Exposure to secondhand tobacco smoke enhances respiratory symptoms and responses to animals in 8,819 children in kindergarten: results from 25 districts in northeast China.
BACKGROUND
Experimental data suggest that asthma exacerbation by allergens is enhanced by exposure to environmental tobacco smoke (ETS); however, there is little supporting epidemiologic evidence. To our knowledge, few studies have assessed respiratory symptoms and allergies in this context.


OBJECTIVE
To evaluate whether the association of exposure to animals (indicators of allergen and endotoxin exposure) with asthma-related symptoms is modified by ETS exposure in Chinese children.


METHODS
A cross-sectional study of 8,819 children in kindergarten was conducted in 25 districts in northern China. Information on respiratory health and exposure to indoor allergens was obtained using a standard questionnaire from the American Thoracic Society.


RESULTS
Among the children with ETS exposure in utero, the effects of exposure to animals were significant with respect to persistent cough [adjusted odds ratio (OR) 1.83; 95% confidence interval (CI) 1.12-2.99] and persistent phlegm (adjusted OR 2.40; 95% CI 1.28-4.54). The combined effect of in utero ETS exposure and animal exposure on doctor-diagnosed asthma was approximately as expected on the basis of their independent effects on an additive scale. There was no interaction between animal exposure and ETS exposure in the first 2 years of life or current ETS exposure.


CONCLUSIONS
This study provides evidence that animal and ETS exposure increases the risk of asthma-related symptoms in children in kindergarten. ETS exposure in utero did modify the effect of animal exposure on persistent phlegm and persistent cough but not on doctor-diagnosed asthma among children.
Department of Biostatistics and Epidemiology, School of Public Health, China Medical University, PR China. ghdong @ mail.cmu.edu.cn
Guang-Hui
GH
Dong
Wan-Hui
WH
Ren
Da
D
Wang
Zong-Hua
ZH
Yang
Peng-Fei
PF
Zhang
Ya-Dong
YD
Zhao
Qin-Cheng
QC
He
D000485:Allergens / Q000009:adverse effects*; D000818:Animals; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003371:Cough / Q000453:epidemiology / Q000209:etiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D057805:Pets / Q000276:immunology; D011247:Pregnancy; D012135:Respiratory Sounds / Q000209:etiology; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology / Q000209:etiology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D000485:Allergens; D014028:Tobacco Smoke Pollution