‘Mad Cow’ Risk in U.S. Tiny but Real, Experts Say


Gaps in U.S. food safety regulations and enforcement and the dearth of information about how “mad cow” disease spreads have raised questions over whether American consumers really are insulated from the disease that has caused the deaths of 94 people across Europe.

While country after country in Europe has fallen prey to Britain’s mad cow epidemic, U.S. regulators have stood firm on their assurances that Americans are safe, citing import bans, animal testing, curbs on blood donations and feed restrictions.

Although no cases of bovine spongiform encephalopathy have yet been reported in the United States, and experts claim it is “highly unlikely” that BSE will become a problem here, the same experts concede that it is impossible to rule it out.


“I don’t think that any country can say they are 100% sure that they are free of BSE,” says Ralph Blanchfield of the independent Institute of Food Science and Technology based in Britain.

“I think it’s reasonable that people are worried,” says Stephen DeArmond, a UC San Francisco neuropathologist who collaborated on the 1997 Nobel Prize-winning research on the agent that causes BSE.

Many food safety advocates are wary of government assurances in the wake of the recent StarLink fiasco, in which a genetically modified animal feed corn not approved for human consumption wound up in everything from taco shells to corn chips.

Though the risks of a mad cow outbreak in the U.S. may be slim, there are concerns about gaps in these areas:

* Feed mills. If BSE does exist undiagnosed somewhere in the nation’s cattle or dairy herds, there’s a chance that it could be spread by mix-ups at feed mills, some of which have been lax in following regulations aimed at stopping BSE. The disease was spread in Europe through contaminated animal feed.

* Imports. American companies imported feed from Britain made of rendered animals for three years after BSE was diagnosed there in 1986. Moreover, over the past decade, 32 cows were shipped in from Britain that U.S. Department of Agriculture officials can’t account for.


* Inadequate testing. Although 12,000 so-called downer cattle, or cattle that could not walk on their own when they were brought in for slaughter, were destroyed in the U.S. this decade and their brains tested for BSE, some industry observers believe that is not enough to guarantee that U.S. herds are free of the disease. There is no test that can detect the disease in live animals.

* Related diseases. Sheep, deer, elk and mink in this country have contracted diseases in the same family as BSE known as transmissible spongiform encephalopathies, or TSEs, which are not fully understood and carry some of the same neurological symptoms.

BSE affects the central nervous system of cattle and is known to cause a human version called new variant Creutzfeldt-Jakob disease, which bores holes into the brain, causing bodily dysfunction, dementia, hallucinations and death.

Worldwide there have been about 178,000 cows identified with the disease since it was diagnosed in Britain 15 years ago. The disease has spread from Britain to native-born cattle in other European countries, such as France, Italy, Switzerland, Germany, Portugal, Ireland and Spain, through contaminated feed and been exported to areas such as the Falkland Islands and Canada.

It is believed to be spread by a mysterious particle called a prion, an infectious molecule in the membranes of cells that is neither a bacterium nor a virus and is largely found in the brain and spinal cord of an infected animal.

If BSE does exist undetected in this country’s herds, the biggest threat to the food chain would come from lax practices at feed mills.


U.S. regulators have barred mills from selling cattle feed made from meat and bone meal from BSE-susceptible animals since 1997.

However, rendered dairy cows, sheep and goats are still used in feed for pigs, a point that concerns some scientists, who fear that the disease could spread to other species. They say the practice leaves the door wide open for mix-ups such as the one at Purina Mills in Gonzalez, Texas.

There, the company acknowledged selling cattle ranchers feed made from rendered cows, prompting a quarantine of 1,222 cattle. The animals, which were bought and taken out of the food chain by Purina, are not believed to have been infected with BSE.

However, the incident highlighted how easily a contamination could start and raised questions about the Food and Drug Administration’s ability to effectively police the food chain.

It was cross-contamination like this that played a part in how the genetically modified and potentially allergenic feed corn called StarLink made its way into the food supply last year.

To ensure that it was operating at “zero-risk,” Purina vowed to stop mixing meat and bone meal into all of its animal feeds.


However, some of the nation’s largest feed companies, such as Land O’Lakes Farmland Feed and Cargill, still use meat and bone meal in feeds for animals other than cows.

And not all of them are using it responsibly, according to a report issued last month by the FDA. In its inspections of more than 1,000 U.S. feed mills, the FDA found that 20% did not have the proper precautionary statements on their labels. And 9% did not have a system in place to prevent commingling of cattle feed with feed meant for other animals. The report did not identify the violators.

Five recalls have been issued for improperly labeled feed since the 1997 ban, the FDA said.

There are probably many more companies not in compliance. The FDA has not yet finished its first inspection of all of the nation’s feed mills and renderers. It has no system in place for regular inspections or sampling, says Stephen Sundlof, director of the FDA’s Center for Veterinary Medicine.

Critics say the agency will also need to take a tougher stance on enforcement to keep companies honest. Currently, offenders of the ban are given an oral warning and a letter asking for a recall before any product is subject to seizure.

“It doesn’t do any good to have regulations if you have no enforcement,” says Mark Ritchie, director of the Minnesota-based agricultural think tank Institute for Agriculture and Trade Policy. “These companies should be [temporarily] shut down if they are violating the rules.”


Some food safety experts insist that because USDA officials acted early to restrict imports and close in on potential problems, current regulations should be sufficient to protect consumers and prevent the spread of the disease.

The U.S. has had a ban on live animals imported from Britain since 1989 and on animals, meat, bone meal and other products from affected European countries since 1997.

However, because some animal products were shipped over after animals were diagnosed in Britain, the risk of BSE existing here cannot be ruled out, Blanchfield says. “The U.S. imported just under [44,000 pounds of British feed] in 1989, when the epidemic started to get going but was not at its peak.”

In addition to feed, the USDA keeps tabs on more than two dozen cattle that were shipped in from Europe during the past decade and still live on farms in Texas, Minnesota, Illinois and Vermont, says the USDA’s head veterinarian and mad cow expert, Linda Detwiler.

So far, none has exhibited symptoms of BSE, and they are believed to be too old to harbor the disease.

However, some observers worry about the 32 cows shipped in from Britain during the past decade that USDA officials still can’t account for.


Academics say the risk to this nation’s 98 million head of cattle from fewer than three dozen animals is too low to even calculate. “The risks of having a U.K.-like [situation] are infinitesimally small” because of the feed ban, says George Gray, researcher at the Harvard Center for Risk Analysis, which has studied the subject for two years.

It was the continued sale of feed made from the meat and bone meal of contaminated animals that was responsible for BSE’s rapid spread across Europe, and that practice was promptly stopped in the United States.

Still, skepticism is understandable, scientists say, given how much is not yet known about the disease. “We don’t have the tests yet to verify that there is no problem [in our herds],” says DeArmond of UC San Francisco.

A number of companies are rushing to come out with a blood test that will detect the disease in live animals. Currently, the disease is diagnosed only by studying brain tissue after an animal dies or is killed.

During the past decade, the brains of 12,000 so-called downer cattle have been tested, and all tests have been negative, Detwiler says.

Contributing to the confusion and fear is the host of similar diseases affecting other animals in this country, such as deer, elk, sheep and mink.


Although these diseases have not been shown to jump species, scientists can’t say they haven’t. And the experts can’t fully explain how the animals developed the cell abnormality to begin with.

Two hunters in this country who ate deer and elk, and one non-hunter who ate venison, have died from Creutzfeldt-Jakob disease, Detwiler says. There was no direct link established, however, because it is not known whether they ate animals infected with TSE.

Ritchie, the think tank director, argues that there hasn’t been enough education for hunters and additional precautions taken to protect consumers.

“Why government hasn’t acted on what it’s known is a very big question,” he says. “This is a direct threat, and it’s not being dealt with.”

So far, cases of so-called mad deer disease have been identified in wild animals in Colorado, Wyoming and Nebraska, and on 13 elk farms in those states plus Montana, South Dakota, Oklahoma and Saskatchewan, Canada.

Regulators won their fight to wipe out the threat from the sheep version of BSE, also known as scrapie, which was found in four animals on a Vermont dairy farm.


A federal judge ruled that the USDA can seize and destroy these animals along with a second flock also imported from Belgium that may have eaten contaminated feed.

Scrapie-infected sheep ground up in feed are thought to be the initial cause of BSE in Britain. So far, scrapie does not appear to affect humans when ingested.

Experts say consumers would have to feast on the brains and backbones of cows to stand a significant risk of exposure to BSE.

The prions causing BSE aren’t found in muscle. There is also no evidence that milk or blood pass on the disease.

“I probably wouldn’t worry too much about eating beef in the U.K.,” says Dean Cliver, a food safety professor at UC Davis. “And I certainly wouldn’t worry about it here.”


Reuters contributed to this report.