Common Daily Benzene Exposures:
The primary daily sources of Benzene and estimated daily exposure levels in micrograms follow:
- Air Pollution: 220 mcg
- Fueling Automobile Tank: 10 mcg per minute
- Driving: 40 mcg
- Other automobile related activities: 40 mcg
- Drinking Water: Up to 3.1 mcg
To add context to these numbers, the average individual would need to drink approximately 12 gallons of water containing the maximum contaminant level of Benzene as established by the EPA to equal the amount of Benzene breathed from the air each day.
Taking into consideration all identified exposure sources of Benzene, it is likely that at least 95% of daily exposure to Benzene comes from inhalation.
The Cosmetic Connection:
Benzene may also be formed when benzoic acid is combined with ascorbic acid. This occurs as the result of a chemical reaction that causes benzoic acid to release carbon dioxide when in the presence of ascorbic acid.
However, the joint presence of benzoic acid and ascorbic acid 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,
- Presence of sugars;
- Presence of chelating compounds.
Addressing each of these individually:
Concentration:
The recommended concentration of one of the most common benzoic acid based preservative systems is between 0.75% and 3%, depending on the formulation. The presence of sodium benzoate represents slightly less than half of that percentage.
Essential oil usage in cosmetics is typically less than 1.0%. However, the concentration of essential oils is not relevant when considering the amount of ascorbic acid or vitamin C they contribute to cosmetic formulas. All vitamins – including vitamin C – are either fat soluble or water soluble. Since essential oils contain neither fat nor water, essential oils cannot “hold” vitamins. As such, the presence of citrus essential oils in cosmetics does not increase the likelihood of the formation of benzene.
Copper, Iron Sulphate, Other Minerals:
The presence of these metals in water ingredients used for manufacturing is the most likely source in cosmetics. Cosmetics that uphold the standard of relying only on purified water are unlikely to test positive for these metals. 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 2 or less is considered the pH level optimally needed for the combination of benzoic acid & vitamin C to result in the formation of benzene. Benzene production drops sharply at pH levels of between 3 and 5 and laboratory tests indicate that benzene does not form at pH 7.
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, such exposures would be extremely atypical in standard production processes for cosmetics.
Presence of Sugars:
Sodium Benzoate makes up slightly less than 50% of the preservative system most commonly linked to concerns regarding Benzene formation. The other ingredient present in this preservative is Gluconolactone. This naturally occurring compound is a cyclic ester of D-gluconic acid which forms from the oxidation of glucose. The joint inclusion of this sugar derivative along with sodium benzoate further inhibits the formation of benzene.
Chelating Compounds
In addition to the inhibitory characteristics of the sugar components present in gluconolactone, this compound is also capable of chelating metals. Laboratory testing indicates that the presence of chelating agents drastically reduces the likelihood that benzene will form – even in an environment where benzoic acid and ascorbic acid are present.
Summary:
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 in an environment typical of cosmetic production. 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 conditions 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 should the toxicity of benzene be questioned nor should the importance of minimizing exposure to benzene be minimized. However, it is important that concerns regarding the formation of benzene in cosmetics be weighed in proper context and in consideration of relevant information.
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