Andrea Baccarelli on precision environmental health, the exposome, and the importance of mentors
In a wide-ranging interview with Rick Woychik, director of the National Institute of Environmental Health Sciences (NIEHS), Andrea Baccarelli, dean of the faculty at Harvard T.H. Chan School of Public Health, discussed cutting-edge environmental health research areas such as precision environmental health and exposomics, as well as his personal path to becoming a scientist.
The interview was published in the February/March 2025 edition of NIEHS’ online news outlet, Environmental Factor. Here are some highlights:
What helped Baccarelli pursue a career in scientific research:
The collective answer is definitely my mentors—people who inspired me, acted as role models, and helped guide me when I was heading in the wrong direction.
This started even before high school. I come from a family in Italy where both my parents worked in HR [human resources], and they wanted me to follow in their footsteps. Their idea was that I could stop studying at 14, join the family business [a small HR firm], and that would be enough. My parents didn’t attend college, so for them, it seemed normal to suggest that I skip higher education.
However, one of my teachers, when I was 13 years old, saw my potential and took the effort—during the summer, no less—to visit my parents and explain that I was a great student and that stopping my education at 14 would be a mistake. Thanks to that teacher’s intervention, I kept studying—for another 20 years after that initial conversation.
The promise of precision environmental health (PEH) [a field that uses environmental exposures, genetics, and data science to study the environmental causes of disease and develop prevention and intervention strategies]:
As a doctor, I’ve seen that health doesn’t only happen in the doctor’s office. In fact, the focus in that setting tends to be on disease—people are sick, and it’s our job to fix them. But true health develops during the months, years, and lifetime before someone gets a diagnosis—the times when we are best poised to intervene. So, a big part of PEH is helping individuals avoid disease altogether. That is far better than treating illness after it occurs.
The importance of studying the exposome [the totality of environmental exposures an individual experiences over their lifetime]:
The exposome has been a significant emphasis in environmental health over the past five years. Years ago, when I started my postdoctoral training and my first faculty position, each of us focused on one exposure at a time. There was an expert in particulate matter, another in dioxins, and so on. Each study addressed only a single exposure. However, we now recognize that our health is shaped by a combination of many exposures, both negative and positive. … Behind this approach is the understanding that exposures interact with one another. Exposure A alone and exposure B alone might not have the same effect as when they occur together, where their interaction could create a synergy that must be studied and understood.
In terms of tools to study the exposome, the ability to measure hundreds or even thousands of chemicals simultaneously has advanced the field and encouraged us to move beyond the “one chemical at a time” framework. For example, here at Harvard, we are launching a new exposome lab that will … measure up to 1,000 chemicals at once.
Baccarelli’s innovative research on extracellular vesicles (EVs):
Extracellular vesicles are fascinating because they offer a way to study tissues that we can’t easily access through traditional methods. These tiny, membrane-bound vesicles are released by all cells and circulate in the blood. They carry molecular messages, like RNA, proteins, and lipids, that reflect the health and function of their cells of origin. For instance, neurons in the brain release vesicles into the bloodstream, allowing us to study brain health using just a blood sample. Similarly, vesicles from lung cells or liver cells can provide insights into those organs. This noninvasive approach, often called a “liquid biopsy,” has the potential to revolutionize how we monitor and understand organ health.
In my lab, we’ve developed techniques to isolate vesicles from neurons, astrocytes, and other cells, which enables us to analyze environmental impacts on those tissues. For example, we can study how air pollution affects brain cells by analyzing neuron-derived vesicles from blood samples.
EVs are essentially a previously hidden communication system between cells, and unlocking their secrets could transform both environmental health and biomedical research.
Read the full interview in Environmental Factor: Epigenetics and the exposome: A new era of disease prevention
