Concern over high levels of toxic chemicals found at two California schools in Malibu have some students being kept home from class by worried parents, including supermodel Cindy Crawford.

The mother of two teens has been keeping her kids home after elevated levels of a cancer-causing chemical often found in older buildings were detected inside the schools attended by her children.

“I look 10 years down the line. What if my kid, God forbid, had a problem?” Crawford told NBC special correspondent Maria Shriver in a segment that aired Tuesday on TODAY. “How could I live with myself, if I knew that it was a possibility, and I still sent them to school there?”

At issue is the detection of high levels of PCBs, which Congress banned in 1976 after the chemical was found to cause cancer and damage the immune and reproductive systems. PCBs often are found in the window caulking of older buildings, but the chemicals can leech into dirt, dust and air.

“PCBs disrupt the function of hormones in our bodies, especially thyroid hormone. They can contribute to worse brain development in children, and inability of children to perform well in school,” said Dr. Leonard Trasande, a public health expert at New York University’s School of Medicine.

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After Malibu teachers raised concern about their health, the district tested window caulking in 10 random classrooms. Four of them came back with levels above the federal PCB limits.

School district officials say they plan to remove the caulking in four rooms at the Malibu schools and conduct periodic monitoring of air and dust for PCBs in every classroom. It says tests so far have indicated normal levels.

Crawford and other parents say that’s not enough to make them feel secure.

“I don’t feel 100 percent safe,” Crawford said, who last week even offered to pay for all the caulk testing at Malibu High School.

“I think that air testing and wipe testings are a great piece of the puzzle. Unless they're testing every day, how do I know that every day it's safe for my kid?” she said.

Some health experts say that while air and dust testing is a reliable way to determine PCB exposure, levels can vary weekly, depending on conditions.

“In the short term it may be appropriate to do monitoring, but in the long term schools need to eradicate the PCBs from these building materials,” Trasande said.

How to remediate PCBs has become a concern for schools nationally, not just in California. Under federal law, administrators are not required to test for the chemicals at all.

Malibu school officials issued a statement to NBC saying that ensuring student safety and health is the first priority of the district. It also said that “using federal EPA standards, our schools are safe for students and employees."

The EPA agreed, saying the district’s plan addresses "the human exposure pathways of greatest concern, namely air, dust and soil." It also said until further problems are raised, "EPA does not recommend additional testing of caulk."

Crawford and other parents say that would like to see federal regulators require all school buildings constructed from 1950 through 1970s be tested for PCBs.

“This is not a Malibu issue,” Crawford said. “This is really an issue in a lot of older schools, and I just think the laws need to be changed.”