Cosmetic Product Testing

Testing a cosmetic to ensure a long shelf life free of microbial contamination has always been a fundamental part of cosmetic formulation. More recently the toxicity and efficacy of cosmetics and their ingredients has been under the spotlight. Now, with the enactment of the Sixth Amendment (93/35/EEC) to Directive 76/768/EEC the need for testing all such attributes is part of European law. Nor is such a need restricted to Europe, all cosmetics imported into the European Union must also comply and Japan, the USA and most other countries of the world have similar legislation.

This feature will cite the relevant legislation requirements, will identify the major tests available to satisfy those demands and will conclude with a summary of laboratories offering product- testing facilities.

Shelf-Life

A cosmetic product must remain suitable for use for a minimum period of thirty months after manufacture or carry a best-before date. The IFSCC has published a monograph on the fundamentals of stability testing which describes in a clear and concise manner the practical aspects. Shelf life is defined as that period of time during which a product remains in compliance with its specification when stored under the conditions of the market. It emphasises the need for a release specification and a check specification wherein limits are widened to allow for changes with time that do not however, affect the integrity or safety of the product.

In many cases the chemist may initiate stability testing without knowing what the final pack will be and probably every formulator can recall a last-minute change of colour, perfume or pack by the marketing department. Unfortunately, for a stability test to be valid it must be the total product in the final pack. Compatibility between the product and its package are one of the fundamental test requirements. In today’s rapidly changing marketplace the time allowed from product concept to its appearance on the retail shelf is critical and anything that reduces this time is an advantage. Certainly few companies can afford the luxury of three years testing before marketing a new cosmetic. Reducing this period is termed accelerated ageing and the most commonly used methods are testing at elevated temperature and humidity, the use of north-facing windows or light cabinets and by using freeze/thaw cycles.

Visual inspection will reveal whether a clear lotion is clouding or a liquid emulsion is creaming but analysis will be necessary to show whether an active ingredient is degrading or a preservative is being absorbed by the plastic container. Rheology studies are a precise measurement of changes in emulsions. Dr Hans Brand of Elzbieta Cosmetics is an acknowledged expert in this field and undertakes such work on a consultant basis. A relatively new instrument, the Turbiscan, appears to have great potential for predicting emulsion stability. It measures particle size and distribution within a sample and minor changes in these values may be detected as an early sign of instability.

Microbial contamination has always concerned the responsible cosmetic manufacturer and microbial standards are part of current EU legislation. Micro-organisms inside the product may cause spoilage through chemical or physico-chemical deterioration. Aqueous base preparations are particularly vulnerable to certain species such as Pseudomonas and Enterobacteriaceae. Mucocutaneous infections have been observed after use of cosmetic products. Skin and mucous membranes are normally protected from microbiological stress by natural defence mechanisms but if this becomes damaged infection can occur. Some cosmetic products need special study, mainly those used around the eyes and cosmetics intended for infants. Such products must have a total aerobic viable count (TVC) of no more than 10 micro-organisms per 1 ml and there must be an absence of the pathogenic organisms, Staphylococcus aureus, Pseudomonas species, Enterobacteriaceae and Candida albicans. Other cosmetics may have a maximum of 10 3 micro-organisms per ml and pathogens must still be absent.

To ensure that a cosmetic product is going to remain free from microbial contamination in its manufacture, storage and use it is subjected to a challenge test by artificial contamination using selected organisms. The decrease in the number of micro-organisms in the preparation is measured at selected intervals and expressed as a logarithmic reduction. The methodology for such tests is described in various publications including the British Pharmacopoeia and publications by the CTPA. [Refs. 2 / 3]. Seldom will an aqueous-based product pass a challenge test without the additional help of a properly designed preservative system but preservatives cannot replace good manufacturing practice. They must be used at the minimal concentration that ensures their efficacy and this must be assessed experimentally during the product development process. Further challenge testing is necessary during product stability testing as loss of preservative through interaction with product ingredients or absorption by the pack is a common problem. The challenge test must be repeated whenever there is suspicion that the preservative's efficacy is no longer assured.

Safety Assessments

According to Council Directive 93/35/EEC, Article 2: "A cosmetic product put on the market within the Community must not cause damage to human health when applied under normal or reasonably foreseeable conditions of use, taking into account, in particular, the product's presentation, its labelling, any instructions for its use and disposal as well as any other indication or information provided by the manufacturer or his authorised agent or by any other person responsible for placing the product on the Community market". While no responsible company would deliberately market a cosmetic that could cause damage to human health there have been many instances during the past fifty years of damage being caused. Best known may be the overdose of hexachlorophene in a baby powder that resulted in the deaths of a number of infants in France. The author has also seen references to the use of radioactive substances in a skin moisturiser; of 1% formaldehyde in a deodorant, the use of a local anaesthetic in a sun screen product and there have been frequent examples of high levels of heavy metals occurring in imported decorative cosmetics.

Such instances are relatively easy to spot and avoid but there are many less obvious means of causing damage to ones customers so the use of a trained and qualified toxicologist is of paramount importance. However there are a few simple steps to take before submitting a product for final approval. The Council Directive 76/768/EEC, as amended by Council Directive 93/35/EEC lists those chemicals which must not be contained in finished products (Annex II); those which cosmetic products must not contain except under the restrictions and conditions laid down in Annex III and a list of authorised antioxidants, hair dyes, preservatives and ultraviolet filters (Annexes IV, VI, VII).

When a formulation is being considered for safety an assessment must consider the general toxicological profile of the ingredients and their level of exposure. With sufficient knowledge of the toxicity of the ingredients there may be no need to test the final product. However if the base formula results in greater skin penetration than that observed in the toxicity studies on the ingredients or if interaction between ingredients is likely to result in the formation of a new, potentially toxic substance then testing of the full product may be necessary. Also when there is a claim of reduced skin penetration or of reduced toxicity resulting from the formulation then this claim must be substantiated.

Before any safety evaluation and risk assessment of a finished product is made, the degree and route of consumer exposure must be ascertained. This has to be done on each formulation and is dependent on the type of product; the area of application; the concentration of the ingredients; its frequency of use and whether the product is a rinse-off one or whether the site of application is likely to be exposed to sunlight. The age of the intended user and any foreseeable misuse should also be taken into consideration. The relevant exposure is dependent on the toxicological effects under consideration. For skin irritation or photoxicity the exposure per unit area of skin is important, while for systemic toxicity the exposure per unit of body weight is of more significance.

The exposure route must be considered in designing any test programme and in risk analysis. The possibility of secondary exposure by routes other than those resulting from direct application also should be considered, e.g. inhalation of hairsprays or ingestion of lip products. Usage of cosmetic products depends on several factors, some of which will vary over time, such as age group, seasonal variations, local habits, fashion trends, disposable income and product innovation. [Ref. 4]

Proving the Claim

Ever since her beautician advised Cleopatra that bathing in asses' milk would bring her everlasting youth, cosmetic claims have been noted for their hyperbole. Now such claims have to be proven. This has caused many problems for the industry with the chemists’ natural caution being set against the marketing department’s natural wish to exceed the competition. Either advertising copy becomes so bland as to become meaningless or the efficacy of the product must be substantiated. It has also led to a new class of product termed cosmaceuticals that are said to bridge the gap between beauty aids and medicines. The use of such a term however is to be discouraged as it may cause confusion and conflicting legislative requirements. There is however a risk that if a cosmetic product actually has a physiological effect then it may be classified as a medicine. [Ref 5].

There are many different ways of substantiating the claim and several independent laboratories offer a specialised service to assist in providing the proof. The first and most obvious step is for the product brief to include a list of the claims required yet how often is the chemist asked “Can I say ......?” by the marketing department as the formulation nears its final stages of creation, stability, safety assessment and challenge testing? Providing the proof may be by documented evidence, by in-vitro or in-vivo testing and increasingly, by clinical trials on people. This latter has obvious advantages but it does raise ethical considerations and it is not surprising that most laboratories offering this service also serve the pharmaceutical industry.

1. The fundamentals of stability testing; IFSCC Monograph No. 2, Micelle Press 1992.

2. Microbial Quality Control; CTPA.

3. British Pharmacopoeia

4. "Notes of Guidance for Testing of Cosmetic Ingredients for Their Safety

5. Evaluation" Scientific Committee on Cosmetology (SCC)

6. Cosmeceuticals; SCS Symposium Torquay, March 1999.

The following table lists a number of companies that offer consultant product testing services. Many more may be found in the CTMS Directory etc.

Laboratory	Stability	Micro		Safety	Efficacy	Sensorial	Comments
Adams, Wilson & Assoc. Ltd., Charles House, 61-69 Derngate, Northampton UK NN1 1UE	No	No	Yes		Yes	Yes	Consultants in safety and regulatory affairs.
Aster-Cephac, 12-14 rue Desnouettes, 75015 Paris France	No	Yes	Yes		Yes	Yes	Specialises in oral care, dermatology, ophthalmology and photobiology. Extensive use of human volunteers and instrumental measurements.
Elzbieta Cosmetics, Bronsmos 41, 2914 AD Nieuwerkerk a/d Ijssel, The Netherlands	Yes	No	No		No	No	Dr. Hans Brand is an expert in rheology and the application of rheology studies to predicting product stability.
Globecrown International, Ltd. 32 High Street, Maldon, Essex, UK, CM9 5PN	No	No	Yes		Yes	Yes	Extensive use of human volunteers and instrumental measurements. Specialists in non-animal toxicity testing.
Hazel Pool Associates, Suite 4.5 Litchurch Plaza, Derby, UK DE24 8AA	No	No	No		Yes	Yes	Independent free-lance R&D facility offering product formulation and evaluation.
Hill Top Research Inc. 223 Highway 18 Suite 203, East Brunswick, NJ 08816 USA	Yes	Yes	Yes		Yes	Yes	Safety evaluation and claims support using clinical trials and extensive instrumentation techniques.
Inveresk Research International Ltd., Tranent, East Lothian, UK EH33 2NE	Yes	Yes	Yes		Yes	Yes	Wide-ranging services including preparing the required dossier for new cosmetic ingredient notification.
Joyce Ryan Consultancy, 116-118 Bradshaw Brow Bolton, Lancs., UK BL2 3DD	No	No	No		Yes	Yes	Personalised service offering sensory & instrumental testing. Test design, operator training and statistical data analysis undertaken.
Microbial Systems Int. Ltd., Gothic House, Barker Gate, Nottingham, UK NG1 1JU	No	Yes	No		No	No	Full consultant microbiology testing service including preservative challenge testing and stability.
Microbiological Consultant Services, 16 Station Hill, Bures, Suffolk, UK CO8 5DD	No	Yes	No		No	No	Microbiological consultancy offering challenge testing and routine microbiological service. Rapid response with 7 day working.
Panspermia Microbiology, A1 Mildmay Industrial Estate, Burnham-on-Crouch, Essex UK CM0 8SH	Yes	Yes	No		No	No	Stability tests as per IFSCC Monograph and full microbiology testing service.
Proderm Institute, Industriestr.1, 22869 Schenefeld, Hamburg	No	No	Yes		Yes	Yes	Specialises in conducting dermatological studies with extensive use of instrumental techniques on human volunteers.
Quintiles (UK) Ltd., 79 High Street, Bracknell, Berks. UK RG12 1DZ
Reading Scientific Services Ltd., The Lord Zuckerman Research Centre, Reading, Berks. UK RG6 6LA	Yes	Yes				Yes	Specialists in sensory evaluation and qualitative/quantitative consumer research for FMCG and pharmaceutical industries.
Smallburgh Laboratories Ltd., Rowhook, West Sussex UK RH12 3YT	Yes	Yes	No		Yes	No	Claim substantiation, compatibility and stability studies and full microbiology service.
Wickham Laboratories Ltd., Winchester Road, Wickham, Fareham Hants. UK PO17 5EU	No	Yes	No		No	No	Full consultant microbiology testing and extensive analytical service.