Zearalenone, a fungal toxin

• A Journal of Food Science study detected Zearalenone a fungal toxin in wheat, rice, corn and oats from markets in Uttar Pradesh.
• Recent study by Indian Institute of Toxicology Research (IITR), found the substance Zearalenone in 70 of the 117 samples tested.
• Twenty-four of the U.P. samples exceeded the EU regulatory limits of 100-200 mcg/kg of cereals.

What is Zearalenone?

• Zearalenone is a fungal toxin infesting cereals such as wheat, maize and barley. It attacks crops while they are growing, but can also develop when cereals are stored without being dried fully.
• The Food Safety and Standards Authority of India does not impose maximum limits for Zearalenone. This study highlighted that India should set limits on Zearalenone in cereals.

More on Zearalenone

• Grains represent a significant source of food-borne contaminants, the main ones being; mycotoxins including (A) aflatoxin B1; (B) ochratoxin A; (C) fumonisin B1; (D) deoxynivalenol; (E) zearalenone; toxic metals like arsenic, cadmium and lead; as well as process contaminants such as acrylamide.
• Whole grains usually contain more contaminants than refined products. However, whole grains also provide more nutrients that may reduce the impact of these contaminants.
• Strict regulatory thresholds aim to minimize the risk of contaminants to public health. The consumer can further impact on the mitigation of any risk by eating a healthy diet filled with nutrient-dense foods such as whole grains and probiotics.
• The risks posed by contaminants from whole grains do not outweigh the known nutritional benefits of whole grain consumption.
  
  

  Globally, there are over 50,000 edible plants. Just three of these (rice, maize and wheat) provide about 60 per cent of the world's food energy intake.  The Food and Agriculture Organisation (FAO) forecasts that world grain utilization in 2018/19 will reach a record level of 2646 million tonnes.

• Fungal toxins are commonly found in food, and can be a public health concern. India regulates the levels of some of these, including aflatoxin, deoxynivalenol, ergot and patulin. The first three infest cereals, while patulin is found in apples.
• Each of these toxins has been associated with disease outbreaks. For example, in 1974, a hepatitis outbreak in Rajasthan and Gujarat, which made 398 people sick and killed 106, was linked to aflatoxin in maize.
• Meanwhile, chronic aflatoxin consumption has been shown to cause liver cancer. International Agency for Research on Cancer (IARC) classifies aflatoxin as a Group 1 carcinogen, meaning there is enough evidence for its carcinogenicity.
• In Zearalenone’s case, there is no strong evidence of toxicity in humans so far, though several research groups are investigating. As a result, the IARC classifies it as a Group 3 carcinogen, which means evidence is not sufficient for an evaluation yet.

Why does it matter?

• Zearalenone behaves like oestrogen, the female sex hormone, and could cause endocrine disturbances in humans. Its nasty effects in animals, such as pigs, are documented. When fed with mouldy corn, pigs develop inflamed vaginas, infertility and other symptoms.
• This is why countries like Brazil regulate Zearalenone levels in animal feed. In humans, the data are fuzzier.
• Some experiments suggest its ill-effects: in one, when oestrogen-sensitive breast cancer cells were exposed to the chemical in a lab, they proliferated.
• In 2014, a Tunisian case-control study found a correlation between a Zearalenone metabolite in urine and breast-cancer risk in women. But other studies did not find similar links

What next?

• More data are needed from cereals in other States, and from other storage conditions, before India decides to set limits.
• Since Zearalenone favours cool climates, such contamination could be limited to a few States. Also, strong epidemiological data linking human Zearalenone levels with diseases such as breast cancer are important.