Preservatives Used in Personal Care Products
Date: 14th January 2011
AUSTRALIAN SOCIETY OF COSMETIC CHEMISTS
Preservatives Used in Personal Care Products
Rita Sellars & Ric Williams
Date: September, 2010
1. This paper is an ASCC first issue position statement prompted by recent publicity about parabens and consumer trends that have resulted from this.
2. Discussions are based on the fact that when used correctly, with the judicious choice of preservative types, and at appropriate levels, they will prevent incidental contamination of products, and do not impact on the safety of cosmetics during use.
3. This paper provides information on potential irritation, preservative free products, status of parabens, recent regulatory status and provides guidance for formulator on the appropriate selection process for preservatives.
4. One over-riding consideration is that preservatives are not designed to render the product sterile, or compensate for unhygienic manufacturing methods or inadequate packaging. Preservatives are there to help the product overcome the incidental introduction of microbial contamination during processing and use.
Convention is that preservatives are to prevent microbial growth (bacteria, mould and yeast) in the product, whereas antimicrobials are used in disinfectants and antiseptics to kill bacteria on surfaces and skin, while antioxidants are substances that prevent oxidation of ingredients (usually characterized by free radical formation), usually causing rancidity of natural oils and destruction of organic compounds, such as vitamins, proteins, etc.
We will endeavour to state why we believe preservatives are necessary in cosmetic products and that they are safe when used correctly; citing theoretical considerations, processes commonly used in the development of a product and government regulations as evidence.
Considerations with preservatives
When formulating a product, the scientist will select a level of preservative which is toxic to all microorganisms (ie Bacteria, Moulds and Yeast) and safe for the application which it is intended.
Preservatives at the appropriate levels should be lethal to bacteria, moulds and yeasts (if not they would not act as preservatives). As a minimum, an effective level of preservative will be able to restrict growth from incidental introduction of microbial contamination during use, however continual contamination from outside sources will overcome this in a short period of time. For example, a poorly preserved product which has fingers frequently touching the cream to extract product will become contaminated very quickly.
During the manufacture of cosmetic products, preservatives should be added according to the product manufacturing process and instructions, and these are generally based on those outlined in the preservative manufacturers data sheets or MSDS. Rinse off products for humans will, generally, tolerate higher levels of preservatives than leave-on products for humans. Products that are intended for use around the eyes, in oral cavities or in contact with mucous membranes, for babies or for people with sensitive skin have much narrower criteria when it comes to choosing a preservative, as these should have evidence of better skin compatibility.
Formulators look for the ideal preservative which should strive to contain the following properties:
It should kill gram-positive and gram-negative bacteria, moulds and yeasts.
Efficacy at low concentrations
Preservatives should be used as a low as possible to avoid potential irritation, however there is still a need to have proven efficacy at the level chosen.
An ideal preservative will also be effective at a level that will not affect the function, aesthetics or safety of the product as a whole.
Preservatives should have sufficient water-solubility to produce effective levels in the water phase; as micro-organisms generally grow in the water phase and at the water-oil interface, hence preservatives must have some solubility in the water phase to function properly.
So as not to lose any activity of the preservative or the system, it must be compatible with all ingredients.
Colourless and odourless
The preservative should not create any colour or odour when added, although the use of essential oils as preservatives may replace or modify fragrance and hence be acceptable.
Due to changes in temperature and pH during manufacturing, plus the temperature extremes encountered in storage or use, the preservative needs to be able to handle the changes in these conditions.
Easy to analyse
The preservative should be easy to analyse using current analytical techniques.
Another interesting approach is that also used by the food industry, in that, they do not tend to use one preservative that will keep the product microbe free but use what is called the “Hurdle Approach”. The hurdle approach is where, instead of using one material that has 100% efficacy, they may use 10 ideas that provide 10% each towards product preservation, thereby achieving the end result. Combinations of multiple mild preservatives, post sterilization/Pasteurisation/sterilization, hermetically sealed packaging; storage in cold conditions (eg the fridge) and short shelf life all contribute to providing a food product that will not spoil during intended periods of use. While this approach is not normally used in personal care products, variations of this theory may be appropriate in certain circumstances. Steps taken in the cosmetic industry include; testing susceptible raw materials, using water treated and tested for microbial contamination, cleaning and sanitization of manufacturing equipment, the use of protective clothing and routine health checks for people working in manufacturing environments, and preventing airborne contamination both in the factory (by air filtration) and in final products (by moving away from packs that can be easily contaminated).
Irritation vs Sensitisation vs Allergic Reaction.
If a consumer has an adverse reaction they should seek medical advice.
It must be noted though that sometimes a user may have an irritation reaction and there could be many factors, some of which are not related to the formulation (eg a person's health, the effect of medication or specific diet effects, effects of sunburn, windburn or other environmental factors, other irritant materials (eg fragrances), etc.,). All of which can affect skin's reaction to common (normally non-irritant) materials.
Preservative Free Products
These are becoming more popular due to the concerns consumers have over the use of “chemicals” in general or reported side effects of commonly used preservatives.
While some products can be “self-preserving” or offer minimal potential contamination by bacteria, moulds or yeast; others can be difficult to formulate and have in-use problems. The major problem with preservative free products are that sometimes they are not broad spectrum or do not have enough antimicrobial “power” to act as a complete preservative by themselves and contamination may occur during use. This will result in subsequent spoilage before the product is completely used. This is particularly true when the product is completely preservative free, and other means to ensure no spoilage occurs, have not been properly addressed.
Note; squeeze packs, tubes, pumps and bottles are not generally “non-invasive” as air may re-enter after the pressure on the container is released; and air re-entering may contaminate the product. Apart from aerosols and single use packs, there are “air-less” dispensers where no air is returned to the container when the product has been dispensed. This effect is created a rising disc in the container barrel, due to the vacuum effect. These containers appear to be the very few that prevent oxygen from entering the pack during use, hence suitable for preservative free products.
In any case there is also a real potential for contamination from product residue at the outlet – this can be contaminated then the contamination spread back into the product.
Products that offer minimal potential contamination by bacteria, moulds or yeast include; anhydrous products where the lack of water may preclude the growth of water-borne bacteria, still require care be taken to exclude some moulds and yeast that do not require large quantities of water; or aerosol products where there is a lack of oxygen that may prevent growth. Post sterilization and the use of non-invasive packaging (single shot packs, sachets or “airless” containers) are essential, in such cases.
Despite a pack that excludes oxygen (an essential element from common microbial growth, anaerobic growth is possible (ie. there are microorganisms that do not require oxygen, from the atmosphere, to sustain life).
As a general theory “Preservative-Free” products should not be recommended as all have a potential for contamination as outlined above.
Cosmetic regulations differ from country to country. Because of this, there is not one harmonised regulation. The major regulating agencies in personal care are; European Union (EU), Brazil, Japan, USA Food & Drug Administration (FDA), and The Cosmetic Ingredient Review (CIR). The CIR was set up by the former Cosmetic Toiletry and Fragrance Association (CTFA) for industry self-regulation; it is therefore not really a regulatory agency but is accepted as a leading authority on cosmetic ingredients. The above bodies regulate and treat preservatives in different ways.
In Europe, the use of preservatives is regulated by Annex VI of the Cosmetic Directive of the European Union (EU). The Annex VI is an extensive list and does contain most of the cosmetic preservatives used elsewhere in the world. It approves preservatives based on a positive list. Brazil adopted a similar method and list to the EU.
Annex VI establishes maximum use levels that may differ from the levels recommended by the Cosmetic Ingredients Review (CIR) in the United States and the Ministry of Health and Welfare in Japan.
Japan approves preservatives and also works on a Positive List, however, the list is a much more restricted one. The most restrictive country for cosmetic preservatives from a regulatory standpoint is Japan. This does not mean that Japan has the safest products – just that there are far less options in selection of a preservative for use in Japan.
The U.S. FDA works on a negative list. The FDA stipulates that cosmetic products must be firstly safe; but in the end, “adequately preserved”.
The ASEAN group of countries also work on a Cosmetic Directive which is equivalent to the EU.
When formulating preservatives, standard product development should be employed.
1. Selection of Excipients and Actives
Care must be taken to select a preservative that will not be affected by required actives. For examples; ethoxylated compounds will reduce the effectiveness of parabens, and cationic preservatives will be inactivated by anionic surfactants (eg in a shampoo). Good reference books and most preservative manufacturers will provide information on the materials incompatible with the preservative system they sell.
2. Select the pH of the Product
The relationship between pH and preservative efficacy may be an important factor. For example if using Benzoic Acid then the lower the pH the more effective the preservative action (note Sodium Benzoate or Benzoic Acid neutralized in an alkaline medium is virtually inactive). Good reference books and most preservative manufacturers will provide information on the effective range of the preservative system they sell.
3. Select the type and concentration of the preservative
Selection of the type and concentration of the preservative should be based on the end usage of the product and the pH selected for the product. Particular note must be made of;
a. the regulatory restrictions (notably country of sale) that you will encounter.
b. the area of the body where the product will be used. This is particularly important when formulating products that are used around the eyes, in contact with mucous membranes or used internally.
c. the aesthetics (odour, colour, etc.), solubility in the base or effect on formulation characteristics;
d. the label concerns (eg putting formaldehyde on the label may be unacceptable to your consumers).
4. Choose the appropriate delivery system or point of addition for the preservative.
Preservatives should be added as soon as possible in the manufacturing stage however caution should be taken to;
a. not add the preservative above a temperature which will affect stability or volatility;
b. not add the preservative before adjusting pH to a level that will not affect the stability of the preservative.
5. Conduct a Preservative Efficacy Test
The British Pharmacopoeia or United States Pharmacopoeia both have method designs for standard Preservative Efficacy tests, however the final test should be discussed with the microbiological testing authority to ascertain the final requirements, particularly with selected organisms. The reason for this is that you may want to test against a microorganism that is a particular “in-house” organism (particularly one that may have been prevalent in your factory) or a microorganism that would commonly be encountered in use.
6. Optimise the formulation
a. Repeat from step 1. if necessary.
b. Conduct stability trials
c. Repeat from step 1. if necessary.
A review on preservatives would not be complete without a final word surrounding the controversy about Parabens. Following one article “Concentrations of Parabens in Human Breast Tumors”, Dabre PD. Et al, Journal of Applied Toxicology, 24, 5-13 (2004), reports proliferated about the dangers of parabens. The scientific community immediately refuted the claims made by Dabre, pointing out the poor science used in the methodology and conclusions. Recent evidence also shows that while parabens may have weak estrogenic activity, this activity is short lived and the degradation products do not show this effect.
At this stage, and despite many studies, no regulatory authority has made any attempt to limit the use of parabens in cosmetics or foods, citing their benefits and lack of adverse findings.
Still bad news persists, and despite overwhelming evidence that parabens do not have the effects presumed, the public still appear to consider any product with parabens, are harmful. This is probably also fuelled by uninformed press and companies reacting to public opinion.
References and articles for further reading
1. “Preservatives for Cosmetics – Second Edition” by David C.Steinberg ISBN 978-1-932633-12-2
2. Wikpedia Dictionary - http://en.wikipedia.org/wiki/Main_Page
3. http://www.science.org.au (December 15th 2005)
4. Hampton, A., Natural Organic Hair and Skin Care, Organica Press, 1987
5. Papadakis, M., “Chemical Cocktail in Cosmetics”, The Sunday Herald Sun, 2004, pp.21-22
6. Reisch, Mark. S., “Keeping Well-Preserved”, Chemical and Engineering News, November 14, 2005 Volume 83, Number 46, pp. 25–27.
7. Seal, Kenneth. J., “A New Generation of Isothiazolinones for the Preservation of Cosmetic Products”, Euro Cosmetics, 2004 Volume 10, pp. 22–27.
8. Soni M.G. “– Evaluation of Health Aspects of Methylparaben (including other parabens)”. Food and Chemical Toxicology, Volume 40, 2002, pp. 1335-1373.
9. Cosmetic Preservatives – Nasty Chemicals or Necessary Ingredients? by Rita Moubarak , 2005 Society of Cosmetic Chemists – Distant Learning Course – Extended Essay Titles
10. "Natural Preservatives" by Anthony C. Dweck BSc CChem FRSC FLS FRSH Cosmetics and Toiletries: August 2003
11. Colipa - http://www.colipa.com/site/index.cfm?SID=15588
12. The safety of Parabens, CTFA publication 12.1.04
13. The European Cosmetic, Toiletry and Perfumery Association (COLIPA) ; Letter 29 march 2004
Re; Publication by Dabre et al “Concentrations of Parabens in Human Breast Tumors”.
14. NICNAS Report on Parabens in Deodorants and Antiperspirants Linked to Breast Cancer 28.06.2004
15. EUROPEAN COMMISSION HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL
Scientific Committee On Consumer Products opinion on “Parabens, underarm cosmetics and breast cancer”
28 January 2005
16. American Cancer Society “Antiperspirants and Breast Cancer Risk” 06.05.2004
17. Other references as listed in the body of the text.