CATEGORY*: Endocrine disruptor
USED IN: Preservatives for food, pharmaceuticals, and cosmetics
THE GIST: Parabens are used to prevent the growth of yeasts, molds, and bacteria in cosmetics products. Parabens appear in some deodorants and antiperspirants, in addition to personal care products that contain significant amounts of water, such as shampoos, conditioners, lotions, and facial and shower cleansers and scrubs. They’re also widely used as preservatives in food and pharmaceutical products. These estrogen mimickers are found in nearly all urine samples from U.S. adults of a variety of ethnic, socioeconomic and geographic backgrounds.
State of the Evidence on Parabens
Parabens are a group of compounds widely used as antimicrobial preservatives in food, pharmaceutical and cosmetics products, including underarm deodorants. Parabens are absorbed through intact skin and from the gastrointestinal tract (Soni, 2005).
Measurable concentrations of six different parabens have been identified in biopsy samples from breast tumors (Darbre, 2004). The particular parabens were found in relative concentrations that closely parallel their use in the synthesis of cosmetic products (Rastogi, 1995). Parabens have also been found in almost all urine samples examined from a demographically diverse sample of U.S. adults through the NHANES study. Adolescents and adult females had higher levels of methylparaben and propylparaben in their urine than did males of similar ages (Calafat, 2010). Higher levels of n-propylparaben were found in the axilla quadrant of the breast (the area nearest the underarm) (Barr, 2011). This is the region in which the highest proportion of breast tumors are found, although paraben concentration in the tissue samples was not related to location of breast tumors in individual women.
Parabens are estrogen mimickers (agonists), with the potency of the response being related to the chemical structure (Darbre, 2008). Parabens can bind to the cellular estrogen receptor (Routledge, 1998). They also increase the expression of many genes that are usually regulated by the natural estrogen estradiol and cause human breast tumor cells (MCF-7 cells) to grow and proliferate in vitro (Byford, 2002; Pugazhendhi, 2007). Nevertheless, parabens as a class do not fully mimic estradiol as regards these changes in cellular gene expression, nor are the effects of all parabens identical (Sadler, 2009).
*For chemicals that have been shown to be carcinogens, we provide classifications from two authoritative bodies: the International Agency for Research on Cancer (IARC, an international body) and the National Toxicology Program (NTP, a division of the U.S. Department of Health and Human Services). We have categorized endocrine-disrupting compounds where the body of peer-reviewed research indicates a strong foundation for doing so.