New research on the risks of aflatoxin contamination in milk suggests that policymakers should revise regulations that hurt children and dairy farmers.

TAMPA FL, December 7, 2022 — Food scientists at Michigan State University (MSU) have found that far fewer cases of liver cancer worldwide are caused by aflatoxin M1 (AFM1) in milk and other dairy products compared to its parent compound aflatoxin B1 (AFB1) in maize and nuts. Their research suggests that policymakers around the world should rethink the strictness of AFM1 regulations that cause milk to be dumped in regions of the world like Eastern Europe and sub-Saharan Africa, where milk is a vital source of nutrition for children.

Felicia Wu, professor of food science and human resources at MSU, will present her team’s findings during the Society for Risk Analysis Annual Meeting Dec. 4-8 in Tampa, Florida. Her results indicate that AFB1 in maize and peanuts causes between 25,200 and 155,000 liver cancer cases annually worldwide — primarily in China, sub-Saharan Africa, and South and Southeast Asia. By comparison, AFM1 may cause 13 to 32 liver cancer cases worldwide each year at most. In fact, there are no documented cases of human illness caused by AFM1.

Aflatoxin B1 (AFB1), a mycotoxin produced by Aspergillus fungi, has been known to cause liver cancer in humans since the 1960s. It is the most potent naturally occurring liver carcinogen. In warm climates where the mold easily grows, AFB1 can contaminate food and animal feed containing maize, peanuts, and tree nuts. Once it is ingested, a metabolite called aflatoxin M1 (AFM1) is excreted in the milk and urine of humans and dairy animals.

There are no documented cases of AFM1 causing cancer in humans, yet dairy farmers face strict regulations on AFM1 concentrations in milk and other dairy products. The U.S. standard for AFM1 is 0.5 micrograms per liter of milk, while the European Union standard is a stricter 0.05 micrograms per liter. This can be “extremely difficult for farmers to meet,” says Wu. “So they are dumping their milk.” (This includes farmers in Eastern European and African nations that have adopted the EU standards.)

Wu and her team conducted a quantitative risk assessment to determine the total number of human liver cancer cases caused by AFB1 in maize and peanuts versus those linked to AFM1 in milk and dairy products. The researchers used information on the cancer potency of the two aflatoxins and studied the amount of maize, nuts, and milk that people in different nations consume, on average, worldwide. Then they estimated the total expected cancer cases per country, taking into account the prevalence of chronic hepatitis B virus (HBV) in each nation, which increases the carcinogenic potential of aflatoxins. The study shows that Ethiopia, Mexico, Pakistan, Sudan, and Syria have higher exposure to AFM1, based on average daily consumption of liquid milk and the concentrations of AFM1 contamination. Still, the estimated annual number of cases of AFM1-related liver cancer is less than one.  

“It’s important to understand that the cancer risk is so much lower in milk than in maize and nuts,” says Wu. “Yet regulations around the world are much stricter for aflatoxin in milk than they are for aflatoxin in maize and nuts.” Those strict regulations, she argues, have put many dairy farmers out of business and raised public concern about AFM1 in milk without any evidence yet of human health risk. Many populations worldwide would suffer nutritional losses if milk is dumped rather than being fed to children. Dairy is an important source of nutrients such as protein, fat, calcium, and vitamin B-12, which are critical for child development.

Wu and colleagues are currently conducting a study of 1,000 dairy-producing households in Ethiopia to see if AFM1 in milk is impacting the growth of young children.


Editors Note: Dr. Wu is available for media interviews. Please contact Patrick Hynes at patrick@bigvoicecomm.com for all interview requests.  Her research A Tale of Two Aflatoxins: Cancer Risk in Maize and Peanuts vs. in Milk and Dairy will be presented December 7th from 10:30-10:50 as part of the Symposia: Food Safety Risks, Disease Burden, and Technological and Behavioral Solutions