Parabens are preservatives that are found in about 90% of all skincare and cosmetics products. Antibacterial and antifungal p-hydroxybenzoic acid esters, the six most commonly used forms of paraben are Methylparaben, Ethylparaben, p-Propylparaben, Isobutylparaben, n-Butylparaben and Benzylparaben. They are commonly used due to their relatively unique property of being effective preservatives and being correlated with a low incidence of contact dermatitis, according to the American Journal of Contact Dermatitis. However, controversy has risen over paraben use in skin care and cosmetics, implicating that parabens may cause cancer, influence estrogen levels, accumulate in tissues, and increase UVB-mediated DNA damage. Despite these findings and consumer alarm, based on current scientific findings, parabens in skin care and cosmetics are safe, although sunscreen use with paraben-containing products may be suggested. Here is what has been established:
Parabens and Breast Cancer
Controversy over parabens began largely in the late 1990′s, due to the suggestions that parabens bind to estrogen receptors in MCF-7 breast cancer cells and rat uteri [after oral administration of parabens]. It was also 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. It was finally suggested that parabens increased breast cancer cell proliferation, and parabens were found in breast tumor samples.
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. Similarly, parabens bound to estrogen receptor sites in rat uteri at far higher concentrations than paraben levels found in skin care products. In the study with fish, parabens were ingested by the fish in doses between 100 and 300 mg/kg, which amounts to about 15000 mg of parabens for the average 74 kg American woman. (To put this in perspective, a normal application of a skin care product [sunscreen] amounts to 1 mg of product per cm2 of skin, the average human body has 14800 cm2 of skin, the average skin care product is about 1% parabens and 20-60% [depending on paraben type] crosses the skin, resulting in about 60 mg of parabens, or roughly 1/24 the amount used in the study).
With regards to the parabens found in breast tumors, it sounds scary, but it is reassuring to know that 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 10-6 M. 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.
Parabens and Long-Term Use
In 2007, a French study reopened speculation 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.
Butylparaben and sperm counts
In a 2002 study, it was found that butylparaben consumption as 1% of the daily diet in the mouse significantly reduced sperm counts, and as little as 0.1% butylparaben in the daily diet somewhat altered sperm counts. However, just 0.1% butylparaben in the daily diet amounts to about 775 mg/day of butylparaben for the average American consuming 775 g of food each day. This is hundreds of times more than the average skin care product application over the entire body*. As such, it is very impractical to assume that sperm counts in humans can be reduced from using skin care products.
*Assuming, as above: a normal application of a skin care product [sunscreen] amounts to 1 mg of product per cm2 of skin, the average human body has 14800 cm2 of skin, the average skin care product is about 1% parabens and 20-60% [depending on paraben type] crosses the skin, resulting in about 60 mg of parabens per full-body skin care product application].
Methylparaben may increase UV-induced damage
In a 2006 study in Toxicology, cultured keratinocytes (human skin cells) subjected to practical levels of methylparaben and cultured in methylparaben-containing solution for 24 hours were more subject to UVB-damage than cells that were not cultured in methylparaben. However, cells cultured in methylparaben and not subjected to UVB damage were unaffected.
From this study, two questions are raised. One, does this apply to skin cells in vivo, or only in culture? Clinical trials with patients should be conducted. (If they are and I see it, I will post.) Two, does this suggest that sunscreens should always be used in conjunction with methylparaben-containing products? One cannot really answer the second question without answering the first. Hopefully, the scientific community will provide the answer soon!
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. I think my favorite quote on avoiding parabens and using paraben-free products comes from OprahMagazine‘s beauty editor, Valerie Monroe: “If you’re the kind of person who triple-locks and checks her doors, you’ll use [paraben-free products].” Yet, based on the current scientific research, there does not seem to be health risks from paraben use in typical skin care products, so I myself am sticking to my tried-and-true favorite beauty products, regardless of paraben content.
I will certainly repost if I read any scientific studies or articles that suggest risks of parabens in the future.