Deciphering the chemical cocktail of daily life
Environmental chemist Nina Zhao seeks to understand the chemicals in our lives, and why people respond so differently to the same drug, pesticide, or pollutant.
We live in a chemical world. I want to understand all the chemical exposures in our daily life and how that connects to our health.
Scientists have characterized a lot of plasticizers, PFAS, pesticides, and other chemicals, but there are many more chemicals in the environment that we don’t know about.
I have always been interested in human-made chemicals, how they ended up in the environment, and whether they are toxic to humans or wildlife. For example, during my PhD studies, we identified a single chemical out of thousands in tire rubber that was leaching from roadways and killing coho salmon.
During my postdoc, my research focus shifted more to human health. Using public mass spectrometry data collected by researchers around the world, my team and I characterized thousands of drug metabolites – the byproducts left over when your body breaks down a drug – at once.
At Stanford, I am building a research program that uses such computational approaches to make the investigation into environmental chemicals faster and more systematic. The big problem that my lab seeks to address is how to map this largely hidden chemical world and explain why the same chemical exposure may affect one person or species very differently from another. I want to achieve better predictive power for the health outcome of each individual. Now with the help of AI, what took months in the past probably takes me only days to weeks.
A project we are currently pursuing asks how gut microbes transform medicines. We are testing approximately 200 drugs with a defined community of human gut microbial species, then using mass spectrometry to detect the new molecules that the microbes produce. The goal is to create a systematic map of microbial drug metabolism rather than studying one drug or one microbe at a time.
We plan to publish our discoveries as an open-access library so other researchers can better understand drug metabolism in their own datasets. Although there is still a long way to go, we hope our data can contribute to the precise modulation of people’s gut microbiomes to make drugs more effective for – or less toxic to – each individual person.
Drugs have also been recognized as major contaminants in water bodies. In addition to supporting human health, our data will help researchers understand the environmental impacts of these metabolites and design chemicals that minimize risks to both people and ecosystems. There are many researchers at the Doerr School of Sustainability working on water contamination issues and water treatment technology that mass spectrometry can play a role in, so there’s a lot of natural collaboration I can build here. I’m really looking forward to that.
- As told to Katie Clary
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