A campaign is under way to replace the sands of Rio de Janeiro's Copacabana beach, which is infested with parasites and contaminated by refuse.

Two banks have announced their financial support for the project, and more is being sought from Rio de Janeiro's hotels. Under the plan, about 1,350 truckloads of sand would be removed from the three-and-a-half mile stretch of Copacabana and replaced with clean sand.The operation is scheduled to take four months to complete. The head of the city's garbage collectors' union said he hoped the new sand would be in place by December, in time for the beginning of the summer season.

The pollution problem arises because Copacabana beach was artifically created 30 years ago as landfill. In contrast to naturally occurring beaches, the ocean waves do not wash the upper reaches of sand. The parasites are reported to be hookworms and a variety of roundworm, both associated with human feces.

Signs from the city's Health Department on whether the water is safe enough to swim in are widely ignored by bathers.

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A highway connecting Grantley Adams International Airport with the west coast of Barbados is now open. The Adams-Barrow-Cummins highway bypasses the city of Bridgetown, and is said to reduce the travel time from Barbados's air and seaports to the west coast by 50 percent.

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"From Pop Art Onward" is the inaugural exhibition for the new wing of Rome's Modern Art Museum. The wing houses the Sonnabend Collection, a private collection of contemporary art. The exhibition shows 160 works by contemporary American and European artists. The show, which runs to Oct. 2, is open Tuesday through Saturday from 9 a.m. to 2 p.m., and Sundays from 9 a.m. to 1 p.m. More information: Galleria Nazionale Arte Moderna, 131 Viale Belle Arti; telephone 802751.

"Italian Art: Protagonists 1900-1945" opens Sunday at Palazzo Grassi on the Grand Canal in Venice. The show will feature some 300 Italian modern art works. The show will be open daily from 10 A.M. to 7 P.M. until Nov. 5. Entrance at San Samuele 3231. More information: 5221375. The entrance fee is $5.60.