The Environmental Protection Agency yesterday adopted exposure standards aimed at limiting radiation-caused cancer deaths from a planned nuclear waste disposal site to no more than one per decade for the next 10,000 years.

The standards, nine years in development, probably will mean only 1 to 10 percent as many deaths as the projected limit of one cancer death per decade. The higher figure is a conservative outside estimate, agency officials said.

The regulation was changed in many details from the draft proposed 2 1/2 years ago, but the one-death-per-decade standard was not altered even though the EPA's Science Advisory Board said it could be 10 times more lenient.

Background radioactivity from natural ores and cosmic rays causes about 1 percent of the 400,000 cancer deaths annually in this country, and any increase from a waste repository should be undetectable and comparable to the risks incurred in leaving uranium unmined, the agency said.

The EPA left it to the Nuclear Regulatory Commission to decide what it should do to make sure radioactivity does not escape. Several states asked the agency to adopt such requirements, but the NRC said that was its job for the repositories it will license and the EPA agreed.

Dan Egan, in charge of drafting the regulation for the EPA, said the commission had promised to incorporate "comparable requirements" in its own regulations.

If the EPA is not satisfied with what the commission does, it could tighten the exposure standards, but "we don't expect any problem," Egan told a news conference.

The Energy Department is studying three sites for deep underground disposal of spent fuel from power-generating reactors and other highly radioactive wastes starting in 1998.

Under a 1982 law, the EPA was supposed to publish the regulations in January 1984, but the agency missed the deadline. A lawsuit by five environmental groups ended in a consent decree under which the EPA was bound to act by yesterday.