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Childhood asthma and early life exposure to indoor allergens, endotoxin and β(1,3)-glucans


Randi Jacobsen Bertelsen, Department of Environmental Immunology, Division of Environmental Medicine, Norwegian Institute of Public Health, PO Box 4404, Nydalen, NO-0403 Oslo, Norway. E-mail:


Background Divergent results have been reported regarding early life exposure to indoor environmental agents and the risk of asthma and allergic sensitization later in life.

Objective To assess whether early exposure to indoor allergens, β(1,3)-glucans and endotoxin modifies the risk of allergic diseases at 10 years of age.

Methods The concentrations of mite, cat and dog allergens, endotoxin and β(1,3)-glucans were determined in dust from the homes of 260 two-year-old children with lung function measured at birth (tidal flow volume loops) in the Environment and Childhood Asthma study in Oslo. At 10 years, the health status was assessed in a follow-up study including a structured interview of the parents and an extended clinical examination.

Results Cat and dog keeping at 2 years of age was reported in 6.5% and 5.5% of the families, respectively. Mite allergens were detected in only 4/260 dust samples. The adjusted odds ratio for asthma at age 10 was 1.20 (95% confidence interval: 1.01–1.43) and 1.22 (1.02–1.46) for bronchial hyperresponsiveness (BHR) per 10 μg/g dust increase in cat allergen exposure at 2 years of age. No association was seen with allergic sensitization. Moreover, endotoxin and β(1,3)-glucan exposure did not modify the risk of asthma or allergic sensitization. None of the measured environmental factors were associated with lung function at 10 years of age or a relative change in lung function from birth.

Conclusion In a community with a low prevalence of pet keeping and low mite allergen levels, exposure to cat allergens early in life increased the risk of late childhood asthma and BHR, but not the risk of allergic sensitization. No risk modification was seen for dog allergens, endotoxin and β(1,3)-glucans.

Cite this as: R. J. Bertelsen, K. C. Lødrup CarlsenK.-H. Carlsen, B. Granum, G. Doekes, G. Håland, P. Mowinckel and M. Løvik, Clinical & Experimental Allergy, 2010 (40) 307– 316.