What Ed Barrese, 29, decides each day at his job may effect the way history is written 50 years from now or 150 years from now or even 500 years from now.

Barrese is one of a bakers dozen of appraisers on the staff of the National Archives who play a key role in deciding which, of the millions of federal records generated each year, to keep and which to destroy. In just 15 minutes, for example, he can determine whether 2,000 documents will be preserved "forever," at a cost of 54 cents a year, or reduced to pulp.

Barrese, the father of two children, who is working toward a Ph. D. in history at George Washington University, acknowledges that sorting through carton after carton of bureaucratic correspondence or bookkeeping can be excruciatingly dull.

But he also says the job is important, it's more secure than teaching, and is occassionally rewarding.

Barrese is the kind of man who can be turned on by a signature. "The most exciting thing I've found," he said while poring over documents the other day at the American Revolutionary Bicentennial Administration, "was a letter from (philosopher) ALfred North Whitehead. He was recommending someone for a job."

Barrese's boss, Thomas Wadlow, says, "We're making judgements not just for our time, but for all time. This work is extremely important. You can't rush it. I don't care if we have a backlog of a million cases. You can't rush it."

Wadlow was making a point. He finds his staff of 13 too small. Especially since one of his appraisers has been detieled to St. Louis to organize 90,000 cubic feet of military records. That is 180 million pieces of paper. Who knows when he'll be back.

Mabel Deutrich, assistant archivist for the National Archives, who must resolve disputes about what to keep and what to dispose of, said in a recent interview: "I guess we're sort of playing God when we decide we're going to throw certain records out."

James B. Rhoads, archivist of the United States, put it in slightly less cosmic terms, but the message was the same:

"There's not much question that (appraisal) is the most important responsibility we have. A decision of this kind is pretty that many of the decisions they make are fairly easy if not self-evident. Housekeeping records, for example, are turned into pupl and recycled. The number of typewriter ribbons used by the Department of Health, Education and Welfare each year is not considered to be a stastic of enduring historical value.

The opposite would be true of the transcripts of Secretary of State Henry A. Kissinger's office telephone conversations.

But to the chargin of the archivists, Kissinger has offered the transcripts to the Library of Congress. In response, exercising what he says are "legal responsibilities," Rhoads has asked for access to the telephone records to determine whether they are personal or official documents.

Kissinger has turned down the archivist's request, but if he ultimately is forced to accede to it, Rhoads says someone from the appraisal staff is certain to play a role in evaluating the material.

There is a statutory basis for selecting what to retain and what to dispose of, "but the statute by implication leaves most of the decisions to our judgement," Rhoads said.

Some basic criteria are that the records document the function of the agency that generated them, that they protect the legal rights of individuals or that they have information value.

If the records satisfy one or more of those criteria, the appraiser must weigh the "amount of use that is apt to be made of them against the amount of money it will cost the government to save them forever," Rhoads said.

The Archives already 13.8 million cubic feet of government records in 15 centers around the country at a cost of 54 cents a cubic foot. In 1977, it will pay $20 million in rent to the General Services Administration for that storage space.

But 18.8 million cubic feet of records are stored by the agencies that produce them at a cost of $6.79 a cubic foot, or $127.7 million, more than 12 times the cost of keeping them in an Archives record center.

Rhoads, Deutrich, Wadlow and his staff are now wrestling with a particularly difficult case, which has boiled down to this: Does the Archives have the space and the money to store 154,000 cubic feet of patent records at 54 cents a cubic foot?

The Patent Office says it ought to find room. Smithsonian Institution experts brought into the matter agree. But Wadlow's appraisers say there must be a way to select a sample of the total that will satisfy the needs of future historians.

Barresse, who has no engineering background, is working on a similar case involving 20,000 cubic feet of aeronautical drawings. He says he's trying to devise a selection process that will show how aircraft drawings were made over the period involved.

"Appraising is something of an art," he said. "It's not something you can do by the numbers. We can't appraise piece of paper by piece of paper. We do it by series." The records area usually filed by category and Barrese may examine one or two in each category.

In recent years, another choice has been added for archivists: Whether to keep microfilm instead of paper. The choice is not always clear. Microfilm takes up much less space, but good bond paper lasts longer and is easier to work with.

Organization may be a critical factor. If a case is marginal and a group of 1 million documents is not organized in a useful way, Barrese and his colleagues would very likely reject it.