Parabens: A Review of Epidemiology, Structure, Allergenicity, and Hormonal Properties

Allison L. Cashman; Erin M. Warshaw


Dermatitis. 2005;16(2):57-66. 

In This Article

Hormonal Activity of Parabens

The estrogenic activity of parabens was first described by Routledge and colleagues in 1998[118] and has subsequently been substantiated by several in vitro and in vivo studies.[118,119,120,121,122,123,124,125] Methyl and ethyl esters have less potent in vitro and in vivo estrogenic activity than either butylparaben or propylparaben.[120,122,123] Parabens have been shown to bind to rodent uterine estrogen receptors[86] and to human estrogen receptors.[123] Because estrogen is a major etiologic factor in the development of human breast tissue and breast cancers, Darbre proposed that parabens and other chemicals that are used in underarm cosmetics may contribute to the increasing incidence of breast cancer.[126] In an uncontrolled study of 20 patients with breast tumors, the mean concentration of parabens was 20.6 ± 4.2 ng per gram of tissue, and methylparaben was present at the highest level.[127]

In addition to studies of estrogenic activity, several studies have evaluated the antispermatogenic potential of parabens. Oishi reported that exposure of postweaning rats and mice to butylparaben or propylparaben (but not methylparaben or ethylparaben) adversely affected the secretion of testosterone and the function of the male reproductive system.[14,128,129] Because these studies indicated a possible relationship between paraben exposure and breast cancer and/or male reproductive function, the Cosmetic Ingredient Review Expert Panel in 2004 announced its intention to reevaluate the safety of parabens.[13]