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Survey of chemical substances in dandruff shampoo 1. Introduction1.1 Formation of dandruff, treatment and products for treatment 1.1 Formation of dandruff, treatment and products for treatmentDandruff is a condition that many people, at some point in their life, suffer from. Dandruff shows as an itching of the scalp and as excessive flaking of dead skin cells. It is important to discern between dandruff requiring direct medical treatment and dandruff as a result of dry skin. This report discerns between shampoos bought as medicinal products (in the following termed medical dandruff shampoo) and shampoos bought as cosmetic products (cosmetic dandruff shampoo). 1.1.1 Dandruff requiring medical treatmentDandruff requiring medical treatment (seborrhoeic dermatitis) is a condition in which the skin is affected by a small lipohile yeast fungus of the Malassezia species, also known as Pityosporum. The most common development of the condition includes the occurrence of oily, red and flaky patches [1] on the scalp, in the nasolabial folds (the skin between the upper lip and the nose), on the exterior ears, eyebrows, and/or eyelid edges. The most significant clinical symptoms in people suffering from dandruff of the scalp typically vary from person to person. Some "only" experience profuse reddening of the skin, while others experience extreme symptoms such as sore scalp and purulent blisters. When the skin naturally rejects dead skin cells from its most outward layer - stratum corneum - the cells disappear as microscopic waste in connection with brushing, washing and mere touching of the hair. However, when this mechanism is weakened, as in the case of dandruff, in stead of microscopic dead skin cells the skin rejects oily flakes of accumulated dead skin cells (Clinical Exp. Der. 1997). 1.1.2 Dry scalpWhite flakes falling from the scalp is not necessarily a sign of dandruff in the medical definition. If you suffer from dandruff as described above, the dandruff will often stick to the hair, whereas rejected skin flakes in connection with dry scalp will fall from the hair as snow. Moreover, there will not be itching to the same degree in connection with dry scalp. A dry scalp is often caused by shampoos that are to rough on the scalp, or due to chemical hair treatment products (e.g. perm or dye). 1.1.3 Cosmetic dandruff shampooAccording to legislation, cosmetic dandruff shampoo is a product made exclusively or mainly for hair and scalp-caring and hair-beautifying purposes, and which can prevent cosmetic dandruff. 1.1.4 Medical dandruff shampooContrary to the definition above, medical dandruff shampoo is defined as a product the primary purpose of which is to treat clinical symptoms that are clearly defined for the product, in this case dandruff and skin irritation. In order to apply the active remedies to the hair and scalp, the remedies have been integrated into the shampoo. According to the manufacturer, this is the easiest and most comfortable way to perform the treatment. However, defining which type of product belongs to the cosmetic category and which to the medical category presents a legal grey zone. This means it is possible to buy dandruff shampoos containing the same active agent (e.g. zinc pyrithion), however which are subject to two different Statutory Orders: namely the Statutory Order on cosmetic products and the Statutory Order on labelling etc. of drugs. This is often explained by the fact that products are registered as either medicinal or cosmetic products, depending on whether the manufacturer predominantly makes medicinal or cosmetic products. Following the development of this type of cosmetic/medicinal products is interesting, not the least from a health and environment perspective. This is partly because the market is demographically representative of all of Denmark, and partly because manufacturers are constantly developing existing products further in order to differentiate them from other dandruff shampoos on the market, as well as to satisfy consumer needs. Seen in relation to legislation on dandruff shampoo, that is the Statutory Order on cosmetic products and the Danish Medicines Act, it would moreover be interesting to identify which substances pose a risk in terms of discharges to the environment, since both sets of rules only take account of human health. 1.2 Substance groups and their functionAnti-oxidants: substances that prevent the product's constituents from oxidating and thus changing the chemical composition of the product. Examples are e.g. acetyl cystein, different acids, such as e.g. derived compounds of citric acid and ascorbin acid, diammonium EDTA, BHA, and BHT. Softeners (emollients): added to the cosmetic product in order to make hair more flexible. Examples are: hydrogenated castor oil, Chamomile Recutita extract and dimethicone. Buffers: substances which are added to the cosmetic product in order to give it the same pH value as skin (pH 5-6), or to maintain the most optimal pH value. Emulsifiers: emulsifiers are added so that oil mixtures which are not readily soluble in aqueous solutions can be mixed with such solutions thereby creating an emulsion. The mixture is now a cream or lotion,
which will not separate into oil and water. Emulsion stabilisers: added in order to ensure that the products maintain stable consistencies. Examples of substances are cocamid DEA and carbomer. Colourants: added to give the product a certain colour. Colourants are typically added to shampoos so that the shampoo appears glossy or transparent. Example of these are CI 42090, CI 15985 and lactoflavin. Film formers: film formers cover a number of substances that are added to cosmetic products in order to form a thin film over the skin surface. Examples of these are: polyquaterium compounds, panthenole, and sodium styrene/acrylates copolymer. Thickening agents/binding agents/viscosity controlling substances (gelation agents): substances that are added in order to improve the consistency, stability, and viscosity of the shampoo. These can be e.g. carbomer, sodium lauroyl sarcosinate, and stearamide MEA. Humectants (hygroscopic compounds): function to bind moisture in the lotion as well as to the skin. Examples are glucose and propylene glycol. Preservatives: substances that inhibit bacterial growth, and thereby prevent the product and its ingredients from changing into unintended substances. Examples are e.g. derived compounds of p-hydroxy-benzoic acid (parabenes) and Kathon. Solvents: solvents are used to ensure that all substances added together constitute a homogeneous mixture. The solvents used in the majority of all dandruff shampoos are deionisized and distilled water. Fragrances (perfumes): an aromatic mixture of selected oils, which together give the product the desired scent. Fragrances are sometimes added in order to disguise the smell of other components in the product. Plant extracts and oils: These substances can have many different functions in cosmetics. Some stimulate the skin, others act as disinfectants and some contain vitamins. Examples are Tussilago Farfara extract (coltsfoot), Citrus Aurantium Dulcis extract (orange), and Quercus Robur extract (English oak). Soap components/surfactants: Soap components have several functions. Soap is cleansing due to its properties as a hydrofile/hydrofobic substance and contributes to the foaming effect of the shampoo. The soap component in shampoo is often compounds of sulphates, sulphonates, sarcosinates, or mixtures of these. The functions of the sulphates are anionic surfactants, and are e.g. alkyl and alkyl ether sulphates that contains between 12 and 16 carbon atoms. The counter-ion of the anion, the cation, is typically a mono or divalent ion, such as sodium, potassium, calcium, ammonium, or magnesium. Sodium is used most often. Footnotes [1] Also termed papule - small, solid circumscribed elevation of the skin or mucous membrane.
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