UC Berkeley

We are exposed to multiple chemicals throughout our lives from the air we breathe, the water we drink, the food we eat, the products we use, and the social context in which we live. These factors are interconnected and each affects our vulnerability and resilience in the face of cumulative exposures and their potential health implications. Yet we have little guidance on how to capture and quantify multiple chemicals in a construct that is truly relevant for human health.

In this dissertation, I address one piece of this complex picture by advancing a method that combines endocrine-disrupting chemicals into a cumulative framework for use in exposure science, risk assessment, and epidemiology research. The metric relies on benchmark doses and recommendations set forth by a 2008 National Academy of Sciences (NAS) report, Phthalates and Cumulative Risk Assessment: The Tasks Ahead.

In Chapter 1, I describe the historical backdrop of cumulative methodologies in the United States, introduce the concept of endocrine-disrupting chemicals and anti-androgenic phthalates, and describe why they are suitable candidates for cumulative assessment. I develop a potency-weighted cumulative metric for phthalates exposure in Chapter 2, providing rationale, sample calculations, and an evaluation of the method’s limitations by comparing the metric across racial/ethnic groups of U.S. reproductive-aged women. Chapter 3 includes another use of the metric to characterize phthalates exposure in a small cohort of Vietnamese immigrant nail salon workers. In Chapter 4, I use the metric to investigate dietary sources of cumulative phthalates exposure in U.S. children, adolescents, and adults; namely, by comparing consumption of food prepared away from home (i.e. dining out) to eating food prepared at home (i.e. purchased at a store). Chapter 5 concludes the dissertation by reflecting on the strengths and challenges of the cumulative exposure metric, providing recommendations for how to resolve some of its limitations and apply the method in future work.