The quadrennial revolving doors are beginning to pick up speed in various federal agencies, and few portals are being watched more closely than the one at the Environmental Protection Agency.

Environmentalists -- and some industry representatives -- are worried that the new year will bring a reprise of the budget-cutting, regulation-scuttling philosophy that characterized the EPA under the Reagan administration's first two years. They're watching for any sign of early bail-outs that would suggest turbulent times ahead.

Administrator William D. Ruckelshaus, who rebuilt the agency's top management team less than two years ago, repeatedly has denied that he has any immediate plans to leave. Shortly before the election, he told reporters that he was planning to make renewal of the nation's major environmental laws -- some of which technically expired more than three years ago -- a priority in 1985.

But few in industry and environmental circles or on Capitol Hill believe that Ruckelshaus will have much success without significant support from the White House, and there are no signs that the administration's antipathy toward environmental regulation has softened.

The White House moved recently to squelch speculation about high-level turnover when President Reagan passed the word to several Cabinet members that they were welcome to stay on in the second term.

Ruckelshaus has yet to get such reassurances, but he expects to meet with Reagan, Vice President Bush and several top White House aides within the next couple of weeks to discuss the agency's future -- and presumably his as well. TOXITRENDS . . .

In case the agency hadn't figured this out for itself, a consulting firm has told the EPA's Office of Toxic Substances that it can look forward in the next decade to more congressional impatience, more public outrage and an ever-longer string of lawsuits about chemical health hazards.

But that's just the dry part of the 215-page, $65,000 report, entitled "Toxics '95: Outlook of Factors and Trends for Toxic Chemicals." The report was produced for the EPA by J.F. Coates Inc., a Washington firm specializing in "futures research."

The lively stuff is in the "scenarios" section, where the seers imagine what the chemical trade press will be reporting in a decade. A scenario is a standard device in the crystal-ball industry, which calls it a "tool for presenting integrated images."

Scenario 1 is the rose-colored version and the fictitious news story includes the following points. Galvanized by the 1988 election successes of the "Reunion Party" (a coalition of labor, public interest groups, scientists and businessmen), the chemical industry has seen the error of its ways and come up with a self-policing system that everybody trusts.

The issue of victims' compensation has been resolved with a national health insurance program, and the industry is enjoying "an era of unprecedented innovation and prosperity."

A massive reshuffling of federal agencies has thrown the Occupational Safety and Health Administration, the Food and Drug Administration and the EPA's toxics office together into a huge "directorate of public, occupational and environmental health" run by the EPA.

Scenario 2, by contrast, assumes that the current situation has deteriorated. This make-believe story reports that radicalism is on the rise, as illustrated by the new National Society for Safety Through Environmental Enforcement (NSSTEE, pronounced "Nasty"), whose guerrilla-style tactics include bomb threats and kidnapings of chemical executives.

The industry's viewpoint, meanwhile, is epitomized by Global Petrochemicals chairman O.B. Duracy, who says: "Life is full of risks. If workers want jobs, they have to get their hands dirty."

The federal regulatory apparatus has been largely dismantled in favor of block grants to the states. But the U.S. chemical industry, under the burden of an ever-growing caseload of victim compensation suits, is retreating from the field, cutting research budgets and searching for nonchemical product lines.

Scenario 3, the last of the group, assumes that things go along for the next decade pretty much as they have for the last. In this story, the chairman of the White House Council on Environmental Quality expounds on the virtues of cost-benefit analysis and tosses bouquets to state and local governments, which have taken over most hazardous-waste programs.

But two of his colleagues (the three-member CEQ has been expanded to seven under this scenario) take strong exception, pointing out that toxic cleanups are still a problem, nobody knows how to regulate biotechnology and the nuclear waste question has not been solved.

In a winsome touch of reality, the story mentions that the full CEQ report is available from the Government Printing Office -- for $37.50.