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Finding Antibiotics In Milk

November 28, 2016



Those milk moustaches are a stroke of marketing genius. Just seeing them through the years evokes the health benefits of milk, from its proteins and calcium to its fortified vitamins. What we never see, however, is the growing global concern over the amount of antibiotic residuals that can be found in milk.

We have a lot more in common with cows than we think.  For one thing, cows, like us, are susceptible to different kinds of bacterial infections. The most common of these is mastitis, an utter infection in lactating cows that breastfeeding moms can develop as well. Veterinarians treat the bovine infection with a variety of antibiotics. When they do, dairies are required to follow strict regulations about keeping the treated cow’s milk and beef out of circulation until the medication has passed through the cow’s system.

To ensure that happens in the U.S, raw milk and beef are screened for the most common types of antibiotics used in cows. For dairy, raw milk is tested at the farm and again at the processing plant to ensure that all drug residues are below established tolerance levels. While that works for more than 98% of the milk and beef produced in the U.S., some antibiotics can still avoid detection. These drugs often fall outside of the screened antibiotics and some are not for animal use at all. The result is about 1.15% of raw milk tainted with some form of antibiotics evades detection every year. That may not seem like much until you realize it is equivalent to about five million 8-ounce glasses of milk! 1

Scary as that seems in the U.S., the situation is far worse in developing countries. India, for instance, is the world’s leading milk producer, responsible for up to 15% of the world’s total milk production. 2 Unfortunately, Indian dairy cows have a higher rate of bovine infections and are sometimes treated with drugs that do not even show up in current tests. In other cases, farmers do not quarantine infected animals properly further raising the risk of human exposure to contaminated milk. 3, 4 Considering that drug residuals in food and milk also pose significant threats to human health, including the potential for the creation of drug-resistant bacteria, most countries—including India—have established tolerance levels for antibiotics that are measured in nanograms per milliliter. A nanogram, by the way, is equal to one billionth of a gram.

Advances In Detection

Traditional microbial tests for antibiotic residuals in milk may not be sensitive, selective, accurate and fast enough to detect the growing number of drugs found in raw milk. A recent Spanish study of the sheep and goat milk industry found that microbial inhibitor tests detected 62.8 - 82.4% of the antibiotics employed. 5 The incidence of newer, undetected drugs in raw milk and in smaller amounts is thus prompting regulators to call for expanding the number of screened drugs at lesser amounts. 6 To do so may prompt regulators and dairy industry leaders to adopt more accurate and comprehensive analytical detection and quantification methods. One such newer technology is liquid chromatography coupled with mass spectrometry (known as UHPLC/MS/MS) that provides better accuracy, sensitivity and quantification in less time than existing methods for detecting antibiotics in milk.

As a global leader in detection and analytical technologies, PerkinElmer has worked with the dairy and food industries for years to improve analytical techniques that help verify the authenticity, safety, and quality of their products. Recently, PerkinElmer scientists used the Altus™ UPLC® System in conjunction with the new QSight™ 210 Triple Quadrupole MS/MS to determine and quantify multiple antibiotic residues in five different varieties of milk samples. This latest process, UHPLC/MS/MS, is able to detect trace amounts of antibiotics in amounts up to 100x below current tolerance levels. That means even the smallest measureable quantities of antibiotics are now traceable thanks to PerkinElmer innovation. Long term stability data demonstrated that PerkinElmer LC-MS/MS system can be used for analysis without any maintenance downtime for running samples with dirty matrices such as milk. As the need for better analytical tools continues to improve, PerkinElmer already has a fast, accurate, robust, rugged and proven solution to help keep our milk supply safe now and into the future. So bring on those milk moustaches! We are PerkinElmer, a global leader committed to innovating for a healthier world.


  1. FDA, Milk Drug Residue Sample Survey, Center for Veterinary Medicine, Food and Drug Administration, Department of Health and Human Services, March 2015, accessed November 21, 2016.
  2. Katrien Vant Hooft, “New Hope For Dairy Farmers In India & The Global Threat Of Multi-Resistant Micro-Organisms: Medicinal Plants For Mastitis Treatment,” Dutch Farm Experience, May 14, 2013, accessed November 21, 2016.
  3. Ibid.
  4. Maneka Gandhi, “Cows Are Injected With Illegal Drugs For Milk, Condition Of Indian Dairies Appalling,” F. LIVING, May 28, 2016, accessed November 18, 2016.
  5. M. Carmen Beltrán, Rafael L. Althaus, Ana Molina, M. Isabel Berruga, and M. Pilar Molina, “Analytical Strategy For The Detection Of Antibiotic Residues In Sheep And Goat’s Milk,” Spanish Journal of Agricultural Research, Volume 13, Issue 1, January 26, 2015, accessed November 22, 2016.
  6. FDA, Milk Drug Residue Sample Survey, op. cit.

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