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Shampoos, conditioners, mousses and gels PDF Print E-mail

Shampoos commonly consist of a surfactant, fragrances, foaming agents, colours, preservatives and viscosity modifiers (e.g. thickeners). Surfactants such as sodium lauryl sulphate remove oil from the hair and keep it suspended in water, allowing both it and dirt to be washed away; they may also produce a lather. Because the surfactants can dry out the hair too much, conditioning agents are often added.

Common ingredients in shampoos include:
* Paraffins as thickeners.
* Preservatives such as parabens and immazolidinyl urea.
* Solvents and emulsifiers such as phenoxyethanol (an ethylene glycol ether) and alcohols (e.g. propanol, ethyl alcohol).
* Fatty acids including palmitic acid (hexadecanoic acid) and stearic acid (cetylacetic acid/octadecanoic acid) which act as emulsifiers and binding agents.
* Foaming agents such as cocamide.
* EDTA (ethylenediaminetetra-acetic acid) as a sequestering agent i.e. to wash out scums.
Conditioners have similar ingredients to shampoos with an emphasis on the conditioning agents, for example oils to replace those removed; silicones (such as dimethicone) as water-repellent lubricants to smooth the hair; quaternary ammonium salts to make the hair easier to comb; or polyvinylpyrrolidone plastic (PVP) to make the hair shine.

Products to hold the hair in place, such as mousses and gels, are similar in composition to conditioners without the surfactants. They may also have coal tar and methacrylates (also known as polyacrylic acid and carbomer) to fix the hair in place and add shine.

Special-purpose shampoos may contain coal tar (for eczema or psoriasis) or zinc pyrithione (for dandruff) and often have antifungal chemicals (such as bifonazole).

Because there are ingredients that can cause skin problems, anti-irritants may be added!

CHOICE magazine presents regular trials about the effectiveness of shampoos, along with discussion on how they work.

Hair dyes
These are products used to colour or tint hair (permanent dyes or non-permanent rinses and tints). They use similar ingredients to shampoos as well as the dyes. Most permanent dyes contain the coal tar derivatives toluene-diamine or paraphenylenediamine (benzidine) which are aromatic amines, and are activated by mixing with hydrogen peroxide immediately before use. Non-permanent dyes usually contain a mild acid, such as citric or tartaric acid, plus dyes (such as anthraquinone dye types). For just bleaching, hydrogen peroxide with persulphates as boosters (to make the hair more receptive) is used.

Hair sprays
Hair sprays are used to hold the hair in place in a particular style. They are available as pump packs or aerosols; the aerosols use hydrocarbons (e.g. propane or butane) as the propellant. Common ingredients are glutaraldehyde; paraffins; methacrylates for glueing the hair together and to add shine; and various alcohols.

Permanent solutions
These are used to fix the hair in a waved style. They are based on glycolic acid and its derivatives, which break the bonds within the hair and allow them to be set in a different shape. The rebonding agents include hydrogen peroxide, and setting ingredients such as carbomer are also added.

Health effects
There are regulations about listing ingredients of all kinds under the Trade Practices Act, but ingredient labels can be confusing since so many different names may be used for the same ingredient. Take 'panthenol', a conditioning agent. We followed a long trail via the Internet to establish its chemical composition. It is also called 'Pro Vitamin B5', that is, it is equivalent to Vitamin B5 (pantothenic acid). The closest we came is that it is the alcohol derivative of pantothenic acid, which is apparently synthesised by combining pantoic acid with beta-alanine (an aromatic amine). Books took us no further.

The most reliable source of information is the material safety data sheet for the product which should have real chemical names, rather than common names (see also Cosmetics).

Most of the ingredients are non-toxic although they may pose problems for people with chemical sensitivities, in particular skin and eye irritation. Remember also that chemicals can be absorbed through the skin, and you may ingest them unintentionally. There may be only minute amounts of each ingredient in a product, but many products share the same ingredients so users can be exposed to a cumulative load.

Hairdressers are those most likely to suffer adverse effects and in fact have a high rate of contact dermatitis. Surfactants, preservatives, glycolic acid, glutaraldehyde, aromatic amines and zinc pyrithione are known to cause various skin reactions. Potential eye irritants include some surfactants, zinc pyrithione, glutaraldehyde and quaternary ammonium salts (a Schedule 6 poison).

There are chemicals with potentially more severe effects. These include:
* The methacrylates, which can cause skin and eye reactions. They are low to moderately toxic if ingested and of moderate toxicity by inhalation or through the skin. They are also mutagenic.
* EDTA is moderately toxic by ingestion.
* Coal tar can produce skin reactions, and may lead to an exaggerated response to sunlight (photoallergic or phototoxic contact dermatitis).
* Aminoanthraquinone has been associated with cancer in rats.
* The persulphates can lead to contact dermatitis, as well as producing allergic reactions such as asthma and rhinitis if inhaled. Long-term exposure can lead to sensitisation to persulphates.
* The aromatic amines are absorbed through the skin and may be carcinogenic.

Some hair dyes and 'colour restorers' contain lead acetate, which is absorbed through the skin and accumulates in the body (see Lead). The presence of dye in the body is indicated when urine is brown. Some dyes cause severe skin reactions. When considering using a hair dye, first do a patch test by applying a small quantity of the product to the skin behind the ear, then wait 24 hours to see if a reaction occurs. (If there's no reaction, the product is safe for you to use.) Some of the chemicals in dyes could cause blindness if they get into the eye.

See also individual entries for other chemicals mentioned. Note that this is only a sample of ingredients; there are too many to cover all of them here.

Environmental effects
Any product sold as an aerosol contributes to air pollution and you are liable to breathe in some of it when you use it. Look for trigger pump packs instead. (See also Cosmetics.)

Remember that even hair products advertised as 'natural' may contain toxic ingredients (e.g. henna may induce asthma). Wear gloves when using dyes or permanent solutions. Instead of dyes, try using lemon juice for blond hair and vinegar for brown, to bring out the highlights. Use soap instead of shampoo in soft water, vinegar or lemon juice in hard water. There are mechanical ways of setting the hair (rollers, plaits which you later release). Try to keep all these products out of your eyes and off your lips, rinse your hair well and try to extend the time between applications.

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