P-AMINOPHENOL HCL

Name / description

p-Aminophenol Hydrochloride; 4-Hydroxyanilinium Chloride

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Function(s) of this ingredient in cosmetic products

HAIR DYEING

Colours the hair

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Occurrence in cosmetics

Oxidation hair colourant (permanent hair dyes)

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Occurrence in other products

Photo developers, medicinal products, colourants (eg fur colourants)

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Background information on use in cosmetics

Cosmetic hair dyes are subdivided according to different operating principles. There are temporary dyes (tints), semi-permanent dyes (semi-permanent hair colours) and permanent dyes (oxidation dyes or bleaches). Temporary dyes are characterised by the use of direct dyes (eg cationic dyes such as Basic Red 56 or Acid Blue 62). There is no chemical reaction with other components; the dyes adhere to the hair surface and last for one to two hair washes. For temporary hair dyes, azo, triphenylmethane or anthraquinone dyes are used. The temporary dyes are sold as aqueous alcoholic solutions. In combination with hairspray, it is also possible to apply very small golden or silver gloss pigments or even fluorescent substances to the hair. Semi-permanent dyes (tints) also use direct dyes (eg nitro dyes such as HC Blue 2 or HC Yellow 10). The hair is coloured circularly, which ensures that it lasts for eight to 10 hair washes. Nitro dyes diffuse because of their low molecular size into the hair but are washable. Other dyes which are used include nitrophenyl diamines, azo and quinonimine dyes in combination with organic solubilizers such as glycol ether or polypropylene. In the event of permanent dyes (oxidative hair dyes), colourless precursors, also referred to as developers and couplers, are first used. The actual dyes are formed through a chemical reaction. The entire hair is dyed and the colour is not washable.

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Information on safe use

Hair colourants are at present amongst the most thoroughly examined cosmetic products on the EU market. Since 2003 the European Commission has pursued a global strategy for the safety assessment of hair colourants and hair dyes in Europe. More than 100 individual hair colourants were considered as safe by the Scientific Committee for Consumer Safety (SCCS) of the EU Commission after a comprehensive assessment and are allowed for use in Annex III of the EC Cosmetics Regulation. https://ec.europa.eu/health/scientific_committees/docs/citizens_hairdyes_en.pdf

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Why are we talking about it?

P-aminophenol is suspected of being corrosive for the skin and of causing allergies (sensitising). The facts: Although p-aminophenol is potentially irritating in excessive concentrations, its use in cosmetic products is regulated and its concentration restricted. Thus, it is used in hair and eyelash colouring products by professionals only, and at concentrations guaranteeing the absence of irritation. However, it is necessary to respect the precautions of use in order to avoid any undesirable effect: it should not be used in the event of a skin rash on the face or in the event of sensitivity, irritation or lesions of the scalp. The allergenic power of p-aminophenol is known. Therefore, here again, precautions should be taken and its use should be avoided in the case of a previous reaction to hair or eyelash colouring. As the use of black henna (temporary tattoos) can increase the risk of allergy, it is recommended to avoid the use of dyes containing p-aminophenol in case of previous reaction to a black henna tattoo. Key points to take away: At the concentrations authorised in cosmetic products, p-aminophenol is considered safe for use by European and American experts. It is recommended to follow the precautions for use, for the safety of both professionals who use it and the consumers.

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Further information

For the clarification of a suspicion of a contact allergy this substance can be routinely tested in the epicutaneous test at the dermatologist. Cross-allergies with other aromatic p-amino compounds and azo dyes are possible.

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Belongs to the following substance groups

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Regulating cosmetics

Cosmetics Ingredients are subject to regulation. Please note, different regulations may apply to cosmetic ingredients outside the EU.