The Food and Drug Administration charged this week that chloramphenicol, an antibiotic for dogs, is being used illegally to treat cattle and pigs, despite findings that humans who consume residues of the drug in meat risk developing fatal blood problems.
The FDA proposed banning chloramphenicol oral solution, sales of which have increased sixfold since 1978, although it is legally restricted to use in treating dogs.
Residues of the drug have been found in slaughtered cattle and swine, the FDA said, and inspectors found evidence of use or intended use in cattle and pig operations in nearly 100 on-site inspections between 1982 and 1984.
"The drug has been used widely for treatment of food-producing animals, a use for which the drug is specifically contraindicated," the FDA said in a formal notice of the proposed ban.
"Residues of the drug, which have been found in food products, can cause serious human blood disorders including aplastic anemia," the agency said. "Unless the drug license approvals are withdrawn, the misuse in food-producing animals is likely to continue."
David Meisinger of the National Pork Producers Council in Des Moines said the proposed ban is unlikely to have much impact on pork producers, because the drug is used only by a few outlaws.
"I'm sure it's used by some unscrupulous individuals," Meisinger said. "They ought to come down hard on those people.
"But I don't think it's going to have that much effect," he added. Although chloramphenicol is "the best wonder-drug available today," Meisinger said, it is not widely used because of the risks.
Susan Cruzan, an FDA spokesman, said use of the substance has apparently declined in recent months. But she said the agency is concerned that its use will increase if the drug is not banned.
In its ban notice, the FDA said consumption of the drug has escalated out of proportion to its proper use. Though the substance is supposed to be restricted to use for infections in dogs, sales of it increased from 4,300 kilograms in 1978 to 28,400 kilograms in 1982.
The increase is even more remarkable because the medicine is so bitter that dogs will not swallow it; it must be pumped in through a stomach tube. More convenient forms of the drug, such as capsules, have not shown a similar increase.
But the oral solution often is injected into food-producing animals, the agency said, to treat or prevent a wide range of animal infections. The agency said it found indications of widespread use of the drug for improper purposes.
The agency said Agriculture Department inspectors found chloramphenicol residue in 11 cattle carcasses of 3,889 inspected between 1981 and 1983. Although that number is small, the FDA said, the way the department conducts its sampling is likely to underestimate the amount in the food supply.