A streamer of yellow caution tape encircles the lush green vegetable garden belonging to Cynthia Babich, who learned last week that soil tests in her yard near Torrance had detected the banned pesticide DDT at a level roughly 2.5 times higher than that considered safe by the U.S. Environmental Protection Agency.

Testing in a neighbor's yard found even higher levels of the pesticide.

As a result, the EPA will conduct soil tests in the yards of up to 100 homes in an unincorporated neighborhood east of Torrance.

The agency plans to excavate most of the two yards where the DDT was found. The source of the DDT is not known, and EPA officials say that while it may be an isolated occurrence, they want to be sure that other homes are not affected.

Babich said she has been told that she will be moved out of her house for about a week while the work is done, probably in early April.

Babich said she was stunned by the news, especially since testing last fall had found much lower DDT levels. Officials tested the earth again as a precaution.

DDT is a poison that kills insects by affecting their nervous systems. It is suspected of causing cancer in humans and damages the reproduction of wildlife.

"That breaks my heart. That's my garden," said Babich, who was notified of the test results last week, just as she finished turning the soil for spring planting, placing broccoli seedlings and moving strawberry plants.

She criticized government officials for not doing more extensive testing earlier in her neighborhood, which lies just south of a hazardous-waste dump and east of the Montrose Chemical Corp., a federal Superfund site. The area is southwest of the intersection of the San Diego and Harbor freeways.

Babich and her neighbors, complaining of strange rashes, nausea and other physical ailments, are calling for faster cleanup of hazardous-waste dumps in the area.

"They've been 10 years doing nothing--testing, testing, testing," said Marla Frame, who lives with her children three doors away from Babich on West 204th Street and who said she was deeply alarmed to hear about the results of testing in Babich's yard.

"You could have swept me off with a broom. I didn't think it would be that high," Frame said.

The EPA tests found DDT levels of 245 parts per million in Babich's yard and 606 p.p.m. in a neighbor's yard. Federal officials recommend taking precautions when DDT concentrations exceed 100 p.p.m., and recent changes in how human risk is assessed could lead to more stringent standards.