Early life exposure to phthalates and immune response at one year of age in the Canadian healthy Infant Longitudinal Development (CHILD) birth cohort

摘要

Phthalates are implicated as immune-modulators in animal and human diseases including asthma and allergy. The Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort is a national study examining how the environment interacts with a child's genetics, immune system and other personal characteristics to cause these diseases. The 3,300 children in the cohort currently range from 6 mo. to 4 yrs. Comprehensive exposure assessment from mid-gestation through 5 yrs includes a home assessment, serum, urine and house-dust sampling, land-use regression model estimates of ambient air pollution and repeated questionnaires in multiple domains in an effort to estimate important exposures during key periods of development. Exposure questionnaire and home assessments were used to characterize potential sources of phthalate metabolite levels at age 3 mo. in the first 1,539 CHILD subjects. Seven phthalate metabolites were measured. The data suggest several potential sources of exposure including use of plastic food storage containers, home consumer products and moisture in the home. Preliminary analysis on the first 597 children with urinary phthalate metabolite measurements at both 3 and 12 mo. and allergy skin testing at 12 mo. suggests a role for DBP in the development of atopy. Logistic regression model results (uncorrected for co-variates) suggest that subjects who were in the highest quartile for urinary MBP concentration at both 3 mo. and 12 mo. have a higher risk of sensitization (defined as＞=2 mm weal to＞=1 allergen) compared to other subjects. Sensitization to a food allergen (OR=2.0, CI: 1.01-3.51); sensitization to any allergen (OR=1.75, CI: 1.00-2.97). No such relationship was found for the other 6 metabolites tested. This Canadian national birth cohort demonstrates ubiquitous phthalate exposures in the first months of life. Estimates of some phthalate exposure can be made using questionnaires about product use in the home environment. Due to the longitudinal nature of the exposure assessment we will be able to track these relationships over time. Preliminary analyses suggest a role for DBP in the development of atopy at one year, but these results need to be confirmed once data collection has finished.