Rockville, MD—During fiscal year 2021 (Oct. 1, 2020-Sept. 30, 2021), a total of 451 milk samples out of a total of 3,894,704 samples analyzed were positive for an animal drug residue, according to the US Food and Drug Administration’s (FDA) National Milk Drug Residue Database Fiscal Year 2021 Annual Report, which was released Wednesday.

That’s the lowest number of milk samples that tested positive for a drug residue in the history of these reports, which date back to fiscal year 1994. The previous low, 536 milk samples, was achieved in fiscal year 2019.

Fiscal 2021 was the fourth straight year in which fewer than 600 milk samples tested positive for a drug residue, and the 10th straight year in which fewer than 1,000 samples tested positive.

The number of positives peaked at 5,117 in 1997.

The Grade A Pasteurized Milk Ordinance (PMO) requires that all bulk milk tankers and/or all raw milk supplies that have not been transported in bulk milk tankers, regardless of final use, be sampled and analyzed for animal drug residues before the milk is processed.

Any bulk milk tanker and/or all raw milk supply that has not been transported in a bulk milk pickup tanker that is found positive is rejected for human consumption.

During fiscal 2021, a total of 4,043,513 tests were reported on the 3,894,704 milk samples for four different groups or families of drugs, including beta lactams, tetracyclines, sulfonamides, and aminoglycosides. Because some samples are analyzed for more than one drug residue, the number of tests conducted is greater than the number of samples, the report explained.

During fiscal 2021, a total of 455 tests were reported as positive for a drug residue. Some 23 testing methods were used to analyze the samples for drug residues.

As used in the FDA report, a sample is defined as representing a load or lot of milk sampled and analyzed. Samples may include, for example, milk collected from a bulk milk pickup tanker, a raw milk supply that has not been transported in a bulk milk pickup tanker, a producer’s bulk milk tank, a milk transport tanker, a plant silo, or a pasteurized finished product.

A positive result, as used in FDA’s report, means that the sample was found to be positive for a drug residue by a test acceptable for taking regulatory action in an accredited laboratory by a certified analyst, or the milk was rejected on the basis of an initial screening presumptive positive test by the milk processor.

In FDA’s report, data are reported by four sources of milk samples:

Bulk milk pickup tanker and/or raw milk supply that has not been transported in a bulk milk pickup tanker: defined as bulk raw milk from a dairy farm. Samples are taken on receipt of every tanker load and/or raw milk supply that has not been transported in a bulk milk pickup tanker at a milk receiving facility.

There were 3,494,330 total samples in this category during fiscal year 2021, of which 290, or 0.008 percent, tested positive for an animal drug residue. The amount of milk found to be positive and disposed of in accordance with the PMO and/or applicable state regulations totaled 13,237,000 pounds.

Pasteurized fluid milk and milk products: a minimum of four samples in at least four separate months, except when three months show a month containing two sampling dates separated by at least 20 days, will be tested for each finished milk or milk product from each milk plant during any consecutive six months.

There were 31,009 total samples in this category during fiscal 2021, of which one, or 0.003 percent, tested positive for an animal drug residue. The amount of milk found to be positive and disposed of was 1,000 pounds.

Producer: each producer will be tested at least four times in at least four separate months, except when three months show a month containing two sampling dates separated by at least 20 days, during any consecutive six months.

There were 326,206 total samples in this category during fiscal 2021, of which 160, or 0.049 percent, tested positive for an animal drug residue. The amount of milk found to be positive and disposed of was 168,000 pounds.

Other: samples are conducted on a random basis.

There were 43,159 total samples in this category in fiscal 2021, none of which tested positive for an animal drug residue.

Overall during fiscal 2021, a total of 13,237,000 pounds of milk was found poisitive for a drug residue and disposed of in accordance with the PMO and/or applicable state rules.

During fiscal 2021, a total of 3,740,107 industry samples were taken by milk plants, receiving and transfer stations, and marketing groups or cooperatives. Of these industry samples, 422 were positive for an animal drug residue.

Also during fiscal 2021, a total of 154,597 samples were taken by state and local regulatory agencies, of which 29 were positive for an animal drug residue.

Of the 4,043,513 tests conducted during fiscal 2021, a total of 3,889,444 were for beta lactams, of which 451 were positive for an animal drug residue; 74,970 were for sulfonamides, of which four were positive (within the sulfonamides category, 124 tests were for sulfamethazine, none of which were positive); 78,972 were for tetracyclines, none of which were positive; and three were for aminoglycosides, none of which were positive.

The National Milk Drug Residue Data Base (NMDRD) is a voluntary industry reporting program.

Mandatory reporting is required by regulatory agencies under the National Conference on Interstate Milk Shipments (NCIMS). Data are reported on the extent of the national testing activities, the analytical methods used, the kind and extent of the animal drug residues identified, and the amount of contaminated milk that was removed from the human food supply.

The system includes all milk, Grade A as well as non-Grade A. Grade A milk represents approximately 99 percent of the milk supply in the US and is regulated through the NCIMS by the regulatory agencies.

Data reported to the NMDRD are for educational and analytical purposes and are not intended or suitable for regulatory action or follow-up, the FDA report noted.

For the fiscal 2021 report, all 50 states, Puerto Rico and two Third Party Certifiers (TPC) authorized under the International Certification Program (ICP) submitted data.