What was going on when I was born?

The eight counties in New York State that lie within 10 miles of a nuclear generating station sent representatives here today to confer with each other and to complain that the state was complicating their emergency planning. Rockland County, across the Hudson River from the three Indian Point plants, does not think that an evacuation plan for a nuclear emergency can be developed without a $3 billion system of new roads. Westchester County, which gets electricity and tax revenue from the Indian Point complex, is more optimistic, estimating that a plan is possible for $1.5 million to $2 million. But it does not know where even that amount will come from.

In a new sign of support for Britain, a majority of the Common Market countries agreed Monday to extend indefinitely the economic sanctions imposed against Argentina in retaliation for its invasion of the Falkland Islands. Italy and Ireland, which dissociated themselves from the ban on Argentine imports that was voted a week ago in Luxembourg, again refused to go along with the eight other countries in continuing the trade measures, which would have expired at midnight. At the same time, Britain, which had vigorously sought further support from the European Economic Community in the Falkland dispute, retreated a considerable distance on two demands in the internal affairs of the community: for a smaller budget contribution from the British and for a commitment that the veto prerogative of members would be respected in the future. Accord on Budget Rebate The British retreat allowed the group to achieve an accord just before 3 A.M. today on a problem that had nearly paralyzed it for weeks: how much of a budget rebate Britain should be given this year.

The nation's leading business economists released a grim forecast today that shows only a weak recovery in the last half of 1982, with high unemployment and high interest rates continuing to the end of the year. A poll of 400 members of the National Association of Business Economists found, however, that they believed that inflation would remain in check, with price rises averaging less than 6 percent this year and next year. The relative pessimism of the economists who advise companies, banks, agencies of the Government and other institutions offered little election-year comfort to the Reagan Administration, now locked in battle with Congress over tax and spending policies.

An article in Business Day on Fri- day incorrectly reported the Xerox Corporation's earnings for the second quarter of 1981. They were $179.7 mil- lion, or $2.13 a share.

International New European support for Britain was expressed by eight members of the 10-member Common Market. They agreed to extend indefinitely economic sanctions imposed against Argentina in retaliation for its seizure of the Falklands. Italy and Ireland again refused to participate in the ban on Argentine imports. At the same time, Britain retreated considerably on two internal Common Market issues. (Page A1, Column 6.) Seven Argentine jets were downed during repeated sorties against British ships off the Falklands in the third large Argentine attack in four days, the Defense Ministry announced. But it conceded that several of the figher-bombers had penetrated a screen of British jets and missiles and had hit several frigates and destroyers. No details were disclosed, but the ministry said that a frigate hit in Sunday's raids had sunk. (A1:3-5.)

Underscoring last week's drop in short-term rates, the Treasury sold $9.8 billion of three-month and six-month bills yesterday at sharply lower yields than those prevailing at the previous Monday auction. The average rates were 11.480 percent and 11.677 percent for threeand six-month bills, respectively. A week ago, the average auction rate was 12.189 percent for three-month bills and 12.187 percent for six-month bills. Last week's rate decline followed moves by the Federal Reserve to make bank reserves more plentiful in the banking system - an action some analysts interpreted partly as a means of calming money markets in the wake of financial difficulties at Drysdale Government Securities.

Aides to Mayor Koch and City Council leaders reached tentative agreement yesterday on a bill to require many property owners to pay real estate taxes twice a year instead of quarterly. The measure would save the city $32 million to $44 million a year, depending on the terms of the final agreement, officials said. It would not apply to property that is assessed below a certain level, probably $25,000 or $30,000. That provision, which was being negotiated, was designed to exempt one-, two- and three-family homes and at least some cooperative and condominium apartments.

At the height of the energy crisis in 1977, Michael and Josephine Wagner spent $1,250 to put urea-formaldehyde foam insulation into their house in Toms River, N.J. Two weeks later Mr. Wagner collapsed and was taken to the hospital. Since then he has suffered formaldehyde sensitization, an acute reaction to the formaldehyde gas released into the air as the ureaformaldehyde bond breaks apart. His wife and four children, to a lesser extent, have also suffered formaldehyde sensitization. Mr. Wagner can no longer live in his house nor function in his old job teaching high school science. Some common substances such as cigarette smoke and perma-press clothing, which contain traces of formaldehyde, quickly make him very sick.

The General Motors Corporation has agreed with Isuzu Motors Ltd., one of its Japanese affiliates, for Isuzu to develop and produce a subcompact car that is expected to replace the current Chevrolet Chevette. The model, which is to be introduced in the 1984 model year, would represent the first time the world's largest automobile company has gone to a foreign manufacturer to replace an existing line of cars. In an announcement today, General Motors said it would buy $200 million of convertible debentures from Isuzu to partially finance production of the model. The debentures would be converted into Isuzu stock after six years, increasing G.M.'s stake in the Japanese company to about 40 percent from its current holding of 34.2 percent, according to a G.M. spokesman, Don Huss.

The House of Representatives, making its first choices on next year's budget, today rejected three liberal proposals. But that left four budget plans covering the political spectrum still to be voted on, and concern grew today that the lawmakers might not be able to pass any of the seven plans. The proposals will be subject to 68 amendments, setting the stage for a free-for-all on the House floor. Under the rules for the debate, the last plan to be approved will supersede all predecessors. It would then have to be reconciled with the budget proposal the Senate approved on Friday.

''We're either going to get better locks or dumber chimps.'' - Parks Commissioner Gordon J. Davis. (B5:4.)

IT is 20 years since Rachel Carson's ''Silent Spring'' first warned against the environmental and health damage caused by chemical pesticides. In the years since, her book has often been cited as perhaps the most influential single factor in creating public concern about the future of the world's ecology. It was Rachel Carson, many people agree, who initiated the modern environmental movement. And the practical impact in some important areas was enormous as well. Her concerns about the deadly effects on animals of DDT and other so-called persistent pesticides, for example, became public concerns. And this public attitude eventually led the Federal Government to establish the Environmental Protection Agency and stricter governmental regulation of pesticides, including partial bans on some of the most controversial chemicals, Among the positive results have been a shift away from persistent chemicals, which remain in the environment for years, a reduction in pesticide residues found in the human body, the recovery of some endangered species and a lessening of pesticide residues in air, water and soil. Nevertheless, environmentalists and pesticide advocates alike now believe that ''Silent Spring,'' despite its broad importance to the environmental movement, has on balance, had only limited influence in the area of its chief concern - pesticides, which include insecticides, herbicides and other chemical pest killers. Although there have been important changes in the kinds of chemicals used, the total volume of pesticides used in this country has continued to soar, unabated.