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Ju-Hyeong Park,¹ Donna L. Spiegelman,² Diane R. Gold,^1,3 Harriet A. Burge,¹ and Donald K. Milton¹

¹Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
²Departments of Epidemiology and Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA
³Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA

Abstract

We identified home characteristics associated with the level of airborne endotoxin in 111 Boston-area homes enrolled in a cohort study of home exposures and childhood asthma, and we developed a predictive model to estimate airborne endotoxin. We measured endotoxin in family-room air and in dust from the baby's bed, family room, bedroom, and kitchen floor. Level of airborne endotoxin was weakly correlated (r < 0.3) with level of endotoxin in each of the four types of dust samples and was significantly correlated with endotoxin in family-room dust (p < 0.05) . Endotoxin in family-room dust accounted for < 6% of the variability of airborne endotoxin. In a multivariate model, certain home characteristics were positively (p < 0.05) associated with airborne endotoxin. These included current presence of dog (difference in level, dog vs. no dog = 72%, partial R² = 12.8%) , past presence of dog (partial R² = 5.5%) , and endotoxin level in family-room dust (partial R² = 5.3%) . Use of a dehumidifier (partial R² = 6.4%) was negatively associated (p = 0.02 ; difference = -31%) with airborne endotoxin. Other home characteristics were identified as important determinants of increased airborne endotoxin in this model, but individual coefficients were not statistically significant ( = 0.05) : total amount of fine dust collected in the home (partial R² = 3.8%) , concrete floor in family room (3.7%) , water damage (3.6%) , and use of cool-mist humidifier in past year (2.7%) . This multivariate model explained 42% of the variability of airborne endotoxin levels, a substantial improvement over that with dust endotoxin alone. Airborne endotoxin in Boston-area homes appears to be determined by the presence of dogs, moisture sources, and increased amounts of settled dust. Key words: airborne endotoxin, dust endotoxin, predictive model, seasonal variability. Environ Health Perspect 109:859-864 (2001) . [Online 14 August 2001]

http://ehpnet1.niehs.nih.gov/docs/2001/109p859-864park/ abstract.html

Address correspondence to D.K. Milton, Environmental Health, Occupational Health Program, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA. Telephone: (617) 432-3324. Fax: (617) 432-0219. E-mail: dmilton@hohp.harvard.edu

We thank K. McGaffigan and D. Sredl for assistance with data management and the research assistants who collected questionnaire information and dust and air samples, and who assayed samples. We give special thanks to the caregivers of the children who participated in the study.

Supported by U.S. National Institute for Environmental Health Science grant R01 ES-07036, by U.S. National Institute of Allergy and Infectious Diseases/National Institute for Environmental Health Science grant R01 AI/EHS-35786, by U.S. National Institute for Environmental Health Science Center grant 2P30ES00002, and by a gift from BioWhittaker, Walkersville, MD. J-H Park was a recipient of a Korea Industrial Safety Corporation Scholarship.

Received 8 November 2000 ; accepted 13 February 2001.