New Research Suggests Environmental Factors at Work in Allergenic Rhinitis and Food Allergies

Researchers studied 288 kindergarteners, taking a nasal lavage to look for biomarkers of epithelial damage. Specifically, they used a ratio of the anti-inflammatory protein called Clara cell protein (CC16) and albumin as an index for epithelial integrity. Exposure to swimming pools decreased this ratio and correlated with early allergy to house dust mites.

Alfred Bernard, PhD, professor of toxicology and research director at Catholic University of Louvain in Brussels and co-author of the study, said he’d been working on developing new biomarkers with which to assess the toxic effects of chemicals in the environment. A chance discovery uncovered time spent in chlorine swimming pools as a factor in the expression of a particular surfactant-associated protein, which was indicative of epithelial damage, in the deep lung.

In the study, he and his colleagues wanted to focus on very young children, which limited the kinds of samples they could take. They devised the CC16/albumin ratio in nasal lavage fluid as a proxy of epithelial cell integrity. In addition to the negative effects of swimming pool exposure, the researchers found a positive effect of probiotic consumption and of house cleaning with bleach products, known to kill allergens such as mold and dust mites.

“Our data support the idea that this chemical [pool chlorine] promotes the expression of atopic disease,” said Dr. Bernard. Allergies to dust mites were present in kids even when the parents were not allergic. “The airway epithelia is very immature in these children,” he added, saying that there may be a specific window of sensitivity during which exposure may trigger allergic sensitization.

Like the NHANES study, the Belgian study was not able to make any claim about causality, but could only show associations between exposures, biomarkers and allergies.

A third new study, published in January, tested the interaction between polycyclic aromatic hydrocarbons (PAHs) and exposure to cockroach allergens in early childhood (Perzanowski MS, Chew GL, Divjan A, et al. [Published online ahead of print January 30, 2013.] J Allergy Clin Immunol.). Researchers studied 349 mother-child pairs in New York City, monitoring the mothers’ exposure to PAHs and cockroach allergens during pregnancy. Children were followed for up to seven years, and 31 percent tested positive for cockroach allergy. The allergy correlated with high PAH exposure.

Sources of PAHs that people commonly breathe in are car exhaust, wood smoke, cigarette smoke and industrial pollution, including coal burning and municipal trash incineration. Eating grilled or charred meats and certain processed or pickled foods can also result in PAH exposure.