Parabens in cosmetics and pharmaceutical medications, role in breast cancer
June 20 2017 by
Ray Sahelian, MD

Parabens are a group of the alkyl esters of p-hydroxybenzoic acid and typically include methylparaben, ethylparaben, propylparaben, butylparaben, isobutylparaben, isopropylparaben, and benzylparaben. Parabens (or their salts) are widely used as preservatives in cosmetics, toiletries, and pharmaceuticals.

Parabens danger, advantage, and side effects
Parabens have a low toxicity profile and a long history of use. Testing of parabens has revealed to varying degrees that individual paraben compounds have weakly estrogenic activity in some in vitro screening tests. Reported in vivo effects include increased uterine weight (i.e., butyl-, isobutyl-, and benzylparaben) and male reproductive-tract effects (i.e., butyl- and propylparaben). However, in relation to estrogen as a control during in vivo studies, the parabens with activity are many orders of magnitude less active than estrogen. However, the risk remains that excessive parabens absorption from cosmetic skin care products could have an influence on breast tissue.

Parabens and Breast Cancer
It appears that parabens have estrogen like activity and hence may influence breast tissue. It remains to be seen whether parabens use increases the risk of breast cancer or perhaps has no practical effect.

Estrogenic activity of p-hydroxybenzoic acid (common metabolite of paraben esters) and methylparaben in human breast cancer cell lines.
J Appl Toxicology. 2005. Pugazhendhi D. Division of Cell and Molecular Biology, School of Animal and Microbial Sciences, University of Reading, Reading, UK.
This paper addresses the question of whether p-hydroxybenzoic acid, the common metabolite of parabens, possesses oestrogenic activity in human breast cancer cell lines. The alkyl esters of p-hydroxybenzoic acid (parabens) are used widely as preservatives in consumer products to which the human population is exposed and have been shown previously to possess oestrogenic activity and to be present in human breast tumour tissue, which is an oestrogen-responsive tissue. Recent work has shown p-hydroxybenzoic acid to give an oestrogenic response in the rodent uterotrophic assay. We report here that p-hydroxybenzoic acid possesses oestrogenic activity in a panel of assays in human breast cancer cell lines. Conclusion: It can be concluded that removal of the ester group from parabens does not abrogate its oestrogenic activity and that p-hydroxybenzoic acid can give estrogenic responses in human breast cancer cells.

J Toxicol Environ Health B Crit Reviews. 2013. Parabens: potential impact of low-affinity estrogen receptor binding chemicals on human health.. Parabens, alkyl esters of p-hydroxybenzoic acid, are widely used in cosmetics, pharmaceuticals, personal care products and as food additives to inhibit microbial growth and extend product shelf life. Consumers of these compounds are frequently exposed via the skin, lips, eyes, oral mucosa, nails, and hair. Parabens are estrogenic molecules but exert weaker activity than natural estrogens, which would imply a low risk. Consistent with this idea, a number of recent commission reports from different countries suggested that parabens pose a negligible endocrine-disrupting risk at the recommended doses. However, individuals are not routinely exposed to a single paraben, and most of the available paraben toxicity data, reviewed in these reports, are from single-exposure studies. Further, assessing the additive and cumulative risk of multiple paraben exposure from daily use of multiple cosmetic and/or personal care products is presently not possible based on current studies.

Cosmetic free parabens are widely available.

Questions
We would appreciate the doctor's opinion of the use of "methyl and propyl parabens" and propylene glycol in products used on the skin, or other personal care products.
   I have not studies parabens in any detail and hence don't have a good understanding of parabens or its various forms.