August 4, 1981

Governor Carey signed a bill today that would make it illegal for a physician to prescribe amphetamines for the sole purpose of helping a patient lose weight. The bill prohibits the use of such drugs for the ''exclusive treatment'' of ''obsesity, weight loss or weight control.'' A doctor who so prescribed an amphetamine would not be subject to prosecution, but Mr. Carey said the legislation would permit the state's Health Department to bring disciplinary procedings against physicians ''who persist in prescribing amphetamines for weight control.''

Egypt and Israel formally signed an agreement today establishing a 2,500-member international peacekeeping force in the Sinai to police their peace treaty. Nearly half of the force will be composed of United States combat troops and civilian observers. Secretary of State Alexander M. Haig Jr. signed the document as an observer in ceremonies at the State Department with the Ambassadors from Egypt and Israel. He said formation of the peacekeeping force, originally called for in the 1979 peace treaty between Egypt and Israel, was a ''clear manifestation of the United States' continuing support for a peace process in the Middle East.''

A demonstration against food shortages turned into a confrontation between the Polish authorities and the Solidarity union yesterday when the police halted a column of about 100 buses and trucks bedecked with flags and placards. The tense showdown between the state and the independent union was the first of its kind involving large numbers of people in Warsaw. Last night, thousands of Poles milled about the major crossroad of Marszalkowska Street and Jerozolimskie Avenue, most of them sympathetic to the demonstrating bus and municipal truck drivers. Scores of policemen and several police trucks were also at the intersection, but by early today all but two vans and a dozen officers had been withdrawn. The number of vehicles in the protest, however, rose overnight when 40 streetcars were parked end to end down Marszalkowska Street.

STING By JOHN NOBLE WILFORD RIDING the tides of summer once again are great shoals of jellyfish, which flourish in the warm coastal shallows through the brief season of their maturity. From July through September, along most American coasts, these translucent blobs of gelatinous matter with trailing tentacles are a menace in the eyes of fearful swimmers but intriguing animals to those few biologists who trouble to explore the nature of their stinging toxins. Scientists know that the jellyfish's reputation is worse in nearly all cases than its sting. The moon jellyfish, Aurelia aurita, so prevalent in New York waters these days is particularly harmless. A brush with these milky saucer-shaped creatures, usually less than a foot wide, will at most produce a tingling itch or a skin rash lasting no more than a few hours.

WASHINGTON SMALL high-technology companies, free of the bureaucratic fetters and institutional inertia of larger enterprises, are the wellspring of pioneering innovations in this country. But such firms, intrinsically fragile and risky, have found it increasingly difficult to make their way in these times of expensive research and high interest rates. Now a sleeper of a bill has suddenly arisen in Congress -a bill that would require all major science and research agencies of the Federal Government to devote 1 percent of their research and development money to help small businesses, as defined under the Federal Small Business Act, with promising ideas through the initial risky phase of demonstrating that a scientific innovation has commercial applications that would attract private venture capital. Having already gained 82 co-sponsors in the Senate, the bill, the Small Business Innovation Research Act, seems assured of passage in that body. And given the political clout of small business - akin to motherhood in Congress - a companion bill introduced last week in the House also has a good chance.