Test for Toxins in Back Yards Turns Up DDT : Pollution: Officials say concentrations of the long-banned pesticide in Harbor Gateway area are not high enough to cause illness.

Federal investigators who took soil samples from the back yards of 12 homes near Harbor Gateway in September were looking for contaminants that might have spread from the nearby Del Amo Pits, a proposed Superfund site.

But they were surprised to find that, while none of the soil samples contained unsafe levels of the toxic chemicals they were searching for, two of the samples contained unusually high levels of the banned insecticide DDT.

Investigators, who announced their findings recently, were in the neighborhood to check whether any heavy metals from a former rubber manufacturing plant nearby had found their way into residents’ yards.

The former plant, a 280-acre site known as Del Amo Pits, produced such byproducts as benzo(a)pyrene, a carcinogen, said Tom Dunkelman, U. S. Environmental Protection Agency project manager. He said the agency is at a loss to explain the source of the DDT.

Although EPA officials do not believe the DDT concentrations are high enough to cause illness, they intend to conduct additional tests next month at the two homes where DDT was found. If the next round of more intensive tests reveal high levels of the pesticide, federal officials might replace the soil.

“These are not levels that would cause anyone to become sick over a short-term exposure,” Dunkelman said. “The way in which EPA evaluates risk is very conservative and puts safety first. The risk numbers assume that people ingest a certain amount of soil every day for years.”

Once a widely used pesticide, DDT has been banned in this country since 1972. People exposed to high doses of the contaminant for short periods typically suffer tremors, rashes and irritation of the eyes, nose and throat. DDT also has been found to cause cancer in laboratory animals.

Typically, federal officials recommend taking precautions when the concentration of DDT exceeds 100 parts per million, although recent changes in how authorities assess human risks will probably lead to more stringent standards in the next few weeks.

Samples from one back yard yielded DDT at a concentration of 32 parts per million, while the other contained DDT at 110 parts per million, leading the agency to advise the residents to wash their hands after working in the yard. Tests at the other 10 homes detected only traces of DDT, no more than 5 parts per million.

The two homes with soil containing substantially higher levels of DDT are next to each other on West 204th Street, between Normandie and New Hampshire avenues in an unincorporated area.

The elderly couple who live at the home with the higher DDT levels could not be reached for comment.

At the home where the lower concentration of DDT was found, renter Cynthia Babich, 44, who regularly eats vegetables from her garden, said she is not worried about contamination because she grows her greens in beds with out-of-area soil. And, she believes, the several chickens she raises in the yard will be fine as long as they continue to lay eggs.

“I am concerned on a planetary level more than a personal level,” she said. “It would take 70 years of me ingesting DDT every day for there to be any health problems. Right now, our main concern is the red-tailed hawks that live in the fields next door.”

EPA investigators are looking at the nearby Montrose Chemical Corp., a 13-acre Superfund site that produced the pesticide from 1947 until the plant closed in 1982, as a possible source of the DDT. The company is currently working with the EPA to evaluate ways to clean up its former facility.

But it is also possible that the two homes were once sprayed with the pesticide to kill mosquitoes.

“You’re going to find DDT just about anywhere you look across the state,” Dunkelman said. “DDT was used across the county for mosquito control at one time. And this area, before it was developed, was an agricultural area, so it is likely the farmers applied DDT.”

Environmental authorities began testing the neighborhoods’ soil in the early 1980s because of its proximity to the Montrose site and Del Amo Pits.

Although the entire Del Amo Pits area is a proposed Superfund site, the EPA has paid special attention in recent years to a 3.7-acre waste dump within the property that investigators said contained harmful levels of the heavy metals.

Last year, Shell Oil and Dow Chemical, the two companies that had operations on the site between 1955 and 1969, agreed to spend $10 million to figure out how to clean up soil and ground water contamination.

The EPA keeps a list of hazardous sites believed to pose the greatest health and environmental threats.

Today, 1,300 sites are on the Superfund National Priorities List, a designation which allows the EPA to enforce cleanup efforts against responsible parties or to spend money to ensure that sites containing hazardous waste are cleaned up.