Caulk with PCBs above 50 ppm is not authorized for use under the federal Toxic Substances Control Act.
One-third of Malibu High's teachers have complained about recent construction and moldy classrooms causing serious health problems.
Four teachers at Malibu High School have been diagnosed with cancer, and they all attribute it to toxic conditions on campus.
Students have been moved from some classrooms because of contamination concerns after some teachers reported they had gotten sick.
Three teachers at the school have thyroid cancer and one has bladder cancer.
In 2010, the district removed 1,000 cubic yards of dirt after it tested positive for carcinogens, lead and pesticides. When asked if parents and teachers were informed at the time, Superintendent Sandra Lyon says the district went through the standard protocol. But many parents say they didn't know.
Testing began Sept. 20, according to a district memo sent to staff.
The EPA released the following statement to Eyewitness News on Saturday:
"EPA is assisting the Malibu High School Environmental Task Force in evaluating PCBs at the high school. Earlier this week, EPA received air sampling data from 10 buildings that were sampled. Based on the agency's preliminary review, the air data shows PCB concentrations to be within acceptable federal health standards. EPA is still reviewing surface wipe sample data. On Wednesday, the district verbally informed EPA technical advisors that some caulk samples were found to be above 50 parts per million (ppm). PCBs in caulk above 50 ppm is not authorized for use under EPA's Toxics Substances Control Act. Because the PCB levels in the caulk exceed the regulatory limit, the agency is working with the school district to develop an appropriate cleanup plan. EPA is coordinating with the California Department of Toxic Substances Control and the school district."