Health Effects of Benzoic Acid, Sodium Benzoate, and Benzene

Updated on August 6, 2017
AliciaC profile image

Linda Crampton is a writer and teacher with a first class honors degree in biology. She often writes about the scientific basis of disease.

Cinnamon contains benzoic acid.
Cinnamon contains benzoic acid. | Source

Benzoic Acid and Benzoates

Benzoic acid and benzoates are common additives to food, drinks, and other products. They are useful chemicals in manufactured products because they kill or inhibit both bacteria and fungi and can act as preservatives. In general, the chemicals are considered to be safe when they're used in small quantities. There are some situations in which they may be harmful, however.

Benzoic acid was first obtained from the resin of trees belonging to the Styrax genus. The fragrant resin smells like vanilla and is sometimes known as gum benzoin. Today benzoic acid is often made in the laboratory from other chemicals instead of being extracted from gum benzoin.

Benzoates are derived from benzoic acid and are more commonly used as food preservatives than the acid. Some people develop allergy-like symptoms when they are exposed to sodium benzoate. When the chemical reacts with vitamin C (ascorbic acid) in drinks under certain conditions, benzene may be produced. Benzene is a carcinogen. A carcinogen is a substance that is capable of causing cancer.

Cranberries are a significant source of benzoic acid.
Cranberries are a significant source of benzoic acid. | Source

Difference Between Benzoic Acid and Sodium Benzoate

Pure benzoic acid is a white to colourless solid which consists of crystalline needles or scales. It's a member of the carboxylic acid family and has the molecular formula C6H5COOH. Benzoic acid is only slightly soluble in water. Sodium benzoate is structurally related to benzoic acid and has the formula C6H5COONa. It exists as a granular powder and is more soluble in water than the acid.

Sodium benzoate is more commonly used as a food preservative than benzoic acid due to its greater solubility in water. Benzoic acid is a more effective germ killer, however. The benzoate form of the chemical is converted into the acid form in our stomach and absorbed into the body through the lining of the small intestine.

Benzoic acid can be changed into sodium benzoate, and vice versa. If the environment is suitably acidic, benzoic acid predominates. If the environment is not sufficiently acidic and sodium ions are present—as they often are—sodium benzoate predominates.

Benzoic Acid in Food and Other Products

Benzoic acid is found in many plants. Significant amounts have been found in some fruits—especially berries—as well as in yogurt, certain spices, and honey. Artificial benzoic acid is added to food and to products such as toothpastes, shampoos, cosmetics, and medicines in order to prevent microbial growth.

Benzoic acid is most effective as a food preservative in acidic food. It seems to harm microbes by preventing them from fermenting glucose, but it may have other effects on the microbes as well.

Gum benzoin is called kemenyan in Java.
Gum benzoin is called kemenyan in Java. | Source

Gum Benzoin and Tincture of Benzoin

Gum Benzoin

Gum benzoin is also known as benzoin resin, gum benjamin, and kemenyan. It's rich in natural benzoic acid and smells pleasant. Two types are available commercially—Siam benzoin and Sumatra benzoin. Siam benzoin is used mainly in the perfume industry while Sumatra benzoin is used in natural health care.

Siam benzoin is produced by wounding the bark of a tree called Styrax tonkinensis, which is found in Vietnam, Cambodia, Laos, and Thailand. Sumatra benzoin is obtained from the bark of Styrax benzoin, which is native to Sumatra. The injury to the bark of either tree causes a yellow liquid to be released. The liquid hardens into a sticky yellow or red-brown solid.

Tincture of Benzoin

Tincture of benzoin is made by dissolving gum benzoin in alcohol. Compound Benzoin Tincture, Compound Tincture of Benzoin, and Friar's Balsam are three different names that refer to the same product. This product contains gum benzoin and alcohol as well as storax, Tolu balsam, and aloe. Storax is a resin exuded by a type of sweetgum tree and balsam is another plant resin.

Like gum benzoin, honey contains benzoic acid.
Like gum benzoin, honey contains benzoic acid. | Source

Uses of Compound Benzoin Tincture

Compound Benzoin Tincture (CBT) is a sticky liquid that is applied to skin to improve the adhesion of medical tape and bandages. It's sometimes applied to skin areas that are subject to high friction because it's thought to reduce the chance of blister or ulcer formation.

Some people inhale steam from hot water containing CBT to relieve the congestion of a cold. Care is needed when using this product because it can act as a respiratory irritant as well as a skin and gastrointestinal irritant.

Plums are another natural source of benzoic acid.
Plums are another natural source of benzoic acid. | Source

Potential Dangers of Benzoic Acid

Like most chemicals that have toxic properties, the effects of benzoic acid depend on its concentration. At the low concentrations found in plants and foods, the chemical isn't dangerous for most people. Once it's eaten or produced, benzoic acid is absorbed through the lining of the digestive tract and eventually converted into hippuric acid, which is excreted in the urine.

According to the Material Safety Data Sheet (MSDS) that is created for chemicals, benzoic acid can irritate the eyes, skin, lungs, and digestive tract. Most people aren't exposed to high enough concentrations to experience this irritation, but people who work with the pure chemical or with concentrated mixtures need to be careful. Benzoic acid can enter the body through the skin as well as the digestive and respiratory tracts.

Maraschino cherries are often preserved with sodium benzoate.
Maraschino cherries are often preserved with sodium benzoate. | Source

Potential Dangers of Sodium Benzoate

Pseudoallergy

There are several ways in which sodium benzoate can be harmful to people. For example, it can cause pseudoallergy symptoms in sensitive people. A pseudoallergy resembles an allergy in its presentation, but unlike a true allergy it doesn't involve an immune response.

A skin rash, itching, a runny nose, and congested airways are possible symptoms of a sodium benzoate pseudoallergy. If a person is asthmatic or has a tendency to develop hives, these problems may become worse after exposure to the chemical. It's thought that a response to sodium benzoate is rare in people who don't already have a true allergy. The chemical may play a role in increasing hyperactivity in children, however, although this is unproven.

Benzene Production

When sodium benzoate reacts with ascorbic acid (vitamin C) in the presence of heat, light, and metallic ions, benzene forms. This reaction may happen in soft drinks that contain the chemicals. This is worrying, since benzene is a carcinogen. In the United States, the FDA (Food and Drug Administration) is aware of the problem. Between 2005 and 2007 the FDA discovered that some soft drinks contained benzene above the allowable level. Since this discovery, many manufacturers have reformulated their products to reduce the amount of benzene.

Benzene Properties and Uses

We are exposed to benzene from a variety of sources, including gasoline at gas stations, car exhausts, emissions from industries that burn coal or oil, emissions from other industrial processes, and cigarette smoke. It's important to avoid adding to the benzene load whenever we can to prevent reaching a critical level that harms our bodies.

A diagram showing the structure of a benzene molecule
A diagram showing the structure of a benzene molecule | Source

Benzene Structure and Potential Dangers

Benzene has many important uses. Before its dangers were understood it was even used as a reactant in school chemistry experiments. Now it's generally used with caution and only by chemists who know how to handle it.

Benzene was discovered by Michael Faraday in 1825. It contains only carbon and hydrogen atoms and is therefore classified as a hydrocarbon. The benzene molecule is a six sided ring, as shown in the diagram above. The single lines represent single bonds holding atoms together and the double lines represent double bonds. Although benzene is often represented by this diagram, chemists have discovered that the bonding between the atoms is not as simple and clearcut as shown in the illustration.

Benzene exposure may produce acute (immediate) effects if a person is exposed to a large amount of the chemical. These effects include a headache, dizziness, vomiting, muscle tremors, a rapid or irregular heartbeat, drowsiness, and loss of consciousness. Exposure to a very high concentration of benzene can be deadly.

Exposure to benzene over a longer period of time can affect the bone marrow, decreasing its production of red blood cells and causing anemia. It can also weaken the immune system. In addition, long term exposure to benzene increases the risk of leukemia.

Simplfied Benzoic Acid Structure

In benzoic acid, the ring has a similar structure to that of benzene, but one of the hydrogen branches is replaced by a group of atoms. In sodium benzoate, the H shown in the diagram above is replaced by a sodium ion.
In benzoic acid, the ring has a similar structure to that of benzene, but one of the hydrogen branches is replaced by a group of atoms. In sodium benzoate, the H shown in the diagram above is replaced by a sodium ion. | Source

Although the benzene molecule is dangerous, slightly altered forms of the molecule form part of many larger and generally harmless molecules, including aspirin. Benzoic acid and the various types of benzoates contain the benzene ring but have different atoms attached to one place on the ring. The change in structure removes the toxicity of benzene.

Significant quantities of benzoic acid have been found in apples. The presence of the chemical may depend on the existence of a fungal infection in the fruit, however.
Significant quantities of benzoic acid have been found in apples. The presence of the chemical may depend on the existence of a fungal infection in the fruit, however. | Source

Safety of Benzoic Acid, Sodium Benzoate, and Benzene

Most people don't need to worry about benzoic acid and benzoates in food, drinks, and other sources, since the chemicals are usually present in small amounts. In addition, most people aren't exposed to high levels of benzene.

Some people do need to be concerned about benzoic acid and sodium benzoate, however, and should reduce their exposure to both substances. It's also advisable for everyone to avoid exposure to benzene as much as possible. We should all be aware of the potential dangers of these three structurally related chemicals.

References

Benzoin information from WebMD

Benzoic acid and sodium benzoate safety from the World Health Organization

Benzene in beverages report from the FDA (Food and Drug Administration)

Benzene in soft drinks from Health Canada

Questions & Answers

    © 2012 Linda Crampton

    Comments

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      • AliciaC profile imageAUTHOR

        Linda Crampton 

        17 months ago from British Columbia, Canada

        Thanks for the comment, Charlie. You can read my mind! I am going to say that neither the hydrogen peroxide nor the benzoic acid in the solution should be taken internally. To find out whether the amount of benzoic acid in the diluted solution (or the amount of hydrogen peroxide in the dilute solution) is "harmful or negligible" you need to ask your doctor or contact the manufacturer of the solution.

      • profile image

        Charlie Berlin 

        17 months ago

        Thank-you for your easy to understand information .

        I am amazed...you even answer readers questions.

        This concerns H2O2 solution 6% w/v.

        It contains Benzoic acid 0.01% w/v as stabilizer .

        I know , you are not a medical doctor .

        The manufacturer recommends external use only .

        If someone would take up to 10 drops of this solution in water orally , avoiding ascorbic acid at the same time ,..would you say the amount of Benzoic acid entering a body (85 Kg) would be harmful or neglibigle .

        I am aware of ,that you can and will not not recommend any internal usage oft his product.

        My question concerns just the amount of Benzoic acid entering the body

        Thanks again have a great new year

        Charlie

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        2 years ago from British Columbia, Canada

        Hi, kaz. I'm sorry about your health problem. It must be so frustrating. I'm not a doctor or a health care provider, so I can't give medical advice to individuals. I would suggest that you visit your doctor, a different doctor or perhaps a dietician to get advice about non-irritating food. You might find toiletries and household products without benzoic acid in health food stores. That's where I go when I want to buy products containing only basic ingredients.

      • profile image

        kaz 

        2 years ago

        i was told at the hospital i am allergic to Benzonic Acid. I have a very sore mouth cant wear my dentures , eat mashed potatoes every day ,also have a rash from my head to my feet .Ihave checked my washing liquids and shampoos they all have it, i;m at my wits end can you help me

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        3 years ago from British Columbia, Canada

        Thank you, Drew. It's nice to meet you. Your decision to eat fresh and organic food sounds like a great idea!

      • Drew Lawrence profile image

        Drew Lawrence 

        3 years ago

        Thanks for this, very informative. I always stick with fresh and organic!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        3 years ago from British Columbia, Canada

        Thank you very much, Jo. As always, I appreciate your visit and comment, as well as the information that you've shared.

      • tobusiness profile image

        Jo Alexis-Hagues 

        3 years ago from Lincolnshire, U.K

        As a young student nurse many years ago, we used Tincture of Bensoin (Friar's Balsam) as a steam inhaler for patients with breathing difficulties such as bronchitis, I can see why it went out of vogue. An excellent and informative article, meticulously researched. Well done.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        4 years ago from British Columbia, Canada

        Hi, ologsinquito. Thank you very much for the visit and the comment. The potential reaction between sodium benzoate and ascorbic acid is definitely scary!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        4 years ago from British Columbia, Canada

        Thank you very much for the comment, the vote and the share, AnimalWrites. I'm sorry about your sensitivity to food additives. There seem to be quite a lot of people that share your sensitivity!

      • ologsinquito profile image

        ologsinquito 

        4 years ago from USA

        This is so informative. It's good to know what can happen when you mix sodium benzoate with ascorbic acid. Yikes.

      • AnimalWrites profile image

        AnimalWrites 

        4 years ago from Planet Earth

        Thanks for all the great information Alicia, as I'm sensitive to quite a lot of additives and preservatives in food and drinks. Great hub voted up and shared

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        4 years ago from British Columbia, Canada

        Hi, midnightbliss. Thanks for the comment. Yes, the number of resources needed to produce goods such as prepared foods can certainly be amazing!

      • midnightbliss profile image

        Haydee Anderson 

        4 years ago from Hermosa Beach

        Interesting hub! Honestly, it never ceases to amaze me the countless amount of resources - both organic and synthetic - that are used in the production of various goods.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Hi, Carole. I’m sorry about your son’s health problem. I’m surprised that your doctor didn’t give you a diet sheet when he or she diagnosed your son’s condition. I’m not a doctor myself, and I don’t want to advise you to eliminate a food from your son’s diet if this isn’t necessary!

        I found a low benzoate diet that was created by an oral health professor at the University of London. (See the link below.) I suggest that you print the diet and take it to your doctor to see if he or she likes it.

        www.bsom.org.uk/PatientInformation/dietcinbenz.pdf

      • profile image

        Carole 

        5 years ago

        Hi, my 6 year old son has just been diagnosed with Orofacial Granulomatosis (Oral Crohns) and has been prescribed a Cinnamon & Benzoate Free Diet. Are you able to tell me which foods have the highest natural Benzoate content please?

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        5 years ago from British Columbia, Canada

        Thanks for the visit, RTalloni. Yes, fresh food is the best type! It's good to eat as much fresh food as we can compared to other types of food.

      • RTalloni profile image

        RTalloni 

        5 years ago from the short journey

        Interesting to read up on this common food additive. Thanks for the reminder that fresh is best!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you for the comment, b. Malin. You're so right, everybody's system is different. Sodium benzoate creates no problems for most people but can produce allergy symptoms in others. Reading product labels is very important.

      • b. Malin profile image

        b. Malin 

        6 years ago

        Who knew, so as Always, I say, Thank You Alicia, for your most Informative and Educational Hub read. It's always good to know the side effects of any Chemical, for everyone's system is so different, and allergies can come out of nowhere and become life threatening. I am one that always reads Labels of just about Everything that I buy. Thanks for sharing.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thanks for the visit and the comment, Nell. Friar's Balsam is certainly interesting! Thank you for sharing your experience with the product.

      • Nell Rose profile image

        Nell Rose 

        6 years ago from England

        Hi, I remember very well when I was small having to take Friar's Balsam for bronchial problems, I can even taste it now, it was revolting! lol! but I never realised that it killed bacteria etc, and where it came from. I think the trouble starts as you mentioned when instead of using the natural substance chemists start to add more, this was really interesting and something I had never though off, voted up and thanks for sharing!

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