Investigators rushed to locate meat from a Holstein sick with mad cow disease that may have made its way into retail markets in eight states and one territory, but Agriculture Department (search) officials insisted there was no health risk to consumers.

Dr. Kenneth Petersen (search), a department veterinarian, said Sunday that an investigation revealed that meat from the infected dairy cow could have reached retail markets in Alaska, Hawaii, Idaho and Montana and the territory of Guam — more locations than originally thought.

Officials had said earlier that most of the meat went to Washington and Oregon, with lesser amounts to California and Nevada, for retail sale.

"The recalled meat represents essentially zero risk to consumers," said Petersen, of USDA's food safety agency.

He said parts most likely to carry infection — the brain, spinal cord and lower intestine — were removed before the meat from the infected cow was cut and processed for human consumption.

Despite their assurances of food safety, federal officials have taken the precaution of recalling 10,000 pounds of meat from the infected cow and from 19 other cows slaughtered Dec. 9 at Vern's Moses Lake Meat Co., in Moses Lake, Wash.

Because it is not known exactly what portions of the meat cut that day came from the diseased cow, health authorities must assume that some could have reached any location where any part of the 10,000-pound supply was distributed.

Officials still are recovering meat and won't know how much was found for days, Petersen said.

Mad cow disease, known formally as bovine spongiform encephalopathy, or BSE, is a concern because humans who eat brain or spinal matter from an infected cow can develop a brain-wasting illness, variant Creutzfeldt-Jakob disease (search). During a mad cow outbreak in the 1980s, 143 people died of it in Britain.

Petersen said the slaughtered cow was deboned at Midway Meats in Centralia, Wash., and sent Dec. 12 to two other plants, Willamette Valley Meat and Interstate Meat, both near Portland, Ore.

Willamette also received beef trimmings, which were sold to some three dozen small, mom-and-pop Asian and Mexican facilities in Washington, Oregon, California and Nevada, officials said.

Several Western supermarket chains — Albertsons, Fred Meyer, Safeway and WinCo Foods — have voluntarily removed ground beef products from the affected distributors. Safeway has said it will look for another supplier.

As the investigation continues, the list of countries banning U.S. beef imports is growing. Jordan and Lebanon joined the list Sunday. U.S. beef industry officials estimated earlier they lost 90 percent of their export market because of the bans by more than two dozen nations.

U.S. agriculture officials in Tokyo tried to persuade Japanese officials Monday to lift its ban. But Japan rejected the request, saying officials should first establish the facts surrounding the infection, a Japanese official said on condition of anonymity. Japan is the largest overseas market for U.S. beef.

Officials with the World Organization for Animal Health recommend countries shut down beef trade with any nation that has mad cow.

Dr. Ron DeHaven, USDA's chief veterinarian, said research shows that certain meats, such as beef steaks and roast, are safe from infection. He said this suggests the trade restrictions "are not well-founded in science."

Investigators have tentatively traced the first U.S. animal with mad cow disease to Canada. This could help determine the scope of the outbreak and might limit the economic damage to the American beef industry.

The findings indicate the cow came from Alberta, the same Canadian province where scientists found a single cow infected with the illness in May. DeHaven and Canadian officials have stressed that this still hasn't been confirmed because U.S. records outlining the animal's history do not match those in Canada. DNA tests will help resolve the matter.

Canadian documents show the cow had two calves in Canada, contrary to U.S. records that said it had never produced calves before it was shipped.

Also, Canadian documents said the diseased cow was 6 years old, but U.S. records said it was younger, around 4 to 4.

The cow's age is significant because it may have been born before the United States and Canada in 1997 banned certain feed that is considered the most likely source of infection.

A cow can get sick from feed that contains brain or spinal tissue of an infected animal. Farmers used to feed their animals such meal to fatten them.

The Food and Drug Administration is investigating whether the cow ate contaminated feed, but the animal may been infected years before it appeared sick. BSE can incubate for four to five years.

It takes as little as half a gram of infected material to sicken an animal, said Dr. Stephen Sundlof, head of the FDA's Center for Veterinary Medicine.

Officials are less certain how much would infect a human, but Sundlof said it would higher for humans than for cattle.

Investigators hope to soon determine whether the strain of BSE, a disease caused by a misshapen protein, is the same one that struck Europe, especially Britain, in the 1980s and 1990s.

The Associated Press contributed to this report.