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A2801 - The Canadian Healthy Infant Longitudinal Development (child) Birth Cohort: Aeroallergens, Air Pollution and Risk of Atopy and Wheeze
Author Block: C. Sierra-Heredia1, R. Allen1, S. B. Henderson2, F. A. Coates3, J. Brubacher1, H. Sbihi2, M. Brauer2, M. R. Sears4, J. Brook5, J. Scott6, D. Lefebvre7, P. Subbarao8, A. B. Becker9, P. Mandhane10, S. Turvey11, the CHILD Study investigators, T. K. Takaro1; 1Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada, 2School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada, 3Aerobiology Research Laboratories, Nepean, ON, Canada, 4St Josephs Hosp, Hamilton, ON, Canada, 5Air Quality Research Division, Environment Canada, Toronto, ON, Canada, 6Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada, 7Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada, 8Respiratory Medicine, Hosp for Sick Children, Toronto, ON, Canada, 9Department of Pediatrics And Child Health, Univ of Manitoba, Winnipeg, MB, Canada, 10Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada, 11Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
Rationale: Knowledge of early life determinants of asthma and allergy could offer opportunities for prevention of these prevalent chronic childhood conditions. In addition to genetic risk, environmental factors including aeroallergens and air pollution may contribute to the development of childhood atopy and asthma. We studied the onset of atopy and wheezing in relation to exposure to Ambrosia pollen (ragweed) and Traffic-Related Air Pollution (TRAP) in one city from a Canadian birth cohort.
Methods: The Canadian Healthy Infant Longitudinal Development (CHILD) enrolled pregnant mothers between 2008 and 2012 from four major Canadian cities, and is following 3495 eligible children, including 770 from Toronto, where pollen data were available. We examined atopic status of children at age three years by skin-prick test, and evidence of wheeze by repeated questionnaires and clinical examination. We assessed risk of exposure to pollen (tertiles) and/or TRAP on atopy, wheeze by logistic regression, controlling for sex, maternal education, family income, parental atopy and two indoor exposures (mold and pets).
Results: In a preliminary analysis of 608 children with full early-life exposure and atopy data, 80 were positive to at least one food or aeroallergen (52.5% males) and 65 reported wheeze by age 3 years(63.1% males). Exposure to Ambrosia pollen during pregnancy was associated with:1) increased risk of atopy with average exposure during pregnancy (middle tertile, 4.9-5.4 pollen grains/m3) [OR= 2.08; 95% CI: 1.14- 3.9]; pollen exposure during the first year of life [OR= 2.17; 95% CI: 1.14- 4.2]; exposure to TRAP (> 13.7 ppb nitrogen dioxide) during pregnancy [OR= 1.95; 95% CI: 1.05- 3.7], and during the first year of life [OR= 2.07; 95% CI: 1.07- 4.1] (unadjusted). 2) increased risk of wheeze with the highest tertile of exposure to pollen (>5.4 pollen grains/m3) and TRAP (> 13.7 ppb nitrogen dioxide) during pregnancy and first year of life [OR= 3.17; 95% CI: 1.01- 10.88] (fully adjusted).Conclusions: Children with an average exposure higher than 4.9 pollen grains/m3 for Ambrosia pollen and 13.7 ppb for TRAP during pregnancy were more likely to develop wheeze by age 3. These early exposures when the immune system is developing may contribute to the future risks of allergic conditions. The statistical power in this single city is limited. More robust exploration of these risk factors will be possible with additional data for the three other cities in CHILD.