James A. Dosman

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.

Possible Protective Effect against Chronic Obstructive Airways Disease by the GC 2 Allele

The frequencies of GC phenotypes in 104 patients with chronic obstructive airways disease (COAD) were compared with those in 413 control subjects. The distributions were significantly different with fewer patients with the GC 2 allele than expected (relative risks = 0.8, 0.7 and 0.5 for 2-2, 2-1S and 2-1F, respectively) and more 1F-1F patients than expected (relative risk = 4.8). These data suggest that the GC 2 allele exerts a protective effect, whereas 1F, when homozygous, increases the risk of developing COAD.

Total dust and endotoxin in poultry operations: comparison between cage and floor housing and respiratory effects in workers.

Objective: The objective of this study was to assess respiratory outcomes and environmental exposure levels of workers in cage-housed and floor-housed poultry operations. Methods: Poultry operations were evaluated for total dust, endotoxin, and ammonia, and respiratory symptoms and lung function tests of workers were conducted. Results: Workers in floor-housed poultry operations had significantly greater exposures to total dust and ammonia, whereas workers from cage-housed poultry operations reported greater frequency of current and chronic symptoms overall and significantly greater current and chronic phlegm (39% vs 18% and 40% vs 11%, respectively). Endotoxin concentration (EU/mg) was a significant predictor (P = 0.05) of chronic phlegm for all poultry workers. Conclusions: Greater endotoxin concentration in the presence of significantly lower total dust, in conjunction with greater respiratory symptoms in workers from cage-housed poultry operations, as compared with workers from floor-housed poultry operations, appears to indicate that differences in environmental exposures may impact respiratory outcomes of workers.

Effects of repeated swine building exposures on normal naive subjects

Exposure to swine confinement buildings has a negative impact on respiratory health. A short exposure to this environment results in an acute airway inflammatory response. The present study was performed to confirm and further define the acute effects of working in a swine building, and to determine whether these effects are reproducible. Seven previously nonexposed normal subjects underwent evaluations that included hourly measurement of forced expiratory volume in one second (FEV1), methacholine challenge (the provocative concentration producing a 20% fall in FEV1 (PC20)), bronchoalveolar lavage (BAL), nasal lavage (NL), and blood analyses, before (control) and after each of two 5 h exposures to a swine building environment. The exposures were conducted 8 days apart. The levels of total dust, endotoxins, and ammonia (NH3) in the confinement building were measured on each day of exposure. Both exposures resulted in a significant reduction in FEV1 (mean+/-SEM change in FEV1: control = 7+/-2%; exposure 1 = 15+/-3%; exposure 2 = 23+/-3%), decrease in PC20 (median value (25th-75th percentile): 223 (23-256), 20 (15-198) and 20 (11-71), respectively; p=0.05) and increase in BAL cells (129+/-20, 451+/-43 and 511+/-103x10(3) cells x mL(-1), respectively) and NL cells (6+/-4, 126+/-58 and 103+/-26x10(3) cells x mL(-1), respectively), mostly neutrophils. Levels of interleukin-8 (IL-8), but not interleukin-1 (IL-1) or tumour necrosis factors (TNF-alpha), increased both in BAL and nasal fluids with exposure. In normal naive subjects, repeated exposure to the environment of a swine building induced a marked and reproducible reduction in forced expiratory volume in one second, increase in airway responsiveness, and increased neutrophilic inflammatory response. These results could not be accounted for by any of the environmental factors measured.

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

The relation between past induced abortions and subsequent fetal loss is still unclear. We report a case-control study with 331 cases of first spontaneous abortion and 993 controls with no previous spontaneous abortion and a normal pregnancy at the same period of pregnancy. In comparison with primigravid women, the odds ratio for a fetal loss in the current one was 1.41 [95% confidence interval (CI) = 0.81-2.43] among women with one previous pregnancy ending in induced abortion, 4.43 (95% CI = 1.46-13.36) among those with two previous induced abortions out of two pregnancies, and 1.35 (95% CI = 0.64-2.82) among women with three or more previous pregnancies ending in one or more induced abortions.&NA; 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 nonallergic 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. Our study indicates that allergic status does alter the relation between exposure to environmental tobacco smoke and childhood asthma.

Predictors of longitudinal changes in pulmonary function among swine confinement workers.

OBJECTIVE To determine predictors of longitudinal changes in pulmonary function in swine confinement workers. DESIGN Longitudinal study conducted from November 1989 to June 1991 and January 1994 to May 1995. SETTING Swine confinement workers in Saskatchewan. PARTICIPANTS Forty-two swine confinement workers who were studied in 1989/90 and studied again in 1994/95. RESULTS Of 98 male swine confinement workers (mean age SD 36.3 11.1 years) studied at baseline, 42 were studied again five years following. Complete information on baseline across-shift pulmonary function (preshift forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC], and every 2 h FEV1 and FVC during the shift), and five-year follow-up pulmonary function (with FEV1 and FVC) were available on all 42 subjects. Mean across-shift changes (preshift measurement to last measurement of the day) at baseline were -159. 8 61.7 mL in FEV1 and -35.3 65.6 mL in FVC. Mean annual rate change between baseline and follow-up for FEV1 was -53.9 61.7 mL/year and for FVC -48.9 71.6 mL/year. After adjusting for age, height, smoking and hours spent in the barn, the baseline across-shift change in FEV1 and FVC was a significant predictor of annual rate change in FEV1 (P=0.01) and FVC (P=0.02), respectively. To determine the effects of indoor air quality on longitudinal lung function decline, indoor air environmental measurements were analysed. Complete information on respiratory health and indoor air quality was available on 34 of the 42 subjects. Assessment of indoor environment of swine barns included a summer and winter measurement for airborne dust, gases and endotoxin levels. After adjusting for age, height, smoking, ammonia and hours spent in the barn, the endotoxin level (Eu/mg)was a significant predictor of annual rate change for FEV1 but not FVC. CONCLUSIONS These results suggest that shift change is an important predictor of longitudinal changes in lung function in swine confinement workers and that endotoxin exposures may mediate annual decline in FEV1 in these workers.

Waist circumference associated with pulmonary function in children.

In adults abdominal obesity is related to lung dysfunction and waist circumference (WC) predicts pulmonary function. It is not known how WC affects pulmonary function in children. A cross‐sectional study of 718 children 6–17 years of age was conducted in a rural community to determine the predictability of WC for pulmonary function in children. Height, weight, WC, and pulmonary function were measured. Multivariate analysis was conducted. WC was positively associated with FVC and FEV1 and was more strongly associated with FVC than with FEV1. Increase in WC significantly predicted a reduction in FEV1/FVC. After adjustment for sex, age, and height, an increase of 1 cm for WC was associated with an increase of 7 ml of FVC and 4 ml of FEV1, and with an increase of 4 ml of FVC and 2 ml of FEV1 with an additional adjustment for weight. Height and weight were not significantly associated with FEV1/FVC. WC but not body mass index predicted a decline of FEV1/FVC. WC had a larger impact on FVC than FEV1. WC, but not BMI, was negatively associated with FEV1/FVC in children. Pediatr Pulmonol. 2009; 44:216–221.

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.

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.

Risk factors for work-related injury among male farmers

Objective: To identify risk factors for serious farm work related injury among men. Methods: A case–control study was conducted in Victoria, Australia. Eligible cases (n = 252) were males aged ⩾16 years injured while working on a farm and scoring 2 or higher on the Abbreviated Injury Scale. Non-fatal injury cases were identified on presentation to hospital. Fatal cases (next of kin) were recruited via the Coroner’s Office. Two age-matched controls per case were recruited by telephone. Data were collected with a structured telephone questionnaire. Logistic regression was used to compare risk factors between cases and controls, adjusting for design factors and average weekly hours worked. Results: The most common external causes of injury were machinery (26%), falls (19%), transport (18%), animals (17%) and being struck by an object (11%). Increased injury risk was observed for being an employee/contractor (odds ratio 1.8, 95% CI 1.2 to 2.7), not having attended farm training courses (1.5, 95% CI 1.0 to 2.1), absence of roll-over protective structures on all/almost all tractors (2.5, 95% CI 1.7 to 3.8), absence of personal protective equipment for chemical use (4.7, 95% CI 1.6 to 13.9) and a low average annual farm income of AUD