Looking for mycotoxins in dairy products - New detection methods can be lifesavers

Derived from fungi and mold, these toxins can occur in crops in the field prior to harvest and in foods, nuts, and feeds that are improperly stored or exposed to moisture.¹​

Because they are nearly impossible to prevent, the American Phytopathological Society, which studies plant diseases, estimates that mycotoxins and their derivative aflatoxins infect up to 25% of the world’s food crops. That results in the loss of one billion metric tons of food every year and billions of dollars in lost revenue.²​

The impact on farmers and agricultural economies around the world is staggering.³ ​  Worse still, these toxins are not only the leading cause of illness among farm animals, they are especially dangerous to humans, and can cause acute and chronic diseases, including birth defects and cancer.⁴​  

In fact, the World Health Organization recently stated that “human health is the most significant impact of mycotoxins, with significant losses in monetary terms (through health care costs and productivity loss) and in human lives lost.”⁵​  

Aflatoxins and milk

Bred specifically for their ability to yield large quantities of milk, each dairy cow regularly produces more than 20,000 pounds of milk a year.⁶​  That is equivalent to more than 37,000 eight-ounce glasses of milk.⁷​ 

In order to produce that much milk, dairy cows need to eat about 120 pounds of wet food, or about 55 pounds of dry food, every day. Their feed usually includes hay and grain.

The grain potion is a mixture of soybean meal, minerals, corn, and vitamins.⁸​  The grain and food a cow eats while grazing could also contain natural aflatoxins B1 and B2, which a cow’s digestive system converts into aflatoxins M1 and M2, both known carcinogens.

These aflatoxins are particularly resilient compounds, and are hard to eradicate, even after sterilization and pasteurization.⁹​  

Since first discovering aflatoxins in the 1960s, researchers found milk to be the primary carrier of these toxins in human diet. These compounds can be present in all forms of milk, from yogurt, cheese, and any milk-based processed food, as well as infant formula and mother’s breast milk. Since children consume more milk by body weight than adults, they are particularly at risk.¹⁰​

The regulatory front

To protect the public, regulatory agencies in most developed countries have set limits on the amount of aflatoxin M1 in human food and milk. The problem is that these limits are not uniform in the global economy. The EU, for example, has set a limit of 0.05 parts per billion (ppb) for the toxin in milk. The US limit is significantly more tolerant, setting the limit at 0.5 ppb. Other countries in South America, Asia, and Africa, meanwhile, have no limits at all.¹¹​

There is also the issue of global enforcement. For instance, in the US, the dairy and food industries self-regulate the monitoring of aflatoxins in their products. While that arrangement works reasonably well, there are several other aflatoxins beyond M1 that may also be found in milk and which have no established maximum levels.¹² ​  

Another challenge is purely practical. Aflatoxins are difficult to accurately measure in large quantities of foods, grains, and milk without the proper instruments and training.

Testing methods

There are several methods available to test for mycotoxins and aflatoxins in food, feed, and milk.

For rapid field and lab testing, Bioo Scientific, a PerkinElmer company, has developed AuroFlow™ Aflatoxin M1 test strips, treated with gold particles, for rapid detection of the M1 toxin in milk.

While this technique provides a quick, onsite analysis of cow’s milk, for lab based lower level detection of aflatoxins in milk immunochemical methods using enzyme-lined immunosorbent assays (ELISA), high performance liquid chromatography (HPLC) and LC/MS/MS (liquid chromatography, triple quadrupole tandem mass spectrometry) are the recommended techniques.

Each has its own advantages, and sometimes disadvantages.¹³​ 

Here is a closer look at a few of these options.

Immunochemical Method: ELISA

This method requires some understanding of chromatographic principles to solve potential separation and interference problems.

It is often the preferred method for testing aflatoxin in cheese.

High Performance Liquid Chromatography (HPLC)

In testing milk and its affiliated products for aflatoxins, high-performance liquid chromatography (HPLC) is the global gold standard. It is employed in more than 80% of organic analyses, and is often coupled with UV absorption, fluorescence, mass spectrometry, and amperometric detectors.

Liquid chromatography, triple quadruple tandem mass spectrometry (LC/MS/MS)

Finally, LCMSMS offers the highest quantitative sensitivity and the ability to analyze multiple species at once.  These technologies can deliver PPT level limits of quantitation however these technologies are typically higher cost.

¹​ Silvia W. Gratz, Neil Havis, Fiona Burnett, “Fusarium Mycotoxin Risj In The Human Food Chain,” New Food, Vol. 18, Issue 4, 2015, http://www.newfoodmagazine.com/category/new-food-magazine/past-issues/issue-4-2015/​, accessed September 10, 2016.

² ​David G. Schmale III and Gary P. Munkvold, “Mycotoxins in Crops: A Threat to Human and Domestic Animal Health,” The American Phytopathological Society, 2016, https://www.apsnet.org/edcenter/intropp/topics/Mycotoxins/Pages/EconomicImpact.aspx, accessed September 10, 2016.

³ ​Ibid.

⁴​ World Health Organization, “Mycotoxins,” WHO Training Package for the Health Sector, October 2011, http://www.who.int/ceh/capacity/mycotoxins.pdf​, accessed September 10, 2016.

⁵​ Ibid.

⁶​ USDA, “Milk Cows and Production Final Estimates 2003-2007,” Statistical Bulletin Number 1022, March 2009, http://usda.mannlib.cornell.edu/usda/nass/SB988/sb1022.pdf​, accessed September 10, 2016.

⁷​ Anon., “1 Gallon Of Milk To Pounds,” OnlineConversion.com, http://www.onlineconversion.com/forum/forum_1115182754.htm​, accessed November 13, 2016.

⁸​ Dave Fischer and Mike Hutjens, “How Many Pounds Of Feed Does A Cow Eat In A Day?,” University of Illinois - Illini DairyNET, August 13, 2007, http://articles.extension.org/pages/37808/how-many-pounds-of-feed-does-a-cow-eat-in-a-day​, accessed September 10, 2016.

⁹​ Alex P. Wacoo, Deborah Wendiro, Peter C. Vuzi, and Joseph F. Hawumba, “Methods for Detection of Aflatoxins in Agricultural Food Crops,” Journal of Applied Chemistry, Vol. 2014, https://www.hindawi.com/journals/jac/2014/706291/​, accessed September 10, 2016.

¹⁰​ Gratz, op. cit.

¹¹ ​USFDA, “CPG Sec. 527.400 Whole Milk, Lowfat Milk, Skim Milk - Aflatoxin M1,” USFDA Inspections, Compliance, Enforcement, and Criminal Investigations, updated March 20, 2015, http://www.fda.gov/ICECI/ComplianceManuals/CompliancePolicyGuidanceManual/ucm074482.htm​, accessed September 11, 2016. See also,

FAO, “Worldwide Regulations For Mycotoxins In Food And Feed In 2003,” Food and Agriculture Organization of the United Nations, http://www.fao.org/docrep/007/y5499e/y5499e00.htm​, accessed September 12, 2016.

¹²​ Doug Powell, “Presence Of Mycotoxins In Animal Milk: A Review,” barfblog.com, http://barfblog.com/2015/02/presence-of-mycotoxins-in-animal-milk-a-review/​, accessed November 14, 2016.

¹³​ Department of Animal Science, “Aflatoxins: Occurrence And Health Risks,” College of Agriculture and Life Sciences, Cornell University, http://poisonousplants.ansci.cornell.edu/toxicagents/aflatoxin/aflatoxin.html​, accessed November 14, 2016.

¹⁴​ Wilhad M. Reuter, “Analysis Of Aflatoxin M1 In Raw Milk By HPLC With Fluorescence Detection,” PerkinElmer Application Note, 2016, https://www.perkinelmer.com/lab-solutions/resources/docs/APP_012972_01_Analysis_of_Aflatoxin_in_Raw_Milk_by_HPLC.pdf​, accessed September 9, 2016.

¹⁵ ​Ibid.