Number

366-EN

Section

General Section

Use

Abstract

Cosmetic formulations are prone to contamination due to their high water content, pH and temperature range and ingredients used, which can act as nutrients. In the past, parabens, formaldehyde-donors or halogenated products were most frequently used to preserve the formulation. Due to different reasons these preservative groups are in discussion and can be replaced by a combination of organic acids like benzoic acid, sorbic acid or anisic acid and sorbitan caprylate at a pH < 6.0.

Substituted substances

Alternative Substances

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Reason substitution

CMR
other toxic effects
ecotoxicity
skin/respiratory sensitizing

Hazard Assessment

Substances to be substituted: Parabens are of concern because of their endocrine disruptive properties. Methyl-, ethyl-propyl- and butylparaben are on the hazardous Substance Database according to SUBSPORTplus Screening Criteria due to their presence on the EU Commission database of potential endocrine disruptors. Imidazolidinyl urea, diazolidinyl urea and DMD hydantoin are all formaldehyde donors and formaldehyde is on the SDSC since it is a category 1B carcinogen, a category 2 mutagen (CLP Regulation) and a sensitiser (H317, H334; CLP Regulation), as listed in the Substance Database according to SUBSPORTplus Screening Criteria (SDSC). Chloromethylisothiazolinone has no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Iodopropyl carbamate is toxic if inhaled, causes damage to organs through prolonged or repeated exposure, is very toxic to aquatic life, is very toxic to aquatic life with long lasting effects, is harmful if swallowed, causes serious eye damage and may cause an allergic skin reaction. Alternative substance: Sorbitan caprylate is not on the hazardous Substance Database according to SUBSPORTplus Screening Criteria and does not have any official classification.

Description of Substitution

Finding the right preservative for a formulation is a challenge. The ideal preservative would be highly efficient, safe, and effective against bacteria and fungi and in addition be heat stable and cost effective. Such a preservative is however difficult to find. In the past the cosmetic industry used mainly parabens, formaldehyde-donors and halogenated products, as they are highly effective against all kinds of microorganisms and cost effective. Phenoxyethanol is often used as a solvent for other preservatives and often shows a synergistic effect. Due to its strong smell it is not used at high concentrations. For different reasons the above mentioned products are under discussion and cosmetic manufacturers and consumers want to have the freedom to choose between different preservatives. Sorbitan caprylate is a preservative boosting ingredient which is based on renewable resources. It is a liquid ingredient which can be used over a wide pH range (pH 5.0-8.0). It boosts the performance of phenoxyethanol so that a balanced and highly efficient blend is obtained. This blend is pH independent. The strong smell of phenoxyethanol can also be reduced by a 1:1 combination with sorbitan caprylate.

	Velsan® SC	Phenoxyethanol	Velsan® SC, ?Phenoxyethanol ?1:1 blend
Pseudomonas aeruginosa	1	0.25	0.25
Staphylococcus aureus	0.25	0.125	0.063
Candida albicans	0.016	0.032	0.008
Aspergillus brasiliensis	0.5	0.5	0.25

Table 1. Minimum Inhibition Concentration (MIC) of the single substances and the 1:1 combination of sorbitan caprylate (Velsan SC) and phenoxyethanol. The lower the numbers, the more effective the substance is against bacteria and fungi. The gap against Gram-negative bacteria Pseudomonas aeruginosa of sorbitan caprylate can be easily closed by combining it synergistically with phenoxyethanol or by lowering the pH value < 6. Leave-on cosmetics are especially hard to preserve. In the past, mainly parabens in combination with phenoxyethanol as solvent and performance booster were used. Halogenated products like iodopropynyl butylcarbamate, chloromethylisothiazolinone or chlorphenesin or formaldehyde-donors like DMDM hydantoin are used less and less in leave -on cosmetics in Europe, but they can still be found in leave-on products globally. As a replacement, organic acids like benzoic acid, sorbic acid or anisic acid are used. A pH value < 6.0 is needed to have these acids in their active form. However, as a stand-alone anti-microbial active, these ingredients are all too weak. Sorbitan caprylate is in the position to increase the performance of organic acids synergistically. A combination of 0.4 % benzoic acid and 1.5 % sorbitan caprylate is in the position to outperform the combination of five different parabens and phenoxyethanol in a very hard to preserve formulation. At pH values < 6.0 this combination acts superior, can be used in natural formulations and does not belong to the above mentioned preservative groups. Costs are in the same magnitude as classical preservative blends. Sorbitan caprylate is not soluble in water and is best added at the end of the process into the cool formulation. Depending on the formulation and concentration used, sorbitan caprylate can influence the viscosity of the formulation slightly. Some customers say, that sorbitan caprylate helps to improve the skin feel. Table 2. Challenge Test results of a very hard to preserve leave-on formulation. European Pharmacopoeia Ph.Eur. results A, B and F are colour coded. A denotes an excellent preservation, B a moderate preservation and F requires a re-work of the preservation system. Pure benzoic acid is too weak at pH 5.5 to fully preserve the formulation. By adding sorbitan caprylate at 0.5 % intervals the formulation can be excellently preserved at the addition of 1.5 % sorbitan caprylate. The combination is superior to a blend consisting of five different parabens and phenoxyethanol.

Case/substitution evaluation

This case story describes a substance that can be used to enhance the preservative properties of other preservatives. This means that milder preservatives can become more effective and that lesser amounts of preservatives are needed. In this case story sorbitan caprylate is combined with organic acids and with phenoxyethanol. Please note that the use of phenoxyethanol has been questioned in some countries including in France and in the US. Also, the SUBSPORTplus team has not evaluated the data on efficiency presented by the producer in the case description.

State of implementation

Full capacity

Producer/Provider

https://www.clariant.com

Type of information supplier

Producer / distributor

Contact

https://www.clariant.com

Date, reviewed

November 26, 2021