By Hannah Sivak, PhD
Biochemist
Skin Actives Scientific LLC

What do parabens do?

Parabens are esters of 4-hydroxybenzoic acid widely used as antimicrobial agents in a large variety of food, pharmaceutical, and cosmetic products because of their excellent antimicrobial activities and low toxicity. They are stable, effective over a wide pH range, and active against a broad spectrum of microorganisms, including bacteria and fungi.

The mechanism of action of the parabens is a matter of discussion, maybe because more than one mechanism exists and the importance of one or another varies with the bacterial species. For example, it has been proposed that parabens act by disrupting membrane transport processes, leading to leakage of vital chemicals from the bacterial cell. Other mechanisms proposed have been the inhibition of synthesis of DNA and RNA or of some key enzymes, like ATPases and phosphotransferases.

It is worth mentioning that preservatives are just part of the equation. It is important to start with a clean product, i.e. to limit the bacterial and fungal presence as much as possible. It has been shown that the concentration of parabens required to inhibit fungal growth depends on the initial concentration of the organisms. In short, if you are planning to make a serum, work clean, disinfect everything you will use with rubbing alcohol (let it air dry, do not blow on the utensils!) and add the preservative at the time of preparation, NOT as an afterthought one week after making the serum.

Myths and realities on parabens

Nobody likes to use preservatives: they don’t help your skin or make you younger. But preservatives prevent the multiplication of bacteria and mold in the skin care product. If it were just a matter of throwing away a half-use product because there is some mold growing in it, I would not bother using them. But it is a lot more than that: even when you start with a perfectly clean product, spores are floating in the air, and nasty bugs, capable of causing very dangerous infections, could grow in the product unless the correct preservative (or mixture of preservatives) is included.

Clients ask me why we at SAS use preservatives in our products. My answer is that preservatives give me the peace of mind I need, because I know that our products will not cause a skin or eye infection

There has been a lot of bad press about parabens, and I feel pressed to come in their defense. Why? Because the arguments against parabens are bogus when the “evidence” is examined. Parabens have some estrogenic activity, but so are thousands of chemicals which we consume daily in our food. What matters is how strong is the estrogenic activity a chemical has. Strength in this case is measured by the concentration of the putative analog required to displace the natural ligand, in this case estrogen. If you need very high concentrations of the estrogen-like chemical to dislodge the estrogen from the receptor, then the activity is very low and unlikely to be of significance in real life. This is what happens with parabens: they have very low affinity for the estrogen receptor.

Parabens have a long record of safety. They are non-allergenic, effective at very low concentrations and they don’t contribute a smell to the finished product. Smell is one of the problems of natural preservatives containing a mixture of extracts from oregano, rosemary and more. The smell can be a overpowering (at least to my nose), plus several of the extracts are allergenic. In the words of Dennis Sasseville “The history of preservatives goes back to the 1930s, and ironically, the parabens, which the industry has sought to replace with "safer" alternatives, are still the most frequently used biocides in cosmetics and appear to be far less sensitizing than most of the newer agents.”

We (people who do like parabens) may eventually lose the "media war" against, as more people are convinced to avoid parabens. In this case, the general public will suffer, because there are no good substitutes for parabens that will work for all products. The result will be new preservatives coming to the market too early, without enough testing, because preservatives are essential to keep skin care products safe. Then, in one or two decades, or even sooner, we may start seeing side effects from unproven preservatives.

References

Ross, Gilbert (2006) A perspective on the safety of cosmetic products: a position paper of the American Council on Science and Health.International Journal of Toxicology, 25: 269-277.

Golden, Robert; Gandy, Jay; Vollmer, G. (2005) A Review of the Endocrine Activity of Parabens and Implications for Potential Risks to Human Health. Critical Reviews in Toxicology, 35: 435-458.

Sasseville, D. (2004) Hypersensitivity to preservatives Dermatologic Therapy 17: 251–263.