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Biomedical subjects

J A Dosman

Publications and source records attributed to J A Dosman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of environmental tobacco smoke on cough in children with a history of tonsillectomy or adenoidectomy.

We examined the possible impact of tonsillectomy or adenoidectomy (T/A) on the relationship between environmental tobacco smoke (ETS) exposure and respiratory outcomes. This study was conducted in Humboldt, Saskatchewan, in 1993. The target population included all residents aged 6-17 yrs. Of the 1,019 eligible subjects, 892 participated (88%). Estimates of ETS exposure were based on the reported smoking habits of the children's household members. We defined current cough as a positive response to the question: "Does this child usually have a cough?". Information also included morning cough, night cough and a history of T/A. For children with no history of T/A, the prevalence of current cough was 8.9%, 12.2% and 14.5% for those living in families with 0, 1, and 2+ smokers respectively. The corresponding prevalence was 7.0%, 30.2% and 36.8% for children with history of T/A. Similar effects of ETS exposure were observed on morning cough and night cough. The results did not change significantly when we used various ETS measures and controlled for confounding factors. Compared to children living in nonsmoking families and without history of T/A, the adjusted odds ratio for children with a history of T/A was 7.19 (p<0.001) if they were living in families smoking >20 cigarettes x day(-1) at home. The corresponding odds ratio was only 1.64 (p=0.11) for children without a history of T/A. We concluded that children living in smoking family were more likely to cough than those living in nonsmoking families and tonsillectomy or adenoidectomy increased the apparent influence of environmental tobacco exposure on cough.

Adenoidectomy↗
PubMed1997

Major genetic effect on forced vital capacity: the Humboldt Family Study.

Familial correlation and segregation analyses of forced vital capacity (FVC) were performed on data from 309 nuclear families with 1,045 individuals in the town of Humboldt, Saskatchewan, in 1993. FVC was preadjusted for age, height, and weight in four separate groups (mothers, fathers, daughters, and sons). Residual FVC was standardized within the four groups. Class D regressive model was first used to examine the familial resemblance of FVC without a major gene. While mother-father correlation was not significantly different from zero and mother-sibling and father-sibling correlations were not significantly different from each other, sibling-sibling correlation was greater than parent-sibling correlation. Segregation analysis for all 309 families indicated that both the Mendelian and no-parent-offspring-transmission models fitted the data as did the general model with arbitrary transmission probabilities. Likelihoods under the Mendelian model (LMendelian) and the environmental model (Lenvironmental) were calculated. Based on the value of In(LMendelian/Lenvironmental), 309 families were divided into two groups: 196 families with the value of In(LMendelian/Lenvironmental) greater than zero (group I) and 113 families with the value In(LMendelian/Lenvironmental) less than zero (group II). The Mendelian transmission model without familial correlations was the most parsimonious model for the families in group I. For group II, there were two best models of choice: 1) no-parent-offspring-transmission model with possible heterogeneity plus familial correlations [Akaike's information criterion (AIC) = 1,213.76] and 2) Mendelian transmission plus sibling-sibling correlation model (AIC = 1,202.36). The results suggest there are major genetic mechanisms in FVC with possible heterogeneity.

Adolescent↗
PubMed1997

Positive human health effects of dust suppression with canola oil in swine barns.

A crossover trial was conducted to evaluate the acute human health effects of a dust control technology in a swine confinement facility. Twenty lifetime nonsmoking male subjects, with no evidence of allergy or asthma and no previous swine barn exposure, participated in the study, which included a laboratory session (baseline), 5-h exposure in a swine room sprinkled with canola oil (treatment) and 5-h exposure in a traditional swine room (control). Mean values of inhalable dust concentrations and endotoxin levels in the control room were significantly greater than those observed in the treatment room. Mean shift changes in FEV1 from preexposure to end of exposure were 1.1% (standard error, 0.63%) on baseline day, -1.9% (0.63%) on treatment day, and -9.9% (1.12%) on control day; the differences in the shift changes were statistically significant. Mean value of methacholine concentration that reduced the FEV1 by 20% (PC20) in bronchoprovocation tests on baseline day was significantly different from that on treatment day (p = 0.04) and that on control day (p < 0.001). Significant increases were also observed in white blood cell counts and nasal lavage cell counts on the control day in comparison with the other two days. Blood neutrophil counts after control room exposure were twice those observed on baseline and after exposure to the treatment room. Significant differences were also observed in IL-1 beta, IL-6, and IL-8 nasal lavage cytokines and in IL-6 serum cytokine. These results suggest that the canola oil dust control method is effective in improving indoor air quality in swine barns and reducing acute health effects in naive healthy subjects.

Adolescent↗
PubMed1997

Accelerated lung function decline in swine confinement workers.

We conducted a longitudinal study to determine the annual rate decline in pulmonary function measurements in male swine confinement workers. For comparison, a grain farming group and a nonfarming rural-dwelling control group were also chosen for the longitudinal study. Two hundred seventeen swine confinement workers, 218 grain farmers, and 179 nonfarming control subjects had valid pulmonary function measurements at the baseline observation conducted in 1990 to 1991 and at the second observation conducted in 1994 to 1995. The swine confinement workers were younger (mean age=38.3+/-11.7 [SD] years) than the nonfarming control subjects (42.6+/-10.4 years) and the grain farmers (44.5+/-11.9 years). When stratified by age, nonfarming control subjects had the lowest mean annual rate decline in FEV1 and FVC in all age categories. The swine confinement workers had the largest annual rate decline in FEV1 and FVC, and this was most obvious in the middle age categories. After controlling for age, height, smoking, and baseline pulmonary function, swine confinement workers had excess annual decline of 26.1 mL in FEV1 (p=0.0005), 33.5 mL in FVC (p=0.0002), and 42.0 mL/s in forced expiratory flow between 25% and 75% of FVC (FEF[25-75%]) (p=0.02) over nonfarming control subjects. Grain farmers had excess annual decline of 16.4 mL in FEV1 (p=0.03), 26.7 mL in FVC (p=0.002), and 11.2 mL/s in FEF(25-75%) (p=0.38) over control subjects. These findings suggest that workers engaged in the swine industry and grain farmers appear prone to accelerated yearly losses in lung function and may therefore be at risk for the future development of chronic airflow limitation.

Adult↗
PubMed1996

Recommendations for reducing the effect of grain dust on the lungs. Canadian Thoracic Society Standards Committee.

OBJECTIVE: To assess the appropriateness of the current Canadian standards for exposure to grain dust in the workplace. OPTIONS: The current permissible exposure limit of 10 mg of total grain dust per cubic metre of air (expressed as mg/m3) as an 8-hour time-weighted average exposure, or a lower permissible exposure limit. OUTCOMES: Acute symptoms of grain-dust exposure, such as cough, phlegm production, wheezing and dyspnea, similar chronic symptoms, and spirometric deficits revealing obstructive or restrictive disease. EVIDENCE: Articles published from 1924 to December 1993 were identified from Index Medicus and the bibliographies of pertinent articles. Subsequent articles published from 1994 (when the recommendations were approved by the Canadian Thoracic Society Standards Committee) to June 1996 were retrieved through a search of MEDLINE, and modification of the recommendations was not found to be necessary. Studies of interest were those that linked measurements of total grain dust levels to the development of acute and chronic respiratory symptoms and changes in lung function in exposed workers. Papers on the effects of grain dust on workers in feed mills were not included because other nutrients such as animal products may have been added to the grain. Unpublished reports (e.g., to Labour Canada) were included as sources of information. VALUES: A high value was placed on minimizing the biological harm that grain dust has on the lungs of grain workers. BENEFITS, HARMS AND COSTS: A permissible exposure limit of 5 mg/m3 would control the short-term effects of exposure to grain dust on workers. Evidence is insufficient to determine what level is needed to prevent long-term effects. The economic implications of implementing a lower permissible exposure limit have not been evaluated. RECOMMENDATIONS: The current Canadian standards for grain-dust exposure should be reviewed by Labour Canada and the grain industry. A permissible exposure level of 5 mg/m3 is recommended to control short-term effects. Further measurements that link the levels of exposure to respiratory health effects in workers across Canada should be collected to establish an exposure-response relation and possible regional differences in the effects of grain dust. VALIDATION: There has been no external review of these recommendations. However, the American Conference of Governmental Industrial Hygienists has recommended an 8-hour average exposure limit of 4 mg/m3 for wheat, oats and barley.

Air Pollutants, Occupational↗
PubMed1996

Segregation analysis of two lung function indices in a random sample of young families: the Humboldt Family Study.

The Humboldt Family Study was conducted in the town of Humboldt, Saskatchewan, in 1993. Familial correlations and segregation analyses of lung function were carried out in 799 individuals in 214 nuclear families that included 214 fathers, 214 mothers, and 371 children. Forced expiratory volume in 1 second (FEV1) and maximal mid-expiratory flow rate (MMFR) were first regressed on age, height, weight, and their quadratic and cubic terms as well as on smoking status in four groups separately (mothers, fathers, daughters, and sons), with terms significant at the 0.10 level being retained. Residual phenotypes were standardized within the four groups. Class D regressive models were used to perform familial correlations and segregation analyses. For both FEV1 and MMFR, father-mother correlations were not significantly different from zero, and mother-offspring, father-offspring, and sibling-sibling correlations showed no statistically significant difference from each other. Based on the "polygenic" models, the estimated intraclass correlation is 0.132 (+/- 0.035) for FEV1 and 0.171 (+/- 0.039) for MMFR, and the narrow-sense heritability is 0.264 for FEV1 and 0.342 for MMFR. Segregation analysis shows that the "mixed" model with both single locus and polygenic components had a better fit for FEV1 than single-locus or polygenic only models. However, the model which included a nontransmitted environmental factor [tau(AA) = tau(AB) = tau(BB) = qA] and polygenic loci had a better fit than the Mendelian model [tau(AA) = 1, tau(AB) = 1/2, tau(BB) = 0] [Akaike's information criterion (AIC) = 2219.47 vs. AIC = 2222.14]. For MMFR, the Mendelian "mixed" model gave a nonsignificant improvement in loge likelihood compared to the simple polygenic model. Comparison of the single-locus model and Mendelian "mixed" model shows no difference in fitting the data. This study suggests that FEV1 and MMFR are controlled by many loci with no major effects and/or common environmental factors.

Adolescent↗
PubMed1996

Occupationally induced airways obstruction.

The studies reviewed in this article indicate the association of occupational exposure to a variety of organic and inorganic dusts and various gases and fumes with chronic bronchitis and decrements of FEV1. Usually an obstructive pattern was noted, although in some occupations a similar decrement in FVC was noted. The effect of smoking on chronic bronchitis, respiratory symptoms, and FEV1 was usually additive, although workers exposed to cotton dust in one study demonstrated an interaction between exposure and smoking, as did a study of a general population sample. In coal workers, exposure to dust in younger workers resulted in a greater decline in lung function than if the exposure occurred in older workers. Studies in coal miners and grain workers further suggest that occupational standards in effect are not sufficient to protect the working population from adverse effects. The magnitude of the effect of occupation on decrement in FEV1 is usually less than cigarette smoking. Studies in coal miners indicate, however, that a minority of workers could be more severely affected by exposure. When considered together with cigarette smoking, additional decrements in lung function because of occupational exposure could contribute to disability. Additional study is needed for better understanding of exposure-response relationships, host factors, potential interaction with cigarette smoking, and pathophysiology of the development of occupationally induced airway disease.

Adult↗
PubMed1996

Persistent wheeze in grain elevator workers should not be ignored.

We investigated the relationship between annual change in pulmonary function and changes in respiratory symptoms among male grain elevator workers who participated in a health surveillance program mandated by Labour Canada. The surveillance was conducted every 3 yr starting from the period 1978 to 1981. The 1,211 workers who participated in the second (1981 to 1984) and fifth (1990 to 1993) surveillance were included in the analysis and the mean duration of the follow-up was 8.6 yr. In the analysis we also included the pulmonary function measurements that were available for some subjects at the third and fourth surveillance. The subjects who reported persistent wheeze had the largest mean annual rate change in FEV1 (-44.4 ml/yr) and FVC (-55.3 ml/yr). When adjusted for age, height, weight change, smoking, baseline lung function, location of grain elevators, and duration of employment, the subjects with persistent wheeze had an annual rate change of -28.3 ml/yr (SE 10.5; p = 0.007) in FEV1 and -37.3 ml/yr (SE = 12.3; p = 0.003) in FVC in comparison to subjects without any respiratory symptoms. The subjects who reported new onset of wheeze had significantly greater annual rate changes only in FEV1 (-13.7 ml/yr; SE 6.0; p = 0.02) in comparison to asymptomatic subjects' symptoms. Persistent wheeze is an important predictor of decline in lung function among grain elevator workers and should not be ignored in surveillance programs or clinical evaluations.

Adolescent↗
PubMed1996

Influence of environmental tobacco smoke on asthma in nonallergic and allergic children.

The relation between exposure to environmental tobacco smoke and childhood asthma is not clear. A 1993 study of 892 subjects age 6-17 years (87.5% of 1,019 eligible subjects) living in Humboldt, Saskatchewan, showed that a lifetime history of asthma and asthma attack during the past 12 months were more common among allergic children than among non-allergic children. The number of household smokers and total daily cigarette consumption by household members were linearly related to both lifetime history of asthma and recent asthma in nonallergic children, but not in allergic children. Out study indicates that allergic status does alter the relation between exposure to environmental tobacco smoke and childhood asthma.

Adolescent↗
PubMed1994

Longitudinal estimates of pulmonary function decline in grain workers.

We conducted a cohort analysis of longitudinal changes in pulmonary function test values in male grain elevator workers in five regions of Canada over a 6-yr period involving three observations. Pulmonary function tests were obtained approximately each 3 yr during an observation interval called a "cycle". The periods of the cycles were 1978-81 (Cycle I), 1981-84 (Cycle II), and 1984-87 (Cycle III), respectively. Data on respiratory symptoms and pulmonary function tests were collected on the same 881 workers in Cycles I and II (mean ages +/- SE: 37.0 +/- 0.48 yr at Cycle I), on the same 1,294 workers in Cycles I, II, and III (34.6 +/- 0.34 yr at Cycle I), and on the same 1,021 workers in Cycles II and III (33.9 +/- 0.38 yr at Cycle II) for a total of 3,196 workers with two or more observations over the 6-yr period. The proportion of current smokers decreased from Cycle I to Cycle III. Autoregression analysis of longitudinal changes in lung function data showed that predictors of FEV1 were height, years in the industry, smoking status, and geographic region. The mean annual losses in FEV1 (FVC) were 28.7 ml (26.4 ml), 38.4 ml (41.9 ml), and 41.7 ml (32.3 ml) for nonsmokers, ex-smokers, and current smokers, respectively. The annual loss of FEV1 (FVC) was 9.2 ml (21.1 ml) for those who were in the grain industry for less than 5 yr and 52.6 ml (60.8 ml) for those who were exposed for 20 yr or more.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Respiratory health status in swine producers relates to endotoxin exposure in the presence of low dust levels.

We conducted an assessment of respiratory health status including questionnaire and spirographic measurements in 54 male swine producers age 36.3 +/- 11.1 years (mean +/- SD) who worked an average of 10.7 +/- 6.3 years in the industry and spent 4.7 +/- 2.1 hours per day in the swine barns, and we also measured atmospheric contaminants including carbon dioxide, ammonia, total dust, respirable dust, and airborne endotoxin. Mean atmospheric dust contaminant levels were as follows: carbon dioxide, 2632 +/- 807 ppm; ammonia, 11.3 +/- 4.2 ppm; total dust, 2.93 +/- 0.92 mg/m3; respirable dust, 0.13 +/- 0.05 mg/m3; and endotoxin, 11,332 +/- 13,492 endotoxin units/m3. Of these, endotoxin related to forced vital capacity (P < .05) and endotoxin x hours per day was related to forced vital capacity (P < .05) and to forced expiratory volume in 1 second (P = .06). Respiratory symptoms and lung function studies did not relate to categories of low, medium, and high exposure to respirable dust. However, categories of endotoxin (available on 46 workers) related to respiratory symptoms (cough, P = .02; chronic bronchitis, P = .06; and to forced vital capacity, P < .01). These data suggest that respiratory health status relates to endotoxin levels but not to dust level exposures in the presence of low dust levels and indicates that control measures should include endotoxin as well as dust control.

Adult↗
PubMed1993

Respiratory health status in swine producers using respiratory protective devices.

A cross-sectional survey on respiratory health in swine producers showed that 30% of 301 examined men usually used a dust mask when working inside a barn. They did not differ significantly from dust mask nonusers in respect to respiratory symptoms and lung function. This analysis was undertaken to determine whether the respiratory health of dust mask users was associated with reasons why they had started individual respiratory protection. The subjects were recontacted in order to identify those who started using a mask to deliberately prevent symptoms (42 men) and those who started protection because of pre-existing respiratory symptoms (44 men). Not unexpectedly, between-group comparisons of respiratory symptoms and lung function suggest that swine producers who wear dust masks for preventive purposes have better respiratory health than those who wear dust masks because of symptoms or those who do not use individual respiratory protection. The individual reasons for starting dust mask usage should be examined among potential determinants of the outcomes of prospective studies which can then provide more valid assessment of the effect of individual respiratory protection.

Adult↗
PubMed1993

Respiratory disorders in agriculture.

Work in agriculture is associated with exposure to respiratory biohazards. The most important airborne substances include grain dust and its constituents, bacteria and metabolites (endotoxin), fungi and metabolites (glucan), and storage mites. The degree of dysfunction in exposed persons depends on the biological potency and concentration of exposure as well as on individual susceptibility. Airborne contaminants frequently occur in concentrations and compositions that challenge the defence mechanisms of the lung. This may be of particular importance in the case of susceptible workers and minors, whose exposure by the virtue of family-type operations is difficult to avoid. Epidemiological and clinical studies have contributed to the identification of associations between respiratory disorders and agricultural exposures. Chronic bronchitis, asthma, hypersensitivity pneumonitis, organic dust toxic syndrome and chronic airflow limitation have been found to occur in agricultural workers. Clinical and experimental studies have advanced the understanding of immunologic and non-immunologic mechanisms involved in respiratory responses to a wide spectrum of inhaled organic dusts. Although the evidence has provided substantial insight into the occurrence and pathogenesis of respiratory disorders in agriculture, further investigation is necessary. There is a need for research involving accurate assessment of exposures and their respiratory effects. There is also a need for the establishment of preventive programs, with emphasis on reduction of harmful exposures. Increasing concern about respiratory disorders in agriculture justifies further scientific effort in both areas.

Adolescent↗
PubMed1993

Body weight and weight gain related to pulmonary function decline in adults: a six year follow up study.

BACKGROUND: Obesity increases the risk of cardiovascular disease, hypertension, diabetes, digestive diseases, and some cancers. Several studies have shown that excess weight or weight gain is related to pulmonary dysfunction, but this issue needs to be further clarified. METHODS: The analysis was based on data of the Humboldt cohort study which was conducted in the town of Humboldt, Saskatchewan, Canada. The baseline survey in 1977 included 1202 adults, comprising 94% of all residents aged 25-59 years. Of these, 709 (59%) were followed up in 1983. Pulmonary function (forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and maximal mid expiratory flow rate (MMFR) and weight were measured in both surveys. Weight gain was determined by subtracting weight at baseline from weight at follow up. A residual analysis was used to examine the relationship between body mass index (BMI) at baseline, weight gain, and pulmonary function decline. RESULTS: Both BMI at baseline and weight gain were significantly related to pulmonary function at follow up. The effect of weight gain during the study period, however, was more prominent. The results showed that both mean residual FVC and FEV1 were highest in the group that gained < 1.0 kg, lowest in the group that gained > or = 4.0 kg, and intermediate in the group that gained 1.0-3.9 kg in both men and women after taking age, BMI at baseline, and smoking into account. The effect of weight gain on pulmonary function was greater in men than in women. Multiple regression analysis showed that each kilogram of weight gain was associated with an excess loss of 26 ml in FVC and 23 ml in FEV1 in men, and 14 ml and 9 ml respectively in women. CONCLUSIONS: Weight gain is significantly related to lung dysfunction. The effect of weight gain on pulmonary function is greater in men than in women.

Adult↗