Infants exposed to outdoor traffic pollution and indoor endotoxin are at increased risk for asthma, researchers say.Endotoxin — a component of bacteria believed to trigger an immune response in humans — is found in dust.

University of Cincinnati College of Medicine researchers found persistent wheezing (an early warning sign of asthma and other lung conditions) in 36 percent of 3-year-olds who were exposed to high levels of traffic pollution and indoor endotoxin as infants.

In comparison, wheezing was seen in 11 percent of children exposed to low levels of outdoor and indoor allergens as infants, and in 18 percent of children exposed to high levels of traffic pollution and low levels of indoor endotoxin. Endotoxin exposure alone appeared to have little effect on children, the study authors noted.

“There is a clear synergistic effect from co-exposure to traffic-related particles and endotoxin above and beyond what you would see with a single exposure that can be connected to persistent wheezing by age 3,” study author Patrick Ryan, a research assistant professor of environmental health, said in a university news release. “These two exposure sources — when simultaneously present at high levels — appear to work together to negatively impact the health of young children with developing lungs.”

“Traffic-related particles and endotoxin both seem to trigger an inflammatory response in the children monitored in this study. When put together, that effect is amplified to have a greater impact on the body’s response,” Ryan explained. “The earlier in life this type of exposure occurs, the more impact it may have long term. Lung development occurs in children up through age 18 or 20. Exposure earlier in life to both endotoxin and traffic will have a greater impact on developing lungs compared to adults whose lungs are already developed.”

The findings are published in the Dec. 1 issue of the American Journal of Respiratory and Critical Care Medicine.

(HealthDay News)