July 5, 1981

YONKERS THE Westchester County Fair, dormant since 1949, will be revived at the Yonkers Raceway this Friday, and its nine-day stand may bring back memories for many. ''It is with a great deal of enthusiasm that we are bringing the fair back to Westchester,'' said Timothy J. Rooney, president of the Yonkers Raceway. ''Parimutuel racing doesn't return here until next month. And so we opted for a fair to give visitors a chance to enjoy some of the old country carnival flavor of yesteryear.'' By bringing people into the area, he added, ''We hope it also will give the city of Yonkers and the county an economic boost.'' Among the attractions scheduled are exhibition harness-horse racing, industrial and agricultural displays, a livestock exhibit, fireworks, vaudeville and, on the final day, an antique car parade. Mr. Rooney said the colorful midway would be filled with carnival rides, games and concession stands, provided by the James E. Streat's Shows of Orlando, Fla., to appeal to the young at heart. Rounding it all out, on the last two days there will be automobile thrill shows in the afternoon and evening by Joey Chitwood's internationally known daredevil drivers.

The possibility of manufacturing new forms of life or genetically altering human beings, who are described in Christian and Jewish Scriptures as created ''in the image of God,'' is raising new problems for theologians attempting to assess the morality of modern bioethics. The rapid advances in genetic research, which has succeeded in fabricating living organisms by gene splicing, or artificially combining genes, mean that ''those who would play God will be tempted as never before,'' according to a statement issued by officials of the National Council of Churches, the United States Catholic Conference and the Synagogue Council of America. But, theologians interested in science and scientists versed in theology say that what constitutes ''playing God'' is as yet undefined. The scriptures and traditions of religious communities do not address such modern scientific techniques. Genetic engineering enables the scientist to create new life forms by altering existing species through rear@ranging the genes passed on from generation to generation. A relatively new science, it has expanded rapidly in the last six years and now has a number of industrial and medical applications. Sometime in the future inherited illnesses may be eliminated by replacing abnormal genes carrying the diseases, and tests are under way on genetically produced interferon, an antivirus agent for humans.

FOR PERFORMERS AND PRODUCERS By TONY SCHWARTZ During the past several months on Bravo, a new cable-television network, Leonard Bernstein conducted the American Symphony Orchestra in a tribute to Aaron Copland, a group of jazzmen celebrated Eubie Blake and the Indiana University Opera Theater performed the ''The Greek Passion.'' On ABC's Arts, a second cable network, the schedule last month included a ballet choreographed by George Balanchine, profiles of Jean Renoir, Edgar Degas and Henri Toulouse-Lautrec and the St. Louis Ragtime Band performing a selection of Scott Joplin songs. On CBS Cable, which will make its debut in October, the schedule includes the premiere of a dance choreographed by Twyla Tharp, a one-woman show featuring Jane Alexander and twelve hours devoted to a drama about the life of Giuseppe Verdi. It sounds like a video version of the Renaissance. Indeed, in the most optimistic scenarios for the future, this flowering of the arts will be just one part of cable TV's brave new world. New cable systems promise up to 100 channels, and already networks aimed at specific interests - movies, sports and news, for example - are springing up. But many more channels will have to be filled, and that raises the possibility of even more specialized networks - ones devoted to narrow interests such as tennis and knitting, or even networks that feature a single art form - modern dance or theater, for example.

STAMFORD PAST the white picket fence and under the American flag that flies from the porch at 955 Cove Road come the sick, the suffering and the questioning. They are veterans of the Vietnam War, but to them the battle is not over. An enemy more deadly, they say, than the one they faced in the jungles of Southeast Asia still stalks them. The small green house serves as the Connecticut office of Agent Orange Victims International, a nonprofit organization that seeks to inform Vietnam veterans that some of the health problems they or their children suffer from could have been caused by exposure to a herbicide called Agent Orange that was used in Vietnam and elsewhere between 1962 and 1970. The co-directors of the two-and-a-half-year-old Connecticut chapter are James A. Sparrow, a 34-year-old former Marine, and Roger Pappas, 47, who is not a veteran. The men, both divorced, share the rented house and run the chapter from their living room. The Connecticut chapter was the first branch office established by the organization, which is based in New York City.

CENSUS figures indicating that the Island's population has stabilized and the impact of this on companies that previously grew with the population have sparked a debate among Long Island planners over the strength of the Island's economy. Some say that the Island has entered a ''no-growth'' or mature period - a polite way of describing economic stagnation. Others counter, saying that different economic measurements indicate continuing strength. Those who support the ''maturity'' thesis see the Long Island Lighting Company's entry into the retail energy systems business as evidence that changes in the Island's economy have prompted a shift in the strategy of one of the Island's oldest businesses, whose growth has traditionally been tied to increases in residential electrical and gas hookups - a source that is closely tied to growth in housing.