The National Museum of Natural History has temporarily barred the public from visiting its stored collection of North American Eskimo and Indian artifacts because of concerns about asbestos contamination.

Candace Greene, collections manager for the department of anthropology, said the department decided Tuesday not to escort visitors to see the thousands of baskets, weavings, and other objects stored in the museum's attic until staff members receive more information about whether the asbestos insulation there poses a health risk.

Museum staffers are also worried about how the fragile objects, some of which are 150 years old, can be cleaned of the asbestos fibers that are believed to have settled on their surfaces -- a problem that also concerns the National Museum of American History.

John Pate, chief of the industrial hygiene division for the Smithsonian Institution, of which the natural history museum is a part, said the level of the asbestos in the attic presents no danger to visitors or staff as long as they wear protective masks.

Jerry Conlon, an assistant to the director of the museum, also said that the collections management division has no reason for concern.

He said tests for the airborne fibers, which can cause cancer if inhaled, show less than 0.01 fiber per cubic centimeter in the attic. The level deemed safe by the National Institute for Occupational Safety and Health is 10 times higher or 0.1 fiber per cubic centimeter, according to Conlon.

Conlon said he hoped the collection staff's concerns are the result of "a miscommunication that we will be able to work out."

Though Pate said that his staff has conducted tests of the attic within the last three months, Greene and other curators of the collections said they have not seen any test results for more than a year, despite their requests for updates.

"We have seen no official reports" said Greene. "We have gotten verbal things -- 'don't worry about it' -- but we felt the time had come when we really needed some factual information."

Greene said the department will resume taking appointments for visits if the asbestos has not deteriorated. "The thing is, nobody knows," said Linda Eisenhart, a specialist who helps take care of the collection. "What about the stuff that falls in your hair? You go home and brush your hair. I have a child . . . . "

Five to 10 people a week from all over the world -- three elderly Navajo Indian weavers came in this week -- seek access to the attic of the museum on Constitution Avenue at 10th Street NW, according to Greene. The area contains about 60,000 items collected from Indian and Eskimo cultures that make up the North American ethnology collection, which Greene described as "the largest and best in the world."

It also holds archeological findings and items such as animal bones and antlers from the museum's division of vertebrate zoology.

How those items can be cleansed of asbestos fibers that industrial hygienists presume now cover at least some of them is a matter of growing concern to museum staff members. "I know of no safe method for removing it at this time," said Carolyn Rose, director of the museum's anthropology conservation laboratory. "I think they need to bring in an asbestos expert. That's the only way it's going to be resolved."

No water or solvents can be used on many delicate objects such as snowshoes "or things will start popping," said Eisenhart.

"What they may end up doing is just bagging everything and telling people, 'If you want to look at this stuff, do it at your own risk.' "

Greene said the issue "has not been one that has received as much attention as we would like it to. The museum needs to develop unique methods to clean the objects."

The museum undertook a project about two years ago to clean about 5,000 precious pots that make up some of the sturdiest objects in the collection. But the pots still sit in plastic bags because staffers are uncertain whether all dangerous fibers have been removed. "It's very unfortunate because we have a group of potters coming in from the Pueblo Zuni and they'll have to look at them through bags," Greene said. "For an artist that will be very frustrating."

Pate, of the industrial hygiene unit, said he is convinced that the pots are clean and can be touched, though he acknowledged that no standarized tests have been developed that show when asbestos on objects, as opposed to asbestos in the air, creates a hazard.

Staff members at the National Museum of American History are facing much the same problem with contaminated furniture and other ojbects stored at a building in Suitland. For industries, "it's a matter of literally bagging up all the contaminated material and taking it to a dump site," said Martin Burke, a conservator for the museum. "We want to save everything we have.

"We're caught . . . . we're really on soft ground."