Client education can prevent residue violator label
The Department of Agriculture is publishing the names of packing plants and farms responsible for repeat drug and contaminant residue violations.
Dr. James D. McKean, chair of the AVMA Food Safety Advisory Committee, said education is needed at the farm level to make sure residues do not occur and clients are not placed on the USDA lists. He thinks placement on the lists will eventually hurt producers financially.
"I would expect, over time, that it will have an impact on market access for producers," Dr. McKean said.
The Same Source Supplier Residue Violator List includes the species of animals involved, details about the residue violations, and information on what tissues contained the residues. The list has been published weekly since Aug. 20, and it includes violations since January.
The USDA Food Safety and Inspection Service defines same-source supplier residue violators as slaughter establishments responsible for multiple residue violations by repeatedly purchasing animals from the same sources without using information about residue violations to "reassess the adequacy of their hazard analysis."
"FSIS hopes that by making public information on residue violations, establishments and producers will work together to ensure that animals presented to slaughter do not contain violative levels of residues in tissues," said Brian Mabry, a spokesman for the agency.
"FSIS encourages veterinarians to ensure the care of production animals—specifically that the use of pharmacological agents take place within the veterinarian-client relationship."
Since 2001, the USDA-FSIS has produced the Residue Violator Alert List, a separate monthly list of farms with repeat violations within a 12-month period.
Most violations described on the Same Source Supplier Residue Violator List involve dairy cows and veal calves, and few involve animals other than cattle.
Statistics from the USDA indicate fewer than one percent of tests uncover residue violations, even among animals that inspectors single out as suspect.
The USDA-FSIS 2007 National Residue Program Data indicate there were 42 chemical violations found in 20,853 samples obtained through scheduled sampling for veterinary drugs and pesticides, 1,360 violations found in 149,590 samples obtained from animals that inspectors deemed suspect, and 225 violations in 27,905 samples obtained from animal populations deemed to be suspect. Together, violations were found in about eight-tenths of one percent of those samples.
FDA warning letters give additional details
The Food and Drug Administration separately posts online copies of letters the agency has sent to residue violators, along with letters to pharmaceutical companies that make unwarranted claims about their products and to food producers with unsanitary facilities. The warning letters have some overlap with the Residue Violator Alert List, and the letters provide some details about the results of FDA investigations into the causes of drug residue violations.
Of 25 letters from 2009 that involved residues of drugs used in food animals, 12 specifically state a veterinarian was not involved in the drug administration.
For example, the FDA determined a dairy from Minnesota sent a cow to slaughter in March 2009 with 129 times the allowable concentration of penicillin in the cow's kidney tissue because the owners routinely administered penicillin G procaine to dairy cows without using the approved dosage or injection site or a veterinarian's supervision.
The other letters do not indicate whether a veterinarian was involved, but they cite poor record keeping, failure to implement an appropriate withdrawal time, and use of a drug in a manner that is unapproved by the FDA.
Laura Alvey, a spokeswoman for the FDA-CVM, said both veterinarians and producers have been involved with improper drug residues, but veterinarian involvement decreases the likelihood of such residues existing. She said the residues are more often caused by use outside the approved labeling or approved extralabel uses than by legal extralabel use with improper withdrawal times.
As for legal use with improper withdrawal times, Alvey said, "It's more likely that a veterinarian was not involved or the recommendation/instructions of a veterinarian were not followed when there's an improper withdrawal time."
Alvey said there will be mistakes that lead to unintentional drug residues, and those residues will probably never be completely eliminated.
"That said, FDA is concerned about the sale of animals for human food that may contain illegal levels of animal drugs because of the potential for adverse effects on human health," Alvey said. "FDA approves new animal drugs with requirements, including a specified time period to withdraw an animal from treatment prior to slaughter, to assure that a drug has been depleted from edible tissue to a level safe for humans."
Veterinarians and producers are responsible for ensuring drugs used in an extralabel manner do not result in residues, Alvey said. The FDA is working with both groups on outreach and education on the correct use of drugs in food and companion animals.
She said the FDA also issues reminders and publishes violations, and the agency cooperates with the USDA-FSIS in taking enforcement action when there are residues that present a public health concern.
Lists, letters provide opportunities
Dr. Christine B. Navarre, president-elect of the American Association of Bovine Practitioners, said awareness of violations can be helpful, particularly if veterinarians notice trends involving particular drug residues repeatedly discovered in meat or milk. She is also the representative for the American Association of Small Ruminant Practitioners on the AVMA Food Safety Advisory Committee and is a professor in the Louisiana State University Extension Service.
Dr. Navarre said the lists can also help practitioners learn about violations by clients who may not have informed their veterinarian about their appearance on a list.
Dr. McKean said the FDA has restricted some antimicrobials because of possible human health risks related to residues, and recent conversations with an FDA official indicated to him that, in addition to concerns about antimicrobial resistance, the emergence of cephalosporin residues in food animals may influence restrictions on extralabel use of this antimicrobial drug class. He suggests that, by reducing residues, veterinarians can affect regulations.
"They can reduce the risks of having residues become an excuse for regulatory action by being more aware of the need for education—client education relative to withdrawal times," Dr. McKean said.
Violative cephalosporin residues are one factor being examined by the FDA as the agency considers placing restrictions on the extralabel use of cephalosporin drugs, as the agency sees such residues as evidence that suggests improper extralabel use is occurring.
The FDA published in July 2008 an order of prohibition that would have banned all extralabel use of cephalosporin antimicrobials in food-producing animals by October 2008. In publishing the order, FDA officials said the ban was intended to reduce the risk that antimicrobial resistance in food animals would reduce the effectiveness of drugs used in human health care.
The rule's implementation date was delayed to Nov. 30, and the FDA announced Nov. 25 that the ban had been revoked so the agency could consider the "many substantive comments on the order of prohibition." FDA officials previously indicated a revised version of the cephalosporin extralabel use ban was expected to be published by the end of summer 2009, but it had not been released at press time in October.
Dr. McKean expressed concerns that a ban on some or all extralabel cephalosporin use based in part on residues could be followed by similar bans on extralabel use of penicillin and tetracycline, which are two of the leading drugs connected with violative tissue residues. Both of those drugs are included in a large number of over-the-counter products.
Dr. McKean said such bans could also have unintended negative consequences for human health.
"You'll lose the oversight that veterinarians can provide and the advice that goes with that oversight," Dr. McKean said.