Two UCSF physicians and school officials who participated in WCCUSD’s PCE health webinar Tuesday night reassured the Kennedy High community that the current known levels of PCE in the soil are unlikely to cause any health problems.
Tetrachloroethylene, or perchloroethylene (PCE), is a potential cancer-causing chemical that was commonly used by dry cleaners until California banned it in 2023. Recent testing found PCE in the soil at a Kennedy High School construction site, raising concerns about the chemical’s health effects on children. (The state has said it’s unrelated to the construction.)
PCE has been linked to bladder cancer, liver damage, and changes in the nervous system in adults. However, this correlation does not prove causation. Few studies have examined how PCE affects children.
“Given what we know already, I would not expect anybody to have any obvious symptoms [of PCE exposure],” said Dr. Gina Solomon, chief of Occupational, Environmental and Climate Medicine at UCSF.
Solomon was joined by Dr. Peter Chin-Hong, a professor of medicine at UCSF, for an Ask the Doctors community Zoom webinar hosted by WCCUSD to address parent concerns. Superintendent Cheryl Cotton and Assistant Superintendent Liz Sanders moderated the webinar.
Health risks from PCE exposure depend on how much, how long, and how frequently someone is exposed to it. Individual risk factors also play a large role in determining whether someone gets cancer.
“Detection alone does not automatically mean a health risk. Detecting PCE underground does not mean any exposure above ground,” Sanders said.
How do people come into contact with PCE?
PCE is a manufactured, clear, nonflammable liquid chemical that can travel far and easily turn into a gas. People primarily come into contact with it by drinking contaminated water or by inhaling its vapors.
“The good news is [PCE is] not in our drinking water. It’s not in the drinking water of the high school or of the city of Richmond,” Solomon said.
In Richmond, the California Department of Toxic Substances Control (DTSC) has been monitoring PCE levels for more than 20 years. PCE has been found near multiple Richmond dry cleaner sites, other locations and at the Zeneca site. DTSC has created an FAQ site focused on Kennedy, with links to the Omo drycleaner case and the Miraflores case.
PCE can enter the environment by leaking out of sewer lines or being dumped directly into the ground. If that happens, it can contaminate groundwater. This contamination has happened in non-drinking groundwater in some of the Richmond sites.
PCE can also turn into a gas that rises up through the soil. This is why DTSC conducts soil gas testing, as it did recently at Kennedy. PCE gas from the soil can also enter air in buildings through foundation cracks, which is what DTSC is currently testing at Kennedy High.
an overview of richmond’s pce sites
Six soil samples were taken from Kennedy High School on July 17, 2026. PCE was below DTSC’s safe screening level of 15 micrograms per meter squared in three samples. The other three samples showed between 39 to 5,000 micrograms of PCE per meter squared, prompting the district to close the campus and the city to close the Richmond Swim Center, out of an “abundance of caution,” and triggering further indoor air testing at Kennedy. This testing happened earlier this month, and the results are expected to be released any day now.
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“At this point, I wouldn’t recommend any parents or their children to get tested.”
— Dr. Peter Chin-Hong, a professor of medicine at UCSF
DTSC’s screening level for indoor air is 0.46 micrograms per meter squared, meaning that people exposed to this amount of PCE would be expected to have virtually no health effects. Cotton and Sanders said that these results will determine if Kennedy High School students are relocated to a different site until the PCE can be mitigated.
In the meantime, WCCUSD has purchased new carbon-activated air purifiers to reduce levels of PCE in case they are needed, Sanders said.
What are the health effects of being overexposed to PCE?
The health effects of PCE exposure can be separated into short-term exposure and long-term exposure, Chin-Hong said.
An exposure of less than two weeks of high concentrations of PCE can result in problems with concentration, dizziness and headaches, Chin-Hong said. Solomon said that the levels of PCE found in soil gas testing were unlikely to cause any of these symptoms.
Being exposed to PCE for more than a year has been linked to bladder cancer, liver damage, and changes in the nervous system in adults. Health effects of PCE were primarily discovered in those who work with the chemical on a daily basis.
“Those long-term health effects usually need many years of exposure. It’s not something that happens quickly, and that’s partly why it took people so long to realize how dangerous dry cleaning chemicals are,” Solomon said.
Studies from the late 1990s and early 2000s show higher rates of bladder cancer in dry cleaners and aerospace workers using PCE. Not all studies account for independent risk factors such as smoking, which can dramatically worsen someone’s cancer risk.
PCE vapors can either be breathed out or dissolved into the blood. If PCE is dissolved into the blood, it is processed by the body and its toxic byproducts are excreted in urine. The bladder holds urine, and therefore is the most exposed to PCE byproducts. The liver filters blood, making it another organ that can be exposed to toxic byproducts.
“We don’t have any evidence that people [at Kennedy] became sick from this chemical, but we want to make sure that continues to happen,” said Chin-Hong.
Contra Costa County’s bladder cancer incidence from 2017 to 2021 was not significantly higher than neighboring counties, according to California Health Maps.
What you can do to reduce PCE exposure
It’s safe for Richmond residents to drink tap water and come into contact with regular soil, Solomon said. The PCE vapors are typically found in soil 10 feet underground. Once PCE vapors reach the ground level, they are likely to dissipate into the atmosphere and not cause problems, she continued.
The main concern is if PCE vapors are indoors, Sanders said. To prevent build up of these vapors, DTSC recommends good ventilation, including opening windows to allow outside air in. Air purifiers, especially carbon-activated air purifiers, can be effective in removing harmful chemicals from the air.
While it may be more expensive, DTSC also recommends sealing cracks in building foundations, resurfacing floors with epoxy, and sealing sewer pipes to limit soil vapors from entering buildings.
It is possible to test one’s breath, blood and urine for PCE, but testing has to be done right after a significant exposure, said Chin-Hong. PCE testing is typically done at special research centers and not at most common medical labs, Solomon added. Another problem is that PCE leaves the body in a couple days and is unlikely to be caught even if specialized testing is performed.
“At this point, I wouldn’t recommend any parents or their children to get tested,” Chin-Hong said.
For now, doctors and school officials urge parents to sit tight and wait for the indoor air quality test results before making any decisions.
“I hope that all our predictions come true, which is that the air is safe and clean, and children can continue to learn,” Chin-Hong said.
