Endotoxin Exposure Is a Risk Factor for Asthma: The National Survey of Endotoxin in United States Housing

• Published in: American journal of respiratory and critical care medicine Vol. 172; no. 11; pp. 1371 - 1377
• Main Authors: Thorne, Peter S, Kulhankova, Katarina, Yin, Ming, Cohn, Richard, Arbes, Samuel J., Jr, Zeldin, Darryl C
• Format: Journal Article
• Language: English
• Published: New York, NY Am Thoracic Soc 01.12.2005; American Lung Association; American Thoracic Society
• Subjects: A. Asthma and Allergy; Adult; Air Pollutants - adverse effects; Air Pollutants - chemistry; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Asthma - chemically induced; Asthma - epidemiology; Biological and medical sciences; Blood and lymphatic vessels; Blood. Blood and plasma substitutes. Blood products. Blood cells. Blood typing. Plasmapheresis. Apheresis; Cardiology. Vascular system; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Dust - analysis; Endotoxins - adverse effects; Endotoxins - analysis; Health Surveys; Housing; Humans; Intensive care medicine; Medical sciences; Odds Ratio; Prevalence; Risk Factors; Surveys and Questionnaires; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; United States - epidemiology; United States; North America; America; airway inflammation; Lung disease; Intensive care; Respiratory disease; wheeze; Wheezing; Inflammation; Endotoxin; Asthma; Toxin; house dust; Risk factor; Lipopolysaccharide; Bronchus disease; Obstructive pulmonary disease; Resuscitation
• ISSN: 1073-449X; 1535-4970
• DOI: 10.1164/rccm.200505-758OC

Although research has shown that early life exposure to household endotoxin protects against development of allergies, studies are less clear on the relationship between household endotoxin exposure and prevalence of wheezing and asthma. We assayed 2,552 house dust samples in a representative nationwide sam- ple to explore relationships between endotoxin exposures and risk factors for asthma, asthma symptoms, and medication use. House dust was vacuum-sampled from five locations within homes and assayed for endotoxin. Health, demographic, and housing information was assessed through questionnaire and on-site evaluation of 2,456 residents of 831 homes selected to represent the demographics of the United States. Endotoxin concentration (EU/mg) and load (EU/m(2)) were highly correlated (r = 0.73-0.79). Geometric mean endotoxin concentrations were as follows (in EU/mg): bedroom floors, 35.3 (5th-95th percentile, 5.0-260); bedding, 18.7 (2.0-142); family room floors, 63.9 (11.5-331); sofas, 44.8 (6.4-240); and kitchen floors, 80.5 (9.8-512). Multivariate analysis demonstrated significant relationships between increasing endotoxin levels and diagnosed asthma, asthma symptoms in the past year, current use of asthma medications, and wheezing among residents of the homes. These relationships were strongest for bedroom floor and bedding dust and were observed in adults only. Modeling the joint effect of bedding and bedroom floor endotoxin on recent asthma symptoms yielded an adjusted odds ratio of 2.83 (95% confidence interval, 1.01-7.87). When stratified by allergy status, allergic subjects with higher endotoxin exposure were no more likely to have diagnosed asthma or asthma symptoms than nonallergic subjects. This study demonstrates that household endotoxin exposure is a significant risk factor for increased asthma prevalence.