Nonexposure Theory Is Contradicted

The theory of not exposing children tosubstances that can trigger allergies orasthma because it may protect them fromrespiratory problems later in life has comeunder scrutiny. New findings suggest thatchildren who spend less time during theirearly years around pets and dust do notappear to have a lower incidence of developingasthma or respiratory problems.

The current study tracked 625 childrenfrom birth and tested the levels of dustmites and cat dander in their living roomswhen they were 8 weeks old. In the nextphase of the study, the researchers askedthe mothers annually whether the participantshad had any trouble breathing inthe past year. At 51/2, the children were tested,using a skin-prick test with the specificallergen and noting any reaction, to gaugesensitivity to dust mites or cat dander.

The results, reported in Thorax (October2004), indicated that 1 in 10 of the childrenwere sensitive to dust mites or cat fur,and 1 in 14 had experienced wheezing.The risk of becoming allergic or asthmaticwas higher with exposure to low levels ofallergens during the participants' firstyears of life. That same risk flattened outwith increased exposures, however, notedthe researchers.