Utah Gov. Scott M. Matheson told a Senate panel yesterday that the federal government is responsible for a serious cancer threat in his state from radioactive uranium mill wastes and it should pay the full cost of their removal.

About a half-million persons live near a 107-acre uranium mill tellings" pile that makes downtown Salt Lake City "one of the largest microwave ovens in the West." Matheson testified at a Senate Energy subcommittee hearing.

Matheson said Utah and eight other western states that have a total of 22 radiation danger sites cannot afford to pay 25 percent of the cleanup cost, as the Carter administration has proposed.

Matheson's opposition, in behalf of 13 western governors came after testimony Monday from three federal agencies that the states should share the cleanup cost, except on Indian land, because they benefited from uranium ore processing that produced the waste and because the will benefit by its removal.

Department of Energy spokesman James L. Liverman had contended that responsbility for the waste is uncertain because the now defunct Atomic Energy Commission, which bought the uranium, was "simply a purchaser of a product" from private mill operators.

Matheson said Utah believes the federal government would be subject to legal action for failing to regulate the mill operations during the 1950s and '60s, were it not for a statute of limitations.

Flanked by Utah Republican Sens. Orrin G. Hatch and E. J. (jake) Garn. sponsors of legislation to provide full federal funding for direct cleanup costs. Democrat Matheson offered a sample of the grayish, sandy radioactive material for the subcommittee's record.

Garn told of a Salt Lake City man suffering from a malignant tumor that necessitated removal of an eye after he worked near the uranium wastes for eight years. Doctors could not rule out the tailings as a cause of the cancer, Garn said.

Colorado Health Director Dr. Anthony Robbins said he feared the state legislature would refuse to appropriate its share of the necessary funds, thus forfeiting the federal portion and delaying cleanup, if the administration bill, or an alternative calling for 90 percent federal funding were approved.

An environmental lobbyist, David Berick, argued that neither state nor federal funds but payments by private owners of the mill tailing sites, where they can be identified, should pay to eliminate the risks.

More than half of the abandoned western mills are still owned by uranium mining or mill interests and recent legal precedents fix responsbility for environmental hazards with the commercial owners of asbestos, pesticides and other industries, according to Berick of the Environmental Policy Center.

Berick said the bill should require claims against the owners while removal efforts, funded and conducted by federal agencies are under way.

Berick also suggested expansion of the measure to cover wastes being generated at active uranium mills. The estimated 12 million tons of tailings at abandoned mines are only a "bucket in the bathub" of the larger problem, he said.

Another solution, offered by New Mexico uranium miner Macie Anderson, would have miners recycle the wastes with federal support to extract the estimated one pound of useful ore per ton of tailings.

Several measures directed at the uranium wastes are before House committees as well. A staff worker of the House Committee subcommittee on energy and power said members are leaning toward state-shared funding of the remedies, but have a lot of serious questions" unanswered.