Parabens are some of the most widely used preservatives in the cosmetic industry. They are listed on cosmetic labels under the names methylparaben, propylparaben and butylparaben. Usually, multiple parabens are used in a formulation, and they may be combined with other preservatives to achieve a broad spectrum preservation system. By using a mixture of parabens, products can be preserved using a lower percentage of preservative and have a longer “shelf-life.” The Cosmetic Ingredient Review (CIR) reviewed the safety of methylparaben, propylparaben, and butylparaben in 1984 and concluded they were safe for use in cosmetic products at levels up to 25%. Typically parabens are used in cosmetics at levels ranging from 0.01 to 0.3%. [1]

Any cosmetic product containing water is susceptible to spoiling by the growth of fungi or bacteria. Spoiling can cause problems such as mold, discoloration, malodor or breakdown of the product and may or may not be visible to the naked eye. Under certain conditions, an inadequately preserved product can become contaminated, thus allowing harmful levels of microorganisms to grow. As cosmetic products are consumed, these microbes come into contact with the skin and product applicators that have come into contact with the skin, thus potentially exposing the user to unknown bacteria and fungi.

Considerable controversy surrounded parabens following a 2004 study by British cancer researcher, Philippa Darbre, Ph.D., in which parabens were found to be present in malignant breast tumors. [2] The study opened the door to controversy and left several questions unanswered. For example, the study did not show parabens themselves cause cancer, or that they are harmful in any way, and the study did not look at possible paraben levels in normal, non-cancerous breast tissue. Additionally, it is questionable whether the finding was indicative that the parabens are what caused the tumor or if parabens just happen to settle in some cancerous tissue. Since correlation does not equal causation, it is irresponsible to presume that parabens and breast cancer are linked until further studies have been performed to test the hypothesis.

Another perceived issue with parabens is that they might be endocrine disruptors due to weak estrogenic activity. Endocrine disruptors are chemicals that can interfere with endocrine (or hormone) systems when present at certain doses. These disruptions can cause cancerous tumors, congenital disabilities, and other developmental disorders. Parabens are estrogenic molecules but exert weaker activity than natural estrogens in the human body. Although parabens have weak estrogen-like properties, estrogens made in the body are many times stronger, meaning that natural estrogens (or those taken as hormone replacement therapy) are much more likely to play a role in breast cancer development. [3]

Additionally, there are a series of naturally occurring parabens as well! Some well-known plants containing naturally occurring parabens are fruits like blueberries, mango, strawberries, and peaches; not to mention other plants like carrots, onions, cocoa beans, and vanilla, to name just a few. The naturally occurring compound, 4-hydroxybenzoic acid, forms the basis of parabens and is the most widely distributed aromatic organic acid in the vegetable kingdom. Essentially, parabens are everywhere. [4] 

Ultimately, it is up to the formulator to determine which preservative is the best fit for each particular product they create. Some formulations have special needs when it comes to preservation, so all options should be assessed so that your formula utilizes the best possible t for your specific needs. Furthermore, it is important to understand that one preservative is not the best fit for every single product you formulate. The raw ingredients comprising your formulation and the desired shelf-life of the product should take precedence over personal opinion when selecting the “best fit” for your product. The FDA requires that products you formulate are safe before you market them to the general public for sale, so it is important that you test your formulations for efficacy regardless of the preservative you choose. Testing should include microbiological testing and stability testing to determine if your preservative is compatible with your formula.

In conclusion, the U.S. FDA has stated that there is no reason for consumers to be concerned about the use of cosmetics containing parabens. The FDA has additionally classified both methyl and propylparaben as GRAS, which means they are “Generally Regarded As Safe” by medical and toxicological experts for use in preserving food. 
 

References:
1. “Safety Assessment of Parabens as Used in Cosmetics”: https://www.cir-safety.org/ sites/default/ les/paraben_web.pdf
2. Darbre, P. D., Aljarrah, A., Miller, W. R., Coldham, N. G., Sauer, M. J. and Pope, G. S. (2004), Concentrations of parabens in human breast tumours. J. Appl. Toxicol., 24: 5–13. doi:10.1002/jat.958
3. Antiperspirants and Breast Cancer Risk. American Cancer Society: https://www. cancer.org/cancer/cancer-causes/ antiperspirants-and-breast-cancer-risk.html
4. Dweck, Anthony. Retrieved 8/31/17, Spotlight on Parabens. https://www.dweckdata.com/ Research_ les/Paraben_compendium.pdf
5. Parabens in Cosmetics. FDA: https://www. fda.gov/cosmetics/productsingredients/ ingredients/ucm128042.htm