Washington ? EPA chief Christie Whitman on Tuesday defended cutting in half the number of toxic waste sites being cleaned up around the nation that are not paid for by polluters.

The administrator of the Environmental Protection Agency said the fewer sites arise from having to spread the same amount of money each year for more costly, more complex and larger sites. At the same time, Congress and the Bush administration have been reluctant to reimpose a Superfund tax on polluters and other businesses.

“One of the concerns that I know the president has had about the way the Superfund tax is imposed is that it’s not all on polluters,” Whitman told a House Appropriations subcommittee. “It is on everyone in an industry, so that even those that have the best of environmental records are also paying.”

The special tax on the oil and chemical industries and other businesses that process or use toxic substances expired in 1995. Since then, the Superfund trust fund financed by the tax has dwindled from a high of $3.6 billion in 1996 to a projected $28 million at the end of next year.

President Bush proposed in the budget he submitted last month that the shrinking trust fund pay $593 million of this year’s projected $1.3 billion in cleanup costs for sites where responsible parties either cannot be found or are bankrupt, with the remaining $700 million to come from the Treasury.

About 40 Superfund cleanups a year are expected to be completed during the Bush administration; 47 were done last year. More than 80 sites were cleaned up during each of the last four years of the Clinton administration.

Whitman said EPA expects to complete within several weeks a review of which sites should be given the highest priority.

She said corporations responsible for the contamination have been paying a total of $1.7 billion to clean up 70 percent of the number of sites on the EPA’s national priority list, of which there were 1,222 as of Feb. 26.