SEATTLE (AP) - A woman who says her family ate ground beef linked to the only known case of mad cow disease in the United States has filed a class-action lawsuit against a supermarket chain.

The negligence claim for unspecified damages against Quality Food Centers Inc., owned by Kroger Inc. of Cincinnati, was filed Thursday in King County Superior Court by lawyers for Jill Crowson, 52, an interior designer in Clyde Hill, a suburb east of Lake Washington.

''I was pretty upset about it,'' Crowson said. ''I've spent all of my kids' lives trying to be a responsible parent for them to keep them safe. I felt badly that the food I served could be harmful to their health.''

Kroger and QFC officials could not be reached for comment Thursday, the Seattle Post-Intelligencer reported.

The lawsuit is believed to be the first involving the case of bovine spongiform encephalopathy that was detected Dec. 23 in a slaughtered Holstein from a ranch near Mabton.

According to the lawsuit, a recall order for beef linked to the cow was issued that day but QFC did not begin pulling the ''highly hazardous'' meat from about 40 stores that carried it until Dec. 24.

The Agriculture Department this week revealed that the recall covered 38,000 pounds of beef, nearly four times as much as initially announced, from the infected cow and from the meat of others that was mixed together in processing. One official said as much as 17,000 pounds probably was eaten or thrown out by customers.

The only notice to QFC customers was the posting of small signs in stores starting Dec. 27, according to the lawsuit.

QFC had ''a duty to warn'' buyers under the Washington Product Liability Act and could have done so through newspaper, radio and television advertising and by notifying individuals who made purchases using QFC Advantage discount cards, wrote Steve W. Berman, Crowson's lawyer.

Berman asked that the case be certified as a class action on behalf of everyone who purchased and ate beef that may have been exposed to mad cow disease in the Mabton case.

He said one of his investigators learned QFC buys meat for the product purchased by Crowson in large tubs, then regrinds and packages it for sale - a process the lawyer said makes the chain a manufacturer subject to the state liability law.

Crowson said she bought packages of ''9 percent leanest ground beef'' from a QFC in Bellevue and cooked it for tacos on one night and spaghetti the next, serving it to her daughter, Laura, 22; son, Nicholas, 19, and niece, Claire De Winter, 23.

''When the news about mad cow came out, I instantly became concerned,'' Crowson said, ''but the initial (news) stories didn't mention anything about QFC, so I thought we were OK.''

A few days later, Crowson said, a butcher in the store assured her that QFC had not sold any of the recalled beef, she said.

Only in a newspaper article Jan. 10 about a man on Mercer Island who discovered that he and his family had eaten beef subject to the recall did Crowson learn that some of the meat had in fact been sold by QFC, she said.

She said she called the supermarket chain, then faxed a letter asking that her purchase be traced through her QFC Advantage card and was notified Jan. 10 that her ground beef purchase was from the recalled batch.

The family is ''now burdened with the possibility that they presently carry (the disease) that may have an incubation period of up to 30 years,'' the lawsuit says.

Scientists believe people who eat beef from infected cows can contract variant Creutzfeldt-Jakob, a fatal brain-wasting disease that has been detected in about 150 people worldwide.

Federal officials have repeatedly insisted that the risk from eating muscle meat from an infected cow is extremely low, but since there is no way to determine whether a living person is infected the family's ''stress and fear cannot be allayed,'' the lawsuit said.