Wheat—the most widely cultivated crop in the world—is under growing attack from harmful toxins. Across Europe, almost half of wheat crops are impacted by the fungal infection that gives rise to these toxins, according to a study led by fungal biologist Dr. Neil Brown from the U.K.'s University of Bath, in collaboration with colleagues at the University of Exeter.
Wheat plays a huge role in feeding humanity, providing 18% of the total calories in people's diets globally. Concerns both for our health and for global food supplies were the impetuses for the new study.
Dr. Brown, who works in the Milner Center for Evolution in the Department of Life Sciences at Bath, said, "Contaminated crops and Fusarium toxins are always a worry, as they pose a significant threat to our health, especially as we only partially understand their effects on our well-being."
"But on top of these health concerns, we must remember that wheat is a hugely important global crop, so it's essential for us to maintain high yields along with safe food production—not least because climate change, and now the war in Ukraine (the world's fourth largest exporter of wheat), are already impacting on wheat yields and grain prices."
Preventing toxin contaminations is therefore important both to help maintain the stable price of wheat and to protect our food security, ensuring global stability.
Fungal toxins present in almost half of wheat
In their study published in Nature Food, the research team examined the largest datasets available from governments and agribusiness, both of which monitor Fusarium mycotoxins in wheat grain entering our food and animal feed supply chains. By using data from across Europe (including the U.K.) from the past 10 years, the team built the most complete picture yet of the mycotoxin threat and how it is changing.
The high cost of toxins
When mycotoxins reach a certain level, the contaminated grain is diverted from human food to animal feed. "This comes at a cost to the cereal farmer, impacts cereal market prices, and shifts the health problem to our livestock," said Dr. Brown.
Consequently, the team found worryingly high levels of DON mycotoxin in wheat fed to livestock.
Ms. Louise Johns, a Ph.D. student in Dr. Brown's group, said, "It's far higher than in human food. This is a concern for animal health, but it also paints a picture of what mycotoxin levels in food wheat could look like without current regulations."
For the first time, the Bath team has put a price on the impact of Fusarium Head Blight mycotoxins by estimating the value lost due to wheat being too contaminated with DON for human consumption.
"Across Europe, we estimate that 75-million tons of wheat (5% of food wheat) exceeded the limit allowed for human consumption between 2010 and 2019. Downgrading this to animal feed equates to a loss of around 3,000 million euros over the last ten years," said Ms. Johns.
Interacting toxins
Alarmingly, the researchers found that 25% of food wheat containing the mycotoxin DON also contained other Fusarium toxins. And this is likely an underestimate because not all wheat is routinely tested for other toxins. This means other potentially harmful toxins are likely to be slipping beneath the radar. It's possible that these toxins interact synergistically with DON to have adverse health effects that are greater than one toxin working alone.
Dr. Brown said, "We don't understand the health implications of being exposed to multiple toxins at the same time, especially when that exposure is chronic. We're worried about growing levels of co-contamination and possible synergies between toxins."
Increasing threat
Fusarium Head Blight is a disease that fluctuates year-to-year, but the authors of this study have found that in the Mediterranean, mycotoxin levels in high-disease years have become more severe since 2010. Here, mycotoxin levels recorded during the 2018 and 2019 outbreaks were higher than at any other time this decade.
"We don't know what's causing the increase in Fusarium mycotoxins, which is why we need more research, but we suspect that changes in farming (such as soil preservation practices that provide a home for the Fusarium fungus) and climate change (such as warmer, more humid weather which favors the Fusarium fungus) are playing an important role," said Ms. Johns.