EPA Administrator William Reilly, saying the nation must aim its environmental cleanup efforts more effectively, announced a crash program to cut the most dangerous toxic discharges by 500 million pounds within five years.

In a major policy speech at the National Press Club on Wednesday, the Environmental Protection Agency chief said the country must do a better job of determining which pollution problems posed the biggest health and ecological risks and then focus its cleanup efforts on those targets.Toward that end, he released a study identifying four environmental concerns as meriting priority attention: indoor and outdoor air pollution, worker exposure to chemicals and drinking water contamination.

He also announced a major EPA effort to single out "bad actor" toxic chemicals for immediate reductions and promised new federal initiatives to encourage recycling, including a possible move to resolve confusion over "recyclable" and "biodegradable" consumer products.

More broadly, Reilly said with the United States now spending an estimated $90 billion a year on pollution control, "It seems only prudent to ask ourselves: Are we spending all this money on the right things? Are society's resources being used in ways that will contribute most directly to the health and well-being of our citizens and our environment?"

Reilly said the nation had achieved some success by enforcing "traditional" environmental laws separately addressing air pollution, toxic waste disposal and water contamination.

But he said the "piecemeal" approach did not enable the nation to determine if, overall, it was getting the biggest bang possible for its environmental buck.

Reilly compared the nation's environmental policy-making over the past two decades to the video game "Space Invaders" in which a player blasts away with unbridled abandon at enemy ships.

To improve the EPA's aim, Reilly said his agency just completed a study identifying four pollution problems as posing "relatively high risks" to health and the environment requiring priority attention from his agency.

The "comparative risk" study, based primarily on scientific evidence about public exposure to known toxic substances, said significant dangers were posed by smog, acid rain and other "ambient" air pollution; worker exposure to chemicals in industry and agriculture; drinking water contamination; and indoor air pollutants such as radon.

Reilly said the EPA already was reshaping its budget and enforcement priorities.