Endotoxin levels in farming: absence of symptoms despite high exposure levels.

Rask‐Andersen, Anna; Malmberg, Per; Lundholm, Monica

doi:10.1136/oem.46.6.412

Cited by 37 publications

(36 citation statements)

References 16 publications

(7 reference statements)

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“…End otoxins may thu s increase bronchial reactivity. Howe ver, it is not known whether endotoxins alone are responsible for the change in bronchial responsiveness caused by inhaled swine dust (28,30,32). For technical reasons, expo sure to endotoxins was not asse ssed in our study.…”

Section: Discussionmentioning

confidence: 80%

Respiratory symptoms and bronchial reactivity among pig and dairy farmers.

Choudat¹,

Goehen²,

Korobaeff³

et al. 1994

Scand J Work Environ Health

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ratory symptoms and bronchial reactivity among pig and dairy farmers. Scand J Work Environ Health 1994;20:48-54. OBJECTI VES -This study assessed the prevalence of respiratory manifestations among French pig and dairy farmers and determined the relationship between bronchial reactivity and respiratory manifestations. METHODS -The pig farmers included 102 men working more than halftime inside swine confinement buildings. There were 51 male dairy farmers and 81 male referents. The demographic characteristics of the three groups were similar except for more smokers among the referents. Each subject completed a standardized questionnaire. Pulmonary function tests were performed before and after a methacholine challenge (cumulative doses 80, 240, and 560 ug), Airborne dust, ammonia, and carbon dioxide were measured inside 28 swine confinement buildings. RESULTS -The pig farmers were exposed to a total dust level of 2.4 I mg . nr-'. The respirable particle concentration was low. The pig and dairy farmers had a significantly higher prevalence of cough and morning phlegm than the referents. Before the methacholine challenge, the dairy farmers had nonsignificantly lower mean lung function values than the other groups. Among the subjects with no history of asthma, nonspecific bronchial hyperreactivity was significantly higher among the pig and dairy farmers than among the referents. There was a fall in the forced expiratory volume in I s (FEY, ,) that was greater than 10% in 6.7% of the referents, 17.9% of the swine workers, and 35.6% of the~airy farmers. This result was unchanged after adjustment for the initial FEV] o: CONCLUSIONS -The prevalence of respiratory symptoms was significantly higher among the pig' farmers without base-line lung function impairment. However, both the pig and the dairy farmers had increased bronchial reactivity.Key terms: agricultural workers, epidemiology, occupational airborne exposure.Epidemiol ogic studi es have demonst rated an increased ri sk of respiratory dysfunction am ong farmers (1---4) and, especially, am ong workers in swine co nfinement building s (5-24). Th ese studi es iden-

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Section: Discussionmentioning

confidence: 80%

Respiratory symptoms and bronchial reactivity among pig and dairy farmers.

Choudat¹,

Goehen²,

Korobaeff³

et al. 1994

Scand J Work Environ Health

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show abstract

“…Finally, our previous exposure-response studies have shown that inhaled grain dust and endotoxin produce similar physiologic and biologic effects in humans (47,52,53) and mice (53)(54)(55)(56); the and contraction of smooth muscle (62). However, the concentration of endotoxin in the bioaerosol is not always predictive of respiratory symptoms among agricultural workers (63,64). These studies suggest that other components may be important in the development of organic dust-induced airway disease.…”

Section: Scope Of the Problemmentioning

confidence: 76%

Etiology and pathogenesis of airway disease in children and adults from rural communities.

Schwartz

1999

Environ Health Perspect

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Asthma is the most common chronic disease of childhood and affects nearly 5 million children. The prevalence and severity of childhood asthma have continued to increase over the past decade despite major advances in the recognition and treatment of this condition. A comparison of urban and rural children suggests that the etiology of airway disease is multifactorial and that unique exposures and genetic factors contribute to the development of asthma in both settings. The most important environmental exposure that distinguishes the rural environment and is known to cause asthma is the organic dusts. However, animal-derived proteins, common allergens, and low concentrations of irritants also contribute to the development of airway disease in children and adults living in rural communities. A fundamental unanswered question regarding asthma is why only a minority of children who wheeze at an early age develop persistent airway disease that continues throughout their life. Although genetic factors are important in the development of asthma, recurrent airway inflammation, presumably mediated by environmental exposures, may result in persistent airway hyperresponsiveness and the development of chronic airway disease. Increasing evidence indicates that control of the acute inflammatory response substantially improves airflow and reduces chronic airway remodeling. Reducing exposure to agricultural dusts and treatment with anti-inflammatory medication is indicated in most cases of childhood asthma. In addition, children with asthma from rural (in comparison to urban) America face multiple barriers that adversely affect their health e.g., more poverty, geographic barriers to health care, less health insurance, and poorer access to health care providers. These unique problems must be considered in developing interventions that effectively reduce the morbidity and mortality of asthma in children from rural communities.

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“…(1,2,6,7,12,14,15) Occupational exposure to endotoxin occurs in a variety of industries including agriculture, wastewater plants, refuse-derived fuel production, metals machining, snowmaking, and in the manufacture of pharmaceuticals and medical devices. (3,11,12,14,18,(19)(20)(21)(22)(23)(24) Although occupational exposure limits have been suggested for endotoxin, evaluation of dose-response relationships is problematic, because sampling and analytical methods have not been standardized.…”

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confidence: 99%

Comparison of Endotoxin Assays Using Agricultural Dusts

et al. 2002

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Endotoxins from gram-negative bacteria pose a significant respiratory hazard. Establishing dose-response relationships is problematic because there are no standard procedures for sampling and analysis. The goal of this study was to compare endotoxin analyses in six laboratories using Limulus-based assays for analysis of organic dusts from three agricultural environments: chicken barns, swine barns, and corn processing facilities. For each dust generation experiment 14 side-by-side air samples were collected on 37-mm glass fiber filters at flows of 1.8 L/min. Each laboratory was randomly allocated two filters from each of seven experiments per dust type. Three laboratories used the QCL-1000 endpoint assay, and three used the kinetic-QCL method. To eliminate variability among different lots, a single lot of Limulus amebocyte lysate for endpoint assays and one similar lot for kinetic assays was provided. Precision of assays performed within labs was very good, with pooled coefficients of variation for replicate samples ranging from 1 to 11% over all labs and all dust types. There were significant differences between laboratories for all three dust types (p < 0.01). The pattern of differences between labs varied by dust type. For chicken dust, labs using the endpoint method reported higher results than those using kinetic methods. For swine and corn dusts, labs using the kinetic method reported the highest endotoxin values. For chicken dust, results from all labs except A and B were highly correlated (r = 0.86-1.00). For swine dust, only labs B and E, and C and D were correlated. For corn, A, B, and D were significantly correlated with most other labs. In conclusion, statistical differences in performance between laboratories were apparent and may be related to the extraction and analytical methods. The results of this study will be useful for standardization of sampling and analysis of airborne endotoxin in agriculture.

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Endotoxin levels in farming: absence of symptoms despite high exposure levels.

Cited by 37 publications

References 16 publications

Respiratory symptoms and bronchial reactivity among pig and dairy farmers.

Respiratory symptoms and bronchial reactivity among pig and dairy farmers.

Etiology and pathogenesis of airway disease in children and adults from rural communities.

Comparison of Endotoxin Assays Using Agricultural Dusts

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