Indoor pollutant exposures modify the effect of airborne endotoxin on asthma in urban children.
BACKGROUND
The effect of endotoxin on asthma morbidity in urban populations is unclear.


OBJECTIVE
To determine if indoor pollutant exposure modifies the relationships between indoor airborne endotoxin and asthma health and morbidity.


METHODS
One hundred forty-six children and adolescents with persistent asthma underwent repeated clinical assessments at 0, 3, 6, 9, and 12 months. Home visits were conducted at the same time points for assessment of airborne nicotine, endotoxin, and nitrogen dioxide (NO2) concentrations. The effect of concomitant pollutant exposure on relationships between endotoxin and asthma outcomes were examined in stratified analyses and statistical models with interaction terms.


RESULTS
Both air nicotine and NO2 concentrations modified the relationships between airborne endotoxin and asthma outcomes. Among children living in homes with no detectable air nicotine, higher endotoxin was inversely associated with acute visits and oral corticosteroid bursts, whereas among those in homes with detectable air nicotine, endotoxin was positively associated with these outcomes (interaction P value = 0.004 and 0.07, respectively). Among children living in homes with lower NO2 concentrations (<20 ppb), higher endotoxin was positively associated with acute visits, whereas among those living in homes with higher NO2 concentrations, endotoxin was negatively associated with acute visit (interaction P value = 0.05). NO2 also modified the effect of endotoxin on asthma symptom outcomes in a similar manner.


CONCLUSIONS
The effects of household airborne endotoxin exposure on asthma are modified by coexposure to air nicotine and NO2, and these pollutants have opposite effects on the relationships between endotoxin and asthma-related outcomes.
1 Division of Pediatric Allergy and Immunology and.
Elizabeth C
EC
Matsui
Nadia N
NN
Hansel
Charles
C
Aloe
Allison M
AM
Schiltz
Roger D
RD
Peng
Nathan
N
Rabinovitch
Mary Jane
MJ
Ong
D'Ann L
DL
Williams
Patrick N
PN
Breysse
Gregory B
GB
Diette
Andrew H
AH
Liu
D000293:Adolescent; D000393:Air Pollutants / Q000009:adverse effects* / Q000032:analysis; D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis; D001249:Asthma / Q000209:etiology* / Q000628:therapy; D015142:Baltimore; D002648:Child; D002675:Child, Preschool; D004731:Endotoxins / Q000009:adverse effects* / Q000032:analysis; D004784:Environmental Monitoring; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects* / Q000032:analysis; D008297:Male; D015233:Models, Statistical; D009538:Nicotine / Q000009:adverse effects* / Q000032:analysis; D009585:Nitrogen Dioxide / Q000009:adverse effects* / Q000032:analysis; D011446:Prospective Studies; D014504:Urban Health
D000393:Air Pollutants; D004731:Endotoxins; D009538:Nicotine; D009585:Nitrogen Dioxide