New Delhi, May 23: Much of the bread sold in India contains residues of possible carcinogenic or thyroid-harming compounds, an NGO claimed today, flagging government inaction on baking ingredients banned in many countries.

The New Delhi-based Centre for Science and Environment (CSE) said its laboratory had detected potassium bromate or potassium iodate residues in 34 of 38 samples of various kinds of bread taken from local markets. It said it was unable to differentiate between the two compounds.

The CSE said the International Agency for Research on Cancer had classified potassium bromate as "possibly carcinogenic" in 1999. Consumption of potassium iodate, the NGO added, may increase the body's iodine intake and raise the risk of thyroid disorders.

"We need to prevent near-routine exposure to this bromate... and iodate (through the consumption of bread)," Chandra Bhushan, deputy director-general of the CSE and head of its pollution-monitoring laboratory, said.

The CSE's findings have not yet been published in a scientific journal and have thus not been subject to peer review, the standard protocol practised by professional scientists worldwide to reveal research results. The Telegraph is, therefore, withholding the brand names of the samples that CSE says tested positive for bromate or iodate.

While the spectrometer the CSE used in the tests does not differentiate between potassium bromate and potassium iodate, Bhushan said four of the 34 samples that had tested positive had been sent to an independent laboratory. It confirmed bromate in two samples and iodate in one but the fourth contained neither.

If a bread sample contains one-fifth of the maximum level of 50 parts per million (ppm) of potassium iodate that bakers are allowed during bread-making, eating just two slices of that bread would deliver more iodine than the body's daily requirement, Bhushan said.

The CSE study has found bromate or iodate levels varying from 1.15 ppm to 22.54 ppm in various varieties of breads, including white slice, brown slice, buns, sandwich bread, burger breads and pizza breads.

The CSE has called on the Food Safety and Standards Authority of India (FSSAI) to ban the products with "immediate effect".

A statement issued by All India Bread Manufacturers Association president Ramesh Mago said tonight: "The FSSAI regulations permit the use of potassium bromate and potassium iodate at 50 parts per million in bread and 20 parts per million in maida for bakery purposes."

But ideally, the bromate should turn into harmless bromide during baking and there should be no bromate residues in the finished product, said Amit Khurana, programme manager for food safety and toxins at the CSE.

"We shouldn't find any residues of bromate or iodate in baked ready-to-eat bread," he said.

It's because a full conversion to bromide does not always happen that the use of potassium bromate in bread-making is banned in countries such as the European Union members, Australia, Canada, Brazil, China, New Zealand, Nigeria and Peru, the CSE said.

Potassium iodate is not an approved food additive in the European Union, Australia or New Zealand. The European Union's food safety agency had in 2014 observed that chronically excessive intake of iodine may accelerate the development of thyroid disorders to hypothyroidism or hyperthyroidism and increase the risk of thyroid cancer.

Studies have indicated that potassium bromate can cause tumours of the kidney and thyroid and cancer of the abdominal lining in laboratory animals.

Members of India's scientific community had three years ago expressed concern relating to the use of potassium bromate in bread-making.

Scientists from the National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, and other institutions had highlighted that while potassium bromate was used to bake bread of high quality, it had been "abandoned" in many countries.

The Thiruvananthapuram scientists also said that glucose oxidase, a harmless compound, had been used to achieve the effects of bromate.

In 2012, doctors in a Kanpur hospital had detected what they suspected was "accidental" potassium bromate poisoning.

Forensic medicine and medical specialists Sushil Kumar and Pankaj Pranjal had documented nine patients with abdominal pain, vomiting and diarrhoea and attributed the symptoms to accidental ingestion of potassium bromate, mistaken as milk powder.