An investigator for the Environmental Protection Agency said yesterday that it could take up to a month to clean up a Beltsville industrial park where considerable PCB contamination was discovered this week. But he said that it remains unclear who will shoulder the cost of the operation.

Robert Caron, the federal agency's on-site coordinator, said that $50,000 has been appropriated from EPA's Superfund to control and stabilize leakage of the hazardous chemicals at the United Hauling and Rigging Inc. property on Ammendale Road.

The $1.6 billion Superfund was set up by Congress in 1980 to rectify problems at the nation's worst chemical waste dumps.

"Within a week we will know whether to request additional funds" for the Beltsville site, Caron said.

Dee Witt C. Sperlau, executive vice president of United Hauling and Rigging, said yesterday that his company should not be held responsible for the cost of the cleanup, which could include hauling truckloads of contaminated soil away from the site.

"That doesn't mean that down the road [the EPA] won't determine that we are" responsible, he added.

EPA spokesman Robert Chadwick said that the agency's attorneys will investigate the case to determine liability.

Maryland health officials had notified the federal agency Wednesday of the presence of an unusually high level of PCBs leaking from transformers stored at the property. PCBs, or polychlorinated biphenyls, have been found to cause cancer, birth defects and other effects in laboratory tests on animals, but their effect on humans have not been shown conclusively.

The PCB leakage in Beltsville poses no immediate health hazard, officials said, but the area where up to 800 contaminated electrical transformers are stored has been cordoned off as the investigation continues. The transformers had been lubricated with oil that contained PCBs.

"I've seen worse," Caron said. "This is not a heavy-duty residential area. We're lucky from that standpoint."

Residents of the Vansville neighborhood bordering the industrial park said yesterday that they first learned of the contamination in news reports.

"I'm worried about how long this has been going on," said lifelong Beltsville resident William F. Smith, 60, who lives about half a mile from the site on Old Baltimore Pike.

Leonard Ross, who lives next door to Smith, said that the community has been concerned about possible transgressions by its industrial neighbors for years.

"We want somebody to come and talk to us as a group," said Ross, a 63-year-old retiree who has lived in the neighborhood since 1950.

Sperlau said that the transformers have been stored in open areas on company grounds for more than a year. He said that his company did not knowingly haul or store contaminated instruments.

The 16-year-old firm contracts to transport large or heavy items, and participated in salvage operations that followed the crash of Air Florida Flight 90 into the Potomac River in 1982. Selling copper wiring stripped from dismantled transformers, Sperlau said, was "an infinitesimal part of our business."

EPA and county health officials said that only employes who came in direct contact with the transformers could have been affected.

"What we're doing now is preventing direct contact and the threat of off-site migration" of the chemicals, Caron said. Indian Creek, a shallow tributary of the Anacostia River, flows by the company's 12-acre site.

"We're as concerned about contamination as anyone," Sperlau declared.

Government officals said that the firm, which employs 78 persons, has been cooperating fully in the investigation.

James Dew, Prince George's director of environmental health, said that his department is isolating wells in the area that might be affected by contaminated runoff from Indian Creek.