What foods contain benzene?

December 2, 2025 •

4 min read

According to a 2022 review, benzene contamination has been reported in various food groups, often at low levels. So, what foods contain benzene? This article explores the primary sources of this chemical in foods, from chemical reactions in processed drinks to environmental contamination during manufacturing.

Quick Summary

Benzene, a human carcinogen, can form in certain foods and beverages, especially from the reaction of preservatives like benzoates and ascorbic acid. Other sources include processing methods and environmental pollution, though levels are often very low.

Key Points

Source of Formation: The most common dietary source of benzene is the reaction between sodium benzoate preservatives and ascorbic acid (vitamin C) in acidic beverages.
Processing Contamination: Smoked meats, canned fish, and thermally processed foods can contain higher concentrations of benzene due to the manufacturing process.
Environmental Factors: Environmental pollution can contaminate raw water and other ingredients used in food production, introducing trace levels of benzene.
Packaging Risk: Benzene can migrate into food products from packaging materials, especially over time and under specific storage conditions.
Minimize Exposure: To reduce intake, consumers can limit certain processed foods, choose reformulated beverages, and store products away from heat and light.
Health Risk: While long-term, high-level exposure is a known health risk, current dietary levels of benzene are generally considered very low and not a significant health concern.

Understanding How Benzene Gets into Food

Benzene is a volatile organic compound classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), meaning it is carcinogenic to humans. While occupational exposure through inhalation is the most common route, people can also be exposed through diet. The presence of benzene in food is generally attributed to a few key mechanisms, with the reaction between benzoate preservatives and vitamin C being the most well-known.

The Benzene-Forming Reaction

One of the main ways benzene forms in food products is through a chemical reaction between benzoate salts (like sodium benzoate) and ascorbic acid (vitamin C). This reaction is favored by acidic conditions, heat, and light, and can be catalyzed by trace amounts of metal ions, such as iron and copper.

The role of benzoates and ascorbic acid:

Benzoate Preservatives: Used to prevent the growth of bacteria, molds, and yeast, benzoate salts are common in many processed food products.
Ascorbic Acid (Vitamin C): Found naturally in many fruits and often added to foods as an antioxidant or nutrient fortifier.

This reaction is why beverages containing both ingredients, like certain soft drinks and fruit-flavored drinks, were historically a primary concern. Many manufacturers have since reformulated their products to minimize or eliminate this reaction.

Other Sources of Benzene Contamination

Beyond the reaction of preservatives, several other factors can contribute to benzene levels in food:

Food Processing: Methods such as smoking, roasting, and canning have been found to introduce benzene. Studies show that smoked and canned fish and meats, for instance, can contain higher levels of benzene than their raw counterparts.
Environmental Contamination: Benzene can find its way into the food chain from environmental sources. This includes pollutants from industrial activity, car exhausts, and contaminated water used during processing. Raw water used in beverage manufacturing may also contain trace amounts of benzene.
Packaging Materials: Certain plastics and packaging waxes can contain benzene, which may migrate into the food product over time, especially during storage.
Contaminated Ingredients: Polluted carbon dioxide used for carbonation in beverages has been identified as a source of benzene contamination.

Foods and Beverages That May Contain Benzene

While industrial reforms have reduced benzene levels in many products, it is still possible to find low levels in various foods. This list highlights some of the food groups where benzene has been detected in studies:

Beverages: This is the most studied category. Certain fruit juices, fruit-flavored soft drinks, and bottled water have been found to contain benzene, particularly those with a combination of benzoate and ascorbic acid. The levels found today are generally much lower due to reformulation.
Processed Meats and Fish: Smoked and canned meats and fish have shown higher concentrations of benzene. Organ meats have also been cited in some studies.
Flavored Products: Flavors, both natural and artificial, that are used in food processing have been found to contain benzene. For example, aromas with vanilla, nuts, and chocolate have been reported to contain traces.
Oils and Fats: Studies have detected benzene in olive oil, safflower oil, and margarine, with levels potentially linked to extraction processes or environmental exposure.
Pickles and Fermented Foods: Some studies have detected benzene in pickled products, likely a result of the combination of benzoate preservatives and acidic conditions.
Peanut Butter: Traces of benzene have been found in peanut butter in some surveys.

A Comparison of Benzene Exposure by Food Type


Food Type	Primary Source of Benzene	Key Factors Influencing Levels
Processed Beverages	Reaction of benzoate salts with ascorbic acid	Presence of both ingredients, heat, light exposure, metal ions
Smoked/Canned Fish & Meats	Food processing methods (smoking, heat treatment)	Processing conditions, degree of smoking, presence of other components
Oils & Fats	Extraction solvents or environmental contamination	Type of extraction process, environmental conditions during harvest
Flavors & Aromas	High concentration processes during production	Concentration methods, natural or artificial origins
Pickled Vegetables	Reaction of benzoate preservatives and acidic conditions	Presence of preservatives, storage conditions (heat)

Minimizing Your Exposure to Benzene in Food

While health agencies state that current dietary exposure levels from food are generally low and not a significant risk compared to inhalation sources, those concerned can take steps to reduce their intake.

Choose Carefully: Read ingredient labels on beverages. If both a benzoate preservative (e.g., sodium benzoate) and ascorbic acid (vitamin C) are listed, be aware of the potential for benzene formation.
Reformulated Products: Most major beverage companies have already reformulated their products, but it is still wise to check.
Proper Storage: Keep products containing potentially reactive ingredients away from direct sunlight and store them in a cool, dark place to slow down the reaction process.
Limit Processed Foods: Reduce intake of heavily processed foods, especially smoked and canned products, where benzene can form during processing.

For more detailed information on benzene formation in beverages and industry guidelines, you can consult resources like the FDA's Q&A on the subject.

Conclusion

Benzene is a recognized carcinogen that can find its way into food through various pathways, most notably from the reaction between benzoate preservatives and vitamin C in beverages. Other sources include industrial processing like smoking and canning, as well as environmental contamination and packaging migration. While regulatory changes and industry reformulation have minimized the risk, being aware of the foods most likely to contain benzene—including certain processed beverages, smoked meats, and some oils—can help consumers make informed choices to further limit their dietary exposure. Overall dietary intake is considered minor compared to other exposure sources like air pollution, but minimizing it remains a prudent health strategy.

Frequently Asked Questions

Beverages that contain both a benzoate preservative (sodium benzoate) and ascorbic acid (vitamin C) are at the highest risk. This includes certain fruit-flavored soft drinks, fruit juices, and some bottled waters, though many companies have since reformulated their recipes.

Yes, some studies have shown that sugar-free or diet versions of beverages containing benzoate and ascorbic acid may have a higher risk of forming benzene. The sugar in regular versions can act as an inhibitor in the chemical reaction.

Storing drinks that contain both benzoates and vitamin C in conditions involving heat or sunlight can stimulate and accelerate the chemical reaction that forms benzene. Keeping these products in a cool, dark place can help minimize this risk.

Benzene contamination is more prevalent in processed foods, particularly those using benzoate preservatives. However, traces can also be found in some unprocessed foods due to environmental factors, and naturally occurring benzoates in fruits like cranberries can also contribute to the reaction.

Industrial processes like smoking, canning, and high-heat treatment can lead to the formation of benzene through thermal degradation of food components. Studies have found higher benzene concentrations in smoked fish and canned products compared to raw versions.

Health authorities, including the FDA, state that the levels of benzene found in beverages today do not pose a significant safety concern. While benzene is a known carcinogen, oral exposure from food is generally considered very low compared to other sources like inhalation, especially given industry efforts to reduce formation.

To reduce dietary exposure, you can check ingredient labels for the presence of both benzoate salts and vitamin C in beverages. Choosing products with alternative preservatives, storing them properly, and reducing intake of heavily processed and smoked foods are also effective strategies.

In the past, some decaffeination methods, like the early Roselius process, used benzene as a solvent. However, this practice was banned once benzene was recognized as carcinogenic. Modern decaffeination methods are much safer and no longer use benzene.