MALIBU, Calif. (AP) _ Preliminary testing at Malibu High School has turned up levels of a contaminant that exceed regulatory limits, the Santa Monica-Malibu Unified School District announced Friday.

Elevated levels of PCBs were found in caulking around window sills in about four of 20 tested areas, the district said.

The district will work with the U.S. Environmental Protection Agency on what could be a ``very large, very expensive'' plan of further testing and cleanup, district Superintendent Sandra Lyon told the Los Angeles Times

There is no ``acute'' short-term health risk and the campus will stay open during the cleanup, Lyon said.

PCBs, or polychlorinated biphenyls, are man-made chemical compounds once used in electrical equipment and industrial and commercial products before they were banned in 1979. In some studies, the compounds have been associated with cancer and damage to the immune system.

The cleanup decision comes more than a month after parents and teachers voiced suspicions that something at a campus building was causing cancer, migraines and other serious illnesses. Rumors spread about potential contaminants caused by mold or termite treatments.

Students from 11 classrooms were switched to other rooms on campus and a nearby elementary school.

Lyon says the students will remain in those rooms during the cleanup.

The district initially stumbled in reacting to the parents' concerns but it has ``risen to the occasion,'' said Seth Jacobson, a parent who sits on an environmental task force created in response to those concerns.

``My kids are safe, but I want to make sure that going forward, the district does everything it possibly can . to clean up and to minimize any exposure,'' he said.

There still is ``a level of mistrust'' by some parents, said Len Simonian, a member of advocacy group Malibu Parents for Healthy Schools that had questioned the district's response.

``We're not relieved to find out there's a problem, but we're relieved to get some information,'' he said.

Posted by Amy King