IRA FLATOW, host:

You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.

Next, last week, the USDA lifted restrictions on some imports of Canadian cattle into the United States. Previously, the U.S. blocked any cows more than 30 months old from entering this country from Canada. Those restrictions were put in place after mad cow disease turned up there in Canada in 2003. According to the USDA, the new rule which allows the import of cattle up to eight years old recognizes Canada's new and improved safeguards against the transmission of BSE. That's a brain wasting disease transmitted through the meat and meat by-products of infected cows.

But the Consumers Union - the folks behind consumer reports - Consumers Union is worried that cattle infected with mad cow disease will slip through. So for the rest of the hour, we're going to talk with the top USDA official about the reasons behind this new import rule, and with a scientist from Consumers Union who says the rule could put or food supply at risk.

If you'd like to get in on our discussion, our number is 1-800-989-8255. 1-800-989-TALK. And as always, you can surf over to our Web site at sciencefriday.com.

John Clifford, DVM, is the chief veterinary officer for the Animal Plant Health Inspection Services of the U.S. Department of Agriculture in Washington. He joined us by phone from his office there.

Welcome to the program, Dr. Clifford.

Dr. JOHN CLIFFORD (Chief Veterinary Officer, Animal and Plant Health Inspection Services, U.S. Department of Agriculture) Thanks, Ira. Glad to be with you.

FLATOW: Thank you. Michael Hansen is a senior scientist at the Consumers Union. That's a publisher of consumer reports in Yonkers, New York. And he joins us today.

Welcome to the program, Dr. Hansen.

Dr. MICHAEL HANSEN (Senior Scientist, Consumers Union): Thank you. Glad to be with you, Ira.

FLATOW: Dr. Clifford, let me ask you first. As I said in the introduction, the new rule on the import of beef from Canada went into effect just days ago. In effect, this rule relaxed restrictions on import of Canadian cattle. Is that correct?

Dr. CLIFFORD: Yes, sir. That rule would allow animals born, after what we determine to be an effective feed ban date, of March 1999 to come to the U.S. for purposes of feeding, for slaughter and for breeding.

FLATOW: And why the rule changed?

Dr. CLIFFORD: Well, the reason for the rule change is we use the best science known internationally with regards to this. We know that BSE is an issue that needs to be addressed based on the best science. We certainly have concerns for consumers as well as for animal health, but we also know how to deal with this disease internationally. And this is a disease on a decline and you do that through ruminant to ruminant feed bans for protection of livestock. And you also do it through the specified risk materials removed at the slaughter to protest human health.

FLATOW: But did Canada not have several cases of BSE in the last several years?

Dr. CLIFFORD: Yes, they have had several cases of BSE, and some of those animals actually were born after a date, what we determined to be an effective feed ban date. And we took all of that into account and to an extensive risk analysis. That analysis was peer-reviewed by people outside of government and was found to be very sound in the analysis itself. And it shows the risk would be extremely low of establishing BSE in the U.S. livestock population.

FLATOW: And can you - do you have a number for that risk?

Dr. CLIFFORD: Well, when I say low, I mean very, very low. So it's extremely low. When I say…

FLATOW: One in what?

Dr. CLIFFORD: …a number…

FLATOW: One in what?

Dr. CLIFFORD: …basically, what we look at is - in that risk assessment - we took the worst-case scenario and in that assessment, would indicate at most over a 20-year period of potentially bringing in up to 19 animals from Canada that could be - have the possibility of exposure to BSE. Now, with an addition to that, though, with the interlocking safeguards that we have in the U.S., as well as in Canada, the actual likelihood of having a case show up in the U.S. from a Canadian animal would be less than one.

FLATOW: One in what?

Dr. CLIFFORD: One at period.

FLATOW: One in all the cattle that ever comes in.

Dr. CLIFFORD: Yes.

FLATOW: That's pretty low.

Dr. CLIFFORD: Yes, sir.

FLATOW: Michael Hansen. You don't agree with that, do you?

Dr. HANSEN: No. I would just point out that we had problems with the risk assessment that was done. And I would just point out that since the effective date, which is March 1st, 1999, five out of ten of Canada's BSE cases have been borne. So to say that the feed rules are effective, they don't seem to be very effective if half of the BSE cases in Canada were borne after the feed ban was declared effective. I would also point out that, again, using some of the best science, the Center for Disease Control has pointed out that the prevalence of BSE using official statistics is 30 times higher in Canada than the U.S.

So allowing animals from north of the border to come in as problematic. And even though they say they'll only be up to eight years, there's a problem of how you identify the age. In Canada, you have to have a paper documentation and then the inspectors will look at the teeth to verify that age.

What they're going to do with the cows they allow in is they'll just allow an age to be determined by a piece of paper. No one will be required to look at the teeth to verify that age. And of course, the older animals aren't worth much because no one wants to buy them because of increased risk for BSE. So if you can just have a slip of paper and say they're a younger age, they could potentially slip in.

In Canada, that wouldn't happen because the inspectors look at the teeth to make sure to verify the age. That will not be allowed. That's not going to happen in the animals coming in from Canada, so they could be even older animals. And again with this higher risk of BSE up there, we're increasing the risk down here as well.

FLATOW: John Clifford, what's wrong with Michael Hansen's analysis?

Dr. CLIFFORD: Well, there are several things. It is - and we certainly appreciate, you know, the concern out there. But at the same time, though, the problem with the analysis is we have done a good estimate of prevalence in Canada. The prevalence level, which is the same - we use the same techniques that we use to establish prevalence in the U.S. through our enhanced surveillance program, is about 6.8 cases per 10 million adult cows.

The findings of five cases after effective feed ban date does not indicate that the feed ban itself is not effective. You don't expect - you're not going to have 100 percent compliance with any program. However, we're looking for a higher degree of compliance, where you got 90 percent plus of compliance level, and Canada has that pipe system. So…

FLATOW: Mm-hmm. Michael Hansen, why wouldn't a diseased cow or any cattle be picked up by the U.S. system?

Dr. HANSEN: Well, because if they come in and they're not exhibiting symptoms, one, you wouldn't pick them up. And even if they might be exhibiting symptoms, they might not be caught. It should be pointed out in Europe, where the problem is much more severe, even though they pull suspected animals out of the food chain, they still have found hundreds of animals that just we're going to slaughter, and because they were required to be tested they turned up positive.

So there can be animals that have the disease that are incubating it and then can potentially transmit it that aren't expressing symptoms and so would be hard to be caught unless they're tested and we test a very small fraction. Right now, we're testing about one-tenth of 1 percent of the cattle that go to slaughter.

FLATOW: John Clifford, is that right?

Dr. CLIFFORD: Ira, what we do was we test about 40,000 animals but we test the animals with the greatest likelihood of having disease versus all animals. The test that we used is not a food safety test. In fact, there is no Food Safety Test avaianlw and factors no food safety test available for BSE. If you use that test, that test will not show positive and pull the animals within a few months of exhibiting clinical evidence and signs of diseases and therefore, it will not detect every animal at slaughter.

In effect, too, the prevalence is so low that, in fact, you're testing a lot of animals out there that are going to be normally negative. So we test the animals that are most critically important, those that are exhibiting signs of clinical evidence of disease. The FSIS, the Food Safety Inspection Service, has inspectors there at the plants looking for those clinical signs and we do not allow downers into the food supply in the U.S. as well.

FLATOW: Mm-hmm. Michael Hansen, what's wrong with the way they look at the cow coming in?

Dr. HANSEN: Well, again, with they're looking at a very small number to say that there was the highest of the high-risk. I would disagree with that. Even when they did their expanded surveillance program, where they looked at about 10 times their rate that they're looking now, 85 percent of all the animals they looked at were dead on the farm, no other information. So those aren't necessarily high-risk animals. The high risk animals are the ones, for example, that you suspect of having rabies but turned out to be negative or that are exhibiting symptoms and both of those populations were actually under sampled compared to what they're predicted levels was, the vast majority of cows - at least that were sampled in the expanded program - were simply animals that were dead and we didn't know anything more about them. And those aren't necessarily high-risk animals.

If there is a drought, for example, and a bunch of animals die because of that, they're not adding increase risks for BSE but their carcasses could have been shipped off or their brains could have been shipped off for a testing. So there's a debate about how effective that surveillance program was. And I should also point out that many scientists that are Prion(ph) scientist do not agree with USDA and think that the - actually the number of animals that are tested that the surveillance should be greater than it is now.

FLATOW: Why, don't we test more, John?

Dr. CLIFFORD: Ira, we - sample our surveillance and the surveillance is to estimate prevalence and to make sure that the other safeguards that we have are effective. We sample at 10 times the level that is needed for the international community, which is the World Organization for Animal Health, which has set standards for safe trade and animal and animal products, which the U.S. is a member of. In addition, Dr. Hansen mentioned the issue of dentition in cattle coming for Canada. Every animal coming in to the U.S. from Canada for breeding or for feeding is required to have an identification ear tag. In addition, there'll either be branded or have a tattoo identifying them to Canada.

The statement about dentition - animals cannot be identified by age once they get past about four to five years of age, so all of those animals that come in are required to be certified. The government of Canada, based upon their age -and that would be based upon those animals having a record of their birth.

FLATOW: Mm-hmm. Michael, any response?

Dr. HANSEN: Again, it's my understanding that in Canada, the animals are - the inspectors there also look at the dentition to verify age. This is the first I've heard that all the animals' date of birth will actually have to be verified before coming in if proof for that is done that would allay the concerns. But I was just relaying concerns that I had heard from representatives from the inspectors themselves.

Dr. CLIFFORD: And, Ira, one other point I would like to make is relative to this disease worldwide. BSE is on a decline worldwide, not on an increase, and in the main country of the United Kingdom, where you saw hundreds of thousands of cases, In 2007, they have had a total of 37 cases. That is down from a high in 1992 of 36,682 cases. And the reason it's on a decline worldwide is we know how to address this disease as indicated earlier, and that's through having effective feed bans and through the SRM removal, it's slaughtered to protect human health.

FLATOW: All right, let me remind everybody that this is TALK OF THE NATION: SCIENCE FRIDAY from NPR News. Michael Hansen, any…

Dr. HANSEN: Yeah. I would like to respond to that. He is correct when he says that it is declining in the U.K. and internationally. That's because they've taken strong action. The ruminant to ruminant feed ban we have here with a whole bunch of loopholes, when the U.K. did something similar, they had 40,000 animals born after that date that developed BSE.

They didn't start completely controlling this until in 1996, they stopped feeding of all mammalian protein to all food animals. That's the strong measure that needs to happen. We have a feed ban here that is weaker than even the SRM ban that was in the U.K. that didn't - that decreased the instance but didn't get rid of it because of these continual other ways that the infective material can get in.

If you want to control it by a feed ban, you have to take strong action that's what's been done in Europe and Japan, which has had a problem, they stopped feeding of all mammalian protein to food animals. We are allowing lots of material. There's blood, actually, from cows can be fed back to cattle. We know the infectious agent can be transmitted by blood with transfusion in animals and in humans, so allowing cattle blood products to be set back to cattle is not a good idea.

There's also chicken litter that is allowed to be fed. There is about one million pounds - I'm sorry, one million tons or 2 billion pounds of chicken litter and that's primarily chicken feces and spilled feed. I would point out that in August of 2003, Lester Crawford, who is then-head of the Food and Drug Administration, said that chickens waste so much of their spill, so much of their feed that chicken litter can be up to 30 percent meat and bone meal by weight, and material from cows can go into chicken feed. And if you just do the math, if there's two billion pounds of that chicken litter being fed back to cows and of up to 30 percent of it might be spilled feed, which could contain materials from cows and given that the infectious dose is less than - could be as low as 1 milligram. That's a real concern, and so this feed ban that we have is very, very week. It's nowhere near as strong as it needs to be and is nowhere near as strong as it was in Europe and Japan.

FLATOW: Let me give John - I got a minute to respond, John. You want to respond to that or move on?

Dr. CLIFFORD: Yes, please. All right.

FLATOW: Go ahead.

Dr. CLIFFORD: Actually, you know, there's a big difference between the U.S. prevalence and the U.K. prevalence of 180,000 cases versus two cases in the U.S., three if you count the one that where you found in from Canada. Our prevalence is extremely low. We have an effective feed ban. That feed ban is monitored and put in place by Food and Drug Administration.

FDA will tell you that they have a high degree of compliance with that feed ban. And while any more stringent effects will lessen the risk lower, it will not make that much difference overall because the risk is already so extremely low. So, you know, you can do those extra things and you'll lessen the risk a small amount but overall, it won't be that much.

FLATOW: All right. We're going to have to leave it there because we've run out of time. We'll come back to this issue because we never got to the issue about food labeling, how to know if the food is coming from Canada or not. That's another issue. We'll get back to both of you. I want to thank both of you taking time to be with us today.

Dr. HANSEN: Thank you, sir.

Dr. CLIFFORD: Thank you.

FLATOW: Michael Hansen, senior scientist at Consumers Union; and John Clifford, chief veterinary officer for the Animal Plant and Health Inspection Services at the U.S. Department of Agriculture.

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