The most common questions about cosmetic ingredients for the past five years have often included parabens.
The word “paraben” is an abbreviation for para-hydroxybenzoic acids. Parabens are a family of esters within para-hydroxybenzoic acids that differ by chemical substitutions on the benzene ring. They are found in about 90% of all skincare and cosmetics products, with the six most commonly used forms of paraben are Methylparaben, Ethylparaben, p-Propylparaben, Isobutylparaben, n-Butylparaben and Benzylparaben.
Parabens are commonly used due to their relatively unique property of being effective preservatives and being correlated with a low incidence of contact dermatitis (American Journal of Contact Dermatitis). Various controversies over the safety of parabens have been raised in previous years. Below, we will discuss what is fact and what is fiction.
Estrogenic activity of Parabens
Controversy about parabens being estrogenic stems primarily from cellular and animal studies. It has been suggested that parabens upregulate estrogenic gene expression in human breast cancer cells,yeast cells, and in vivo in fish. Studies with immature mice and rats showed that subjection to parabens decreased uterine weight, suggesting that parabens could have bound to developing uteri in place of estrogens.
Estrogen has a benzene ring as its first cyclic structure — that is, a six-carbon ring known as an aromatic ring. In order for a chemical to have estrogenic activity, it must bind to the estrogen receptor in a way that will activate the receptor.
But parabens do not seem to be binding to estrogen receptors, despite similarities in chemical structure. Parabens have been found to be 1,000-1,000,000 times less estrogenic than estradiol,a natural form of estrogen found in the body.
Furthermore, the amount of parabens binding to receptors does not seem to pose a health hazard. If parabens are normally at 0.1-0.5% concentration in beauty products, this is about 500 mg in 100 mL of a product. If you apply 2 mL of a product with 0.3% total paraben, this is 6 mg in your skin. And if the average 30% penetrates the skin, you’re getting 2 mg — tens of thousands of times below the observed no-effect level (NOEL) established by scientists, which is 810 mg per kg of body weight!
Parabens and Breast Cancer
There have been suggestions in the literature that parabens bind to estrogen receptors in MCF-7 breast cancer cells and rat uteri. It was also suggested that parabens increased breast cancer cell proliferation, and parabens were found in breast tumor samples. Scary stuff.
However, none of these studies hold practical implications for skin care products. In the breast cancer cell study, MCF-7 human breast cancer cells are subjected to parabens in one million-fold molar excess, thousands of times beyond the amount of parabens a patient is subjected to in a typical skin care product application.
With regards to the parabens found in breast tumors, the facts may be misleading. No studies have shown that parabens are found in higher concentration in breast tumor samples than any other type of human body tissue! Nor has it ever been established that parabens were the cause of the breast tumors. In fact, parabens in practical concentrations have been established since 1984 as non-mutagenic, and no studies to date have ever shown parabens to be harmful below concentrations of 10-6M.
Finally, no studies have ever established that parabens induce cancer in benign cells. For this reason, the U.S. FDA declared in 2005 that parabens in the concentrations found in skin care products and cosmetics (up to 25%, but typically 1%) pose no logical risk to the consumer.
Using parabens long-term is safe
Speculation opened again in 2007 against parabens when it suggested that parabens may accumulate in tissues over time.
In the study, a realistic amount (0.45 mg) of parabens was applied to the skin’s surface every 12 hours for 36 hours. It was found that repeated applications every 12 hours increased quantities of parabens moving across the skin barrier for the first 24 hours.
However, the results also showed that parabens applied to the skin had no cumulative effect 36 hours later, suggesting that parabens do not accumulate in the skin at all after one-and-a-half days!
As such, parabens in skin care products do not accumulate in tissues after 36 hours, and thereby should not pose a risk for the lifetime skin care product user.
Other sources of excellent factual information on parabens:
Based on current research, typical paraben exposure from skin care products does not seem to increase health risks. Based on the current scientific research, there does not seem to be a health risks from paraben use in typical skin care products,but your products may grow harmful bacteria or fungi without them!