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Biomedical subjects

H H McDuffie

Publications and source records attributed to H H McDuffie.

At least 19 recordsLinked to original sources
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↗
PubMed1994

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-Hodgkin's 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.

Agricultural Workers' Diseases↗
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 of swine producers. Focus on young workers.

In this report, we compare the respiratory health of swine producers, grain farmers, and nonfarming control subjects, separately in all age groups and in young subjects. We examined 249 swine producers (age 37.7 years), 251 grain farmers (age 44.7 years), and 263 nonfarming subjects (age 40.7 years). Swine producers had significantly more symptoms of chronic bronchitis (15.3 percent) than did grain farmers (7.2 percent) or nonfarming men (5.7 percent). After controlling for age, height, and smoking, the functional indices of airflow (FEV1, FEV1/FVC, FEF25-75, Vmax50, and Vmax25) were slightly but significantly lower in swine producers than in grain farmers. In comparison with nonfarming subjects, swine producers also had significantly lower FEV1/FVC, FEF25-75, and Vmax50. Respiratory symptoms were associated with the number of hours of work per day. This indirect index of exposure was also inversely associated with FVC (p < 0.01) and FEV1 (p = 0.06), after adjustment for age, height, smoking, and dust mask usage. A relative excess of respiratory symptoms and lower lung function variables were found in swine producers aged 26 to 35 years. Also in this age group, a multivariate analysis revealed statistically significant effects of daily duration of work on FVC and FEV1. The results confirm that working in swine confinement units is a risk factor for chronic respiratory symptoms and minor lung function changes. An increased risk in young workers may reflect more intense occupational exposure in this subgroup of swine producers.

Adult↗
PubMed1993

Epidemiology of health and safety risks in agriculture and related industries. Practical applications for rural physicians.

Epidemiologic studies document that work in the agricultural sector is associated with many occupational health hazards. Exposure to organic dusts and airborne microorganisms and their toxins may lead to respiratory disorders. The burden of exposure-related chronic bronchitis, asthma, hypersensitivity pneumonitis, organic-dust toxic syndrome, and chronic airflow limitation can be diminished by appropriate preventive measures. The contribution of exposures to agricultural chemicals to cancers and neurodegenerative disorders is being investigated. Some studies document that farmers and those in related industries are at higher risk for the development of cancer of the stomach, soft tissue sarcoma, non-Hodgkin's lymphoma, and multiple myeloma. Chronic encephalopathy and Parkinson's and Alzheimer's diseases are being studied in relation to agricultural chemicals. The possible carcinogenicity and neurotoxicity of pesticides emphasize the need to promote the safe use of chemicals. Another area for health promotion programs is disabling injuries and traumatic deaths. Farm accidents are important because of their frequent occurrence among young people and disturbing fatality rates. Other health issues of concern in these industries include skin diseases, hearing loss, and stress.

Accidents, Occupational↗
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↗
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

Clustering of cancer in families of patients with primary lung cancer.

We have previously shown that patients with a positive family history of lung cancer did not exhibit characteristics expected if the familial association was a surrogate for a genetic mechanism which was absent in those without such a history. In this study, we examine the incidence of cancer (all sites) in two groups of families: (a) those ascertained through a patient with primary lung cancer (n = 359 families) and (b) through a community control subject (n = 234). The index subjects were excluded from all incidence data analyses. Most families (62 vs 57%) reported at least one member with a history of neoplastic disease. Patients' families were more likely to have 2 or more affected members (p less than 0.05), to exhibit a multigenerational pattern (33 vs 24%) and to have a higher risk of multiple tumours (OR = 1.5) in the same individual. However, most of the sites with the highest odds ratios (males, vocal cord/esophagus 8.3; colon/rectum 2.3; lung 1.96; females, pancreas 4.8; vocal/cord esophagus 4.1; lung 1.8) are smoking associated although these were not necessarily the most frequently affected sites. In conclusion, these data support an ecogenetic etiology of cancer within families.

Case-Control Studies↗
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

Atopy and primary lung cancer. Histology and sex distribution.

Atopy, defined as the ability to develop IgE antibodies to commonly encountered allergens under conditions of normal exposure, has an inherited component with pleiotropic effects. An inverse relationship between the occurrence of atopy, allergy-related diseases, and cancers at specific sites has been reported. The familial association of primary lung cancer is most evident among women, nonsmokers, and those with adenocarcinomas. In order to determine whether the relationship between a lower prevalence of atopy among patients with lung cancer compared to control subjects was consistent between histologic cell types, we used seven common allergens to allergy prick skin test 209 community control subjects (46 women), 109 cases with primary squamous cell carcinoma of the lung (25 women), and 67 patients with primary adenocarcinomas of the lung (23 women). We have confirmed earlier reports of an inverse relationship between atopy and lung cancer risk. In analyses focusing on sex and histologic cell type, we found that women with adenocarcinomas were an exception and were as likely to be atopic as control subjects. The evidence does not support a protective role for atopy among these women.

Adenocarcinoma↗
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↗
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↗