The government is asking more than 600 companies to voluntarily cut emissions of 17 toxic chemicals.

The companies urged to participate in the Environmental Protection Agency's Industrial Toxic Project are the largest contributors to the estimated 1.4 billion pounds of toxic wastes released into the air, ground and water each year, the agency said Thursday."Pollution prevention can be the most cost-effective alternative to after-the-fact treatment of pollution," EPA Administrator William K. Reilly said in a statement. "Companies can save on waste management, reduce the use of raw materials and minimize liability."

Just being on the list does not suggest that a company is out of compliance with any pollution control regulations, the EPA said.

The agency said it chose the 17 chemicals because they are among the most toxic and most common substances, and because recognized ways exist to reduce the quantity of releases.

The chemicals are: benzene, cadmium and its compounds, carbon tetrachloride, chloroform, chromium and its compounds, cyanide compounds, dichloromethane, lead and its compounds, mercury and its compounds, methyl ethyl ketone, methyl isobutyl ketone, nickel and its compounds, tetrachloroethylene, toluene, trichloromethane, trichlorethylene and xylenes.

They are used in such industrial applications as metal working, metal plating, machinery degreasing, petroleum refining and the manufacture of chemicals, rubber, plastics, electric equipment, pulp and paper products, furniture and instruments.