Exposure to traffic-related particles and endotoxin during infancy is associated with wheezing at age 3 years.
BACKGROUND
Murine models demonstrate a synergistic production of reactive oxygen species on coexposure to diesel exhaust particles and endotoxin.


OBJECTIVE
It was hypothesized that coexposure to traffic-related particles and endotoxin would have an additive effect on persistent wheezing during early childhood.


METHODS
Persistent wheezing at age 36 months was assessed in the Cincinnati Childhood Allergy and Air Pollution Study, a high-risk birth cohort. A time-weighted average exposure to traffic-related particles was determined by applying a land-use regression model to the homes, day cares, and other locations where children spent time from birth through age 36 months. Indoor levels of endotoxin were measured from dust samples collected before age 12 months. The relationship between dichotomized (<or>or=75th percentile) traffic-related particle and endotoxin exposure and persistent wheezing, controlling for potential covariates, was examined.


RESULTS
Persistent wheezing at age 36 months was significantly associated with exposure to increased levels of traffic-related particles before age 12 months (OR = 1.75; 95% confidence interval, 1.07-2.87). Coexposure to endotoxin had a synergistic effect with traffic exposure on persistent wheeze (OR = 5.85; 95% confidence interval, 1.89-18.13) after adjustment for significant covariates.


CONCLUSIONS
The association between traffic-related particle exposure and persistent wheezing at age 36 months is modified by exposure to endotoxin. This finding supports prior toxicological studies demonstrating a synergistic production of reactive oxygen species after coexposure to diesel exhaust particles and endotoxin. The effect of early versus later exposure to traffic-related particles, however, remains to be studied because of the high correlation between exposure throughout the first 3 years of life.
Ryan
Patrick H
PH
Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA. patrick.ryan@uc.edu
Bernstein
David I
DI
Lockey
James
J
Reponen
Tiina
T
Levin
Linda
L
Grinshpun
Sergey
S
Villareal
Manuel
M
Hershey
Gurjit K Khurana
GK
Burkle
Jeff
J
LeMasters
Grace
G
D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D002675:Child, Preschool; D015331:Cohort Studies; D004731:Endotoxins / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D016017:Odds Ratio; D009820:Ohio; D011446:Prospective Studies; D012135:Respiratory Sounds / Q000209:etiology*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D001335:Vehicle Emissions
D000393:Air Pollutants; D004731:Endotoxins; D001335:Vehicle Emissions