Breads are one of the most commonly used instant food items, consumed by millions of people across the country almost every day. But now, you may have to think twice before eating a loaf of bread from even a well-established brand. A new study conducted by the Delhi-based non-profit organisation, Centre for Science and Environment (CSE), has revealed that these breads may contain elements which could be carcinogenic to humans.

In fact, this doesn’t just include white bread, but brown, multigrain, whole wheat and even the regular buns, pavs and pizza bases.

The study also shows that 84 percent of the samples of bread and other bakery products collected from Delhi had residues of potassium bromate, potassium iodate or both. Potassium bromate and potassium iodate have been banned as food ingredients in many countries following the studies that revealed these chemicals as carcinogenic.

Potassium iodate can lead to a higher intake of iodine, which can potentially affect thyroid function. Potassium Bromate can cause abdominal pain, deafness, diarrhoea, hypotension, kidney failure, nausea, oliguria (low output of urine), vomiting, depression of the central nervous system, and other related health problems. It also affects the nutritional quality of bread by degrading the vitamins and essential fatty acid contents of flour. Potassium bromate helps achieve high rising and a uniform finish in bread, according to the study.

In order to test the presence of these hazardous chemicals in bread, the CSE’s Pollution Monitoring Laboratory collected 38 samples of bread and other bakery products from retail shops, bakeries and fast food outlets in Delhi during May-June 2015.

The highest level of potassium bromate and iodate was found in sandwich bread. This was followed by pav, bun and white bread. Some popular brands of bread, such as Perfect Bread, Harvest Gold and Britannia were found to contain high to average levels of potassium bromate and/or iodate. Harvest Gold Sandwich bread had the highest concentration of the chemicals, the study found.

The products, including pizzas and burgers, of seven popular fast food outlets, such as Domino’s, KFC, McDonald’s and Nirula’s, tested positive for the chemicals. However, their levels were lower than the ones found in bread, pav and bun, according to the study. Meanwhile, McDonald’s India in an official statement released on Monday said that none of their products contains potassium bromate or potassium iodate.

Reacting to the CSE report, India’s health ministry on Monday said that it would order an enquiry into the claims.