If you eat meat or drink milk, you want to know: Are there trace amounts of the veterinary drugs used in food-producing animals entering your diet? And if they are, are the amounts safe for human consumption?
Those questions—among others—are the concern of the Division of Residue Chemistry, which is part of FDA’s Center for Veterinary Medicine.
Sick food-producing animals such as pigs, cows, and chickens can be given antibiotics or other drugs to treat diseases. (Some farms also give animals antibiotics to help them grow faster, a practice FDA is working to eliminate by promoting the judicious use of antimicrobials in food-producing animals.) Producers must then wait for the drug to leave the animal’s system before they can slaughter it for consumption. It’s important to ensure that any remaining trace amounts of the drugs are safe to eat by the time the food reaches our plates.
“Our job is twofold,” says Division Director Philip Kijak, Ph.D. “We validate the methods drug companies use to test for drug trace amounts in foods from animals, and we help develop newer and better methods for testing.”
On the first point, the sponsor—usually, the animal pharmaceuticals company—of a drug to be used in a food animal must complete required testing that establishes the drug’s tolerance (a measure of safety), and develop a method to show whether the trace amount in the animal food product is within that tolerance.
“Then we are responsible for validating that method—making sure not only that it works and is accurate, but that it’s a practical method any standard chemical laboratory can use,” Kijak says.
Making Sure Milk Is Safe
For example, the Division examines the methods used to test milk for trace amounts of veterinary drugs used in dairy cows.
Under the Grade “A” Pasteurized Milk Ordinance standards issued by the FDA and the U.S. Public Health Service, all milk must be tested for beta-lactam antibiotics, the most common drugs used by dairy farms. FDA’s role is to evaluate and approve the data and methods submitted by companies that manufacture rapid-screening tests for these drugs. Rapid screening is important because milk is perishable, and results are needed on the spot.
“Think of these as off-the-shelf kits, like those consumers buy for pregnancy testing,” Kijak says. It’s up to the individual dairies and state regulators to choose the approved kits they want to use. Since 1994, when FDA began evaluating test-kits, the amount of milk containing beta-lactam drugs has dropped from 0.15 percent to 0.014 percent—more than a tenfold decrease, Kijak adds.
Developing Methods to Test Meat
In addition, FDA works with the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA’s FSIS) and state regulators to monitor meat, poultry, eggs, and milk for trace amounts of unapproved or unsafe drugs. FSIS tests the foods for a variety of these medications and reports violations to FDA, which follows up with regulatory action when needed.
“To do this job, we had to focus on developing new methods to detect trace amounts of penicillin and other antibiotics,” Kijak says. “With the older method, we were able to tell if penicillin or penicillin and other drugs were present, but we were unable to measure the exact amount of the penicillin when the sample contained more than one drug.” Without this specific information, it was possible for products with unsafe amounts of penicillin to pass inspection. The newer method, which was developed in close cooperation with USDA, enables inspectors to determine if multiple drugs are present, and the amount of each.
Testing for Fungus in Animal Feeds
Recently, the division has become increasingly involved in developing methods to detect mycotoxins and other contaminants in animal feeds. Mycotoxins are toxic compounds made by fungi that grow on grains. Poor growing methods and improper storage conditions can promote the development of these compounds, which that can enter our diets in meat from animals that consumed the contaminated feed.
“While these fungi are almost always present in grain, it’s the amount of mycotoxins that can make the difference between safe and unsafe foods from animals,” Kijak explains. “The new methods enable us totake whatever steps are necessary to make sure the tested products are safe for consumers.”