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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

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

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↗
PubMed1979

Nonsmoking grain handlers in Saskatchewan: airways reactivity and allergic status.

This study was carried out to determine whether respiratory disease in Saskatchewan grainhandlers was or was not due to hypersensitivity to grain dust. Sixty nonsmoking grainhandlers, half of whom had low FEV1/FVC ratios and half of whom had high, were studied. The findings in grainhandlers were compared with those in 30 age-matched, nonsmoking teachers. In the group of grainhandlers with low FEV1/FVC ratios, one had developed asthma associated with exposure to grain dust. The majority were healthy, had FEV1/FVC ratios of 70% or greater, and had less evidence of allergic respiratory disease than had age-matched teachers. The studies suggest that non-atopic, nonsmoking men can work in grain elevators without developing respiratory disability, though they may develop a small but significant increase in nonspecific bronchial reactivity to histamine.

Agricultural Workers' Diseases↗
PubMed1979

Peripheral airways obstruction in patients with rhinitis.

Nine young lifetime nonsmoking patients with symptoms of rhinitis but without any history of asthma or wheezing and nine age-matched healthy lifetime nonsmoking control subjects were studied with respect to subdivisions of lung volume, forced vital capacity, forced expiratory volume (1.0 sec), and flow-volume curves breathing air, and also breathing a mixture of 80% helium--20% oxygen (He-O2) from which were obtained airflows at 50% VC (Vmax50), the percentage increase in Vmax50 breathing He-O2 as compared to air (deltaVmax50) and the point where He-O2 and airflow-volume curves became identical (Visov). No significant differences between the two groups in age, subdivisions of lung volume or forced expiratory airflow rates were recorded. However, deltaVmax50 was significantly lower in the patients (16.4 +/- 12.0) compared to the controls (47.7 +/- 16.4) (p less than .001) and Visov was higher in the patients (28.4 +/- 14.9) as compared to the controls (14.4 +/- 7.6) (p less than .01). After bronchodilator therapy Vmax50 increased in the control subjects (p less than .005) but not in the patients and deltaVmax 50 decreased in the control group but was unchanged in the rhinitis patients. These results suggest that patients with rhinitis who have normal airflow rates may have peripheral airways obstruction not readily reversible with bronchodilators.

Adult↗
PubMed1975

Uric acid kinetic studies in the immediate post-myocardial-infarction period.

The etiology of hyperuricemia following myocardial infarction was investigated by uric acid kinetic studies carried out on seven male patients following myocardial infarction and on two control subjects. The patients selected had uncomplicated myocardial infarction and were maintained on a low-purine diet. Measurements of uric acid pool size and turnover rates using 2-C14 uric acid were made, commencing on days 2-5 following myocardial infarction. Initial concentration of serum uric acid ranged from 2.9 to 9.8 mg/100 ml. Uric acid pool size was elevated in six of seven patients. Five had a pool size of from 36.9 to 79.6 mg/kg, while the single gouty subject demonstrated 104 mg/kg compared with 12.6 and 16.8 mg/kg for the control subjects. Turnover rates were also increased, ranging from 1036 to 2772 mg/day (controls, 612 and 872 mg/day). Twenty-four-hour urine uric acid excretions ranged from 358 to 623 mg/24 hr. Serum lactic acid concentration was normal (1.03 plus or minus 0.17 muM/ml), and endogenous creatinine clearance in all cases was 77.9 ml/min or greater. These data suggest that following myocardial infarction there is an expansion of the uric acid pool with an increased uric acid turnover rate. Only the patient with a previous history of gout had uric acid excretion outside the normal range.

Body Weight↗
PubMedDate not supplied

Respiratory health effects of alkali dust in residents near desiccated Old Wives Lake.

Several years of drought have contributed to the desiccation of Old Wives Lake, a shallow, alkaline lake in southern Saskatchewan. The prevailing northwest wind, which blows across the 177-km2 dry lake bed, has generated airborne sodium sulfate, silt, and clay. Residents have reported nasal, eye, and respiratory irritation. A cross-sectional design that included 300 controls and 300 exposed subjects elucidated the potential adverse respiratory health effects of exposure to blowing alkali salt and dust. An increased prevalence of current cough, current wheeze, chronic cough, chronic wheeze, chronic eye irritation, and chronic nasal irritation was identified in the exposed population. Smoking-adjusted odds ratios were consistent with the prevalence ratios. Lung function did not differ between the exposed and the control populations. Rainfall during the study period reduced airborne dust levels and may have precluded demonstration of previously reported adverse effects.

Adult↗