Analysis of the suspected cancer‐causing potassium bromate additive in bread samples available on the market in and around Dhaka City in Bangladesh

Abstract Bread is one of the most popular foods consumed worldwide. It is a very popular foodstuff consumed in almost every house in Bangladesh as breakfast. Bread is prepared predominantly from flour to meet the daily carbohydrate demand and enhances its overall nutrition value using various ingredients. Potassium bromate (KBrO3) is an alluring additive to improve bread quality by bread makers. But due to the well‐known toxic and carcinogenic effect, certain levels of KBrO3 residue are not suitable for bread, and it is therefore forbidden in many countries. The key objective of this study is to evaluate the safety status of bread in Dhaka City and its proximity to Bangladesh. Twenty‐one randomly collected bread samples were tested in this study from different bakeries or shops in and around Dhaka City. The levels of KBrO3 were analyzed spectrophotometrically, and the maximum concentration found in the bread sample was 9.29 μg/g. A total of 67% of collected bread samples showed elevated levels of KBrO3 relative to the allowable amount prescribed by various Food and Drug Administration worldwide. KBrO3 is toxic to consumers and could endanger their health over continuous regular consumption and thus need to be monitored strictly.

keeps the dough more elastic by increasing the volume and softness of bread to maintain the carbon dioxide gas created by the yeast. In baked products, toxic KBrO 3 gets reduced to potassium bromide (KBr) (Figure 1), which is thought to be harmless in the finished baked end product ( Cogswell, 1997;Emeje et al., 2010).
However, if an excessive amount of KBrO 3 is used, or if the bread is baked for a shorter period of time, or if the process is not carried out at a sufficiently high temperature, the remaining quantity of KBrO 3 can be noticed and provide the toxic effect (Bushuk & Hlynka, 1960). The use of bromate has been the topic of ongoing controversy. Many scientists reported in the early 1990s that the use of KBrO 3 is likely to be safe as a bread additive, ensuring it is completely degraded during baking to less dangerous products.
But when the World Health Organization (WHO) declared in 1993 that large quantities of residual bromate were observable in 75% of the loaves tested in the UK, this was followed by its prohibition in the UK (Joint & Additives WECoF, Organization WH,,). As KBrO 3 is detrimental to health and should be prohibited to use in bread. It is reported that continuous consumption of KBrO 3 can result in sore throat, diarrhea, nausea, vomiting, abdominal pain, low blood pressure, depression, thrombocytopenia, cancer, and other health problems (Ajarem et al., 2016;Atkins, 1993;Robert & William, 1996). In living organisms as well as in humans, nephrotoxic and toxic effects of KBrO 3 have been observed. It is a genotoxic carcinogen capable of causing renal, mesothelioma, and thyroid follicular cell tumors in rats (Kurokawa et al., (1990)). Due to health-related issues, the use of KBrO 3 is now prohibited in many countries. Its consumption in the United States was reduced to 75 μg/g of flour (U.S Food and drug administration., (2018)). In 1999, the International Agency for Research on Cancer (IARC), associated with the WHO, classified KBrO 3 as a possible carcinogen for humans. While it is still used in the United States where the maximum permissible level set by the U. S. Food and Drug Administration (FDA) is 50 μg/g of flour and 10 μg/g of flour in Japan ( Abu-Obaid et al., 2016). During the heating process, bromate should be almost completely reduced to bromide, the harmless form of the oxidizer. The bakery industry needs to follow policies and procedures to minimize any possible residues of bromate in the baked goods to a safe level established by the FDA risk analysis at 0.02 μg/g (American Bakers Association (ABA),; Ekop et al., 2008; ). In addition to its carcinogenicity, KBrO 3 has been found to impact the nutritional consistency of bread. The major vitamins in bread, including vitamin A2, B1, B2, and niacin, are depleted using excess KBrO 3 (Okafor et al., 2011).
In Bangladesh, as per the Bangladesh standards and testing institution (BSTI) regulations in 2018, the use of KBrO 3 is not permissible (BSTI). Despite the option of many other non-toxic substitutes, many bakers still use KBrO 3 to prepare their bread to jeopardize public life. The current spectrophotometric analysis aimed to examine the residues of KBrO 3 in finished bread in Dhaka and its nearby cities, recognizing the possible threat posed by these agents so that the related authorities can take necessary and drastic measures to limit the use of this food poison.

| Materials and sampling
All reagents used were of analytical grade obtained from recognized chemical companies. For example, hydrochloric acid (HCl) from Thermo Fisher Scientific, USA, potassium bromate from Sigma-Aldrich, Germany, and promethazine hydrochloride from Sigma-Aldrich, Germany, were purchased and used as received. The deionized water was used throughout the experiment unless otherwise noted. A total of randomly chosen 21 bread samples of different brands were purchased from various bakeries, retailers located in and around Dhaka City, Bangladesh. All the bread samples were manufactured from wheat flour and denoted from the letters A to U before analysis.

| Sample preparation
First, the hard surrounding portions were cut off from the bread with a clean and sharp knife. The central white portion of each bread was dried in the oven for 1 hr at 85°C and was finely ground manually using mortar and pestle. The powdered and dried bread was stored in sealed containers for analysis (Alli et al., 2013). For bread sample analysis, 1 g of each bread powdered was taken in a clean centrifuge tube and 20 ml of deionized water was added.

| Spectrophotometric analysis
The mixture was vortexed for about 2 min and then filtered. The filtrate bread solution was then added to the 10-mL volumetric flask and was applied with 2.0 ml of 0.01 M promethazine and 0.2 ml of 12 M HCl. The mixture was then shaken for 1 min, and the absorption of the pink-colored solution was measured spectrophotometrically. The concentration was estimated from the linear regression curve derived from standard KBrO 3 solutions.  (Girard et al., 1987;Hanson & Norman, 1973;Kojlo et al., 2001). The sulfur atom in the phenothiazine is very susceptible to oxidation, and the oxidation products are colored free radicals with absorption maxima at 500-640 nm. The free radicals are stable in acidic media, and the sulfur bridge makes resonance to stabilize the product. Phenothiazines are reversibly oxidized to a colored free radical or semiquinone with KBrO 3 and further oxidized irreversibly to a colorless sulfoxide. The heterocyclic centered radical cations in general produce red-pink color, subsequent oxidation such as 4-hydroxy-3-oxo-3H-phenothiazine −5 -oxide, thus promethazine oxides with bromate to produce a red-pink with absorption maxima at 515 nm. Spectrophotometrical quantitative analysis for most of the samples exhibits positive results (Table 1 and Figure 4). The highest concentration of 9.29 μg/g was found in sample C which was collected from Mohammadpur, Dhaka.

| RE SULTS AND D ISCUSS I ON
The KBrO 3 residue was not detected in the samples E, K, O, P, R, S, and U. The other anions including Cl -, Br -, I -, NO 3 -, and NO 2 present in breads had no interference with bromate in the spectroscopic measurements.
The result obtained from the bread analysis showed that a great number of bread makers use KBrO 3 as a bread improver. Bakeries and confectioneries are using KBrO 3 in their bread manufacturing for economic benefit. It is used as a dough enhancer, and it has a pronounced action in maintaining the size, color, and texture of a bread. The more the quantity, the more appealing is the bread to the consumer.
There has been a serious argument over the use of KBrO 3 . Many scientists indicated that KBrO 3 was likely to be harmless as a bread additive because the compound was broken down to negligible amounts during baking (Akunyili, 2004 (Emeje et al., 2010). The state of California needs a warning label to contain food containing KBrO 3 . The varying residual amounts of KBrO 3 in the finished products may arise due to bread baking for a shorter time period, or the process is not being conducted at a high enough temperature. The persistence of KBrO 3 may also occur in the bread due to the excess use of the KBrO 3 (Bushuk & F I G U R E 2 UV-vis spectrum of oxidizing product between promethazine hydrochloride and KBrO 3 (3µ g/mL) solution in deionized water. The wavelength corresponding to absorption maximum (λ max ) is observed at 515 nm F I G U R E 3 Standard calibration curve of KBrO 3 for spectrophotometric determination of bread sample Hlynka, 1960). In Bangladesh so far, there is no report regarding the scenario of the presence of bromate in bread.
After absorption into the bloodstream, KBrO 3 is converted into oxides and radicals. These highly reactive ingredients may affect DNA and play a role in developing cancer. Scientists noted damages like this in human liver and intestine cells that resulted in DNA strands splitting and chromosome damage caused by exposures to KBrO 3 (Geter et al., 2006;Zhang et al., 2011). It can also damage the genetic material in cells. Researchers also reported substantial damage to cell membranes of lysosome, which are the small intracellular bodies responsible for essential cell functions such as cellular digestion. Models of the interaction between DNA damage and KBrO 3 indicate a consistent low-dose linear response, which means that the amount of DNA damage observed is proportional to the amount of KBrO 3 ingested (Spassova et al., 2013).
In consideration of the data showing that KBrO 3 can be genotoxic and carcinogenic, foods containing the KBrO 3 should be avoided.
Although the lethal dose of KBrO 3 in humans has not been precisely  (Kurokawa et al., 1990). The bakeries should be looking to manufacture their baked products using better natural methods and materials (Cranton 2004

| CON CLUS IONS
In the current study, KBrO 3 was found to be approximately above its acceptable level in 67% of collected bread samples in and around Dhaka City. Most of the bread samples had a high KBrO 3 content, which is very harmful to health. The price or status of the bread samples did not influence the amount of KBrO 3 present. There is indeed a need for more aggressive supervision by regulatory authorities in order to ensure the safety of customers. The government agencies are assigned to educate people on the use of hazardous KBrO 3 as a food additive. The use of natural dough enhancers should be promoted, such as vitamin C powder, egg, apple, sauce, and so on.

ACK N OWLED G M ENT
T. Foyez cordially acknowledges the support received from North South University, Dhaka, Bangladesh.

CO N FLI C T O F I NTE R E S T
The authors declare no conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
Data available on request from the authors

E TH I C A L A PPROVA L
This article does not contain any studies with human participants or animals performed by any of the authors.