lung function was not statistically significant in men. The data also show that female non-smoking grain farmers had an identical prevalence of chronic bronchitis compared with non-smoking female non-farmers, 2.0% versus 2.1%. But in women with a positive smoking history, the prevalence was 13.2% and 5.9% respectively, giving an adjusted odds ratio in grain farmers compared to non-farmers of 3.55 (95% confidence interval (Cl): 1.06-11.30). It was found that the prevalence of chronic bronchitis increased more rapidly with increasing cigarette consumption in grain farmers than in non-farmers in women. It was estimated that 85%, 72% and 66% of the prevalence of chronic bronchitis was attributed to the joint effects of grain farming and ex-smoking, light smoking (1-19 cigarettes/day) or heavy smoking (20+ cigarettes/day) status, respectively. In contrast to women, the effect of grain farming on the prevalence of chronic bronchitis was similar in men with and without a positive smoking history. Our data suggest that there is a positive interactive effect of grain farming exposure and smoking on lung function and the prevalence of chronic bronchitis in women. The difference in the interaction between men and women requires further study.

Adult↗
PubMed1991

Increased susceptibility to lung dysfunction in female smokers.

The interaction between sex and smoking habits on pulmonary function was examined among 1,149 adults 25 to 59 yr of age in a rural community in Saskatchewan. Pulmonary function tests included FVC, FEV1, maximal midexpiratory flow rate (MMFR), the slope of phase III of the single-breath nitrogen test (delta N2/L), and closing volume as a percent of vital capacity (CV/VC). The data show that after fixing the effects of age, height, and weight by analysis of covariance, the adjusted means of delta N2/L in nonsmokers, ex-smokers, and current smokers were 0.92, 1.10, and 1.60% in women and 0.97, 1.05, and 1.23% in men, respectively. The difference in the adjusted means for delta N2/L between smokers and nonsmokers was larger in women than in men, 0.67% versus 0.26%, respectively. Multiple multivariate analyses show that the regression slopes for the residuals of FEV1, MMFR, and delta N2/L versus pack-years were significantly different between men and women. The regressions of FEV1 and MMFR decreased and the regression of delta N2/L increased with increasing pack-years more rapidly in women than in men. The combined effect of sex and pack-years on pulmonary function was not significant for ex-smokers. These data suggest that cigarette smoking may be more detrimental in its effects on lung function in women than in men.

Adult↗
PubMed1991

Effect of cold air on the bronchial response to inhaled histamine in patients with asthma.

We measured the concentration of inhaled histamine required to reduce the FEV1 by 20% (PC20) in seven asthmatic patients immediately following the inhalation of warm air (mean temperature +/- 1 SD, 21.1 +/- 1.1 degrees C) and following cold air inhalation (-10.2 +/- 5.0 degrees C). Patients breathed either warm or cold air for 10 min before 30-s challenges with doubling concentrations of aerosolized histamine that were nebulized while the subject breathed warm air. Before histamine inhalation minute ventilation (VI) was 8.41 +/- 1.38 L/min breathing warm air and 7.86 +/- 0.97 L/min breathing cold air. Respiratory heat exchange (RHE) was 0.25 +/- 0.05 kcal/min with warm air and 0.24 +/- 0.03 kcal/min with cold air. The PC20 obtained following cold air breathing (0.48 +/- 4.63 mg/ml) was lower than that following warm air breathing (0.85 +/- 4.60 mg/ml; p less than 0.02). We conclude that breathing cold air increases the bronchial reactivity to inhaled histamine in asthmatic patients.

Adult↗
PubMed1991

Increased airways responsiveness in swine farmers.

A respiratory questionnaire, pulmonary function tests, and an examination of airways responsiveness were conducted on 20 swine farmers and 20 control subjects. The swine farmers represented almost the complete work force from 13 Hutterite colonies and had worked in confinement buildings with more than 2,000 swine (3,270 +/- 1,221 swine) for at least four hours (6.6 +/- 1.8 hours) per day for more than two years (10.5 +/- 7.5 years). The control subjects were randomly selected from outdoor city workers from the city of Saskatoon and were matched for gender, age (+/- 2 years), and smoking status. Eleven swine farmers (55 percent) had chronic cough, compared with three (15 percent) of the control subjects (p less than 0.01). Eight (40 percent) of the swine farmers had symptoms of wheezing, compared with three (15 percent) of the control subjects (p less than 0.05). The FEV1 was significantly lower in swine farmers (97.2 +/- 11.5 percent predicted) than in control subjects (106.0 +/- 12.0 percent of predicted) (p less than 0.05). Airways responsiveness was measured by methacholine challenge with doubling concentrations ranging from 0.25 to 256 mg/ml. The provocation concentrations resulting in a reduction of 10 percent (PC10) and 20 percent (PC20) in FEV1 were lower in swine farmers than in control subjects (PC10, 77.2 +/- 78.8 mg/ml vs 180.8 +/- 96.5 mg/ml; p less than 0.01; and PC20, 154.5 +/- 99.9 mg/ml vs 229.6 +/- 66.8 mg/ml; p less than 0.05). Twelve swine farmers (60 percent) had PC20 of less than 256 mg/ml, compared with three (15 percent) of the control workers (p less than 0.01). Fewer swine farmers demonstrated atopy as measured by skin prick tests than did control workers (21 percent vs 56 percent; p less than 0.05). These findings suggested that occupational exposure in swine confinement buildings is associated with mild increases of nonspecific, nonatopic airways responsiveness in swine farmers.

Adult↗
PubMed1991

Atopic status as a factor in job decision making in grain workers.

We conducted allergy skin-prick testing on 207 young cereal grain workers within 0.27 years of the commencement of their employment in the grain industry and again after 1.34 years of employment on 124 workers. We also studied 120 control subjects on the first observation and 105 on the second observation. Grain workers had lower prevalence than did the controls of positive skin tests on the first observation, and this difference increased by the second observation. Respiratory symptoms were more frequent among grain workers with positive skin tests who dropped out of the industry than among those who stayed in the industry. We conclude that atopic status may be a factor in job selection and drop out decision making and may be a factor explaining the healthy worker effect.

Agricultural Workers' Diseases↗
PubMed1991

Respiratory disorders in agriculture from an epidemiologic perspective.

Epidemiologic studies show a relative excess of respiratory symptoms in persons dwelling in farming communities. An association of respiratory health with work conditions in agriculture has been suggested by investigations into chronic bronchitis, bronchial asthma, extrinsic allergic alveolitis, organic dust toxic syndrome and airflow limitation. However, the occurrence and determinants of these diseases have been recognized for selected exposure categories. The evident lack of adequate information for a majority of agricultural respiratory hazards and respiratory responses invites further epidemiologic, experimental and clinical research into this major industry.

Agricultural Workers' Diseases↗
PubMed1990

Technical workshop report: Working Group I: Occupational health and safety strategies for agriculture.

The six workshops in this subgroup--Injuries, Respiratory Diseases, Acute Chemical Toxicity, Cancer, and Health Surveillance--competently outlined the principal health and safety issues in agriculture, documenting the increased and unacceptable morbidity and mortality in farmers and their families. It became evident that although research knowledge is just now unfolding, sufficient data exist to permit comprehensive program planning for research and prevention. It is necessary that farmers and their families be considered an occupational grouping and that specific programs aimed at ongoing risk assessment and early diagnosis are important. At the same time, a more broadly based approach to rural family life enhancement is essential, including the following: 1) education; 2) prevention; 3) family life enhancement; and 4) research. Because of the scope and nature of the problem, program development should include a multidisciplinary approach that involves the local community, state government, university (professional) resources, farm/organizations, and industry.

Agricultural Workers' Diseases↗
PubMed1990

Relationship between airways responsiveness and the development of chronic obstructive pulmonary disease.

The idea that increases in airways responsiveness--either as a result of exposure to cigarette smoke and/or pre-existing increases in bronchial responsiveness, possibly genetically mediated--might be causal in the pathogenesis of the development of COPD in cigarette smokers presents an attractive hypothesis. The fact that a relatively small proportion of cigarette smokers develop COPD begs for specific susceptibilities as an explanation of selective pathogenesis. In our view, the evidence for modest increases in airways responsiveness in cigarette smokers who do not have asthma or allergies is convincing. Such increases in bronchial responsiveness are modest when compared to patients with asthma and may have a different mechanism. However, the demonstration by Verma et al that two types of patients with cigarette smoke-induced COPD, "bronchitis" patients and "emphysematous" patients, have virtually identical alterations in bronchial responsiveness, and that these alterations appear to be a function of airways caliber, has led us to believe that the changes in airways tone in patients with COPD may be reflective more of changes in airways geometry imposed by the development of disease rather than a measurement of a risk factor in the development of COPD. Of the epidemiologic studies that have emerged throughout the 1980s, problems of possible inclusion of asthmatic subjects in the study groups and of baseline airflow rates as a function of bronchial responsiveness have limited the ability of data to implicate increases in airways responsiveness as a risk factor in the development of COPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchi↗
PubMed1990

Occupational obstructive disorders: nonspecific airways obstruction and occupational asthma.

Airways obstruction as a result of occupational exposure may be divided into two categories on the basis of whether or not occupational asthma is present. The first category, nonspecific airways obstruction, takes place in the absence of occupational asthma, and demonstrates only modest changes in airways responsiveness. The second category, occupational asthma, usually has a causal relationship to exposure, and demonstrates marked changes in airways responsiveness. These distinctions are of use in diagnosis, treatment, and disability assessment.

Asthma↗
PubMed1990

Determinants of cell type in patients with cancer of the lungs.

In order to evaluate the determinants of cell type in patients with primary lung cancer, we compared smoking characteristics in 1,939 patients (1,474 men and 465 women). Patients with squamous cell carcinomas, adenocarcinomas, or small-cell carcinomas were eligible. This study did not consider smoking as a risk factor for lung cancer, as all subjects had a confirmed diagnosis. We were interested in smoking history and the pattern of smoking among those whose risk was 100 percent. Among these patients, we confirmed that a larger subset of nonsmoking individuals developed adenocarcinomas than squamous cell or small-cell carcinomas; however, the duration and intensity of cigarette smoking, as measured by pack-years, were not determinants of tumor cell type in male patients. Small-cell carcinomas in women were more strongly associated with cigarette smoking than either squamous cell carcinomas or adenocarcinomas. More than 3,500 different substances have been measured in tobacco smoke, including tumor initiators, promoters, and those involved in tumor progression. These data confirm the hypothesis that factors other than cigarette smoking are more likely to be involved in the initiation of adenocarcinomas than other cell types. Endogenous and exogenous factors related to gender may be more important than the duration or intensity of cigarette smoking.

Adenocarcinoma↗
PubMed1990

Is pesticide use related to the risk of primary lung cancer in Saskatchewan?

Ascertaining cases from a population-based tumor registry in which registration of primary lung cancer is virtually complete, we have consistently found that 40% to 50% of male lung cancer patients were farmers. We interviewed 273 newly diagnosed men and compared their occupational exposures, medical history and smoking characteristics to those of 187 male randomly selected community control subjects. We found that more of the control subjects were farmers (53.5% v 41.4%), that the control subjects tended to have larger farms (P less than .05), and that more control subjects spilled chemicals on their hands or clothing (47% v 28%, P less than .01) and had an accidental inhalation of a chemical directly into the lung (54% v 33%, P less than .005). We report an absence of correlation of lung cancer risk with occupational exposure to any specific pesticide or pesticides grouped by chemical composition. Adjusting for smoking pack-years or extent of pesticide use did not alter our preadjustment conclusions.

Aged↗