UC Riverside

Organophosphate esters (OPEs) are a class of semi-volatile organic compounds that are used as flame retardants, plasticizers, and anti-foaming agents. Due to their ubiquitous use and ability to migrate out of end-use products, elevated concentrations of OPEs have been detected within indoor dust samples, a prevalent source for human exposure. Similar to the built environment, organophosphate esters are introduced into vehicles as plasticizers and flame retardants and have the potential to migrate and accumulate within vehicle dust. While human exposure to OPEs via indoor dust is well characterized, more information is needed to address the extent of OPE exposure and subsequent risk with time spent in vehicles and understand mechanisms underlying OPE-specific toxicity during early development. Therefore, the primary objectives of this dissertation are to 1) increase our understanding of the mechanisms of developmental toxicity for triphenyl phosphate (TPHP), a high-production volume OPE, 2) measure human exposure to OPEs within a population that spends a significant amount of time in personal transportation, and 3) calculate the risk associated with ingestion of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), another high-production volume OPE, within car interiors. For Aim 1, using whole-embryo exposures and a combination of mRNA-sequencing, phenotypic assessments, neutral lipid staining, and metabolomics, TPHP was shown to result in adverse effects on the liver, lipid abundance, and osmoregulation within the developing zebrafish. For Aim 2, using silicone wristbands to monitor personal OPE exposure within a subset of commuter vs. non-commuter undergraduate students at the University of California, Riverside (UCR), we identified that longer commutes were associated with increased TDCIPP exposure. Building on the results of Aim 2, in Aim 3 we demonstrated that a reduction in car dashboard dust does not affect increased TDCIPP exposure as a result of longer time spent in vehicles. Lastly, for Aim 4, a risk assessment identified that the ingestion of TDCIPP from car interior dust does not pose a cancer risk for commuters in California. Overall, our findings contribute to our understanding of human OPE exposure in relation to commute times and how TPHP – a ubiquitous OPE – may alter embryonic development.