As much as 84% of bread samples collected in Delhi contained high levels of toxic chemicals potassium bromate and potassium iodate, a study by the Centre for Science and Environment found. Both chemicals are used as flour treatment agents, a Down to Earth report said. The CSE study is based on analysis of 38 samples of bread, including varieties of white bread, brown bread, sandwich bread, multigrain bread, pav buns, and ready-to-eat burger and pizza bread.

The International Agency for Research on Cancer classified potassium bromate as “possibly carcinogenic to humans”, after it was found to cause renal tubular tumours, among other things, in laboratory animals. Potassium iodate is banned in several countries as it can lead to an increased iodine intake, which causes thyroid problems. However, India continues to allow its use as a treatment agent.

Of the 38 samples collected by CSE for the study, 32 were found to contain high levels of potassium bromate and/or iodate, the highest levels of which were found in sandwich bread. When contacted by CSE, six companies “categorically denied” the use of these additives in their bread, while five companies did not respond. Of the 12 companies approached by CSE, one said it was not aware of what chemicals were used in the improver mix they sourced to make bread, Down to Earth reported.

The Indian bread industry was valued at Rs 33 million in 2015 and is expected to touch Rs 53 million by 2020. The Food Safety and Standards Authority of India had earlier discussed the issue of banning potassium bromate in the country, but it has yet to come to a decision.

The CSE report, with a list of the breads tested and the levels of the chemicals they contained, is available here.