The Environmental Protection Agency yesterday suspended the registration of new pesticides after a federal judge in St. Louis declared portions of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) unconstitutional.

In a brief ruling issued last week, U.S. District Judge Kenneth Wangelin ordered the EPA to stop making public certain health, safety and manufacturing information that pesticide manufacturers must give the agency.

Chemical manufacturers, which have been fighting the law since 1978, called the ruling a significant victory in protecting trade secrets.

Consumer and environmental groups, meanwhile, criticized the ruling and predicted it will be overturned if EPA, as expected, appeals the case to the Supreme Court.

Stan Abramson, EPA's associate general counsel, said the agency didn't expect "such a sweeping decision. This obviously is a decision that we will want to appeal," he said.

While the agency will continue to process registration requests for new pesticides, it probably will not approve any of them until the court dispute is resolved, Abramson said.

Neither Abramson nor attorneys for Monsanto Co., which in 1979 filed the lawsuit that led to the judge's decision, could elaborate on the two-page ruling. The judge has said he will issue a more detailed explanation later.

Monsanto's chief counsel, W. Wayne Withers, said that the company had argued that sections of FIFRA were unconstitutional because they deprived the company of its "intellectual property."

Under the law, companies have to make certain health and safety data about their products available for public inspection. The information includes the results of tests to prove that the pesticides are not harmful to workers or the public.

Monsanto claimed that its competitors would be able to steal its trade secrets and short-cut the EPA registration process if they had access to those results.

Jay Feldman, a spokesman for the National Coalition Against the Misuse of Pesticides, said that such fears are unfounded because FIFRA contains a number of safeguards to protect trade secrets.

Rep. George E. Brown Jr. (D-Calif.), who chairs the House subcommittee with oversight over FIFRA, said he is worried that "the whole registration and data disclosure processes may now been thrown into months, or years, of judicial gridlock. It is vital that interested citizens have access to the scientific data underlying agency actions."

Because of lawsuits and recent EPA rulings, environmental groups have actually been allowed to inspect pesticide data at EPA only once. Last year nine chemical companies agreed to allow three environmental groups to review briefly their health and safety information.