P.F.J. Vogelzang

Lung function and chronic respiratory symptoms of pig farmers: focus on exposure to endotoxins and ammonia and use of disinfectants.

OBJECTIVES--The prevalence of chronic respiratory symptoms among pig farmers is known to be high, but the aetiology of these symptoms is not yet unravelled. Long term average exposure to dust was evaluated, endotoxins and ammonia and use of disinfectants were compared with chronic respiratory symptoms and depressed base line lung function. METHODS--A cross sectional study was performed among 194 Dutch pig farmers, of whom 100 had not and 94 had chronic respiratory symptoms. Exposure-response relations were evaluated with multiple logistic and linear regression analysis. Estimates of long term average exposure were based on two personal exposure measurements, taken on one day in summer and one day in winter. Information on use of disinfectants and disinfection procedures was assessed by a walk through survey and interview by telephone. RESULTS--Exposure to dust, endotoxins, and ammonia were not related to chronic respiratory symptoms. Duration of the disinfection procedure and pressure used at disinfection were strongly and positively related to chronic respiratory symptoms. A significant inverse association between base line lung function and endotoxin exposure was found only among asymptomatic farmers. Ammonia exposure and duration of the disinfection procedure were significantly associated with base line lung function in the entire population. CONCLUSION--Results suggest that use of disinfectants is an important aetiological factor in chronic respiratory health effects of pig farmers. This factor has not been studied before. Results also suggest an aetiological role for exposure to endotoxins and ammonia in development of chronic respiratory health effects, but longitudinal studies with detailed exposure assessment strategies are required to assess their roles.

Disinfectant use as a risk factor for atopic sensitization and symptoms consistent with asthma: an epidemiological study

Exposure to some nonallergenic compounds has been shown to increase the risk of atopic sensitization and asthmatic symptoms. In order to gain more insight into the largely unknown aetiology of respiratory symptoms in pig farmers, we studied the role of nonallergic exposure. We evaluated associations between chronic respiratory symptoms, specific and total serum immunoglobulin E (IgE) levels, use of disinfectants, and endotoxin exposure levels in a population of 194 Dutch pig farmers. Atopic sensitization (defined as increased production of IgE to common allergens) was found to occur more frequently in farmers who used disinfectants containing quaternary ammonium compounds (QACs) (odds ratio (OR) 7.4; 95% confidence interval (95% CI) 1.3-43.1). ORs for other disinfectants ranged 2.3-4.1 (NS). Atopic sensitization was not found to occur more frequently in farmers with a high endotoxin exposure. The use of disinfectants was only related to respiratory symptoms consistent with asthma in atopics. This is illustrated by the significantly elevated ORs for farmers with IgE to common allergens (house dust mite, grass pollen, birch pollen), and who used disinfectants containing QACs, in the total population and in a subgroup of the total population restricted according to bronchial hyperresponsiveness to histamine (symptomatics with a provocation dose of histamine producing a > or = 10% decrease in forced expiratory volume in one second (PC10) < or = 16 mg.mL-1, compared with asymptomatics with a PC10 > 16 mg.mL-1) (OR 4.4, 95% CI 1.3-14.6; and OR 8.2, 95% CI 1.6-42.6, respectively). Atopy and use of QACs and endotoxin exposure level taken individually were not associated with respiratory symptoms. A combination of atopic sensitization and high endotoxin exposure (> 101 ng.m-3) was strongly associated with respiratory symptoms in the restricted population (OR 6.1; 95% CI 1.0-36.2). Our results suggest that occupational exposure to nonallergenic agents (disinfectants) may induce immunoglobulin E sensitization to common aeroallergens, and that the combination of atopy and exposure to nonallergenic agents (disinfectants and endotoxin) is an important risk factor for development of symptoms consistent with asthma.

Organic dust toxic syndrome in swine confinement farming

BACKGROUND Pig farmers are exposed to organic dust with pro-inflammatory capacities. This makes it likely that they suffer from organic dust toxic syndrome (ODTS). No studies that included unexposed control populations are available so far. METHODS The prevalence of ODTS was established by the use of questionnaires in a group of 239 pig farmers and 311 rural controls working in nonagricultural occupations. RESULTS Pig farmers suffered more often from ODTS than controls (6.4% vs. 2.6%, P < 0.05). Organic dust toxic syndrome was associated with symptoms of atopy (prevalence odds ratio (POR) 3.1, 95% confidence interval (CI) 1.2-8.0) and with the use of wood-shavings as bedding (POR 4.3, 95% CI 1.2-15.6). An inverse association with the number of years worked as pig farmer was found (up to 5 years vs. more than 5 years; POR 5.0, 95% CI 0.8-32.9). CONCLUSIONS The prevalence of ODTS was elevated among pig farmers when compared to nonfarming, rural controls.

Longitudinal changes in lung function associated with aspects of swine confinement exposure.

Several aspects of swine-confinement farming appear to be leading to adverse respiratory effects. This study was set up in a longitudinal design to study the association between certain characteristics of farms or the way they are run and a decline in lung function. A cohort of 171 pig farmers was observed for 3 years. Lung function was measured. Exposure to farm characteristics was determined at the start of the observation period, using data from standardized farm surveys and from diaries kept by the participants. Mean decline in lung function was 73 mL/year for forced expiratory volume in 1 second (FEV1) and 55 mL/year for forced vital capacity (FVC). A longitudinal decline in FEV1 was significantly associated with the use of quaternary ammonium compounds as disinfectants (an additional 43 mL/year) and also with the use of an automated dry feeding system (an additional 28 mL/year). The association with the use of wood shavings as bedding material was not statistically significant. The impact of these characteristics in a longitudinal study provides stronger evidence for causal inference than that shown in previous cross-sectional designs. This may be useful in promoting preventive measures.

Longaandoeningen en werkgebonden risicofactoren bij varkenshouders

SamenvattingChronische obstructieve longaandoeningen (COPD) komen veel voor onder Nederlandse varkenshouders. De prevalentie van COPD is bij hen beduidend hoger dan bij streekgenoten die niet als boer werken. De prevalentie van astma is niet hoger, maar jonge varkenshouders vormen een selectie van personen met weinig atopie in de vroege jeugd en daarmee weinig aanleg voor astma. Langdurige blootstelling in varkensstallen leidt echter tot een prevalentie van astma die even hoog is als bij mensen werkzaam buiten de agrarische sector. Een nadelig effect op de longen blijkt uit de geconstateerde versnelde achteruitgang in longfunctie en de toename in prevalentie en mate van hyperreactiviteit. De volgende factoren in de varkenshouderij geven aanleiding tot het ontstaan of verergeren van longaandoeningen: gebruik van houtkrullen als strooisel, gebruik van ontsmettingsmiddelen (met name quaternaire ammoniumverbindingen), gebrekkige ventilatie en toepassing van een mechanisch droogvoersysteem. Steeds werd een duidelijker effect vastgesteld bij rokers dan bij niet-rokers. De behandeling van astma en COPD bij varkenshouders dient steeds gepaard te gaan met een advies over te treffen arbeidshygiënische maatregelen en gebruik van mondmaskers in de stallen, en het advies om te stoppen met roken.

Longaandoeningen en werkgebonden risicofactoren bij varkenshoudersastmaberoepsziekteluchtweg- en longaandoeningenonderzoekwerk

Chronische obstructieve longaandoeningen (COPD) komen veel voor onder Nederlandse varkenshouders. De prevalentie van COPD is bij hen beduidend hoger dan bij streekgenoten die niet als boer werken. De prevalentie van astma is niet hoger, maar jonge varkenshouders vormen een selectie van personen met weinig aanleg voor astma. Langdurige blootstelling in varkensstallen leidt echter tot een prevalentie van astma die even hoog is als bij mensen werkzaam buiten de agrarische sector. Een nadelig effect op de longen blijkt uit de geconstateerde versnelde achteruitgang in longfunctie en de toename in prevalentie van astma en mate van hyperreactiviteit. De volgende factoren in de varkenshouderij geven aanleiding tot het ontstaan of verergeren van longaandoeningen: gebruik van houtkrullen als strooisel, gebruik van ontsmettingsmiddelen (met name quaternaire ammoniumverbindingen), gebrekkige ventilatie en toepassing van een mechanisch droogvoersysteem. Steeds werd een duidelijker effect van deze factoren vastgesteld bij rokers dan bij niet-rokers. De huisarts dient bij varkenshouders met longklachten na te gaan in welke mate beroepsexpositie een oorzakelijke factor is, zo nodig in overleg met een bedrijfsarts.

Disinfectant Use as a Risk Factor for Atopic Sensitization and Symptoms Consistent With Asthma: an Epidemiological Study

Abstract Exposure to some nonallergenic compounds has been shown to increase the risk of atopic sensitization and asthmatic symptoms. In order to gain more insight into the largely unknown aetiology of respiratory symptoms in pig farmers, we studied the role of nonallergic exposure. We evaluated associations between chronic respiratory symptoms, specific and total serum immunoglobulin E (IgE) levels, use of disinfectants, and endotoxin exposure levels in a population of 194 Dutch pig farmers. Atopic sensitization (defined as increased production of IgE to common allergens) was found to occur more frequently in farmers who used disinfectants containing quaternary ammonium compounds (QACs) (odds ratio (OR) 7.4; 95% confidence interval (95% CI) 1.3-43.1). ORs for other disinfectants ranged 2.3-4.1 (NS). Atopic sensitization was not found to occur more frequently in farmers with a high endotoxin exposure. The use of disinfectants was only related to respiratory symptoms consistent with asthma in atopics. This is illustrated by the significantly elevated ORs for farmers with IgE to common allergens (house dust mite, grass pollen, birch pollen), and who used disinfectants containing QACs, in the total population and in a subgroup of the total population restricted according to bronchial hyperresponsiveness to histamine (symptomatics with a provocation dose of histamine producing a ≥10% decrease in forced expiratory volume in one second (PC10) ≤16 mg· mL−1, compared with asymptomatics with a PC10>16 mg·mL−1) (OR 4.4, 95% CI 1.3-14.6; and OR 8.2, 95% CI 1.6-42.6, respectively). Atopy and use of QACs and endotoxin exposure level taken individually were not associated with respiratory symptoms. A combination of atopic sensitization and high endotoxin exposure (>101 ng· m−3) was strongly associated with respiratory symptoms in the restricted population (OR 6.1; 95% CI 1.0-36.2). Our results suggest that occupational exposure to nonallergenic agents (disinfectants) may induce immunoglobulin E sensitization to common aeroallergens, and that the combination of atopy and exposure to nonallergenic agents (disinfectants and endotoxin) is an important risk factor for development of symptoms consistent with asthma.