What was going on when I was born?

The index of leading economic indicators fell 0.6 percent in January, the ninth consecutive decline. The December figure was revised to a 0.3 percent decline; it had been reported earlier as a rise of 0.6 percent, and the first sign that the recession was ending. The January decline would have been steeper had officials not omitted one of the 10 components, the average manufacturing work week. They said this figure had been distorted by cold weather. (Page D1.) Members of the teamsters' union ratified a wage freeze for at least two years. But the new contract continues the cost-of-living escalator in the old contract. There was widespread opposition to the wage freeze within the union, but the margin of approval far exceeded that required. In the past year, as the recession has worsened, more than 120,000 teamsters have lost their jobs. (A1.)

Despite his conviction in December on Federal mail fraud and extortion charges, Joseph M. Margiotta remains one of the most powerful political leaders in New York State, according to Republican and Democratic officials. As chairman of the Nassau County Republican Committee, Mr. Margiotta is the absolute ruler of a political organization that he says raises more than $1 million a year, prints four to six million pieces of campaign literature in an election year in its print shop and plays a critical role in hiring and promoting municipal employees, from high-ranking county officials to part-time lifeguards at public beaches. Mr. Margiotta's friends and foes agree that he dominates the government and civic life of Nassau County. There is also a consensus that the organization he heads has remained well disciplined in the months since his conviction on Federal charges of having split $685,000 in municipal insurance commissions among party supporters. ''The only thing you can liken it to is an army,'' Assemblyman Lewis J. Yevoli, a Democrat from Bethpage, said of Mr. Margiotta's organization. ''There is never a break in the ranks. I don't think Tammany Hall in its heyday had anything like what he has.''

City officials yesterday released a report on the 1981 rental housing market showing that only 42,000 of New York City's 1.9 million apartments were vacant and available. The citywide vacancy rate, according to the report, dropped sharply in a three-year period, to 2.13 percent from 2.95 percent in 1978. Mayor Koch stated that the vacancy rate showed the continued need for the city's two-tiered rent-regulation system. The rate is the lowest in a decade.

AFEW years ago, scientific concern over cancer-causing substances in the workplace and the general environment was running especially high. Experts from three Government health agencies estimated for the Occupational Safety and Health Administration that poisons in the workplace might play a role in 20 percent to 38 percent of all future cancer deaths in the United States, an astonishing leap from previous projections. And other scientists worried that poisons escaping from smokestacks, toxic waste dumps, nuclear reactors and hazardous products would cause numerous deaths among the general public as well. Hardly a week went by without some politician or environmental speaker warning of a ''cancer epidemic'' that was either already upon us or shortly on the way. Today, however, a less alarming view of the danger from carcinogenic pollutants has regained the ascendancy among cancer authorities. Some of the world's leading cancer epidemiologists have published estimates that occupational exposures and environmental pollution are relatively minor causes of cancer compared to such personal ''lifestyle'' factors as smoking, diet, alcohol, and even sexual and reproductive behavior.

Tanzania, in sticking to its socialist path, stumbles A2 Papandreou urges international conference on Cyprus issue A2 Weinberger is cautious on Jordanian bid for advanced arms A3 Around the World A4 Excerpts from toasts by Brezhnev and Jaruzelski A5 Red Cross says its aides met with Walesa in private A5 Government/Politics Deep South is cool to new Reagan budget plans A10 Justice aide warns of voting rights measure A11 Transportation chief backs new revenue sources for transit A12 Supreme Court Roundup A15 President reorganizes his Office of Policy Development A17 Koch in Albany to Mend Fences With Upstate Democrats B3 Senator says Reagan's outlook hurts Republican Party D22 Washington Talk Briefing A14 The Presidency: Assessing jokes about Reagan A14 National Zoo houses an endangered species A14 Required Reading A14 General Around the Nation A10 Contradictory testimony emerges on Air Florida crash A10 New York students win top prizes in national science contest B1 City is assailed on hiring of special-education teachers B2 Metropolitan Museum to mount Israeli exhibit B3 Wall Street explosions said to mark resurgence of F.A.L.N. B3 Board votes to evict Huntington Hartford from apartment B4 New York insurance industry: growing but leaving D23 Science Times Cancer experts are vigilant, but less alarmed, on environment C1 About Education: keeping colleges open to all C1 The Doctor's World: implications of new drug ads C2 Science Watch C3 Science Library C3 Q&A C4 Industry/Labor Deputy Mayor offers financial and labor aid to Daily News B5 Arts/Entertainment Theater museum opens at the Minskoff on Broadway C7 Reuben Frank named president of NBC News C7 Two theaters given reprieve by judge as actors protest C7 "The Journey of the Fifth Horse" by Ronald Ribman at Harvard C9 Baryshnikov renews contract with Ballet Theater to 1986 C9 Dylan Thomas plaque unveiled in Westminster Abbey C9 Placido Domingo and Tatiana Troyanos sing in Met concert C9 Ludlum's new thriller, "The Parsifal Mosaic," reviewed C10 Portrait of Carl Sandburg on PBS's "American Playhouse" C11 "An Innocent Love," math tutoring in television movie C11 Style Notes on Fashion A16 Prairie skirt sweeping the field A16 Obituaries Walter J. Mahoney, ex-G.O.P. leader of New York Senate D23 Julian Levi, painter and Art Students League instructor D23 Charlie Spivak, big-band leader of the 1940's D23 Sports Dave Anderson on the dinner for Ken Boyer A18 College scholarships at stake in Colgate's Women's Games A18 Islanders rout Maple Leafs, 9-5 A19 Oregon State is No. 1 in Times computer ranking A19 Foster is focus of attention as Mets' full-scale workouts begin A19 Knicks considering front-office changes for next season A19 Garden in court fight with its landlord, Penn Central A19 A 13-year-old horse just keeps running A19 Piniella saves $7,000 in fines by making weight A20 Staten Island wins its second straight City U. title A21 Features/Notes Issue and Debate: Reagan's plan for more aid to El Salvador A6 Sports People A18 Man in the News: Charles Luisi, head of bomb squad B3 Notes on People B5 Going Out Guide C9 News Analysis John Vinocur examines effects of Bonn bribery investigation A3 Editorials/Letters/Op-Ed Editorials A22 Unpopular case for tax leasing Strangling civil rights Topics: list, missed Letters A22 Sydney H. Schanberg: shoot the messenger A23 Lawrence E. Harrison: Sandin- ists' "foreign devil" A23 Lloyd J. Dumas: swords into plowshares A23 Norma Acevedo Heine and Jorge Heine: women's house work A23

The Supreme Court agreed today to hear an appeal that could produce an antitrust ruling in a case involving the Robinson-Patman Act, which prohibits sellers from charging different prices to different purchasers. The act permits sellers to defend themselves against a charge of illegal price discrimination on the ground that the selectively lower prices were necessitated by a good faith effort to ''meet competition.'' The question the Justices agreed to decide is whether the ''meeting competition'' defense applies to pricing systems that are based on geography, sales volume or other general criteria. The case, Falls City Industries v. Vanco Beverage, No. 81-1271, will not be argued until the next Supreme Court term, which begins in October.

New York City students won the top three prizes today in the annual Westinghouse Science Talent Search, one of the most prestigious competitions in the nation for teen-age scientists. Reena Beth Gordon of Brooklyn, who worked eight months on an experiment involving mathematics and linguistics, was awarded the first-place $12,000 scholarship. Miss Gordon, 16 years old, is a senior at Midwood High School in Brooklyn. Ronald M. Kantor, 17, of the Riverdale Country School in the Bronx, won the second-place $10,000 scholarship for a study of nuclear fusion, and Ogan Gurel, a 17-year-old student at Stuyvesant High School in Manhattan, won the third-place scholarship of $10,000 for an experiment in computer programming.

''It is really very difficult to turn a business on and off like a faucet,'' observed Richard M. Smith, vice chairman at the Bethlehem Steel Corporation in Pittsburgh, which is operating at about 60 percent of capacity. ''We can't just turn the taps on our steel blast furnaces.'' Difficult though it may be, Mr. Smith and other corporate managers have been getting a good deal of practice in recent months shutting down their operations. The nation's manufacturing sector operated at only 70.4 percent of capacity during January, down from 80 percent last May and just slightly above the 69 percent level reached in March 1975, which was the lowest level since 1948, when the Federal Reserve Board began keeping statistics. Industries such as automobiles and lumber are running at less than 50 percent of capacity. And some economists predict that production and capacity utilization will decline further before the recession ends and industry starts the climb back to the 85 percent or 90 percent capacity utilization rate that is the sign of a healthy economy.

Judge Aileen H. Schwartz of Family Court in Manhattan began the day with polite requests that gradually became firmer. By day's end, she was fuming. No one, it seemed, could verify the alibi of a 16-yearold charged with destroying a car who had missed a court appearance a month earlier. The youth said in his morning appearance that he had been attending a school for troubled children on the day of the previous hearing. But his lawyer knew nothing about it. The Probation Department knew nothing about it. And his mother could not be found. As the long court day drew to a close, Judge Schwartz demanded the answers by the next morning. And ''to be certain he just doesn't disappear,'' she ordered the youth held overnight. Late the next afternoon, she got her answer: the school had never heard of him. The alibi was phony. But in the meantime, she was told, the youth had walked away from the courthouse, leaving as easily as he had arrived. In court parlance, he had ''absconded.''

A Soviet spacecraft landed gently on Venus yesterday, transmitted the first color pictures of the surface and scooped up a soil sample for the most detailed analysis thus far of the planet's chemistry, the Soviet news agency Tass announced. The robot craft, the fifth from the Soviet Union to land on Venus, is a module detached from Venera 13. It plunged through the dense, baking-hot carbon dioxide atmosphere and touched down in the foothills of a mountainous region known as Phoebe, just south of the Venusian equator and also below the active volcanic region of Beta. An identical lander, from Venera 14, is expected to reach Venus Friday and probably put down on the plains east of the Phoebe landing site.

''The Republican Party has just about written off those women who work for wages.

Egypt expressed concern to the United States today over growing problems with Israel - in particular the Israeli threat to cancel the visit of President Hosni Mubarak if the Egyptian leader does not travel to Jerusalem. Ambassador Ashraf Ghorbal of Egypt, who returned to Cairo last week for a planned two weeks of consultations, came back almost immediately with what the Egyptians called an urgent message from Mr. Mubarak for President Reagan. Mr. Ghorbal spent an hour and a half this morning with Secretary of State Alexander M. Haig Jr. discussing the Middle East situation. Two Areas of Concern An Egyptian source said that Mr. Ghorbal had asked the Americans to use their influence with the Israelis to calm the rising tensions, not only in terms of Israeli-Egyptian relations but also in connection with the concern in the region that Israel might launch a military attack against Palestinian positions in southern Lebanon. Mr. Mubarak had planned to visit Israel sometime this month in advance of Israel's scheduled return to Egypt of the remaining part of Sinai on April 25.On Sunday, the Israeli Cabinet, noting that Mr. Mubarak was reluctant to go to Jerusalem because Israel's annexation of the eastern part of the city is not recognized by Arab countries or by many other nations, declared ''that if President Mubarak refuses to visit Jerusalem during the course of his visit to Israel, we would have to do without this important visit.''