An allergic reaction to cockroaches is a major contributor to asthma in urban children, but new research suggests that the insects are just one part of a more complex story. Very early exposure to certain components of air pollution can increase the risk of developing a cockroach allergy by age 7 and children with a common mutation in a gene called GSTM may be especially vulnerable.
Researchers at the Columbia Center for Children's Environmental Health at the Mailman School of Public Health published the findings, the first on this interplay of risk factors, in the February 6 online edition of the Journal of Allergy and Clinical Immunology.
"Allergy to cockroach is one of the greatest risk factors for asthma in low-income urban communities," says lead author Matthew Perzanowski. PhD. "Our findings indicate a complex relationship between allergen and air pollution exposures early in life and a possible underlying genetic susceptibility. Combined, these findings suggest that exposures in the home environment as early as the prenatal period can lead to some children being at much greater risk for developing an allergy to cockroach, which, in turn, heightens their risk of developing asthma."
Dr. Perzanowski and his co-investigators looked at 349 mother-child pairs from the Center's Mothers & Newborns study of environmental exposures in Northern Manhattan and the Bronx. During the mother's pregnancy, exposure to cockroach allergen (protein in feces, saliva or other remnants of the insects) was measured by collecting dust from the kitchen and bed. Researchers also sampled air to measure the mother's exposure to polycyclic aromatic hydrocarbons, or PAH (combustion products that are harmful components of air pollution). Presence of the GSTM1 mutation was determined through blood samples. At ages 5 and 7, the children had blood tests to identify the presence of IgE antibodies-an immune marker of allergy.