Three teachers have thyroid cancer and one has bladder cancer. Also, one-third of the school's teachers have complained about recent construction and moldy classrooms causing serious health problems.
Parents say they were not notified about the issue until Sunday night.
"I think it's horrifying, and I think it's terrible that they wouldn't tell us," said one concerned parent.
Carrie Krase, another parent, said she is afraid for her kids' health.
"Fear, honestly, fear. I'm afraid. My children spend all day here and if it's not safe, it's a big concern. Everybody is afraid of cancer," said Krase.
Sandra Lyon, the superintendent of the Santa Monica-Malibu Unified School District, said the district hired an environmental testing company that has interviewed teachers and are working to test the school campus.
"At this point, we don't have any evidence that there's any concern that we know about, but we want to make sure our staff feels safe," said Lyons.
Lyon said she is confident the school is safe, or she wouldn't allow students on campus. She ordered tests for mold and other contaminants Sept. 20.
Jerry Block, the school's principal, said he has received no complaints from parents about students being ill.
"Student and teacher safety is our No. 1 concern, and although we don't have any reason to believe that there's any contamination at this school, and we believe the school is safe, we're going to take every precaution to make sure that is in fact the case," said Block.
The complaints from teachers started after the district hired a contractor back in 2010 to dig up the school's 50-year-old quad area. The district admits it was contaminated with cancer-causing PCBs, lead and other pesticides.
"I am definitely a mom who wants answers," said Laureen Fiske, a parent. She said the sick teachers have been working at the school for decades and were exposed to the carcinogens over time. The teachers with cancer were diagnosed in the last six months. Their classrooms are just feet from the quad.
"I've worked in other school districts, and in fact one where there were nine teachers who had cancer, not even just other health concerns, and there was no contaminant found," Lyon said.
The Santa Monica Malibu Classroom Teachers Association released a statement Monday saying, in part, "Once the investigation and analysis are complete we will address the recommendations and will work closely with the district to assure our students and staff are working and learning in a healthy environment."
