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The theory of not exposing children to substances that can trigger allergies or asthma because it may protect them from respiratory problems later in life has come under scrutiny. New findings suggest that children who spend less time during their early years around pets and dust do not appear to have a lower incidence of developing asthma or respiratory problems.
The current study tracked 625 children from birth and tested the levels of dust mites and cat dander in their living rooms when they were 8 weeks old. In the next phase of the study, the researchers asked the mothers annually whether the participants had had any trouble breathing in the past year. At 51/2, the children were tested, using a skin-prick test with the specific allergen and noting any reaction, to gauge sensitivity to dust mites or cat dander.
The results, reported in Thorax (October 2004), indicated that 1 in 10 of the children were sensitive to dust mites or cat fur, and 1 in 14 had experienced wheezing. The risk of becoming allergic or asthmatic was higher with exposure to low levels of allergens during the participants' first years of life. That same risk flattened out with increased exposures, however, noted the researchers.