Despite widespread fears, restrictions and even proposals to ban it outright, genetic modification is becoming biology's fastest-growing field.

A Washington Post survey last week showed that such research - which involves the separation and recombination of dexoyribonucleic acid (DNA), the genetic material that determines an organism's characteristics - is moving ahead at 86 universities and research centers and at least nine private companies.

And the work is advancing rapidly:

In what could be the world's first practical application of the new technology, a University of Washington scientist had just created a vaccine to attack a major swine and cattle disease.

A University of California biologist is trying to make synthetic insulin.

The National Science Foundation will sponsor a conference this month to begin exploring ways to make plant genes manufacture their own nitrogen fertilizer from the air.

In addition to these efforts, perhaps 300 others are going on in the United States alone.

Biologists are doing the gene-splicing to learn how DNA gives live things all their hereditary traits. They want to learn to apply the techniques to make new biological products, like drugs and vaccines.

But they have been facing growing debate over the research's safety. Some scientists charge that researchers are unwisely tampering with evolution by creating new, man-made genes - and new forms of life that might cause some unexpected and heretofore unknown disease, and possibly death.

The Cambridge, Mass., City Council last month put some restrictions on such work at two of the country's proudest and traditionally most independent universities, Harvard and the Massachusetts Institute of Technology. Other cities and states are considering such laws - the California health department last week proposed such a bill - and demands are growing for congressional action.

Congressional health forces will be paying close attention to a public forum on the new technology at the National Academy of Sciences starting at 7:30 p.m. Monday and continuing Tuesday and Wednesday. The forum will include some of the technology's strongest supporters and Hercest detractors.

Rep. Olin E Teague (D-Tex.), chairman of the House Science and Technology Subcommittee, yesterday characterized the debate as "a serious and important matter which involves the freedom of scientific inquiry as well as the protection of the public. . . .It is also at times an emotional affair, which inevitably means that issues become distorted."

The pace of research is accelerating. Only last year some scientists said that any practical applications of the new method were "10 or 20 years away." In interviews last week, several spoke of uses "three to five years away."

The existence of what could become the first successful recombinant DNA vaccine, to use the scientists' term, was disclosed by Dr. Stanley Falkow of the University of Washington in Seattle.

He said in an interview that his group has not just one but a set of related substances ready for trial against scours - a severe, often fatal diarrhea of young pigs and cattle, and one of American agriculture's costliliest diseases.

The same gene-manipulating technology also might be used to make vaccines against human diseases, Falkow added.

His potential vaccines consist of modified or re-engineered strains of E. coli, the bacteria that cause much human diarrhea and dysentery, including much "travelers' diarrhea."

"A great deal of testing of our strains still has to be done in the laboratory, then in experimental animals, then on farms," Falkow said. Veterinary scientists at another, still undisclosed university have applied to the National Institutes of Health for a clearance to do the tests according to NIH's nine-month-old recombinant DNA safety guidelines.

"But the idea looks good," Falkow offered.

The "idea" is essentially a simplification of the idea behind the entire recombinant DNA revolution: using various chemicals and DNA bits as "scissors" and "carriers" to snip away important DNA sections and make new DNA combinations to create, in effect, a gene.

Falkow is an E. coli expert. He and his co-workers first identified and isolated the E. coli gene that makes the poison or enterotoxin, that cause E. coli diarrhea.

Using the new technology, he explains, "we deleted or took out a little piece" of the swine and cattle disease gene. "And now the gene would still produce a protein that would elicit an antibody response" - to protect the animal against the disease - "but it would in itself no longer be disease-producing or toxic. This makes it a vaccine."

All vaccines consist merely of either killed or modified bacteria or viruses. What Falkow has done is to modify the bacteria by a new means. And he has now made a "whole series of deletions," he adds, so various vaccines can be tried.

At other research centers, genes of rabbits, mice, chickens, sea urchins, fruit flies, yeasts, bacteria and viruses have been spliced into the genes of E. coli colonies. But the E. coli in these studies are harmless ones, by all firm evidence, though E. coli is a common inhabitant of human and animal guts. The strains of the bacteria used here are strains that self-destruct outside laboratories and cannot grow in the gut, the experimenters say.

And the E. coli colonies in these studies are used by the scientists as living factories to produce millions of copies of the new genes.

Dr. Herbert Boyer of the University of California at San Francisco is trying to synthesize the insulin gene, so it can be produced in such a bacteria "factory." He and Dr. Stanley Cohen of Stanford University developed much of the new technology, and the two schools are seeking a patent on what they believe could be wide commercial applications.

Seven major drug companies - Holffman-La Roche, Upjohn, Eli Lilly, Smithkline, Merck, Abbott and Miles Laboratories - have started or plan experiments.

The trouble with all these experiments, scientist-objectors claim, is that they produce new life forms with unpredictable characteristics.

"What we're talking about are potential dangers, hypothetical dangers that have never happened," Cohen replies. Most biologists seem to agree.

Last June NIH issued its guidelines to govern all recombinant-DNA scientists getting federal funds. All their work must be done within:

"Physical containment" ranging from P1, meaning standard lab safety measures, up to P4, meaning airlocks, protective clothes and sterilization of all wastes, measures so stringent that there are no certified P4 facilities yet, though there will be some soon.

"Biological containment," meaning many researchers must also use weak laboratory strains of E. coli that have been further altered genetically to make it even less likely they could survive outside the laboratory.

The debate in months ahead will involve such questions as: Are those controls enough? Or too much? And what controls and public disclosure should be required of industry, which is so far under no controls at all?

Whatever the future, a new thing has happened in this country in this debate. In the phrase of two writers in a recent issue of Harpers magazine, "Science has been dragged into City Hall."

The people of Cambridge or their representatives were forced to consider how much risk they wanted to accept to reap possible future benefits. The people of the United States, through Congress, may soon be making the same choice.