Agreement between questionnaire report of allergy-related outcomes in school-age children and objective measures of atopy: the Saskatchewan rural health study.

BACKGROUND AND OBJECTIVES: In population-based studies, questionnaires remain the most efficient tool to assess the presence of allergy and atopic conditions, but the quality of the information obtained needs to be validated. We sought to evaluate the agreement and predictive values of a questionnaire to assess atopy in rural children, an understudied population with regard to atopy and allergic disease. METHODS: A total of 480 schoolchildren (grades 1-8) from rural Saskatchewan completed a questionnaire report of allergy and atopic outcomes and participated in skin prick testing (SPT). SPT for 6 common allergens (local grasses, wheat dust, cat dander, house dust mite mixed, Alternaria, and Cladosporium) was completed. Subjects with at least one positive SPT (≥ 3 mm) compared to the negative control were considered to be atopic. We considered per cent concordance, Kappa, sensitivity, specificity, and the positive predictive value and negative predictive value (NPV, PPV) of reported allergies or allergic conditions in comparison with SPT as the gold standard. RESULTS: We found that 25.0% of children reported a history of any allergy and 19.4% were atopic based on SPT. The agreement between questionnaire report of allergic triggers and atopy measured by SPT was high (83.0-89.5%). The agreement between atopy and report of allergic conditions ranged from 67.1% to 79.6%. Individual allergic conditions demonstrated high specificity but low sensitivity. The questionnaire report of any allergy had a low PPV in detecting atopy (47.3%) and high NPV (86.3%). The PPV of reported allergic conditions was low (24.8-43.9%), but the NPV was again high (82.0-82.9%). CONCLUSIONS: We found that the standardized questionnaire report of allergy and atopic conditions was shown not to efficiently and reliably predict atopy. However, given the good specificity and the NPV, the questionnaire may be an efficient tool for epidemiological studies that involve the differential inclusion of subjects without atopy.

Prevalence and determinants of atopy and allergic diseases among school-age children in rural Saskatchewan, Canada.

BACKGROUND: There have been few investigations of farming-related activities or specific characteristics resulting in the associations between those exposures and atopic disease. OBJECTIVE: To study the associations between farm-associated exposures and atopic diseases. METHODS: As part of a longitudinal study of lung health in rural residents, a cross-sectional baseline study was conducted in rural Saskatchewan, Canada. This included an initial survey phase followed by a clinical testing phase. A subsample of 584 children (grades 1-8) completed skin prick testing to assess atopic status. Atopy was defined as a positive reaction to any of 6 allergens (local grasses, wheat dust, cat dander, house dust mite, Alternaria species, or Cladosporium species) of at least 3 mm compared with the negative control. RESULTS: Of those who completed clinical testing, the prevalence of atopy was 19.4%, that of hay fever was 8.8%, and that of eczema was 27.4%. Based on skin prick testing, sensitization was highest for cat dander (8.6%) followed by local grasses (8.2%) and house dust mite (5.1%). After adjustment for potential confounders, home location (farm vs non-farm) was not associated with atopic status. However, livestock farming was protective against atopy (adjusted odds ratio 0.38, 95% confidence interval 0.17-0.88). In contrast, current residence on a farm was associated with an increase in the likelihood of hay fever in these children (adjusted odds ratio 3.68, 95% confidence interval 1.29-10.45). Also, regular farming activities in the past year were associated with an increased risk of hay fever. CONCLUSION: In children, livestock exposure has a protective effect on skin prick test positivity, whereas farm living and activities increase the risk of hay fever.

Cigarette smoking and risk of Hodgkin lymphoma and its subtypes: a pooled analysis from the International Lymphoma Epidemiology Consortium (InterLymph).

BACKGROUND: The etiology of Hodgkin lymphoma (HL) remains incompletely characterized. Studies of the association between smoking and HL have yielded ambiguous results, possibly due to differences between HL subtypes. PATIENTS AND METHODS: Through the InterLymph Consortium, 12 case-control studies regarding cigarette smoking and HL were identified. Pooled analyses on the association between smoking and HL stratified by tumor histology and Epstein-Barr virus (EBV) status were conducted using random effects models adjusted for confounders. Analyses included 3335 HL cases and 14 278 controls. RESULTS: Overall, 54.5% of cases and 57.4% of controls were ever cigarette smokers. Compared with never smokers, ever smokers had an odds ratio (OR) of HL of 1.10 [95% confidence interval (CI) 1.01-1.21]. This increased risk reflected associations with mixed cellularity cHL (OR = 1.60, 95% CI 1.29-1.99) and EBV-positive cHL (OR = 1.81, 95% CI 1.27-2.56) among current smokers, whereas risk of nodular sclerosis (OR = 1.09, 95% CI 0.90-1.32) and EBV-negative HL (OR = 1.02, 95% CI 0.72-1.44) was not increased. CONCLUSION: These results support the notion of etiologic heterogeneity between HL subtypes, highlighting the need for HL stratification in future studies. Even if not relevant to all subtypes, our study emphasizes that cigarette smoking should be added to the few modifiable HL risk factors identified.

Farm Exposures and Allergic Disease Among Children Living in a Rural Setting.

OBJECTIVES: The purpose of this study was to examine the association between farm exposures and asthma and allergic disease in children while also highlighting the experiences of non-farm rural children. METHODS: This was a cross-sectional analysis of data collected from across the province of Saskatchewan, Canada in 2014. Surveys were completed by parents of 2275 rural dwelling children (farm and non-farm) aged 0 to 17 years within 46 rural schools. Questionnaires were distributed through schools for parents to complete. RESULTS: Asthma prevalence was 7.6%, of which 29.5% of cases were allergic. After adjustment for potential confounders, home location (farm vs non-farm) and other farm exposures were not associated with asthma and asthma phenotypes. Those who completed farm safety education were more likely to have asthma (11.7% vs. 6.7%; p = .001) compared to children without asthma. In sub-analyses among 6-12-year-old children, boys were more likely to have asthma (non-allergic) and use short-acting beta-agonists compared to girls. Doing farm work in the summer was associated with an increased risk of asthma [adjusted OR (aOR) = 1.71 (1.02-2.88); p = .041]. Doing routine chores with large animals was associated with an increased risk of asthma [aOR = 1.83 (1.07-3.15); p = .027] and allergic asthma [aOR = 2.37 (95%CI = 1.04-5.40); p = .04]. CONCLUSION: The present study showed that the prevalence of asthma and asthma phenotypes were similar between farm and non-farm rural children. There did not appear to be differential involvement in farming activities between those with and without asthma although those with asthma had more training suggesting possible attempts to mitigate harm from farm exposures.

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 > or =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$5000 or less (2.7, 95% CI 1.3 to 5.6). Decreased injury risk was observed for several health related characteristics and some farm characteristics. CONCLUSION: We identified some risk factors possibly relevant to farm injury prevention programs. However, other factors were not associated with farm work injury suggesting these may not be as important as previously hypothesised.

Changing prevalence of obesity in a rural community between 1977 and 2003: a multiple cross-sectional study.

OBJECTIVE: To determine the changes in the prevalence of obesity in a rural community between 1977 and 2003. STUDY DESIGN: A multiple cross-sectional study. METHODS: The analysis was based on data from four cross-sectional surveys of adults aged 25-59 years, conducted in the town of Humboldt, Saskatchewan in 1977, 1983, 1993 and 2003. People with a body mass index (BMI) > or =30 kg/m(2) were considered to be obese. RESULTS: Average body weight increased by 8 kg for both men and women during the study period. The increase in BMI was greater in adults aged 25-39 years compared with older age groups. The prevalence of obesity increased from 24% in 1977 to 38% in 2003 for men, and from 16% to 32% for women. The change was more pronounced from 1993 to 2003 than from 1977 to 1993, especially among younger adults. Standardized to the 2003 study population by sex, age and smoking status, the prevalence of obesity was 16.8% in 1977, 22.7% in 1983, 24.7% in 1993 and 34.5% in 2003, and was much higher than the Canadian national average (16% in 2003). CONCLUSION: There was a dramatic increase in the prevalence of obesity in rural adults, and this was greater in younger adults. Changes in cigarette smoking did not explain the increase. There is an urgent need to identify and implement effective interventions to slow if not reverse the trend, particularly in rural populations.

In vitro production of tumor necrosis factor-alpha by human monocytes stimulated with lipopolysaccharide is positively correlated with increased blood monocytes after exposure to a swine barn.

Recently there has been interest in the air quality in and around intensive livestock production facilities, such as modern swine production barns, where agricultural workers and surrounding residents may be exposed to elevated levels of organic dusts. The health effects of these exposures are not completely understood. The study that is reported here is a component of a larger investigation of the relationships among the acute effects of high-concentration endotoxin exposure (swine barn dust), polymorphisms in the TLR4 gene, and respiratory outcomes following exposure to swine confinement buildings. The relationships among a mediator of acute lung inflammation, tumor necrosis factor alpha (TNF-alpha), and clinical responses to acute swine barn exposure were characterized. Analysis of the results showed that in vitro stimulation of human monocytes with as little as 1 ng/ml of lipopolysaccharide (LPS) produced a significant increase in the monocytes that produced TNF-alpha. Although the proportion of TNF-alpha-positive monocytes after in vitro stimulation with 1 ng/ml of LPS was not associated with gender or TLR4 genotype, it was positively associated with the concentration of monocytes in blood after barn exposure. Thus, these two responses to different forms of LPS exposure are significantly correlated, and more responsive monocytes in vitro indicate a forthcoming relative monocytosis, post barn exposure, which may initiate a cascade of chronic inflammation.

Prevention of agricultural injuries: an evaluation of an education-based intervention.

OBJECTIVE: To evaluate the effectiveness of an agricultural health and safety program in reducing risks of injury. DESIGN: Cross-sectional survey. SETTING: 50 rural municipalities in the Province of Saskatchewan, Canada. INTERVENTION: The Agricultural Health and Safety Network (AHSN), a mainly educational program that administered 112 farm safety interventions over 19 years. SUBJECTS: 5292 farm people associated with 2392 Saskatchewan farms. Farms and associated farm people were categorized into three groups according to years of participation in the AHSN. IMPACT: self-reported prevalence of: (1) farm safety practices; (2) physical farm hazards. OUTCOME: (1) self-reported agricultural injuries. RESULTS: After adjustment for group imbalances and clustering at the rural municipality level, the prevalence of all impact and outcome measures was not significantly different on farms grouped according to years of AHSN participation. To illustrate, the adjusted relative risk of reporting no rollover protection on tractors among farms with none (0 years) versus high (>8 years) levels of AHSN participation was 0.95 (95% CI 0.69 to 1.30). The adjusted relative risk for agricultural injuries (all types) reported for the year before the survey was 0.99 (95% CI 0.74 to 1.32). CONCLUSIONS: Educational interventions delivered via the AHSN program were not associated with observable differences in farm safety practices, physical farm hazards, or farm-related injury outcomes. There is a need for the agricultural sector to extend the scope of its injury prevention initiatives to include the full public health model of education, engineering, and regulation.

The Use of a Helium-Oxygen Mixture during Maximum Expiratory Flow to Demonstrate Obstruction in Small Airways in Smokers.

We measured the response to breathing a mixture of 80% helium and 20% oxygen (He) during a maximum expiratory flow-volume (MEFV) maneuver in 66 nonsmokers and 48 smokers, aged 17-67. All of the subjects studied had (forced expiratory volume in 1 s/forced vital capacity [FEV(1.0)/FVC]) x 100 of greater than 70%. While the flow rates of the smokers were within +/-2 SD of those of the nonsmokers at 50% VC (Vmax(50)), both groups showed a reduction in flow with age (nonsmokers: r=-0.34, P<0.01; smokers r=-0.52, P<0.001). Nonsmokers showed no significant reduction with age in response to breathing He, while smokers showed a marked reduction with age (r=-0.63, P<0.001 at Vmax(50)). We also measured the lung volume at which maximum expiratory flow (Vmax) while the subject was breathing He became equal to Vmax while he was breathing air, and expressed it as a percent of the VC. This was the most sensitive method of separating smokers from nonsmokers. These results indicate that the use of He during an MEFV maneuver affords sufficient sensitivity to enable detection of functional abnormalities in smokers at a stage when Vmax while they are breathing air is normal.

The development of the Canadian Rural Health Research Society: creating capacity through connection.

CONTEXT: The organization of rural health research in Canada has been a recent development. Over the past 8 years, rural and remote researchers from more than 15 universities and agencies across Canada have engaged in a process of research capacity building through the development of a network, the Canadian Rural Health Research Society (CRHRS) among the scientifically and geographically diverse researchers and their community partners. The purpose of this article is to discuss the development of the CRHRS as well as the challenges and lessons learned about creating networks and building capacity among rural and remote health researchers. ISSUE: Key elements of network development have included identifying and developing multidisciplinary research groupings, maintaining ongoing connections among researchers, and promoting the sharing of expertise and resources for research training. The focus has been on supporting research excellence among networks of researchers in smaller centres. Activities include a national annual scientific meeting, the informal formation of several regional and national research networks in specific areas, and the development of training opportunities. Challenges have included the issues of sustaining communication, addressing a range of networking and capacity-enhancement needs, cooperating in an environment that rewards competition, obtaining resources to support a secretariat and research activities, and balancing the demands to foster research excellence with the needs to create infrastructure and advocate for adequate research funding. LESSONS LEARNED: The CRHRS has learned how to begin to support researchers with diverse interests and needs across sectors and wide geographical areas, specifically by: (1) focusing on research development through creating and supporting trusting connections among researchers; (2) building the science first, followed by infrastructure development; (3) making individual researchers the nodes in the network; (4) being inclusive by accommodating a wide variety of researchers and researcher strengths; (5) emphasizing social exchange, knowledge exchange, and mentoring in annual scientific meetings; (6) taking opportunities to develop separate projects while finding ways to link them; (7) finding a balance between advancing the science and advocating for adequate funding and appropriate peer review; (8) developing a network organizational structure that is both stable and flexible; and (9) maintaining sustained visionary leadership.

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.

Non-Hodgkin's lymphoma and specific pesticide exposures in men: cross-Canada study of pesticides and health.

Our objective in the study was to investigate the putative associations of specific pesticides with non-Hodgkin's Lymphoma [NHL; International Classification of Diseases, version 9 (ICD-9) 200, 202]. We conducted a Canadian multicenter population-based incident, case (n = 517)-control (n = 1506) study among men in a diversity of occupations using an initial postal questionnaire followed by a telephone interview for those reporting pesticide exposure of 10 h/year or more, and a 15% random sample of the remainder. Adjusted odds ratios (ORs) were computed using conditional logistic regression stratified by the matching variables of age and province of residence, and subsequently adjusted for statistically significant medical variables (history of measles, mumps, cancer, allergy desensitization treatment, and a positive history of cancer in first-degree relatives). We found that among major chemical classes of herbicides, the risk of NHL was statistically significantly increased by exposure to phenoxyherbicides [OR, 1.38; 95% confidence interval (CI), 1.06-1.81] and to dicamba (OR, 1.88; 95% CI, 1.32-2.68). Exposure to carbamate (OR, 1.92; 95% CI, 1.22-3.04) and to organophosphorus insecticides (OR, 1.73; 95% CI, 1.27-2.36), amide fungicides, and the fumigant carbon tetrachloride (OR, 2.42; 95% CI, 1.19-5.14) statistically significantly increased risk. Among individual compounds, in multivariate analyses, the risk of NHL was statistically significantly increased by exposure to the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D; OR, 1.32; 95% CI, 1.01-1.73), mecoprop (OR, 2.33; 95% CI, 1.58-3.44), and dicamba (OR, 1.68; 95% CI, 1.00-2.81); to the insecticides malathion (OR, 1.83; 95% CI, 1.31-2.55), 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT), carbaryl (OR, 2.11; 95% CI, 1.21-3.69), aldrin, and lindane; and to the fungicides captan and sulfur compounds. In additional multivariate models, which included exposure to other major chemical classes or individual pesticides, personal antecedent cancer, a history of cancer among first-degree relatives, and exposure to mixtures containing dicamba (OR, 1.96; 95% CI, 1.40-2.75) or to mecoprop (OR, 2.22; 95% CI, 1.49-3.29) and to aldrin (OR, 3.42; 95% CI, 1.18-9.95) were significant independent predictors of an increased risk for NHL, whereas a personal history of measles and of allergy desensitization treatments lowered the risk. We concluded that NHL was associated with specific pesticides after adjustment for other independent predictors.

Reversibility of pulmonary function abnormalities in smokers. A prospective study of early diagnostic tests of small airways disease.

A prospective study of the reversibility of pulmonary function abnormalities in cigarette smokers was performed. Base line studies of 50 otherwise healthy cigarett smokers included lung volumes, static volume-pressure curves, closing volume, slope of phase III and maximum expiratory flow-volume curves while the subjects breathed air and while they breathed an 80 per cent helium-20 per cent oxygen mixture (He). Ten subjects, seven women and three men, ages 29 to 61, were restudied 6 to 14 weeks after they had stopped smoking. Two of these people had an abnormal closing volume, four had an abnormal slope of phase III and five had an abnormal response to helium. Static volume-pressure curves, slope of phase III and airflow rates were not improved on the repeat studies. There was increases in maximum expiratory flow rates with He at 50 and 25 per cent of vital capacity, reductions in the lung volume at which the maximum expiratory flow rate of air and He became identical, and decreases in closing volume. These reversible functional changes in smokers are thought to indicate improvement of peripheral airways obstruction.

Evidence for major genetic control of wheeze in relation to history of respiratory allergy: Humboldt family study.

We report the results of segregation analyses for wheeze before and after a history of respiratory allergy was taken into consideration. The analyses were based on data from 309 nuclear families with 1,053 individuals living in the town of Humboldt, Saskatchewan in 1993, and were performed by using the REGD program of the SAGE package. For adults, information on wheeze and history of respiratory allergy was provided by themselves, and for children, by their parents. Segregation analyses were first conducted before adjustment for history of respiratory allergy. Other covariates were adjusted including sex, current smoking, household exposure to tobacco smoke, and type of house. A single locus model with residual familial effects fit the data well, but none of the Mendelian models (recessive, dominant, and codominant) could be distinguished. The no-parent-offspring-transmission hypothesis was rejected. However, when the variable of respiratory allergy was included in the models as a covariate, both Mendelian and environmental hypotheses were rejected. The Mendelian model had a relatively lower value of Akaike's Information Criterion than did the environmental model (1095.56 versus 1111.24). The data suggest that a single locus gene explains a portion of wheeze that is related to respiratory allergy, and that common environmental factors and/or polygenes also account for a certain familial aggregation of wheeze.

Segregation analyses of asthma and respiratory allergy: the Humboldt family study.

We performed segregation analyses of asthma and respiratory allergy based on data from 309 nuclear families comprising 1,053 individuals living in the town of Humboldt, Saskatchewan, in 1993, using the REGD program of the S.A.G.E. program package. For adults, information on asthma and history of respiratory allergy was provided by the subjects themselves, and for children by their parents. When asthma was considered as the trait in segregation analysis, models of no major effect, with or without familial effects, were rejected, but they were not rejected after adjusting for history of respiratory allergy. The major gene hypothesis was not rejected before adjusting for history of respiratory allergy. When respiratory allergy was analyzed as the trait, both major gene and multifactorial models fitted the data well, regardless of whether there was adjustment for asthma or not. Other covariates adjusted for in the segregation analyses were age, sex, number of household smokers, current smoking, number of household members, generation, and house type. The data suggest that a major gene related to respiratory allergy may explain the familial aggregation of asthma.

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)

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.

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.

Fatal cases of farmer's lung in a Canadian family. Probable new antigens, Penicillium brevicompactum and P olivicolor.

Three Canadian farmers, including a married couple and another close relative, died from progressive pulmonary fibrosis. Their histories and investigations were compatible with chronic farmer's lung (FL). Our environmental and immunologic studies indicate Penicillium brevicompactum and P olivicolor as probable new antigens of FL in a cool and dry climate.

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.