MALIBU, Calif. — The high school here is ranked among the best in the country, with students each year moving on to Ivy League colleges. The location, on a hill down the block from the beach where “Baywatch” was filmed, offers a multimillion-dollar view of the Pacific Ocean.
Yet parents here have been yanking their children out of Malibu High School, concerned about PCBs, the highly toxic chemical compounds, that have been found in caulking of the school’s windows.
A battle over how to handle the PCBs, which were first discovered three years ago, is now convulsing this famously wealthy beach community, with parents, television stars and a supermodel pitted against one of the most elite public school districts in the country.
The Santa Monica-Malibu Unified School District insists that its classrooms are safe; the Environmental Protection Agency agrees.
But not all parents and teachers are convinced: They blame PCBs for an array of maladies, including migraines, thyroid cancer and common colds, and they have sued to compel the district to remove all contaminated caulking. A judge ruled last week that the lawsuit could move forward.
In the meantime, school board meetings have turned chaotic, with parents shouting down district officials and calling them liars.
“The school district is telling us our kids are safe, but that’s what they were telling parents in Flint, Mich.,” said Jennifer deNicola, a mother of an eighth grader and a 10th grader who has spearheaded the push to remove PCBs. “We know there’s a problem, and they refuse to acknowledge it.”
But school and health officials insist that simply because PCBs are in the building materials does not mean the students are at risk of exposure. The school district tests the air in classrooms — the primary medium through which children could be exposed — and cleans regularly to reduce dust from the caulking, school officials said.
“Just because something is present doesn’t mean it can cause harm,” said Doug Daugherty, a managing principal at Ramboll Environ, the environmental consulting firm the district has hired.
The district has already spent millions of dollars on lawyers, environmental consultants and a public-relations campaign.
But, this being Malibu, parents have waged their own media campaign, complete with environmental experts and celebrity advocates. Cindy Crawford, the supermodel, has gone on national television to explain why she pulled her two children from Malibu High, and offered to pay to test caulking for PCBs throughout the campus, which also includes an elementary school and a middle school. (Her offer was declined.)
PCBs, or polychlorinated biphenyls, were widely used in building materials and electronics until they were banned in the late 1970s, and they remain in many older buildings. Research from the Harvard School of Public Health estimated that the substances could be present in upward of 20,000 schools nationwide. The compounds have been linked to cancer, immune problems and lower I.Q.s among children.
Federal law requires that any building materials found to contain PCBs be removed. But to the chagrin of parents here, there was no requirement to test the caulking in the first place.
The E.P.A. has endorsed the district’s approach to handling the PCBs in its buildings. And scientists who studied PCBs in New York City schools said this method — of testing air quality and cleaning assiduously — was very effective.
Laurie Lieberman, the president of the Santa Monica-Malibu Unified school board, said the administration had confidence in the safety of its facilities and has been doing its best to reassure parents.
“We have tremendous empathy for people who are fearful and scared,” Ms. Lieberman said. “We’ve really tried to explain why the schools are safe now.”
Malibu parents have a history of skepticism about official health advice, including routine childhood vaccinations: At some local elementary schools in 2014, fewer than 60 percent of kindergarten students had received the full lineup of recommended vaccines, far below the state average.
In this case, the distrust on both sides became plain last fall, when supporters of caulking removal secretly took their own samples from classrooms and had them independently tested. Ms. deNicola announced that the results showed extraordinarily high levels of PCBs. The school district asked the sheriff’s office to investigate her for trespassing and vandalism.
The battle now threatens to tear apart the school district: Concern over PCBs has fueled an existing effort here to break away from Santa Monica so that Malibu can be in control of its own schools.
Beth Lucas, a parent, pulled her son, Christian, out of Malibu High after their endocrinologist said it was especially dangerous for him to remain there. Christian, now 17, had a malignant brain tumor at age 6, and the radiation used to treat it left him with a diminished immune system and thus more vulnerable to the effects of PCBs, the doctor told the family.
“We moved to Malibu for the schools, so it has been a big slap in the face to have the school district treat the parents and teachers and children so poorly,” Ms. Lucas said. She is also considering removing her daughter, who is in middle school, at the end of the year, but worried about the cost of private school.
“Yes, we live in this nice house,” she said, sitting on a hilltop porch that overlooked a wide expanse of ocean. “I don’t want to have to sell my house and leave Malibu. The district has put us in a horrible position.”
Currently, only one of the seven school board members represents Malibu. He supports replacing the caulking, but has been voted down by board members who live in Santa Monica.
“I think the board members have convinced themselves that the science is right and the parents are overreacting,” said Craig Foster, Malibu’s representative on the school board, and the father of a seventh grader at the middle school here. “But what if in five years it turns out testing the air and dust wasn’t enough? How do you sleep?”
Some other school districts across the country have acted more aggressively, often at the E.P.A.’s behest, to remove the source of PCBs. Parents here point to Clark Elementary School in Hartford as an example of a school district that handled matters responsibly: In that case, an entire school building was closed — and may be abandoned — because of PCB contamination.
But testing at Clark Elementary indicated elevated levels of PCBs in the air, whereas testing at Malibu High has not, E.P.A. officials said.
Jim Jones, an assistant administrator at the E.P.A., said the agency worked with schools to “get below the risk threshold using the best management practices.”
“We’re always trying to find what’s a cheaper way,” Mr. Jones said, adding that the caulking at Malibu High would all be replaced within several years as part of planned renovations. For now, he said, cleaning and ventilation are “far less costly than removal.”
