Cosmetics as Estrogen

More toxic through the skin



Parabens were considered among those preservatives with low systemic toxicity, primarily causing allergic reactions--but that was before science figured out they were also like taking weak estrogen pills. Toxic pills.

Researchers from the Department of Biology & Biochemistry, Brunel University, Uxbridge, Middlesex, have found that alkyl hydroxy benzoate preservatives (namely methyl-, ethyl-, propyl-, and butylparaben) are weakly estrogenic.

In a test tube, scientists conducted an estrogen receptor-binding assay to see if butyl paraben was able to compete with the real female hormone estradiol for binding to rat cells’ estrogen receptors with an affinity approximately 5 orders of magnitude lower than that of diethylstilbestrol (a highly carcinogenic synthetic estrogen), and between 1 and 2 orders of magnitude less than nonylphenol (another estrogenic synthetic industrial chemical).

When administered orally, the parabens were inactive. But putting the butylparaben into the skin and bypassing the digestive process produced a positive estrogenic response on rat uterine tissues. Although approximately 100,000 times less potent than 17 beta-estradiol, greater exposure to the parabens may compensate for their lower potency. Also, the parabens are not healthy estrogens. They are toxic forms of the hormone that stimulate metabolic pathways within the body that can lead to breast besides other cancers and maladies related to estrogen excess.

The researchers conclude that, “Given their use in a wide range of commercially available topical preparations, it is suggested that the safety in use of these chemicals should be reassessed . . .”


Routledge, E.J., et al “Some alkyl hydroxy benzoate preservatives (parabens) are estrogenic.” Toxicol Appl Pharmacol, 1998; 153(1):12-9.

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