Keeping Our Food Safe from Animal Drugs
Keeping Our Food Safe from Animal Drugs
Besides being responsible for ensuring the safety and effectiveness of human drugs, FDA has a similar, although less well-known, responsibility for veterinary drugs. To a great degree, this involves the safety of these drugs not only for animals but also for people, because of the widespread use of drugs in animals raised for food.
To get a better understanding of how FDA protects the public health from unsafe residues of veterinary drugs in meat, eggs, and milk, FDA Consumer editor Bill Rados interviewed Dr. Gerald Guest, acting director of FDA's Center for Veterinary Medicine.
Q. Dr. Guest, both you and FDA Commissioner Frank Young have been widely quoted in the press as saying that America's food supply "is the safest in the world.' What do you base that on?
A. Let me talk a little about the responsibilities of the Center for Veterinary Medicine and what we're all about. I think then you'll understand why I believe our country's food supply is so safe. The Food and Drug Administration, through this center, is responsible for assuring that animal drugs and medicated feeds are safe and effective and that food from treated animals is safe to eat.
Prior to approval, a new animal drug must undergo extensive testing. The drug sponsor--usually that means the manufacturer--must conduct laboratory and clinical investigations that establish the safety and effectiveness of the substance. The sponsor must also demonstrate that any drug residues remaining in a food-producing animal at slaughter pose no threat to human health.
Once the drug is approved, based on all these data, a monitoring/investigating system takes over. The U.S. Department of Agriculture's Food Safety and Inspection Service obtains samples of body tissue from slaughtered animals and analyzes those samples. Their findings are sent to FDA field offices for follow-up by our field investigators. Regulatory action is taken against those responsible for drug residues above the legal limit, and those animal carcasses found to have dangerous residues are kept from the marketplace.
Taking all of these activities into account--from extensive pre-clearance requirements through rigorous surveillance, monitoring and enforcement activities--I do indeed believe that Americans have the safest food supply in the world.
Q. How much are drugs used in livestock?
A. About four out of five food animals are given drugs during their lifetime. Some receive medication to treat specific illnesses. Often, however, drugs are given to entire herds or flocks-- usually in their feed--to prevent disease outbreaks and to help the animals grow faster on less feed. About 30 percent of the chickens, 80 percent of veal calves and pigs, and 60 percent of the beef cattle raised for food in the United States are routinely given medicated feeds.
Q. How many different drugs are used? Are they all really necessary?
A. About 750 drug products are approved for use in food animals. That's about 100 different basic drugs. Virtually all of these drugs are needed to insure the continued availability of safe, wholesome and affordable animal-derived foods to the American public.
Q. What percentage of the animals that USDA checks are found to have illegal residues?
A. Residues above the legal limits are found in approximately .2 percent of poultry samples; for livestock, the rate is 1 percent.
Q. How is this checked? Does USDA check every animal for every drug?
A. USDA collects samples for routine meat inspection. They refer any violative samples to FDA for subsequent enforcement actions.
Perhaps I should explain here that FDA establishes the allowable conditions of drug use and establishes the allowable tolerances or action levels for residues of those drugs.
Each sample cannot be tested for every drug, nor is there reason to do so. Veterinary drugs are each approved for use in a particular animal species. Test methods are developed for detection and analysis of residues in that species.
USDA actually has two parts to its residue sampling program. First, they randomly check a certain number of animals at a slaughterhouse for certain drugs--or pesticides--without regard to the condition or appearance of the animals. The second type of sampling is more directed: Any animal that appears to have had any kind of an illness or that has a visible mark where a drug was injected or that comes under suspicion for some other reason is tested.
On the whole, the program is set up on a statistical basis so that, even though the number of animals checked is only a small percentage of all the animals that are slaughtered, we can be confident that what we are seeing reflects what's going on throughout the marketplace.
Q. How do you decide what residue levels are safe?
A. A drug sponsor is required to furnish the scientific information necessary to demonstrate that the residues are safe in edible animal tissues--that is, meat, eggs and milk.
This scientific information includes toxicological studies, to see how hazardous the drug is. It also includes metabolism studies, to see how the animal breaks down the drug in its body. There are depletion studies, to find out how long it takes for the drug and its byproducts to clear out of the animal's meat, milk or eggs. For drugs whose early tests indicate they could be carcinogenic [cancer causing], we require lifetime feeding studies in mice and rats to accurately determine the true risk. Finally, the agency, after reviewing all the research data, establishes a tolerance level for tissue residues. Or, in some cases, a zero tolerance will be set, and no residue level will be acceptable.
Q. Are all residues harmful or potentially harmful? Have people ever actually been injured, or gotten cancer, because of drug residues in meat, eggs or milk, or is this just a theoretical risk?
A. One potentially serious risk of excessive drug residues is allergic reactions, which can range from a mild case of hives to severe, life-threatening anaphylactic shock.
Evidence of this actually having occurred in people from eating meat, eggs or milk with excessive drug residues, however, is rare, indeed. In fact, our surveillance has never found any actual cases of such allergic reactions caused by drug residues. There are three or four citations of residue-induced reactions in the scientific literature, but even those aren't all from the United States. One case involved a person who ate raw sausage and had a reaction. The sausage was checked and was found to contain residues of penicillin.
So it's an extremely rare occurrence, but you can't be sure how often it happens because it may go unreported, or the relationship between an allergic reaction and residues in food may not be discovered. It's important to keep in mind that we build a 1,000-fold or 2,000-fold safety factor into our tolerances. This helps to avoid ill effects even when a residue occurs that slightly exceeds the legal limit.
The same holds true for the potential risk of cancer from residues of carcinogenic drugs. We aren't aware of any cases of cancer that can be linked to drug residues in food. Of course, such an association would be almost impossible to establish, given the many potential causes of cancer--viruses, radiation, environmental carcinogens, and so forth.
Nevertheless, you don't need, nor do you want, actual victims to make the case that the food supply must be kept free of cancer-causing residues. And, given our surveillance and enforcement programs, I'm confident it is.
Q. The drug DES, widely used for many years as a growth promoter in livestock and poultry, was completely banned by FDA in 1979 because of evidence it causes cancer. Yet we later found widespread disregard for that ban. Is there evidence that the drug is still being used?
A. Diethylstilbestrol (DES) had been used since 1954 in animal feeds and as implants in various species of animals. The use of the drug in livestock was banned in 1979 because of questions about the safety of its residues and because an adequate analytical method to detect those residues had not been developed.
In early 1980, we discovered that some implants that had been manufactured before the ban were still being used. In 1983, we discovered a small number of veal calves in New York that had been treated with DES. In that case, the drug had been brought into the United States from Europe. In both instances, regulatory actions were taken, and the courts backed the government's position.
There are now no approved veterinary drugs containing DES in the United States or in any country that I am aware of. Further, we aren't aware of any DES being used in livestock in the United States. We believe that this problem has been eliminated.
Q. If a drug is found to cause cancer, is it supposed to be automatically banned from use in food-producing animals?
A. No, not necessarily. A provision of the Delaney anti-cancer clause of the Food, Drug, and Cosmetic Act stipulates that a carcinogenic compound can be used in food-producing animals if the drug will not harm the animals and if "no residue' of the compound will be found in any edible tissues of the animal when tested by the approved methods.
But as analytical methods have become more sensitive over the years, this exception has become unworkable. Levels of residues that were so low they were previously undetectable can now be detected. So we have proposed procedures and criteria to permit these exceedingly low levels of residues that present an insignificant risk of cancer to the public.
Q. What is this insignificant-risk level?
A. One in 1 million. This doesn't mean that one in every million people will contract cancer as a result of this regulation. Rather, it represents a one in 1 million increase in risk over the normal risk of cancer over a lifetime. This is considered an insignificant level of risk.
Q. Recently, some supermarkets have been advertising meat from animals raised without drugs. Is this safer for consumers?
A. Since our residue monitoring program effectively protects the public from any potentially unsafe residues of animal drugs in meat, eggs and milk, I see no health advantage in buying these special meats.
Q. Dr. Sanford Miller, director of FDA's Center for Food Safety and Applied Nutrition, has said that microbiological contamination of food, which can cause outbreaks of food poisoning, is a bigger problem than chemical contamination. Do you agree?
A. Yes, I agree with Dr. Miller's assessment. Microbiological contamination can be a problem. Illegal drug residues could conceivably be eliminated; the risk of microbiological contamination is virtually impossible to eliminate. The contamination can occur at any point in the farm-to-consumer chain--on the farm, through the processing and distribution systems, and in the American kitchen. When you consider the potential for contamination at each of the links in this chain, you have to tip your hat, I think, to the federal, state and local governments and the food industry for the remarkable job they do in safeguarding the food supply.
Q. Former CVM director Lester Crawford has said that the illegal sale of veterinary drugs could have more serious public health consequences than any problem with human drugs. Do you agree?
A. I believe Dr. Crawford was referring to situations of extreme misuse of veterinary drugs. In those cases, I agree that illegal use of veterinary drugs can be an even greater threat to the public health than the illegal use of human drugs. What puts a different light on this issue is that use of illegal human drugs generally involves the consent of the persons involved. But the consumer of meat, milk and eggs has no way of knowing if hazardous substances are present in those foods, and no way of knowing if unapproved drugs have been used on the animals.
The illegal import of veterinary drugs is an insidious practice that also threatens the public health. The DES episode of 1983 happened because the drug was brought from Europe through Canada and into the United States. The U.S. Customs inspectors look for and deny entry of illegal drugs when they are identified, but just as human drugs are successfully smuggled into the country, so are animal drugs.
Q. Is the animal drug industry as well regulated as the human drug industry? Isn't there a pretty widespread problem with uncontrolled sale of prescription animal drugs?
A. In general, we believe that animal drugs are as well regulated as human drugs, although there are chronic problems that we are always watching.
One of these problems is the illegal sale of prescription drugs. In 1985 we took 73 regulatory actions against those firms and individuals found to be violating the law in such cases. We've also encouraged state boards of pharmacy and state boards of veterinary licensing to take more active roles in regulating distribution of veterinary prescription drugs. The states have been very effective in regulating human prescription drugs; we hope that veterinary drugs can be just as well-regulated.
Through a more active surveillance program and some special initiatives in several states last year, we do know which drugs make up the bulk of the illegal market. We're continuing the fight, and we're winning some significant battles.
Q. What happens to farmers whose animals are found to have illegal residues?
A. Two things. First, carcasses found with unsafe drug residues are removed from the slaughterhouse, and USDA will sample the next five animals from that farm. Second, FDA will send a regulatory letter to the farmer, outlining the violation and warning of more stringent legal action if steps are not taken to correct the problem. It is in the farmer's best interest to correct these problems early, to avoid the possibility of more severe legal action, such as an injunction or prosecution.
It's important to remember that at least 99 percent of the livestock producers use drugs properly. We know this from the low rate of illegal residues that we find through our surveillance.
Q. Do you feel like you are walking a regulatory tightrope--on the one hand trying to protect consumers from unsafe food and on the other trying to avoid putting unnecessary constraints on livestock producers' ability to provide a plentiful supply of inexpensive food?
A. Yes, definitely. However, when you've got a hard decision to make, you make the choice on the side of protecting the public's health.
Q. There has been a long-running controversy over the use of antibiotics in livestock. Some believe that the use cuts down on their effectiveness in humans. Is the use of antibiotics in livestock and poultry decreasing as consumers become more concerned about this issue?
A. In November of 1984, the Natural Resources Defense Council petitioned the secretary of health and human services to ban the routine use of penicillin and tetracyclines in animal feeds as an imminent health hazard. After a legislative hearing on the issue and review of contract reports and the published literature, the secretary denied the petition in November 1985.
We believe that over the past year the industry has decreased the routine use of penicillin and tetracyclines in animal feeds. For example, in April 1985, the National Cattlemen's Association recommended that its members suspend the use of tetracycline in beef cattle. [Editor's note: The beef cattle industry does not use penicillin in feeds.] I would rather not speculate further on this question since the agency's still reviewing the issue. However, I will say that as more alternative drugs become available, the industry will have a number of drugs that are not used for treating disease, but are reserved for food production purposes.
Q. Given recent and pending budget cuts, does FDA, and particularly your center, have adequate resources to protect the public from unsafe residues?
A. The budget cuts will have an effect on our activities. However, protection of the public health will, of course, continue to be our top priority. Our cuts in personnel and budget will be taken from areas that have little direct impact on public health. In fact, even with the cuts, we are reprogramming resources in order to increase field activities in areas of prevention of illegal residues and prevention of the illegal sale of veterinary prescription drugs.…
Questia, a part of Gale, Cengage Learning. www.questia.com
Publication information: Article title: Keeping Our Food Safe from Animal Drugs. Contributors: Not available. Magazine title: FDA Consumer. Volume: 20. Publication date: July-August 1986. Page number: 20+. © 1999 U.S. Government Printing Office. COPYRIGHT 1986 Gale Group.