A Food Safety Success Story: Detecting Mycotoxin Contamination

By REBECCA NAGY

This was originally published in ASABE Resource Magazine.

In the early 1960s, nearly 100,000 turkeys died under suspicious circumstances in the U.K. It was soon determined that these birds were given feed that contained peanut meal that was contaminated with a fungus. The fungus produced a lethal, carcinogenic substance known as an aflatoxin. Aflatoxins are naturally occurring compounds and are a type of secondary metabolite, known as mycotoxins, produced by certain fungi.

The U.S. Food and Drug Administration (FDA) and the USDA responded to the U.K. incident with a mandate to test all shelled peanuts produced in the U.S. for aflatoxin contamination during processing. Any lot with more than 20 parts per billion was deemed unsafe.

Unfortunately, the test results were highly variable, which created uncertainty in determining which lots were safe and which were not. Some lots that were actually well below the FDA limit produced test results that were above the limit for aflatoxin contamination, and those lots were rejected. Far more troubling, some lots that were actually above the FDA limit tested below the limit, which cleared them for use in the food supply.

That’s where ASABE Fellow Thomas Whitaker enters the story. When Whitaker arrived at the Department of Biological and Agricultural Engineering (BAE) at North Carolina State University in 1967, aflatoxins had just been discovered. Whitaker joined NC State with a faculty appointment and a position with the USDA-ARS Market Quality Handling Research Unit, which was housed in BAE. Since then, he has dedicated his career to improving food safety. He is internationally known for his work in evaluating mycotoxin sampling methods for agricultural commodities.

A Needle in a Haystack

Working with NCSU’s Department of Statistics and industry partners, Whitaker’s team improved the methods used to detect aflatoxin in agricultural commodities. “The first thing I had to do was learn why there was so much variability,” Whitaker explained. “I looked at the sampling, the sample preparation, and the analytical steps of the aflatoxin test procedure to see where errors could arise.” He determined that uncertainty was associated with all three steps of the test procedure. Uncertainty could occur during sampling, and it could occur in the lab.

The team determined that 80% of the variability in the aflatoxin testing procedure was a result of errors during sampling. Looking for contaminated peanuts in a commercial lot is like looking for a needle in a haystack. “A peanut lot has millions of kernels in it,” Whitaker explained, “And maybe one kernel in a thousand is contaminated. If you find contamination, it’s because you got that one contaminated kernel in your sample, or you can sample the lot and miss the contaminated kernels. That explained why we were seeing so much variability.”

From those findings, the team developed a method to evaluate the risk of accepting a bad lot and the risk of rejecting a good lot for any mycotoxin sampling protocol as a function of the sample size, test portion size, and number of analyses. That method was used by the FDA and USDA to design the peanut industry’s sampling protocol, which is still used today to test all shelled peanuts in the U.S. for aflatoxin.

Because of Whitaker’s success in those peanut studies, he and his team have been asked by domestic and foreign food industries, regulatory agencies, and by the Codex Alimentarius to study mycotoxin contamination in other food commodities. To date, Whitaker and his team have developed methods to design and evaluate mycotoxin sampling protocols for more than 20 different mycotoxin/commodity combinations.

Established by the FAO and WHO, the Codex Alimentarius is the preeminent repository of international food standards. Its standards, guidelines, and codes of practice protect the health of consumers and ensure fair practices in the food trade. The Codex Alimentarius used the methods developed by Whitaker and his team to establish maximum limits for mycotoxin contamination, as well as sampling protocols for commodities that are traded in international markets. The method used to design and evaluate sampling protocols is available at http://tools.fstools.org/mycotoxins/.

The Future of Food Safety

Whitaker is proud of what he and his colleagues have accomplished. His research has assisted domestic and international producers, processors, and regulatory agencies in developing mycotoxin control programs to improve international trade and ensure consumer protection. The sampling methods originally developed for mycotoxin detection have been extended to evaluate the methods used to detect genetically modified grain, TCK spores in wheat, pesticides on seeds, protein allergens in food products, and toxic compounds in fruit.

“When you see a problem that’s difficult and important, you really want solve it,” Whitaker said, “And we had the tools to do it. We shared our research results with other groups around the world who were also working on mycotoxins. There was an economic concern for manufacturers and a safety concern for consumers, so the stakes were extremely high, especially in developing countries. It was rewarding to find a solution to such a high-stakes problem.”

As the global population continues to grow, a new generation is needed to take on these high-stakes challenges.

“There are many hungry people in developing countries, so improving food security can make a huge difference,” Whitaker said. At the request of the Common Market for Eastern and Southern Africa (COMESA), Whitaker and his team have recently developed aflatoxin sampling protocols for groundnuts and maize, which are traded among the COMESA countries.

As Whitaker sees it, the issue of food contamination extends from the farm to the fork, and there are many opportunities for young engineers to get involved across disciplines. “At every step along the way, there are health issues, economic issues, and regulatory issues,” he said. “There are many places that young professionals can get involved in
solving these problems, and there’s much that can be done.” In Whitaker’s case, it all started with a peanut.