Bromate

Bromate is a chemical compound that contains the bromate ion, BrO₃^-. It is a polyatomic anion where bromine is in the +5 oxidation state. Bromates are salts of bromic acid (HBrO₃), which only exists in aqueous solution.

Properties and Occurrence

Bromates are strong oxidizing agents. They are typically colorless, odorless, and exist as crystalline solids. Bromates are not naturally occurring in significant quantities in the environment. Their presence in drinking water and food products is generally a result of human activity.

Uses

Historically, potassium bromate (KBrO₃) was widely used as a flour improver in bread making. It acts as an oxidizing agent, strengthening the gluten network and improving the dough's elasticity and loaf volume. However, due to health concerns, its use is now banned or restricted in many countries.

Sodium bromate (NaBrO₃) is used in some hair perming and straightening solutions. Its oxidizing properties help to set the desired hair shape.

Bromates also find application in some chemical processes as oxidizing agents and in analytical chemistry.

Health Concerns

Bromates are classified as possible human carcinogens (Group 2B) by the International Agency for Research on Cancer (IARC). Studies have shown that bromates can cause kidney tumors and other cancers in laboratory animals.

The primary concern regarding bromate exposure arises from its potential formation in drinking water during ozone disinfection. Ozone, used to kill bacteria and viruses, can react with bromide ions naturally present in water to form bromate. Water treatment facilities often monitor and control bromate levels to minimize this risk.

Ingestion of large quantities of bromate can cause nausea, vomiting, abdominal pain, diarrhea, and even kidney failure.

Regulation

Due to health concerns, regulatory bodies like the World Health Organization (WHO) and the United States Environmental Protection Agency (EPA) have established maximum contaminant levels (MCLs) for bromate in drinking water. These limits are designed to minimize the potential risk of cancer and other adverse health effects. The European Union also regulates bromate levels in food and drinking water.