Reproducibility of allergen, endotoxin and fungi measurements in the indoor environment

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March 2003, Volume 13, Number 2, Pages 152-160

Reproducibility of allergen, endotoxin and fungi measurements in the indoor environment

Joachim Heinricha, Bernd Hölschera, Jeroen Douwesb, Kai Richterc, Kochd, Wolfgang Bischofd, Bärbel Fahlbusche, Raimund W Kinnee and H-h Wichmannf for the INGA study group1

aInstitute of Epidemiology, GSF ¾ National Research Center for Environment and Health, Ingolstädter Landstrae 1. D-85764 Neuherberg, Germany

bDivision of Environmental and Occupational Health, Institute for Risk Assessment Sciences, Utrecht University, The Netherlands

cCenter for Pneumology and Thoracic Surgery, Grosshansdorf Hospital, Hamburg, Germany

dDepartment of Indoor Climatology, Friedrich Schiller University, Jena, Erfurt, Germany

eInstitute of Immunology, Friedrich Schiller University, Jena, Germany

fDepartment of Epidemiology, Ludwig-Maximilians-University of Munich, Neuherberg, Germany

Correspondence to: Dr. Joachim Heinrich, GSF-Institute of Epidemiology, POB 1129, D-85758 Neuherberg, Germany. Tel.: +49-89-3187-4150; Fax. +49-89-3187-3380; E-mail: Joachim.Heinrich@...

1INGA - Study Group: GSF ¾ National Research Center for Environment and Health, Neuherberg Institute of Epidemiology (Wichmann HE, Heinrich J, Schneider P, Cyrys J, Gro I, Houzer A. Wölke G. Silbernagl G. Gehring U. B, Frye C), Institute of Ecological Chemistry (Gebefügi I, Lörinci G). Friedrich Schiller University Jena Institute of Occupational, Social and Environmental Medicine (Bischof W, Koch A, Witthauer J, Heilemann KJ), Institute of Immunology (Jäger L, Fahlbusch B, Schlenvoigt G).

Abstract

Measurements of biocontaminants in settled house dust once a year are commonly used to assess long-term exposure. To examine stability over time and seasonal variation, we measured concentrations of mite and cat allergens, endotoxin and mold spores in living room floor dust in 745 German homes collected twice a year in two different seasons. The study population consisted of adults and children living in five different areas in Germany. All dust samples were collected in a standardized manner from the living room floor and taken during the years 1995 to 1998. The median interval between the two dust samplings was approximately 7 months. Mite and cat allergens were measured in settled house dust by monoclonal antibodies, endotoxin by the limulus amebocyte lysate method, and total spore counts by cultural methods. Crude Pearson's correlation coefficients between log-transformed concentrations in the first and second dust samples ranged between 0.65 and 0.75 for allergens, 0.59 for endotoxin and only 0.06 for total spore counts. The strongest and most consistent seasonal effects were observed for fungi with highest levels in July-September. Cat allergen concentrations were found consistently to be increased in January-March. Mite allergens did not show a strong and consistent seasonal pattern. We conclude that repeated measurements of mite and cat allergens and endotoxin in settled house dust improve the estimate for annual mean concentrations. However, even a single observation of these biocontaminants may be a good proxy for a 1-year exposure since repeated measures were highly correlated. However, repeated measurements of fungi levels were only weakly correlated and thus repeated observations for assessment of annual means of total spore counts are needed.

Journal of Exposure Analysis and Environmental Epidemiology (2003) 13, 152-160. doi:10.1038/sj.jea.7500267