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Early life exposure to phthalates in the Canadian Healthy Infant Longitudinal Development (CHILD) study: a multi-city birth cohort

Abstract

Background

Few studies have examined phthalate exposure during infancy and early life, critical windows of development. The Canadian Healthy Infant Longitudinal Development (CHILD) study, a population-based birth cohort, ascertained multiple exposures during early life.

Objective

To characterize exposure to phthalates during infancy and early childhood.

Methods

Environmental questionnaires were administered, and urine samples collected at 3, 12, and 36 months. In the first 1578 children, urine was analyzed for eight phthalate metabolites: mono-methyl phthalate (MMP), mono-ethyl phthalate (MEP), mono-butyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-3-carboxypropyl phthalate (MCPP). Geometric mean (GM) concentrations were calculated by age, together with factors that may influence concentrations. Trends with age were examined using mixed models and differences within factors examined using ANOVA.

Results

The highest urinary concentration was for the metabolite MBP at all ages (GM: 15–32 ng/mL). Concentrations of all phthalate metabolites significantly increased with age ranging from GM: 0.5–15.1 ng/mL at 3 months and 1.9–32.1 ng/mL at 36 months. Concentrations of all metabolites were higher in the lowest income categories except for MEHP at 3 months, among children with any breastfeeding at 12 months, and in urine collected on dates with warmer outdoor temperatures (>17 °C), except for MBzP at 3 months and MEHP at 3 and 12 months. No consistent differences were found by gender, study site, or maternal age.

Conclusions

Higher phthalate metabolite concentrations were observed among children in lower income families. Examination of factors associated with income could inform interventions aimed to reduce infant phthalate exposure.

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Acknowledgements

We are grateful to the CHILD study families for their participation and the entire CHILD study team including interviewers, research assistants, nurses, computer and laboratory technicians, clerical workers, research scientists, volunteers, managers and receptionists. We also thank Jerome Lavoue for his support with NDExpo. Funding for this study was provided through the Canadian Institutes of Health Research (CIHR), Allergy, Genes and Environment (AllerGen) Network of Centers of Excellence and the Government of Canada’s Chemical Management Plan.

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Navaranjan, G., Takaro, T.K., Wheeler, A.J. et al. Early life exposure to phthalates in the Canadian Healthy Infant Longitudinal Development (CHILD) study: a multi-city birth cohort. J Expo Sci Environ Epidemiol 30, 70–85 (2020). https://doi.org/10.1038/s41370-019-0182-x

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