N-Phenyl-p-Phenylenediamine HCl

What Is It?

N-Phenyl-p-Phenylenediamine and its salts (N-Phenyl-p-Phenylenediamine HCl, N-Phenyl-p-Phenylenediamine Sulfate) appear as needles or crystals in solution. These three ingredients are used in the formulation of permanent hair dyes, colors and tints.

Why Is It Used?

N-Phenyl-p-Phenylenediamine and its hydrochloride and sulfate salts help to impart a color to hair. The exact color obtained will depend on the other ingredients that are used in the preparation and the starting color of the hair.

Scientific Facts

N-Phenyl-p-Phenylenediamine and its hydrochloride and sulfate salts are used in permanent (oxidative) hair dyeing where color is produced inside the hair fiber. The color that is produced results from careful formulation of the product so that the ingredients interact in a highly controlled process.

Safety Information

The safety of N-Phenyl-p-Phenylenediamine and its hydrochloride (HCl) and sulfate salts has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. The CIR Expert Panel evaluated the scientific data and concluded that N-Phenyl-p-Phenylenediamine, N-Phenyl-p-Phenylenediamine HCl, and N-Phenyl-p-Phenylenediamine Sulfate were safe for use in hair dyes at concentrations up to 1.7% (as the free base).

CIR Safety Review:

The CIR Expert Panel evaluated data on N-Phenyl-p-Phenylenediamine and its hydrochloride and sulfate salts. Acute oral toxicity studies showed effects on red blood cells (methemoglobin and Heinz body fromation) at or above 25 mg/kg, a dose much larger than those resulting from the use of hair dyes containing this ingredient. Dose-dependent weight reductions were seen after administration of 2,200 ppm in the diet and above for 90 days. A similar response was seen in another study after administration of 14,700 ppm in the diet. Dermal application of a hair dye formulation containing 2.0% N-Phenyl-p-Phenylenediamine showed no developmental toxicity. No evidence of carcinogenicity was observed in a dietary study N-Phenyl-p-Phenylenediamine. Irritation and sensitization were both observed, but no ocular irritation was seen following exposure to N-Phenyl-p-Phenylenediamine. Clinical data indicated that N-Phenyl-p-Phenylenediamine was a skin irritant and a sensitizer in some individuals. Sensitization reactions were more common among dermatitis patients who work as hairdressers.

More information about the safety of hair dyes

p-Phenylenediamines, its N-substituted derivatives and their salts, and N-substituted derivatives of o-Phenylenediamines are listed in the Cosmetics Directive of the European Union and may be used as oxidizing coloring agents for hair dyeing at a maximum concentration of 6.0% (calculated as free base) in the finished product. Products containing these ingredients must be labeled as indicated in Annex III.

Link to the EU Cosmetic Regulation: http://europa.eu/legislation_summaries/consumers/product_labelling_and_packaging/co0013_en.htm

More Scientific Information

Hair dyeing formulations belong to three categories – temporary, semi-permanent and permanent coloring of hair. The permanent hair dyeing formulations are often referred to as oxidative hair dyes which are generally marketed as two-component products. One component contains the compounds (precursors) that become the colorants and the other component is a stabilized solution of hydrogen peroxide. The two components are mixed immediately prior to use. The precursors and peroxide diffuse into the hair shaft, where color formation takes place after the ingredients combine to produce the coloring mixture. The precursors are oxidized by the hydrogen peroxide to form the colorant molecules. These molecules are too large to escape from the hair structure. The hydrogen peroxide in the oxidative hair dye product also serves as bleaching agent for the natural pigment of the hair. The color that is formed depends on the precursors and direct dyes present in the dyeing solution, pH of the dyeing solution and the time of contact of the dyeing solution with the hair. N-Phenyl-p-Phenylenediamine and its hydrochloride and salts are aromatic amines. These three ingredients function as hair colorants.


The FDA’s factsheet on Hair Dye Products http://www.fda.gov/Cosmetics/ProductandIngredientSafety/ProductInformati…

Search the FDA Code of Federal Regulations http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm

EU Cosmetic Ingredients Inventory http://ec.europa.eu/consumers/cosmetics/cosing/