While educating consumers about the ingredients in the products they put on their skin is generally a good thing, it is not a perfect situation. Some of the non-profit groups behind websites like these advocate for the use of natural ingredients; therefore, they have a tendency to advise against the use of any product that utilizes chemicals. Many researchers and skin care chemists have criticized these and other groups for over-exaggerating the findings of limited studies and creating consumer concern, all in an attempt to change public policy. Furthermore, many argue that these organizations do not do a good job of presenting alternative scientific points of view regarding certain ingredients, which leads to misinformation. Adding to the potential for confusion is the fact that some natural skin care manufacturers have joined the fray to do their own version of educating, which often blurs the lines of marketing and may actually be a tool to dissuade consumers from buying competing brands.
Despite the plethora of information available to them and any criticism regarding that data, consumers must ultimately determine for themselves which ingredients they are willing to accept in their skin care products and which to avoid. As many aestheticians, dermatologists, and plastic surgeons have experienced, clients will often seek your counsel regarding ingredients about which they have potential concerns. For that reason, it is vital that licensed skin care experts have an understanding of all sides of the dispute surrounding “hot button” ingredients. What is more, it is recommended that, as professionals, we become familiar with the research most often referenced by both the for and against camps. Following is a list of just a few of those ingredients currently in the spotlight, along with the main charge, or charges, against them.

Alcohol
Alcohol can be found in skin care products in a variety of forms, including ethanol, cetyl alcohol, cetearyl alcohol, stearyl alcohol and more. While many consumers are led to believe that any form of alcohol is bad for their skin, that assertion is not exactly true, as all alcohols are not created equal. The category can be divided into two groups: denatured alcohol, like ethanol, which can cause redness and inflammation, and fatty alcohols, which are actually beneficial to the skin, especially for those who suffer from dry skin.
Denatured alcohol is typically found in skin toners and is used to dissolve oil while temporarily tightening pores and leaving skin with a refreshed feeling. It is also used to help increase the penetration of other ingredients in the formulation and to reduce the weight of a product on the skin. Most experts agree that ethanol should be avoided in skin care products due to its potential to degrade the skin’s protective lipid barrier. In fact, one study found that ethanol causes apoptosis in skin cells (cell death).1
Fatty alcohols, on the other hand, are considered by most experts to be gentle skin care ingredients. Derived from natural fats and oils, they are typically used as emollients and humectants in moisturizers to keep the skin soft and smooth.

Chemical Sunscreens
Suncreen formulations fall into two categories. The first is sunblock, which includes minerals like zinc and titanium dioxide that sit on the skin’s surface and physically reflects or scatter ultraviolet light. The second is chemical sunscreens, such as oxybenzone, avobenzone and octinoxate, which absorb ultraviolet light and turn it into energy. Within a single sunscreen formulation, a combination of sunscreens and sunblocks may be utilized.

"It is vital that licensed skin care experts have an understanding of all sides of the dispute surrounding
“hot button” ingredients."

Within the past 10 years, sunscreens have come under fire for various reasons. Studies have hinted that some act as hormone disrupters and may increase proliferation of breast cancer cells.2 Others presented the idea that chemical sunscreens can react with the sun and cause the development of free radicals3 that could potentially lead to skin cancer. Despite this, “acute toxicity has not been reported in any of the in vivo or human studies published to date,” according to a recent research review.4
Many researchers claim that negative claims related to sunscreens are generalizations based on incomplete research or laboratory conditions that do not mimic actual usage. While most agree that sunscreens are safe for daily use, those with concerns could look to sunblock formulations instead. Given the advances in nanotechnology, zinc and titanium oxide formulations are no longer as heavy or impart the same white glow to the skin. But that opens up the controversial topic of nanotechnology (see below).

Fragrance
Because product aesthetics are vital to continued consumer usage, skin care chemists spend a great deal of time ensuring that their formulations feel silky and lightweight and have a pleasant smell. Fragrance is added to products not only to delight the senses, but, in some cases, to mask the unpleasant odor that accompanies the use of cer-
tain ingredients.
The problem is that many fragrances – whether natural or synthetic – are irritating to the skin. In fact, according to the American Academy of Dermatology, fragrances are considered the leading cause of cosmetic contact dermatitis, with studies suggesting that sensitivity is on the rise.
Another knock against the use of “fragrance” in skin care products is that the U.S. Food and Drug Administration does not require manufacturers to disclose the actual chemicals that comprise “fragrance” or “parfum.” Therefore, companies can use any number of chemicals to create a fragrance, yet only have to list it once on the ingredient list. Additionally, product manufacturers may use this fragrance formulation to hide the presence of preservatives and other ingredients they do not want to disclose.

Nanoparticles
For cosmetic and skin care chemists working to develop products that are increasingly weightless, deliver invisible coverage or feature improved delivery systems, nanotechnology is the new frontier.
Nanoparticles are so small that they cannot be seen with a regular microscope. The concern is that this miniscule size allows them to penetrate the skin. Indeed, some studies have shown that they can do so.5 That is great if you are working to develop effective anti-aging formulations, but may be negative when we consider that there could be unintended systemic effects of their use.
Currently, the industry regards nanoparticles as safe for use in cosmetic and skin care products. What is more, the FDA does not require manufacturers to outline the use of nanoparticles on product labels. The organization did, however, in 2012, issue a draft guidance encouraging cosmetic manufacturers to subject products containing nanoparticles to additional testing.

Parabens
Despite a decades-long stable history of usage as a preservative in a wide range of personal care products, parabens came under attack in 2004 when a study was published demonstrating that paraben-like substances were found in breast cancer tissue.6 While the study showed no causation of breast cancer by parabens, it was enough to lead many consumer interest groups to demand that these preservatives be removed from personal care products. Since then,
follow-up studies have been conducted, some of which have demonstrated that parabens may act as endocrine disrupters.7 Despite this, a 2008 comprehensive review by the Cosmetic Ingredient Review (CIR) reiterated parabens’ safety. Additionally, the FDA, the National Cancer Institute, and the American Cancer Society, among others, have released statements denying proof of a linkage between parabens and breast cancer. While parabens remain in countless products today, many brands have removed them from their products because of consumer demand.

Sulfates
Sulfates, such as sodium lauryl sulfate and sodium laureth sulfate, are surfactants found in shampoo, body washes, toothpastes, and, of course, skin care products. These ingredients are used in formulations to break down oils and create lather. The problem with sulfates is that they have long been recognized as skin irritants. What is more, they have been shown to disrupt the skin’s lipid barrier,8 which not only can lead to dry skin, but the potential for skin to absorb more than it should, including some potentially harmful ingredients.

Urea
Urea, including hydroxyethyl urea, diazolidinyl urea, imidazolidinyl urea and dmdm hydantoin, is a skin care ingredient that, depending on how you look at it, may get an unfair bad rap. When used in lower concentrations (10 percent), it is an excellent humectant and keratolytic agent. When used in higher concentrations (20 to 30 percent), it is a preservative that can cause irritation and inflammation.
First, an overview of what urea is and is not. Along with lactic acid and free amino acids, urea is one of the three natural moisturizing factors in the stratum corneum. As such, it helps to keep skin soft and pliable by attracting and holding water. The urea added to skin care products and cosmetics is synthetic and created via a combination of ammonia and carbon dioxide. In double-blind studies, moisturizers that contain urea have been shown to reduce transepidermal water loss in those with dry, flaking skin. It also makes normal and atopic skin less susceptible to irritation from sodium lauryl sulfate.9
In addition to its risk of irritation, urea has come under attack because it is a formaldehyde-releasing ingredient. However, the amount of formaldehyde released by urea in skin care products is negligible, which is why the FDA and CIR continue to deem it safe for use in cosmetics.

Of course, this list presents just a snapshot of the skin care ingredients that have raised concern among advocacy groups and consumers. Also, keep in mind that the spotlight regularly moves to different ingredients. Thus, it is important to stay on top of the latest research and controversies surrounding the ingredients used in the products you carry. As you may have experienced, clients will ask you to explain why you carry certain lines if they include controversial ingredients. While this has led many licensed professionals to discard one line in favor of another, the reality is that every line has or will most likely, at some point, include a divisive ingredient or two. Instead, it is wise to do your homework, read clinical research papers, and be prepared to present clients with an unbiased presentation of all sides of the facts. This not only reinforces your status as a trusted and educated skin care advisor, but also allows your clientele to make their own decisions about the products they are – and are not – willing to use.

References
1 Neuman MG, Haber JA, Maliewicz IM, et al. Ethanol signals for apoptosis in cultured skin cells. Alcohol Journal. Apr 2002; 26(3):179-90.
2 Schlumpf M, Cotton B, Conscience M, et al. In vitro and in vivo estrogenicity of UV screens. Environmental Health Perspectives. Mar 2001; 109(3):239-44.
3 Hanson KM, Gratton E, Bardeen CJ. Sunscreen enhancement of UV-induced reactive oxygen species in the skin. Free Radical Biology & Medicine. 2006; 41(8):1205-12.
4 Burnett ME, Wang SQ. Current sunscreen controversies: a critical review. Photodermatology, Photoimmunology and Photomedicine. 2011; 27(2):58-67.
5 Zheng D, Giljohann DA, Chen DL, et al. Topical delivery of siRNA-based spherical nucleic acid nanoparticle conjugates for gene regulation. PNAS 2012; published ahead of print July 6, 2012.
6 Darbre, PD, A Aljarrah, WR Miller, NG Coldham, MJ Sauer and GS Pope. Concentrations of parabens in human breast tumors. Journal of Applied Toxicology, 2004;24:5-13
7 Byford JR, Shaw LE, Drew MGB et al. Oestrogenic activity of parabens in MCF7 human breast cancer cells. Journal of Steroid Biochemistry and Molecular Biology, 2002;80(1)49-60.
8 DaSilva SC, Sahu RP, Konger RL, et al. Increased skin barrier disruption by sodium lauryl sulfate in mice expressing a constitutively active STAT6 in T cells. Archives of Dermatological Research, Jan 2012, 304(1):65-71.
9 Loden M, Role of topical emollients and moisturizers in the treatment of dry skin barrier disorders. American Journal of Clinical Dermatology. 2003;4(11):
771-88.

Dr. Ahmed Abdullah is author of the book Simple Skincare, Beautiful Skin: A Back-to-Basics Approach, founder of Lexli International, Inc., and formulator of the company’s Lexli® line of professional skin care products. A board-certified plastic/reconstructive surgeon and a leading aloe researcher, Abdullah is a recognized expert on the restorative and medicinal effects of aloe vera. He is a pioneer in the use of pharmaceutical-grade aloe in surgical applications to expedite healing, a practice that is growing in popularity. Through his work with patients and the Lexli line, Abdullah has proven that many common skin concerns can be avoided by optimizing skin health.