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Ju-Hyeong Park,¹ Donna L. Spiegelman,² Harriet A. Burge,¹ Diane R. Gold,³ Ginger L. Chew,⁴ and Donald K. Milton¹

¹Department of Environmental Health, and ²Departments of Epidemiology and Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA
³The Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
⁴Division of Environmental Health Sciences, J.L. Mailman School of Public Health, Columbia University, New York, New York, USA

Abstract

To characterize the seasonal variability of endotoxin levels, we measured endotoxin in dust from the bed, bedroom floor, and kitchen floor in 20 homes, and in air from the bedroom in 15 of the homes. All homes were located in the greater Boston, Massachusetts, area and were sampled each month from April 1995 to June 1996. Outdoor air was collected at two locations. We found greater within-home than between-home variance for bedroom floor, kitchen floor, and airborne endotoxin. However, the reverse was true for bed dust endotoxin. Thus, studies using single measurements of dust endotoxin are most likely to reliably distinguish between homes if bed dust is sampled. Dust endotoxin levels were not significantly associated with airborne endotoxin. Airborne endotoxin was significantly (p = 0.04) and positively associated with absolute humidity in a mixed-effect model adjusting for a random home effect and fixed effect of sampling month and home characteristics. This finding implies that indoor humidity may be an important factor controlling endotoxin exposure. We found a significant (p < 0.05) seasonal effect in kitchen floor dust (spring > fall) and bedroom airborne endotoxin (spring > winter) , but not in the other indoor samples. We found significant seasonal pattern in outdoor airborne endotoxin (summer > winter) . Key words: endotoxin, house dust, humidity, indoor air pollution, seasonal variability, temperature. Environ Health Perspect 108:1023-1028 (2000) . [Online 5 October 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p1023-1028park/ abstract.html

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

We thank K. McGaffigan for assistance with data management and analysis, the research assistants who assayed samples, and especially the study participants who answered questionnaires and collected dust and air samples.

This study was supported by National Institute of Environmental Health Sciences grant R01 ES-07036, National Institute of Environmental Health Sciences Center grant 2P30ES00002, and a gift from BioWhittaker, Walkersville, MD. J.-H. Park received a Korea Industrial Safety Corporation Scholarship.

Received 13 March 2000 ; accepted 28 June 2000.