Residents of Tucson's south side might remember drinking from the garden hose and bathing their children in tap water. For years, that water was contaminated with industrial solvents that had leaked into the groundwater their wells drew from.
But four decades after Tucson stopped serving contaminated water on its south side, one in three residents who drank it are still reporting symptoms of post-traumatic stress, a new University of Arizona study has found.
The researchers surveyed 363 people. Among those who lived, worked or went to school in the contaminated area before 1981, or whose parents did, 34% reported enough symptoms to reach a screening threshold clinicians use to flag post-traumatic stress. The survey asked whether worry about contamination had led to certain symptoms in the past month – such as avoiding places that brought contamination to mind, sleeping badly or feeling cut off from other people. Reporting four or more of the seven criteria was considered the threshold.
The study, published in the Journal of Health Psychology , is a collaboration between the Department of Psychology and the Mel and Enid Zuckerman College of Public Health . It was led by Harrison Schmitt, now an assistant professor of psychology at Skidmore College, who conducted the study for his U of A dissertation.
"It was pretty striking how long the impact of this seems to have been," said Daniel Sullivan, the study's senior author and an associate professor in the Department of Psychology.
Sullivan's team has since given the same screening to Los Angeles residents in 2025 whose homes were threatened by wildfires. About 35% of them scored at or above the threshold, which is roughly what the researchers found in Tucson. Sullivan, who studied tornado survivors in Kansas for his own dissertation, has always been interested in looking at technological disasters, which unfold over years and that have no single day of visible damage. He spent years going to community meetings on the Southside before the survey was designed.
Starting in the summer of 2022, about 20 undergraduate volunteers collected the survey door to door in pairs. Surveys were available in English and Spanish, with each pair including a bilingual student. Many volunteers, who were from the south side, learned during the surveys that their own relatives and neighbors had lived through the contamination and rarely talked about it, Sullivan said.
They also selected a neighborhood for comparing the results they obtained. The neighborhood matched the south side on income, race and ethnicity and housing, so that the differences in results would point only to the contamination rather than to the other pressures both areas face.
"You're talking to people and it's every other house. At a community level, the findings are validating. At an institutional level, it still feels like, 'When is it going to be enough evidence to act?'" said Elizabeth Yee, study co-author and a Ph.D. student in psychology who did the survey as an undergraduate and later led the effort to report the findings back to residents.
The researchers describe the pattern as collective trauma – a devastating event shared across a community and passed down through common experiences and stories rather than being experienced only personally.
The survey was shaped in part by the residents themselves. Alisha Vasquez, a disability cultures folklorist at the Southwest Folklife Alliance and a co-director of Tucson's Mexican American Heritage and History Museum, helped connect researchers with south side residents and convened a community meeting that shaped how the results of the survey are being used for political action.
"They fought their entire lives, not just for restitution, but to be heard and believed," Vasquez said.
Working with Vasquez and other community activists, the research team has presented the results to Tucson Water, the Environmental Protection Agency and the Tucson Mayor and Council, which passed a resolution urging the Pima County Health Department to address the impacts.
"Tucson was a historic leader in fighting for recognition of these issues," Sullivan said. "This is a community with a lot of resilience."
Journal of Health Psychology
Survey
People
Collective trauma in the wake of historical environmental contamination
12-Aug-2026
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.