From tropical forests to smallholder farms, Indiana University’s Michael Wasserman is tracing how naturally occurring and human-made chemicals move through ecosystems, and how agricultural change may impact health for both people and wildlife.
Wasserman, Associate Professor of Anthropology and Human Biology in the College of Arts and Sciences at IU Bloomington, focuses his research on how pesticides and other environmental chemicals interact with the endocrine system in primates and humans. The endocrine system is the network of glands that release hormones to regulate many biological processes in the body. Wasserman’s earlier studies documented chemical exposure in wild primates living far from direct human activity. Now, the latest phase of Wasserman’s research places farming communities at the center of the picture, connecting household practices to environmental and biological exposure across entire landscapes.
His research began by investigating naturally occurring plant chemicals in tropical forests, where primates ingest leaves and other foods with hormone-mimicking compounds.
“At a broad level, what I work on are interactions between primates and exogenous, or external, chemicals that interact with the endocrine system,” Wasserman said. “Chemicals coming from the environment into the body that can mimic hormones, bind to hormone receptors and have physiological and potentially behavioral effects because of that activity.”
After joining IU, Wasserman expanded his work to include anthropogenic chemicals through a collaboration with environmental chemist Marta Venier at IU’s O’Neill School of Public and Environmental Affairs. That partnership helped launch one of the few primate-focused studies examining pollution exposure in wild animals.
“When we started it, we didn’t really know what we were going to find,” Wasserman said. “There just aren’t many people studying pollution exposure in primates.”
Working in forested sites in Costa Rica and Uganda, his research team detected pesticides and flame retardants in the air. Using chemical analysis of primate fecal samples, they confirmed that monkeys and apes were not only encountering these pollutants but had ingested them.
Those findings raised broader questions: Where were the chemicals coming from, and how were human activities shaping exposure across ecosystems? To answer those questions, Wasserman adjusted the focus of his research beyond the forest canopy and into nearby farming communities.
With support from a more than $1 million National Science Foundation grant through the Dynamics of Integrated Socio-Environmental Systems (DISES) program, the project now focuses on 12 communities surrounding Kibale National Park in western Uganda.
In Phase 1, completed last year, researchers surveyed roughly 600 households about farming practices, pesticide use, environmental change and access to agricultural products.
“Uganda is going through a major agricultural transition,” Wasserman said. “Moving away from traditional farming methods to more intensive pesticide and fertilizer use to increase productivity.”
Phase 2, now underway, follows 108 households over an entire year to capture seasonal variation in farming and exposure.
“Each household keeps a diary of farming practices, what chemicals they use, when they use them and what crops they’re applied to,” Wasserman explained.
At the same time, the research team is measuring exposure across three interconnected areas: people, wildlife, and the environment.
Human exposure is assessed using silicone wristbands worn by study participants, which absorb airborne and skin-contact chemicals encountered during daily life. Environmental exposure is measured through air sampling in and around communities and farms. Wildlife exposure is assessed through fecal samples collected from primates living in and around the national park.
“We suspect that farmers are using these pesticides more and more because they’re perceiving environmental risk that is changing due to shifts in climate, dealing with more fungal growth, more insect pests,” Wasserman explained. However, some farmers involved in the study are reporting symptoms like nausea, burning eyes, or loss of appetite.
“They have to maintain food productivity for food security, but also, everyone we’ve talked to, from households to government officials, is interested in these tradeoffs with health effects from exposure,” he noted.
The long-term goal is not simply documentation but practical guidance.
“We want to inform communities about what levels of exposure are taking place and suggest ways to reduce that exposure,” Wasserman said. “That protects human health and wildlife health.”
The project plans to share results through community meetings and Ugandan media outlets once the study concludes.
Importantly, this work reflects Wasserman’s interdisciplinary background in anthropology, zoology and environmental science, as well as a research team that spans environmental chemistry, human geography, climatology and primatology.
“The key to this project is bringing different disciplines together,” he said. “That’s what allowed us to move out of the forest and work with communities, while still keeping primates at the center of the ecological picture.”
Moreover, IU students play a central role in the research. Undergraduate and graduate researchers participate in fieldwork across multiple countries, gaining experience that leads to careers in academia, government and health fields.
“I really think experiential learning is critical,” Wasserman said. “Independent research, study abroad opportunities, and fieldwork give students a way to see how science connects directly to people’s lives.” As Director of the Human Biology Program (HUBI), he is working to expand these experiences for undergraduates in HUBI and across Bloomington and other IU campuses.
As agricultural systems continue to intensify worldwide, the project’s findings are expected to resonate far beyond Uganda, offering a clearer picture of how human decisions ripple through shared environments, and across species.