About this Event
"Prenatal Phthalate Exposure and Infant Anogenial Distance: infant size adjustment, evaluating phthalate mistures and exposure patterns"
Public Health/Epidemiology
Committee:
Jennifer J. Adibi (advisor), Department of Epidemiology
Catherine L. Haggerty, Department of Epidemiology
Lu Tang, Department of Biostatistics
Xu Qin, Department of Health and Human Development, School of Education
Abstract:
Anogenital distance (AGD) is the distance from anus to genitalia. It is an important biomarker of adult reproductive disorders, and AGD at birth is used as an endpoint to reflect androgen disruption during fetal period. Phthalates, a group of endocrine disrupting chemicals that are wildly used in plastics, have been shown to be related to altered AGD at birth. Higher prenatal phthalate exposure was associated with shorter AGD in animal studies and several epidemiological studies. However, the results are not consistent, which could be due to several reasons. First, most studies accounted for infant size in their analyses by adjusting for infant size in the model or standardizing AGD by infant size. Infant size is a factor that is highly correlated with AGD and could be an intermediate variable in the association between phthalates and AGD. The approach of controlling for it in analyses has not been evaluated analytically or quantitatively. We simulated the data and quantified the bias of estimate of direct effect when there was unmeasured confounding of infant size and AGD using effect decomposition method. We found that the direct effect of an exposure is a valid estimate only if the unmeasured confounder is weak or does not exist. Second, as humans are exposed to phthalates as a mixture simultaneously, current risk assessments for individual phthalates are insufficient. We examined the mixture effect of phthalates using Bayesian kernel machine regression, and found a decreasing trend for effect of phthalates mixture on AGD in male infants and an increasing trend for female infants. Important contributors of the mixture effect were also identified. Third, the longitudinal effects of phthalates over time have not been reported previously. We used group-based trajectory models to identify phthalate exposure patterns during pregnancy. We also explored maternal predictors of trajectories, and the effect of different trajectories on AGD. Inverse associations were observed between high exposure level trajectories of phthalates and AGD, and the first trimester could be a crucial action period for di-(2-ethyl-hexyl) phthalate metabolites. This work contributes to improved understanding of phthalate effect on fetal reproductive system development and future tailored interventions.
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https://pitt.zoom.us/j/6515672028
Contact Gina Tagliaferri git13@pitt.edu to obtain the meeting password.