For almost six years, Dr. Scott Bartell has been investigating the effects that per- and polyfluoroalkyl substances (PFAS) have on the health of Orange County residents after high levels of PFAS were detected in drinking water supplies.
PFAS is a family of chemicals known for their slow breakdown. Commonly known as forever chemicals, they were first developed in 1930, but their widespread use began in 1950.
Bartell, an environmental occupational health professor, is the lead investigator of UCI’s PFAS Health Study, an extension of the Centers for Disease Control and Prevention (CDC)’s national Multi-Site Health Study on PFAS. The CDC’s study identified multiple sites across the US that had potential PFAS exposure. The study focused on the effects that different PFAS compounds and exposure levels have on health.
Bartell became involved with the study in 2019 when the CDC requested applications. He applied during the spring of that year, and the CDC announced that they would be working with seven study teams across the country in late 2019.
“I said ‘Okay I should definitely apply for this, but let me look and find out where the nearest communities are that are affected by this,’ thinking maybe somewhere else in California or a neighboring state like Nevada would have some places with drinking water contamination by PFAS,” Bartell told New University. “Lo and behold, I found out they’ve been detected here in Orange County.”
PFAS was detected in OC’s water after the Environmental Protection Agency (EPA) required testing to be performed by the Orange County Water District (OCWD) during 2013-2015. The results revealed the presence of Perfluorooctanoic acid (PFOA) and Perfluorooctanesulfonic acid (PFOS), the most common compounds in the PFAS family, in several drinking water wells.
In 2016, the EPA established a combined threshold of 70 parts per trillion for PFOA and PFOS lifetime exposure. Three water retailers for OCWD tested above this threshold and took actions to correct their system levels. In March of 2019, the California Division of Drinking Water ordered 12 water systems within OCWD’s service area to test for PFAS.
UCI’s study recruited individuals who lived in Anaheim, Garden Grove, Orange, Santa Ana, Tustin/North Tustin, Yorba Linda or Irvine anytime between 2000-2019. Participants were asked about their drinking water history and their health. Levels of PFAS concentration in their blood were measured as well. Exposure to PFAS has been linked to high cholesterol, increased risk of kidney, prostate and testicular cancer, decreased immune system response and decreased vaccine response. UCI’s preliminary results reiterated some of these findings.
“We are also seeing a strong association with cholesterol that’s consistent with the other studies where people who have higher PFAS levels in the blood tend to have higher cholesterol levels that we can’t explain through other factors that are in common between those two,” Bartell told New University.
However, Bartell says some of the results from the UCI study contradict previous findings on PFAS health.
“We have some findings on obesity, which is one of the endpoints people have been wondering about, PFAS might be an obesogen and then cause more weight gain if people are exposed,” Bartell said. “But we’re not actually seeing that. Our evidence doesn’t indicate that there’s any increase in obesity with higher exposures, at least in the multisite study participants.”
PFAS exposure levels of Orange County residents generally coincide with average levels of exposure across the county.
“I think that’s really good news for our community, right, that even though these chemicals have been detected, the levels were relatively low compared to some other sites around the country,” Bartell told New University. “Our community members haven’t been exposed in a way that’s very different from most people around the U.S. or around the world.”
Since most of the participants in UCI’s study came from cities in North Orange County, Bartell notes that more participation by South Orange County residents could have yielded different results.
“If we included South Orange County or had more participants from Irvine, we might see more of a difference because we think the levels of Irvine [PFAS], for example, were a lot lower in water than they were in Anaheim and Orange.”
Irvine’s water is supplied by the Irvine Ranch Water District (IRWD). The IRWD also supplies water to parts of Costa Mesa, Newport Beach, Orange, Tustin, Lake Forest and unincorporated Orange County.
PFAS was first detected in one of the IRWD’s drinking water wells in 2018 and was taken out of service immediately, according to James Colston, IRWD Director of Water Quality and Regulatory Compliance.
Testing performed by the IRWD showed the well had a PFOA level of 14.8 parts per trillion and a PFOS level of 22.8 parts per trillion. The maximum contaminant level established by the EPA for both of these compounds is four parts per trillion.
The well was brought back into service at the beginning of 2025 after the IRWD used ion exchange to treat the water. Ion exchange uses resin beads in a column that attract specific compounds. As water flows through the column, the unwanted contaminants stick to the resin beads leading to clean water.
“There’s what’s known as the lead treatment and then the lag, and so what you do is you run the lead and lag system together and once you get some breakthrough in that lead system, then you switch it,” Colston told New University. “You make the lag system the lead system and you put fresh ion exchange media in the lead system and make it a lag system. It protects the consumer because there’s never any breakthrough of the PFOS into the water system that way.”
Since 2018, none of the water the IRWD delivers to homes has had any detectable PFAS, and its water meets the 2029 PFAS standards set by the EPA. Consequently, residents served by the IRWD served as the control group for UCI’s study.
“We’re fortunate that given the size of our agency we’re able to move quickly,” Colston told New University. “We know that these compounds are a threat to public health, so we wanted to make sure that our customers were protected.”
PFAS is found in more than just drinking water. Exposure to PFAS can happen via food, clothing and cleaning products. There are ways individuals can reduce their exposure.
“They can take steps now like Brita filters, or other varieties activated by granular activated carbon (GAC), which is your standard countertop filter or refrigerator filter,” Bartell told New University. “Almost all use GAC, which is actually pretty good at removing at least PFOA and PFOS.”
The future of PFAS research is uncertain. Bartell had hoped to follow up with the OC participants, but without additional funding, it has been difficult.
“Honestly, I think it’s gonna be tough in the current funding environment,” Bartell said. “Historically, the federal government funded a lot of this kind of work, not all of it, but what work was going on in studying PFAS exposure and health effects was usually funded by the federal government prior to 2025. But, I think we’re in a different world now.”
Alejandra Rodriguez Zepeda is a News Intern for the summer 2025 quarter. She can be reached at alejar16@uci.edu.
Edited by Joshua Gonzales
Editor’s Note: This article was corrected on September 18, 2025, regarding the IRWD water supply.