P-phenylenediamine and colours identified by "C.I." followed by a five digit number
In addition to coal tar dyes, natural and inorganic pigments used in cosmetics are also assigned Colour Index numbers (in the 75000 and 77000 series, respectively).
Use in Cosmetics
Coal tar-derived colours are used extensively in cosmetics, generally identified by a five-digit Colour Index (C.I.) number. The U.S. colour name may also be listed ("FD&C" or "D&C" followed by a colour name and number). P-phenylenediamine is a particular coal tar dye used in many hair dyes. Darker hair dyes tend to contain more phenylenediamine than lighter colours.
Health and Environmental Hazards
Coal tar is a mixture of many chemicals, derived from petroleum, Coal tar is recognized as a human carcinogen and the main concern with individual coal tar colours (whether produced from coal tar or synthetically) is their potential to cause cancer. As well, these colours may be contaminated with low levels of heavy metals and some are combined with aluminum substrate. Aluminum compounds and many heavy metals are toxic to the brain. i Some colours are not approved as food additives, yet they are used in cosmetics that may be ingested, like lipstick. (In the U.S. colour naming system, "FD&C" indicates colours approved by the U.S. Food and Drug Administration for use in foods, drugs, and cosmetics. "D&C" colours are not approved for use in food.)
P-phenylenediamine has been linked to tumours in laboratory tests conducted by the U.S. National Cancer Institute. ii A review of the epidemiologic literature confirmed statistically significant associations between hair dye use and development of several types of cancer although the authors concluded that the evidence was insufficient to determine that the hair dyes had caused the cancers. iii A separate study found that women who used hair dyes — especially over extended periods — had an increased risk of developing non-Hodgkin's lymphoma (cancer of the lymph system). iv However, there is conflicting evidence, with other research suggesting no strong association between cancer and hair dye use. v The International Agency for Research on Cancer therefore concluded that personal use of hair dyes is currently "not classifiable as to its carcinogenicity in humans." vi The European Union classifies p-phenylenediamine as toxic (in contact with skin, by inhalation, or if swallowed), and as very toxic to aquatic organisms, noting that it may cause long-term adverse effects in the aquatic environment. vii
Several coal tar dyes are prohibited on Health Canada's Cosmetic Ingredient Hotlist and Canada's Cosmetic Regulations prohibit all but seven of these colours in eye makeup and other products used in the area of the eye. However, dozens of coal tar-derived colours are still widely used in other cosmetics. Some have been flagged for future assessment under the government's Chemicals Management Plan. viii
P-phenylenediamine is permitted only in hair dyes and must be accompanied by a warning that the product "contains ingredients that may cause skin irritation on certain individuals" and if used near the eyes "may cause blindness."
i Grandjean P and Landrigan PJ. "Developmental neurotoxicity of industrial chemicals." _Lancet _368, 9553 (Dec 16, 2006): 2167-8.
ii G. Reznik and J. M. Ward. "Carcinogenicity of the hair-dye component 2-nitro-p-phenylenediamine: Induction of eosinophilic hepatocellular neoplasms in female B6C3F1 mice." _Food and Cosmetics Toxicology_17, 5 (October 1979): 493-500.
iii Rollison DE, Helzlsouer KJ, and Pinney SM. "Personal hair dye use and cancer: a systematic literature review and evaluation of exposure assessment in studies published since 1992." J Toxicol Environ Health B Crit Rev 9, 5 (Sep-Oct 2006):413-39.
iv Zhang, Y. et al. "Personal use of hair dye and the risk of certain subtypes of non-Hodgkin lymphoma." Am J Epidemiol. 167, 11 (June 1 2008):1321-31.
v Takkouche B, Etminan M, Montes-Martínez A. "Personal use of hair dyes and risk of cancer: a meta-analysis." JAMA 293, 20 (May 25 2005):2516-25.
vi IARC. "para-Aramid Filbrils." Monographs 68 :409-439. http://monographs.iarc.fr/ENG/Monographs/vol68/mono68-13.pdf
vii European Commission. Regulation (EC) 1272/2008 , Annex VI, Table 3.2. Sep 2009. http://ecb.jrc.ec.europa.eu/classification-labelling/
viii Health Canada. Cosmetic Ingredient Hotlist — September 2009. http://www.hc-sc.gc.ca/cps-spc/person/cosmet/info-ind-prof/_hot-list-critique/hotlist-liste-eng.php