The Connecticut General Assembly
OFFICE OF LEGISLATIVE RESEARCH
February 24, 1994 94-R-0128
FROM: David K. Leff, Senior Attorney
RE: Antibiotics in Milk
You asked how antibiotics are tested for in milk, what happens to loads in violation of the standards, and how often tests are conducted.
Every tank truck load of milk received by a dairy is tested for four of six beta lactam (penicillin family) antibiotics. No requirement that other antibiotics be tested for is enforced. Loads with antibiotic levels above federal standards are dumped so they cannot get into the human or animal food chain.
Testing requirements for determining antibiotic residues in milk are governed by state laws and regulations, and by Appendix N of the federal Food and Drug Administration's (FDA) Pasteurized Milk Ordinance (PMO) which is referenced in state laws and regulations. Antibiotics are used to combat a variety of infections in cows, primarily mastitis, an infection of the udder. Dairy plants are required to test each tank truck load of milk for beta lactam (penicillin family) antibiotic residues. Under the PMO, other drugs must be screened for by use of random sampling, at least four samples collected in four separate months during any consecutive six month period, but this requirement is not enforced and the tests are not done in Connecticut.
Testing must be done before the milk is processed, and results must be recorded. By state law they must be kept for at least a year (CGS § 22-203a). Regulations of the Milk Regulation Board specify how the records are to be kept and the type of information that must be retained such as hauler and route number and the date the milk was picked up from the farms (Conn. Agencies Reg. § 22-302c-4). The PMO requires records be kept for six months.
When tank truck drivers pick up milk from individual farms they take a sample from the farm's bulk tank. When a milk tanker truck is found positive for antibiotics the samples taken from the farms are tested to determine the farm of origin. The federal ordinance requires that milk pickups from the producer with a positive test be discontinued until subsequent tests no longer show drug residues. Under state regulations a farmer may be required to test milk if the farmer has a positive test in any two consecutive months or has three in a calendar year, and is required to show cause why his permit should not be suspended or revoked (CGS § 22-203a; Conn. Agencies Reg. § 22-203c-5).
State law requires that when a farm's milk is found to contain excess antibiotic residues its milk may not be picked up for two days. A subsequent finding within 12 months suspends milk pickups for four days. A third finding carries the same suspension and allows license suspension and imposition of civil penalties (CGS § 22-203d). These same penalties are required by the PMO.
Under the PMO a farmer with a suspended permit may gain temporary permit status following the penalty when samples indicate residues no longer exist. The farmer and a veterinarian must sign a quality assurance certificate for display in the milkhouse indicating that a residue prevention protocol is in place.
Milk tested positive for drug residues must be disposed of so as to remove it from the human and animal food chain. According to Gabe Moquin of the Connecticut Department of Agriculture, the antibiotic loads are disposed of in farm manure lagoons. State law makes a farmer responsible for antibiotics above FDA levels in a tank truck liable to a processor or marketing cooperative for the contaminated milk (CGS § 22-203b).
FDA has recognized that six beta lactams are widely used in treating disease in milking dairy cattle and are most likely to cause a residue in milk if misused. Because tests are not available to detect all six of these drugs, FDA recommends that a method be used which detects any four of the six. One of the most common tests is known as B. Stearothermophilus Disc Assay which detects penicillin residues at three to five parts per billion (ppb). The drugs and their tolerance levels are:
Drug Tolerance, Safe Level
Penicillin 5 ppb
Ceftiofur 50 ppb
Cloxacillin 10 ppb
Cephapirin 20 ppb
Amoxicillin 10 ppb
Ampicillin 10 ppb
Although all bulk milk tankers are tested for at least four penicillin family drugs, there are many other antibiotics that may be used on dairy cows. Dr. Michael Talley of FDA maintains that 85% to 90% of mastitis treatments in the country are performed with beta lactams. This assertion has been challenged by the Consumer Policy Institute of Consumer's Union, publisher of Consumer Reports, which found the study on which the FDA figures are based to have serious flaws. Moquin states that some beta lactam tests used by Connecticut dairies also detect other antibiotics.
According to a 1992 report by the General Accounting Office, there are about 82 drugs known or suspected of being used on dairy cows that may leave residues in milk. But, Johnnie Nichols, chief of FDA's milk Safety Branch states that no one really knows how many antibiotics or other drugs are in use on dairy cattle. Some drugs are approved by FDA for use on dairy cows. Others are used illegally or under the “Extra-Label use policy” whereby drugs available for some animal use can be used on cows under veterinary supervision. FDA has established tolerances or “safe” levels for 18 antibiotics according to Nichols. For other antibiotics the level is zero. But, Nichols acknowledges there is no way to test for many antibiotics.