LONDON (AP).- An art exhibition involving 100 million porcelain sunflower seeds has been closed to visitors because it is generating dust that is a potential health hazard, the Tate Modern gallery said Friday.

Chinese artist Ai Weiwei filled a giant hall at the London gallery with a 1,000 sq. meter (10,000 sq. foot) carpet of the imitation seeds, hand-crafted by thousands of artisans in China over a two-year period. Visitors were invited to walk across the surface when the show opened earlier this week.

But the gallery said Friday that the "enthusiastic interaction of visitors" was releasing a "greater than expected level" of ceramic dust. It wasn't clear whether the seeds were breaking or simply being worn down.

"Tate has been advised that this dust could be damaging to health following repeated inhalation over a long period of time," the gallery said in a statement. "In consequence, Tate, in consultation with the artist, has decided not to allow visitors to walk across the sculpture."

It said visitors could view the exhibition from a walkway above the hall.

The gallery said the seeds, a common Chinese street snack, represent friendship and compassion, raise questions of individualism and evoke the enforced conformity of the Cultural Revolution, when propaganda posters depicted Chairman Mao as the sun and Chinese people as sunflowers turning toward him.

The commissions in the huge Turbine Hall have become one of the most popular attractions at Tate Modern, a former power station that opened as a gallery in 2000 and draws 4 million visitors a year.

It is not the first time an exhibition there has caused mishaps. In 2007 three visitors tumbled into Doris Salcedo's "Shibboleth," a jagged crack running the length of the room. Several people suffered bumps and bruises on Carsten Holler's twisting slide in 2006.

Last year a man was injured in Polish artist Miroslaw Balka's "How It Is," which invited visitors into a pitch-black room.


Copyright 2010 The Associated Press.