Allergic diseases encompass a group of disorders common in childhood, including eczema, asthma, and allergic rhinoconjunctivitis (ARC). Though disparate in presentation, these disorders share a common biologic origin,1 and over the past quarter century this group of disorders has grown from relative obscurity to near ubiquity, with a lifetime prevalence approaching 20% in school-age children in the United States.2
The natural question is why these rates have increased so rapidly and steadily. In this issue of Pediatrics, Hesselmar and colleagues present their findings from an observational, cross-sectional, questionnaire-based study of families with 7- to 8-year-old children living in 2 geographically distinct areas of Sweden: Kiruna, ∼60 miles north of the Arctic Circle, and Mölndal, >750 miles to the south. The authors use principal component analysis and logistic regression models to explore correlations between allergy history and dietary habits of the families of 1029 children. In addition to demographics and habits of food consumption, the authors queried dishwashing practices. Specifically, the authors asked whether families used hand dishwashing or machine dishwashing most of the time.
Although the authors do not present data about all associations within their dataset, they focus on an inverse correlation between allergic diseases (defined as eczema, asthma, or ARC) and the use of handwashing to clean dishes. Univariate analyses …
Address correspondence to Michael D. Cabana, MD, MPH, 3333 California St, Suite 245, San Francisco, CA 94118. E-mail: