The Environmental Protection Agency has issued a new policy designed to prevent companies involved in enforcement or regulatory actions from dictating the contents of the agency's press releases.

Agency officials said the policy is intended to halt a disquieting trend, especially in the field of toxic-waste cleanups. Companies increasingly have sought to protect the value of their stock by keeping the EPA's estimates on cleanup costs out of news reports.

"We began to see more frequent cases of industry using press releases as bargaining chips," one EPA official said.

Most cases apparently have involved informal agreements between industry and EPA officials, often at the regional level.

At the request of Velsicol Chemical Co., for example, the EPA did not issue a press release last December when Velsicol and Shell International Chemical Co. Ltd. of London voluntarily agreed to cancel registration of the pesticide endrin. The only official mention of the action, which brought an end to the agency's efforts to ban the chemical, was in fine print toward the bottom of a several-page notice in the Federal Register.

More recently, the press office deleted the EPA's estimate of the cost of a settlement involving Chemical Waste Management Inc.'s toxic-waste disposal site at Emelle, Ala.

Company officials had complained that the $10 million estimate was unreasonably high and that publicizing it would depress the price of the firm's stock. The figure made it into print anyway, however, in a quote from an EPA enforcement official that appeared in The Wall Street Journal.

According to EPA officials, the final straw came when the Westinghouse Co., which is negotiating a settlement for the cleanup of a PCB site in Bloomington, Ind., balked at signing the agreement unless the EPA agreed not to divulge its estimate of the cleanup cost. The settlement is still not final.

The EPA's new policy, issued by Acting Deputy Administrator A. James Barnes and circulated to top headquarters and regional officials, says the content of press releases "is an EPA internal matter at all times."

"It is against EPA policy to negotiate the agency's option to issue press releases, or the substance of press releases, with parties outside of EPA, particularly those parties involved in settlements, consent decrees or the regulatory process," Barnes' memo stated.