Ingredient of the Week

a Salon Naturals blog

Preservatives and the Formation of Benzene

Benzene may be formed when benzoic acid is combined with ascorbic acid.

However, the joint presence of benzoic acid and Vitamin C does not create – on its own – sufficient conditions to form Benzene.  Other factors influencing the formation of benzene include:

  • Concentrations of benzoic acid & vitamin C;
  • The existence of certain minerals, including copper and/or iron sulphate;
  • The pH levels of the products containing these additives;
  • Exposure to UV Light.

Addressing each of these individually:


The preservative used in the products offered by Salon Naturals is present in a concentration of roughly one-half of one percent.  The presence of Sodium Benzoate represents slightly less than half of that.

The essential oils used in the line are present in a concentration of roughly one-quarter of one percent.

Considering the extremely low concentration of the two components needed to result in the formation of Benzene, there is no scientific evidence at present that this possibility exists on a realistic level.  All research studies that successfully achieved the formation of Benzene through the combination of Benzoic Acid & Vitamin C did so using concentrations ranging between 4500% and 60,000% higher than those present in personal care formulations.

Copper, Iron Sulphate, Other Minerals

None of these minerals are present in the formulations on any level that can be detected in a laboratory setting.  The absence of these minerals significantly impedes the conditions necessary for Benzene formation.

pH Levels

Benzene formation has been found to occur primarily in extremely acidic conditions.  A pH of 3 or less is considered the pH level optimally needed for the combination of Benzoic Acid & Vitamin C to result in the formation of Benzene.  The pH of the formulations created by Salon Naturals range between 5.5 and 6.5.

Exposure to UV Light

All products tested that demonstrated a propensity to form Benzene through the combination of Benzoic Acid & Vitamin C were heavily exposed to UV light for long periods of time.  In contrast, the products in question are immediately bottled and stored in opaque containers that offer no potential for UV exposure.


Although there is significant research and resulting scientific opinions available concerning the formation of Benzene when Benzoic Acid and Vitamin C are combined, in actuality, this is a difficult thing to achieve.  The absence of even one of the conditions outlined above diminishes the possibility of the formation of Benzene significantly.  The absence of two or more of them results in a scenario approaching impossibility.

It is also important to note that Benzoic Acid and Vitamin C are present together in a large number of fruits – cranberries are an example of this.  There is no evidence that the joint presence of these two additives results in the presence of Benzene in these foods.

Finally, it is worth stating that there have been no studies conducted on the likelihood that Benzoic Acid and Vitamin C may or may not form Benzene in any formulations other than ingestible beverages.  100% of the research studies given serious consideration by the scientific community focused solely on the soft drink and non-alcoholic beverage industries.

Benzene is an environmental pollutant and is most frequently ingested via the respiratory system.  The primary source of Benzene exposure is through petrol that is emitted into the air from exhaust gases.  In no way do we question the toxicity of Benzene or the importance that should be placed on avoiding unnecessary exposure to it. 

Our research of this subject, however, has left us extremely comfortable with the conviction that the particular circumstances surrounding the use of Benzoic Acid and Vitamin C in our hair care products will not result in the formation of Benzene.


July 18, 2011 Posted by | Ingredient of the Week - Yummy! | , , , , , | Leave a comment