The national food regulator and the industry have been quick to react to the discovery of possible cancer-causing chemicals in popular bread brands in India. The Food Safety and Standards Authority of India has removed potassium bromate from a list of permissible food additives and is examining the evidence against potassium iodate. And before a ban can be enforced, the All India Bread Manufacturers Association – an umbrella body – has announced that it will voluntarily give up the use of the chemicals in bread-making processes.
These steps were taken after the Centre of Science and Environment on Monday released a report about high levels of potassium bromate and iodate in samples of white bread, whole wheat bread, sandwich bread, pizza bread, burger buns and pao sold in Delhi. Of the 38 samples tested, the environmental advocacy group found that 32 samples (or 84%) had between 1.15 and 22 parts per million of one or both the compounds.
The food regulator had until now allowed 50 milligrams per kilogram in bread, which is equal to 50 parts per million, and 20 milligrams per kilogram in flour for bakery.
The problem is that potassium bromate is possibly carcinogenic for humans and has been shown to cause cancer in animals.
Banned elsewhere
Japanese researchers first documented the cancer-causing potential of potassium bromate in the early 1980s, in studies that showed the growth of tumours in the thyroids and kidneys of mice exposed to the chemical.
The UK banned the use of bromate in food in 1990. The chemical has also been banned in the European Union, Brazil, Canada, Nigeria, South Korea, Peru, Sri Lanka and China. The US still allows potassium bromate to be used in baking, so long as the amount of bromate remaining in the final product is no more than 20 parts per billion. In comparison, the FSSAI’s regulations are far more lax, allowing a maximum of 50 milligrams per kilogram in bread, which is equal to 50 parts per million.
The International Agency for Research on Cancer, a body under the World Health Organisation, classifies potassium bromate under a group of 290 agents that are “possibly carcinogenic to humans”. Another agent on this list is talc-based body powder, which the IARC specifies can be carcinogenic with perennial use. Processes involved in carpentry, aloe vera, diesel fuel and gasoline, engine exhaust, traditional Asian pickled vegetables are other agents that fall into this group. Coffee is “possibly carcinogenic” specifically for the urinary bladder, but caffeine cannot be classified based on carcinogenicity to humans, according to the IARC.
This group of substances and processes are suspected carcinogens different from known carcinogens like radium, leather dust, coal-tar, tobacco and processed meat, and from “probable” carcinogens like red meat and occupational exposure to hairdressers.
Carcinogens do not cause cancer in every case. Different substances may have different cancer-causing potential depending on how much and for how long a person has been exposed to it, as well as the person’s own genetic make-up.
How bread got its bromate
A traditional loaf for bread needs just four ingredients – flour, yeast, water and salt. Yet, a look at almost any bread packet on department store shelves will list additions such as gluten, vegetable oil, preservatives, acid regulators, flour treatment agents, anti-oxidants and improvers. All these have bean added in industrial bread-making processes to make loaves whiter, fluffier, longer-lasting and to reduce baking time. The last desirable is where potassium bromate comes in.
Mixing flour with water at the start of the bread-making process hydrates proteins in the flour, converting them into gluten that holds the starch granules together. The gluten bridges finally allow the dough to rise into bread during baking. The construction of gluten bridges in dough requires more than mixing. Traditionally, the dough was left for long hours or even days for oxidation reactions to take place and for the dough to ferment suitably. To speed up the fermentation process and make it more cost-effective, industrial bakers began adding oxidation agents like azodicarbonamide, potassium iodate and potassium bromate.
Potassium bromate added to bread is supposed to decompose into the benign byproduct of potassium bromide at baking temperatures. But if there is too much bromate added to flour, or the bromated flour isn’t baked for long enough, it remains in its original, potentially harmful form up to the stage of consumption.
But bromate can enter the human body through other routes as well. Packaged water may contain bromate after ozonisation during disinfecting procedures that convert the naturally-occurring bromides into bromate.