title: Association of time-location patterns with urinary cotinine among asthmatic children under household environmental tobacco smoke exposure.
abstract: BACKGROUND
  Environmental tobacco smoke (ETS) is a hazardous component of indoor air, and may increase the risk of respiratory diseases, atherosclerosis and otitis media in children. In this study, we explored the relationship between time inside the house, ETS exposure and urinary cotinine level, and also determined the association of time inside the house on asthma phenotypes when children exposed to ETS.
  
  
  METHODS
  A total of 222 asthmatic children and 205 non-asthmatic controls were recruited in the Genetic and Biomarker study for Childhood Asthma (GBCA). Structured questionnaires and time-location pattern questionnaires were administered by face-to-face interview. Urinary cotinine was measured by liquid chromatography tandem mass spectrometry (LC/MS/MS). The level of household ETS exposure was assessed using the cotinine/creatinine ratio (CCR).
  
  
  RESULTS
  In general, urinary cotinine and CCR were higher in subjects exposed to household ETS than those who never had ETS at home. A significant positive relationship was found between average time inside the house and urinary CCR in asthmatic children with current ETS at home (β=0.278, p=0.02). After adjustment for age and gender, average time inside the house was positively related to severe wheeze in asthmatic children with household ETS within 1 month (OR: 1.26, 95%: 1.02-1.64).
  
  
  CONCLUSIONS
  Our study suggests that the major source of ETS exposure for children is due to longer period of exposures among children living with adult smokers at home. Home-smoking restrictions that effectively prevent children from being exposed to ETS would be worthwhile.
authors.affiliation: Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan.
authors.forename: Kuan-Yen
authors.initials: KY
authors.lastname: Tung
authors.forename: Kuen-Yuh
authors.initials: KY
authors.lastname: Wu
authors.forename: Ching-Hui
authors.initials: CH
authors.lastname: Tsai
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Su
authors.forename: Chien-Han
authors.initials: CH
authors.lastname: Chen
authors.forename: Ming-Hung
authors.initials: MH
authors.lastname: Lin
authors.forename: Yang-Ching
authors.initials: YC
authors.lastname: Chen
authors.forename: Wen-Chia
authors.initials: WC
authors.lastname: Wu
authors.forename: Yungling Leo
authors.initials: YL
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D016902:Air Pollution, Indoor / Q000009:adverse effects / Q000032:analysis*; D001249:Asthma / Q000209:etiology* / Q000652:urine*; D002648:Child; D003367:Cotinine / Q000652:urine*; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D012044:Regression Analysis; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution / Q000009:adverse effects / Q000032:analysis*
chemical_list: D014028:Tobacco Smoke Pollution; D003367:Cotinine