Background: We compared the effects of an acaricide, benzyl benzoate, with the effects of baking soda control applied to bedroom and living room carpets on house dust mite allergen levels, lung function, and medication use in 12 adult patients with asthma for 12 months.
Methods: This was a randomized, double-blind, placebo-controlled study. Patients were enrolled from the allergy clinic of a large tertiary care center in a metropolitan area. All patients had positive dust mite puncture test results. Six patients used benzyl benzoate, and six used baking soda. Other aggressive mite control measures were implemented uniformly in each group. Subjects were to make two carpet applications, at baseline and at 6 months according to the manufacturer's recommendations. Dust samples were collected in bedroom and living room carpets at 0, 3, 6, 9, and 12 months; and quantities of Der p I and Der f I allergens were determined. Spirometry was done every 3 months, and peak flow rates were recorded for 10 days after each dust sampling.
Results: There were no significant differences in mean allergen levels between the two groups over time at either site. There were no significant changes in lung function or medication use for either group.
Conclusions: Benzyl benzoate powder applications may not be effective when done according to manufacturer's instructions. Further studies are necessary to test effectiveness when applied more frequently and for longer periods.