Potassium benzoate is a synthetic compound in some foods and drinks. Very small amounts can be safe to consume.

Many foods, cosmetics, pharmaceuticals, and hygiene products contain potassium benzoate. It has antifungal and antibacterial qualities that allow it to act as a preservative.

This article looks into which foods contain potassium benzoate and what effects it might have on a person’s health.

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Potassium benzoate and other closely related compounds are in many food and drinks — primarily mass-produced products.

The amount varies from brand to brand, but the following foods and drinks commonly contain potassium benzoate or other types of benzoate:

  • milk and products such as cheese
  • berries and berry products, such as juices and spreads
  • sodas
  • canned or bottled lemonades and iced teas
  • prepared salads
  • emulsified sauces
  • dressings
  • orange juice
  • mayonnaise
  • some baked goods, such as breads
  • tomato paste

Researchers have yet to determine whether potassium benzoate is safe to consume.

According to the Food and Drug Administration (FDA), a similar compound, sodium benzoate, is generally recognized as safe for human consumption, as long as its levels do not exceed 0.1% of a food and manufacturers follow appropriate practices.

The FDA has yet to make a specific ruling about potassium benzoate, and some concerns about long-term exposure to benzoate preservatives remain.

Some companies, such as large-scale soft drink manufacturers, use potassium benzoate as a preservative. They claim that the compound is safe for people based on a long history of its use and the findings of animal studies.

Studies have explored how much potassium benzoate animals could consume without having adverse effects. The results of these studies were the basis for the current limits on the amount of benzoate in foods and drinks.

However, since these initial studies, there have been great advancements in tools that help identify and assess cellular and tissue damage and damage to biological systems.

The safety concerns about potassium benzoate stem from the fact that in warm conditions or with exposure to ultraviolet light, the compound can react with chemicals in some drinks.

These chemicals include:

  • ascorbic acid, better known as vitamin C
  • benzoate salts
  • erythorbic acid, also called d-ascorbic acid

The reaction between potassium benzoate and these chemicals then forms benzene — a chemical common in emissions from vehicles and burning oil or coal.

Manufacturers also frequently add benzene to industrial dyes, chemicals, some plastics, and detergents.

As the Centers for Disease Control and Prevention (CDC) observe, people who work in industries that make or use benzene may be exposed to the highest levels of this chemical. The CDC also warns that benzene can cause leukemia.

According to the Environmental Protection Agency (EPA), the maximum allowable level of benzene in drinking water is 5 parts per billion. However, the agency has yet to set limits for potassium benzoate levels.

New research will help experts fully understand the side effects of potassium benzoate, including their severity, how common they may be, and how much a person needs to consume to experience adverse effects.

So far, most research in humans has focused on the health impacts of consuming benzoate, sodium benzoate, or benzene, in large doses.

Older 2012 research suggests that compounds like potassium benzoate in artificial food colorings can significantly contribute to the development of attention deficit hyperactivity disorder in children. Earlier research had also found that benzoate preservatives had a negative effect on behavior in 3-year-olds.

In 2017, researchers looked into potential effects of benzoate exposure and found that young children may develop an allergy to benzene, which can be produced when benzoate reacts with ascorbic acid in drinks. The authors also write that benzoate can influence cognitive function.

Benzene exposure or consumption produces noticeable and potentially severe symptoms.

According to the CDC, the symptoms that a person might experience in the minutes or hours after they consume high amounts of benzene include:

The symptoms a person might experience in the minutes or hours after breathing in benzene include:

A 2015 study reports that the levels of benzene in foods and drinks are too low to cause health problems, but it emphasizes that more research is needed.

Overall, determining the possible side effects of potassium benzoate requires more studies.

Researchers and health experts have yet to identify the health effects of potassium benzoate.

Other types of benzoate, such as sodium benzoate, are regarded as safe. However, the FDA notes that it has not determined whether it would be safe to consume levels higher than 0.1%. Animal studies have shown that it could be harmful in large doses.

In addition, potassium benzoate can also react with other chemicals to form benzene, a known carcinogen.