Parabens are used to prevent the growth of microbes in cosmetic products and can be absorbed through the skin, blood and digestive system (i). They have been found in biopsies from breast tumors (ii) at concentrations similar to those found in consumer products (iii). Parabens are found in nearly all urine samples from U.S. adults of a variety of ethnic, socioeconomic and geographic backgrounds (iv).
Products That May Contain Parabens
Parabens are several distinct chemicals with similar a molecular structure. Four of these occur frequently in cosmetics: ethylparaben, butylparaben, methylparaben and propylparaben. Methylparaben and propylparaben are the most common of these, each appearing in well over 10,000 of the 25,000 products in the Environmental Working Group's Skin Deep database.
Parabens appear mostly in personal care products that contain significant amounts of water, such as shampoos, conditioners, lotions and facial and shower cleansers and scrubs. While concentration limits are recommended for each paraben, these recommendations do not account for the use of multiple parabens in a single product or for exposure to parabens from several products by a single individual.
EWG's Skin Deep database, which compares cosmetic ingredients to over 50 international toxicity databases, indicates that parabens are linked to cancer, endocrine disruption, reproductive toxicity, immunotoxicity, neurotoxicity and skin irritation (v). Since parabens are used to kill bacteria in water-based solutions, they inherently have some toxicity to cells (vi).
A 2004 UK study detected traces of five parabens in the breast cancer tumors of 19 out of 20 women studied (vii). This small study does not prove a causal relationship between parabens and breast cancer, but it is important because it detected the presence of intact parabens – unaltered by the body’s metabolism – which is an indication of the chemicals' ability to penetrate skin and remain in breast tissue.
Of greatest concern is that parabens are known to disrupt hormone function, an effect that is linked to increased risk of breast cancer and reproductive toxicity. Parabens mimic estrogen by binding to estrogen receptors on cells. They also increase the expression of genes usually regulated by estradiol (a form of estrogen); these genes cause human breast tumor cells to grow and multiply in cellular studies (viii).
Cosmetic manufacturers, particularly those in the natural/organic sector, are seeking effective alternatives to prevent microbial growth in personal care products. Another solution is to sell products with a shorter shelf life. Companies are testing new product formulations and have created preservative-free products with a shelf life of six months to one full year. For the products most people use daily – their favorite lotion, face wash or shampoo – products are likely to be used up before they would expire.
i Gray, J (2008). State of the Evidence: The Connection between Breast Cancer and the Environment. San Francisco, CA: The Breast Cancer Fund.
ii Daubre PD, Aljarrah A, Miller WR, Coldham NG, Sauer MJ, Pope GS (2004). Concentrations of parabens in human breast tumours. Journal of Applied Toxicology 24:5-13.
iii Rastogi SC, Schouten A, Dekruijf N, Weijland JW (1995). Contents of methylparaben, ethylparaben, propylparaben, butylparaben and benzylparaben in cosmetic products. Contact Dermatits 32: 28-30.
iv Ye X, Bishop AM, Reidy JA, Needham LL, Calafat AM (2006). Parabens as urinary biomarkers of exposure in humans. Environmental Health Perspectives114: 1843-1846.
v Environmental Working Group. Skin Deep. Parabens. Available online: http://www.cosmeticsdatabase.com/ingredient.php?ingred06=704450&refurl=%2Fproduct.php%3Fprod_id%3D17311%26. Accessed December 9, 2008.
Environmental Working Group. Skin Deep. Methylparaben. Available online: Environmental Working Group. Skin Deep. Parabens. Available online: http://www.cosmeticsdatabase.com/ingredient.php?ingred06=704450&refurl=%2Fproduct.php%3Fprod_id%3D17311%26. Accessed December 9, 2008.
Environmental Working Group. Skin Deep. Butylparaben. Available online: http://www.cosmeticsdatabase.com/ingredient.php?ingred06=700868. Accessed December 9, 2008.
Environmental Working Group. Skin Deep. Propylparaben. Available online: http://www.cosmeticsdatabase.com/ingredient.php?ingred06=705335. Accessed December 9, 2008.
vi Ishiwatari S, Suzuki T, Hitomi T, Yoshino T, Matsukuma S, Tsuji T. (2006). Effects of methyl paraben on skin keratinocytes. Journal of Applied Toxicology 27:1-9.
Handa O, Kokura S, Adachi S, Takagi T, Naito Y, Tanigawa T, Yoshida N, Yoshikawa T. (2006). Methylparaben potentiates UV-induced damage on skin keratinocytes. Toxicology. 227: 62-72.
vii Darbre PD, Aljarrah A, Miller WR, Coldham NG, Sauer MJ, Pope GS (2004). Concentrations of parabens in human breast tumors. Journal of Applied Toxicology 24:5-13.
viiii Byford JR, Shaw LE, Drew MGB, Pope GS, Sauer MJ, Darbre PD (2002). Oestrogenic activity of parabens in MCF7 human breast cancer cells. Journal of Steroid Biochemistry & Molecular Biology 80:49-60.