Mold exposure in first year of life may lead to asthma.

Belanger K, Beckett W, Triche E, Bracken MB, Holford T, Ren P, McSharry J, Gold DR, PlattsMills TAE, Leaderer BP. 2003. Symptoms of wheeze and persistent cough in the first year of life: associations with indoor allergens, air contaminants, and maternal history of asthma. Am J Epidemiol 158:195-202.

Asthma clinicians and researchers have reported a substantial rise in the prevalence and severity of asthma in children over the past decade. Genetic predisposition and exposure to various environmental agents, such as environmental tobacco smoke, endotoxins, and indoor allergens, especially during early childhood, have been reported as risk factors for the development of sensitivities to inhaled allergens and the development and exacerbation of asthma. NIEHS grantee Brian P. Leaderer of the Yale University School of Medicine and colleagues at the University of Rochester, Brigham and Women's Hospital, Harvard Medical School, and the University of Virginia Medical Center recently investigated exposures to indoor allergens as well as other air contaminants as they affected asthma development in a birth cohort study.

The team enrolled mothers delivering babies in four Connecticut hospitals and one Massachusetts hospital who already had a child under the age of 11 with a diagnosis of asthma. This high-risk cohort ensured that a sufficient number of index infants would develop asthma for subsequent analyses, in 849 infants born to these mothers, the team measured a number of indoor exposures related to dust mites, cockroaches, cats, dogs, gas stoves, wood-burning stoves, and mold. They also measured indoor levels of nitrogen dioxide, which has been linked with asthma exacerbation in children.

The team used questionnaires and measured airborne cultural spores to study the association between these exposures and the development of wheeze and cough by 12 months of age. A strong association was found for mold, and a modest association was found for cockroaches in children whose mothers had asthma. Among children of mothers without asthma, none of the allergens were associated with persistent cough or wheeze, although exposure to mold and use of a gas stove were significantly related to persistent cough.

This is the first study to simultaneously measure early childhood exposure to both indoor allergens and other air contaminants. A few additional studies have shown a link between the risk of a child developing asthma and maternal asthma history. The current findings suggest potential differences in susceptibility to these exposures for children, regardless of whether the mother has asthma. They also suggest that these differences in susceptibility are genetically based, making some children more sensitive to specific environmental agents. The overall results of the study suggest that early mold exposure may increase the risk of asthma.

These findings should be interpreted carefully because of the poor predictability of early wheeze and cough in asthma development. Continued research into specific gene-environment interactions may help to elucidate the cause of these differences.