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Heated Debate Sparks the Sunscreen Symposium

The Florida Chapter of the Society of Cosmetic Chemists enjoys its day in the sun once again with another successful Sunscreen Symposium.

By Tom Branna
Editorial Director

At times, the debate surrounding proper sun care protection nearly became as heated as the sun itself, but in the end, the 12th Sun Care Symposium sponsored by the Florida Chapter of the Society of Cosmetic Chemists was an unqualified success. More than 350 industry executives gathered in Orlando, FL last month to tackle a host of issues, including broad sunscreen protection, the Final Monograph and the need for more protection than sunscreen alone can provide.

Steven Q. Wang, Memorial Sloan Kettering Cancer Center, Basking Ridge, NJ, delivered a keynote address devoted to consumer behavior toward sun protection. The session was moderated by Chris Vaughan, president of SPF Consulting.

Dr. Wang noted that, thanks to an array of public health programs, consumers have more knowledge about the harmful effects of sun exposure.

“The industry has done a great job getting the word out,” insisted Dr. Wang. “Frequent and long-term use of sunscreen can prevent actinic keratosis and reduce squamous cell carcinoma.”

Lots of Work Still Remains

However, Dr. Wang acknowledged that more work remains. For example, while public health messages urge consumers to first and foremost avoid the sun, followed by seek shade, wear protective clothing and use sunscreen; consumers have turned those recommendations upside down. In fact, their behavior pattern is the reverse of his recommendation.

“Increased knowledge does not translate into increased sun protection behavior,” he observed.

While acknowledging that there is some validity to ever-higher SPF numbers, Dr. Wang warned the audience that when the consumer gets confused he or she may not use any sunscreen at all.

Furthermore, since previous generations of sunscreens didn’t provide UVA protection, melanoma cases are expected to climb for the foreseeable future.

He urged the industry to help change consumer UV protection behavior, which is not always an easy task since there is evidence that consumers can become addicted to sun exposure because it makes them feel good. Dr. Wang called for a sustained public health campaign to convince consumers that a tan is not healthy. But he cautioned that the messages must be tailored to individual consumer groups.

Creating Better Formulas

Unfortunately for the sun care industry, non-governmental organizations (NGOs) have done an excellent job of spreading misinformation based on poor science to the consumer. As a result, there is growing public concern about the safety of nanoparticulate zinc oxide and titanium dioxide.

But Patricia Aikens of BASF provided details of a tape-stripping test that proved the materials do not penetrate the stratum corneum. According to her study, virtually the entire amount of both UV blocks applied was recovered in the first five stripping tapes with minute amounts recovered in subsequent strippings, presumably from skin folds and hair shafts. Moreover, no UV filter was found in the receptor fluid.

Finally, even when sunscreens were applied to compromised skin or even introduced directly into the bloodstream, they did not prove toxic to organs.

But for consumers still concerned about nano materials, Yun Shao of Kobo Products explained how silica or jojoba ester surface treatmentcan force primary particles to aggregate to a size over 100nm. While non-nano TiO2 was found to be too whitening, non-nano ZnO showed an acceptable transparency and attenuation power, according to Dr. Shao.

Avobenzone has been the UVA blocker of choice for years, but apparently there’s room for improvement. Christine Mendrock-Edinger, DSM Nutritional Products, compared UVA requirements in the U.S. and EU. She urged the FDA to increase the use level of avobenzone in formulation from 3% to 5%. Such a move, she insisted, would significantly improve the UVA performance of sun care products.

But as long as avobenzone limits are set at 3%, it is crucial to make sure the amount is fully photostabilized, she told the audience. She suggested that several UV filters can do the job, but octocrylene worked best in her research. In fact, octocrylene as a single stabilizer increases photostability of avobenzone above 90%, she reported.

Emulsion structure also impacts a sunscreen’s efficacy. Her studies found that potassium cetyl phosphate boosts SPF significantly.

While UVA has captured most of the headlines in recent years, William Johncock of Symrise detailed new findings in the causes and prevention of UVB-induced damage. He explained how UVB rays cause a toxic response in the skin via activation of the aryl hydrocarbon receptor (AhR), a protein complex found in cell cytoplasm in all vertebrates.

Symrise’s strategy is to inhibit the UVB-induced AhR activation in the skin via a new compound called 2-Benzylidene-5, 6-dimethoxy-3, 3-dimethyllindan-1-one (BDDI). The material is readily soluble in cosmetic oils at recommended concentration levels of 0.1-0.5%. At these levels, BDDI is a potent inhibitor of UVB-induced expression of CYP1A1, CYP1A2, MMP-1, COX-2 and CAT in vivo.

“BDDI is a highly efficient AhR inhibitor,” he said.

The search for natural solutions has permeated every facet of the personal care category, with varying degrees of success. Hugues Beaulieu of Unipex Innovations, explained how Sambucus nigra flower extract boosted skin moisturization levels by boosting hyaluronic acid secreted by fibroblasts and reducing the level of interleukin-6(IL-6) and TNF-alpha production. The recommended use level is 1-2%, he said.

Another material, Cimifuga racemosa root extract, is said to stimulate melanin synthesis and reduce TNF-alpha production. The result is that it protects and soothes UV-induced skin irritations, gives a longer-lasting tanning effect, moisturizes and reduces desquamation caused by UV exposure and provides a refreshing effect and comforting sensation. Its recommended use level is 1-2%.

Lionel Resnick of Florida Atlantic University reviewed the photoprotective properties of Sulindac, an FDA-approved non-steroidal anti-inflammatory drug. When given orally or topically, the material protected mice against skin damage and genetic changes leading to cell transformation resulting from UVB exposure. Dr. Resnick hypothesized that Sulindac may function uniquely inside cells as an antioxidant. It also absorbs throughout the 280-370nm range and a topical formulation containing Sulindac in novasomes was capable of achieving an SPF 3.

Obtaining the Right Measurements

Joseph Stanfield of Suncare Research Labs explained how in vitro measurements of sunscreen products can be improved. Start by using the right substrate; he recommended a molded HD-6 PMMA plate. The proper spectroradiometric instrumentation should possess sufficient dynamic range, signal-to-noise ratio, spatial response, speed of measurement, wavelength accuracy and rejection of out-of-band radiation.According to his presentation, a UV Dose-Response Model facilitates in vitro SPF measurement, provides an index of photostability and enables computation of the integrated absorbance spectrum, which is the appropriate spectrum for determining the degree of broad-spectrum protection.

While most of the session was devoted to traditional sun care ingredients, the morning’s final speaker, Dr. Karen E. Burke, a New York-based dermatologist, reminded attendees that vitamins C and E have a place in every company’s sun care arsenal. When topically applied, vitamin C has an anti-inflammatory effect, while vitamin E has wound-healing properties. Moreover, in an in vivo study on porcine skin, topical application of the two vitamins protected the pig skin from erythema. Furthermore, topical applications of selenium reduced photodamage in mice. Finally, Dr. Burke urged those in attendance to ramp up their daily dose of vitamins. In fact, she recommends 1000-6000mg of vitamin C a day, whereas the U.S. recommended daily allowance is just 65mg.

“Everybody needs to take supplements,” she insisted.

Going Beyond Sunscreens

The idea that sun care is more than just sunscreens and blocks was echoed by Howard Epstein, EMD Chemicals, in his presentation, “Beyond Suscreens—Benefits for Skin.” Dr. Epstein opened Day II of the Symposium, which was moderated by Mr. Stanfield of Suncare Research Labs.

Using electron spin resonance spectroscopy, Dr. Epstein’s team was able to determine the antioxidative power of potential antioxidant candidates. In another test, EMD evaluated anti-aging candidates by conducting in vitro gene activity expression. Viable candidates were then evaluated using in vivo imaging tools.

Chuck Jones of Dow Chemical explained how the addition of methylcellulose (0.50-5.00% by weight) could boost the SPF of zinc oxide. For example, adding 2% methylcellulose homogeneously disperses the zinc oxide in the formulation, which leads to higher SPF.

Uli Osterwalder of Ciba (now BASF), explained how radical sun protection factor (RSF) correlates well with UVA protection factor and other UVA Indices. He noted that good UVA protection also protects against free radicals.

“Regular, long-term use of antioxidants can contribute to sun protection by replenishing the skin’s antioxidant capacity,” he concluded.

Natural Solutions for Formulators

Formulators searching for a naturally derived water-resistant agent for their sunscreen should consider hydrogenated methyl abietate or hydrogenated glyceryl abietate, which are derived from pine rosin. According to Mike Davies of Essential Ingredients, these abietate derivatives showed better stability over time than VP/eicosene copolymer.

Another naturally derived material, sorbitan olivate, can boost the UV protective properties of sunscreen systems, according to Alain Thibodeau of B&T Company. That’s because sorbitan olivate enhances clinical SPF efficacy, promotes water-resistance, disperses UV-attenuating particles, potentiates the action of other emulsifiers and works through a skin-compatible mechanism. It can even act as a substitute for some silicones, according to Dr. Thibodeau.

Oliver Springer, Evonik Goldschmidt, noted that while C12-15 akyl benzoate is a widely used emollient in sunscreen formulations, shorter C-chain lengths give better UV filter solubility. Specifically, 2-phenoxyethyl caprylate and 2-phenoxyethyl ethylhexanoate impart slightly higher in vitro SPF than traditional benzoate esters, according to Dr. Springer.

The Symposium’s final speaker, Niven Narian of Cytotech Labs, explained how a novel anti-cancer agent, API 31510, inhibits cell proliferation of melanoma and squamous cell carcinoma. The material is currently in phase II clinical trials, according to Dr. Narain.