Next Generation Risk Assessment of Phthalates: Integrating New Approach Methods and Exposomic Approaches using a Washington State Agricultural Community Cohort Study

Abstract

This dissertation explores phthalate exposure trends, associated health effects, and using new approach methods (NAMs) to fill data gaps for an agricultural community cohort in the Lower Yakima Valley of Washington State. Phthalates are a ubiquitous group of chemicals present in the environment. Only a few have been thoroughly analyzed and approaches to evaluating their risks are currently being evaluated by federal agencies. The first objective of this dissertation was to utilize the University of Washington Center for Child Environmental Health Risks Research (CHC) dust exposome, open data, and computational toxicology tools to assess the potential for hazards of phthalates based on real-life exposure estimates. We found that open data sources can be used to screen chemicals for risk assessment purposes and are relevant for the CHC agricultural community cohort. The second objective was to determine whether children’s product reporting requirements and regulations at the state and federal level are associated with longitudinal changes in phthalate concentrations. Based on samples of household dust collected from the Child Health Center (CHC) cohort in 2005 and 2011, we observed significant longitudinal and seasonal changes in phthalate concentrations for most of the 16 study phthalates. These changes may be attributable to increased regulations, agricultural spray activities, or other environmental and behavioral factors affecting levels in dust. Collectively, this research demonstrates increased utility of NAMs to promote next generation risk assessment approaches in data-poor chemicals, as well as underscores the complexities of environmental exposures to phthalates that are dynamic in nature.