On a hot day in July 2022, Professor Jay Graham hit the beach with an iPad in hand. He and Meredith Klashman, a student in the UC Berkeley-UCSF Joint Medical Program, approached a number of women at Santa Cruz’s Cowell Beach, asking them to join their study.
Some women were shocked, while others felt affirmed in a long-held suspicion when they heard the study’s hypothesis: that swimming may heighten their risk of urinary tract infection (UTI).
The hypothesis seems to be right. The study found that recreational contact with ocean water was correlated with higher risk of UTI symptoms at Santa Cruz beaches over the summer of 2022. Klashman, who led the study, coauthored the manuscript that is now under review for publication with Graham, who sits in Berkeley Public Health’s Environmental Health Sciences division.
Klashman, who will complete her MD in May, once worked in aquatic toxicology at Santa Clara’s wastewater treatment plant. She spearheaded the study after recent evidence suggested that UTIs may be caused by environmental contamination, rather than personal behaviors around wiping, catheterization, and sexual intercourse, as was previously thought.
Klashman suspected that one source of UTIs could be upstream pollution that flows into sea water. To test this idea, she sought Graham’s guidance, and together they devised an epidemiological study of three Santa Cruz beaches.
Klashman and Graham started the 2022 study in partnership with Santa Cruz County’s Environmental Health Agency and Santa Cruz City’s Department of Public Works. Klashman and Denna Hadipour, who joined through UC Berkeley’s Undergraduate Research Apprentice Program (URAP), collected the data on Cowell Beach, Santa Cruz Main Beach, and Seabright State Beach.
For about four hours, two to three days a week, they walked the beaches, asking women to enroll. Everyone who accepted would fill out a survey on an iPad. Twenty-four hours later, the team followed up: asking if the women had gone into the ocean, if so, how far they went in, and whether they swallowed any water.
Several weeks later, the team followed up once again, to ask if the participants had UTI symptoms in that time period. Each week during the 12-week study, Santa Cruz City and County tested the water quality. Each of the 600 participants was given a beach ball as an incentive.
Klashman noted that recruitment had some challenges.
“When you’re recruiting for a study about potential water contamination, it can cause a lot of anxiety in study participants, so we needed to make sure we were having those conversations thoughtfully,” Klashman said. “It was also a space to inform participants about where to check for warnings at the beach or online. That was an important and challenging part of this work.”
Hadipour felt the same. She noted that the politically charged atmosphere around women’s health added a layer of difficulty.
“It was a pretty polarized time in our country because it was right after Roe v. Wade was overturned, so the toughest part was mitigating those reactions,” she said.
These challenges did not stop the team from finding a significant result: Not only was recreational water use correlated with higher risk of UTI symptoms, but more exposure to the water, by swimming farther out or swallowing water, caused greater risk of both diarrhea and UTIs.
The water quality tests also showed that the water was contaminated with E. coli. This is key because uropathogenic E. coli are the dominant bacterial species in UTIs, causing them 80% of the time.
Prof. Jay Graham and Dr. Meredith Klashman recruiting research subjects at a Santa Cruz beach.
Recreational water can also be a source of eye and ear infections and even sinus infections. The worst-case scenario, Graham noted, are bloodstream infections, which are caused by the same organisms as UTIs and can be deadly, although very rare.
Graham said that E. coli generally seeps into recreational water when infrastructure—such as sewage treatment plants—is overwhelmed, especially from heavy rain, and allows untreated human sewage into water bodies.
“We don’t really understand the extent of contributions of E. coli being made,” Graham said. “But we know there’s wildlife, like birds defecating on beaches, septic tanks that overflow because there is little enforcement to maintain them, and wastewater treatment systems that probably treat their wastewater pretty well, but release a large load of E. coli occasionally, especially if there is a big rain event.
“My guess is the main source is untreated human sewage that makes its way into these water bodies because of our infrastructure system’s inability to capture and treat that wastewater,” he said.
The problem is likely exacerbated by atmospheric rivers and flooding that seem to have become the new normal in Santa Cruz. Graham noted that severe rain brings the highest contamination risk just after a drought; because waste that has built up during a drought is released, and overwhelms the water systems.
Klashman emphasized that this problem is a common problem, not limited to Santa Cruz. Cowell Beach, for example, has long been known for water contamination. But the study showed that the beach’s water quality has improved. In fact, Klashman noted that the water quality was not very different from the city beaches of San Diego, Los Angeles, or San Francisco.
“I see the results of our study as reflective of a more global problem,” Klashman said. “Swimming in saltwater that receives treated wastewater and other sources of fecal contamination is something that we don’t really know the risks of,” said Klashman.
Graham believes that the solution lies in improving aging infrastructure. As heavy rain and flooding become more common as a result of climate change, septic and wastewater systems, many already decades old, will continue to be overwhelmed unless upgraded.
“We don’t make enough investment in that infrastructure to protect public health,” Graham said. “There’s a lot more that needs to be done to help people understand the importance of this infrastructure.”
Klashman stressed the importance of more research: “Why, for instance, were people who swallowed water at the highest risk?” she said. “We need to gather more information on uropathogenesis and the role of gut colonization and environmental sources.”
Klashman and Graham would like to conduct another study on environmental pollution as a cause of UTIs. They plan to again partner with Santa Cruz Public Works, repeating the water sampling and epidemiological study, but adding molecular analysis of the E. coli found in water samples and that found in UTIs confirmed through testing.
If the analysis determines them to be the same organism, then they can definitively say exposure to E. coli in recreational water can cause UTIs.
For Graham, this is one step toward thinking more about how the environment impacts our health. “We have historically focused on what the individual is doing to cause UTIs, but now we’re finally starting to ask where the E. coli came from in the first place,” he said.