Attendees weren’t disappointed as keynote speaker, Reynold Tan of the US Food and Drug Administration provided information on the FDA’s request for more information on sunscreen.
“We are sincere about being more transparent,” he told the audience.
Despite some confusion surrounding UV protection, applying sunscreen early and often remains one of the best defenses against sun damage.
Tan urged the audience to supply more data and information regarding SPF 50+ limits and spray forms. He noted that when the monograph was first proposed in 1978, the maximum allowed limit was SPF 15. By 1993, the limit was raised to SPF 30, by 2007 it had jumped to SPF 50. But he warned, however, that there is insufficient data demonstrating that products with SPFs higher than 50 provide additional benefit. According to Tan, the FDA has three concerns regarding high SPFs:
Consumer overestimation of protection;
Increased potential for skin irritation and sensitization; and
SPF 50 already protects against 98% of UV dose that causes sunburn—there is little additional reduction by higher SPFs.
“We know that higher SPFs may have benefits, but people don’t use enough,” he observed.
Regarding issues of dosage, Tan told the audience that oils, creams, lotions, gels, butters, pastes, ointments, sticks and sprays are all eligible for inclusion in the OTC sunscreen monograph. Wipes, towelettes, powders, body washes and shampoos are not eligible. At the same time, FDA is requesting more efficacy and safety data for sprays.
“We encourage you to submit data,” Tan concluded. “We can make a conclusion based on rich data, but we want comments from other people besides the Personal Care Product Council.”
A sunscreen should offer plenty of protection against UV, but if it is aesthetically unpleasant, consumers won’t use it. Chuck Jones of Dow Chemical provided details on how to create consumer acceptable inorganic sunscreens based on zinc oxide and titanium dioxide. More specifically, the goal of his study was to investigate some factors that impact whiteness and then try to maximize SPF while minimizing whiteness.
There are several ways to accomplish that goal, including adding an SPF booster such as styrene/acrylates copolymer; adding a dispersing agent, such as methylcellulose or galactorabinan, to provide a distribution of inorganic and higher SPF and adding an organic stabilizer/emollient such as butyloctyl salicylate.
“The particle size is not the key element in whiteness,” he told the audience. “Titanium dioxide appears to offer more SPF value with minimum whiteness.
Aside from causing a painful burn, UV light also ages skin. Nava Dayan of Lipo Chemicals explained the harmful effects of high-energy visible (HEV) light to skin. She maintained that HEV generates as many free radicals as UVA and UVB combined. That’s because HEV light penetrates more deeply into the skin, going all the way to the bloodstream. In fact, Dayan maintained that HEV interacts with DNA to produce reactive oxygen species.
Dayan’s research partner, Anna Langerveld of Genemarkers LLC, provided details on a study to measure the effects of HEV at the gene expression level.
Roundtable participants included front row (l-r): Dominique Moyal, Reynold Tan, Olga Dueva-Koganov and Nadim Shaath. Back row (l-r): John Staton, Mike Brown and Dennis Lott.
“This is the first study to use gene expression profiling to understand the effects of HEV light on skin,” she explained.
Gene expression technologies include microassays and qPCR (polymerase chain reaction). The former measure up to 45,000 transcripts at a time and are ideal for discovery-based studies, according to Langerveld, who added that microassay results are often confirmed with qPCR. Langerveld told the audience that PCR methods have improved dramatically. Today’s technology is automated, highly reproducible and more sensitive compared to 15-20 years ago.
In addition to new ways to measure the impact of light on skin, there are also new ways to measure sunscreen efficacy. Bernd Herzog of BASF introduced the audience to Radical Status Factor (RSF), which is a derivative of electron spin resonance spectroscopy (ESR). The RSF is derived from ESR data of UV irradiated pigskin samples in the presence and absence of sunscreen. According to Herzog, there is a good correlation of the RSF with the UVA protective properties of sunscreen. Herzog warned, however, that the experimental RSF values appeared to be higher than expected from calculations, yet RSF is a suitable metric for the characterization of the radical status of the skin.
It’s one thing to protect skin from UV radiation. But what about protecting UV-light sensitive active ingredients that are often used in skin care products? Hallstar’s Craig Bonda explained why retinol and retinyl palmitate are sensitive to UV radiation, undergoing rapid isomerization and production of photoproducts. He noted that retinol is oxidatively and thermally stable for up to eight hours under conditions that simulate application to the skin. But adding ethylhexyl methoxycrylene protects these ingredients from degradation, and probably does so by a singlet-quenching mechanism.
“Keep your skin care actives fully active and doing their jobs by photostabilizing them,” he told the audience.
Consumers prefer sprayable sunscreen formulas because they are easy to apply—especially on squirming children. Olga Dueva-Koganov of AkzoNobel explained how the addition of a water-resistant polymer, acrylates/octylacrylamide copolymer to a sunscreen spray provides a physical protective barrier that reduces TEWL and retains the stratum corneum’s water content.
Dueva-Koganov’s research suggests that optimization of multifunctional sunscreen sprays is possible by using contact angle measurement as a means to predict TEWL and provide comprehensive comparison of benchmarks that have been recently launched in the US.
A lively roundtable debate, moderated by Dennis Lott of Florida Suncare Testing, closed the first day of the Sunscreen Symposium. Participants included first-day presenters such as Tan and Dueva-Koganov, as well as Dominique Moyal, L’Oréal; Happi columnist Nadim Shaath, Alpha R&D; and Joe Stanfield, Suncare Research Laboratories. The panelists weighed in on a variety of topics. Moyal, for example, suggested that the FDA’s critical wavelength parameter of 370nm might not provide sufficient broad-spectrum UV protection. Rather, she suggested that UVAPF/SPF balance is a more important consideration.
To the question, “Should there be an upper limit to the total percentage of actives allowed in a formula?,” Shaath asked: “Should the percentage of actives allowed be limited?” He noted that a typical SPF100 formula is 30-40% active, but that a formula can contain as much as 75% active ingredients. The panelists were in agreement that because the maximum amount of active ingredients in a formula is 39%, the industry is regulating itself.
Another question—“Should SPFs be capped at 50?”—brought strong reaction from panelists. Tan wondered if higher SPF products can be tested accurately and reproducibly, and if they actually provide any additional benefits to the consumer, citing issues such as irritation and vitamin D production. He also suggested that these higher SPF products might give consumers a false sense of security when it comes to excessive UV exposure.
But Lott, like many in the audience, insisted that higher SPF products do provide valuable added protection and should not be capped—and certainly not at 50.
Regarding sunscreen sprays, FDA is requesting additional data. Tan asked if there are better test procedures available and if SPF values for sprays are comparable to SPF values for lotions. But Dueva-Koganov said she conducted a small in-vivo study that found sprays actually provided more coverage to skin than lotion—2.66mg/cm2 for sprays versus .74mg/cm2 for lotion.
Although actions by the US FDA have been in the news of late, it is not the only governing body impacting sunscreens and UV protection. Jennifer Martin Rempe of Energizer provided an overview of ingredients used in the US, European Union, Canada, Australia and elsewhere. The goal, she explained, is to eliminate the current “patchwork quilt” of regulations. That could be difficult, especially now that the Andean countries are getting set to issue their own regulations.
But the US has fewer approved UVA filters than other countries and there is little reason to expect the situation to improve in the near future, according to Martin Rempe. She noted that there are only 16 approved UV filters in the US (and only a few are actually in use). In contrast, Australia has 26, the EU, 27; and Japan, 31. Still, she acknowledged that the FDA’s Final Rule regarding testing and labeling “shows some creativity” on the part of the agency.
Martin Rempe predicted that in the future, UVA will have increasing importance with consumers and have equal weight in formulation if not labeling.
“In a few years, there may be increased tolerance for skin aging claims,” she added.
With so many novel active ingredients still bogged down in the TEA (time and extent application) process, Martin Rempe suggested that the Monograph should never be finalized. Instead, the US should follow the European system, which gets refined as the science changes.
“That doesn’t happen so easily in the US,” she concluded. “We need to be able to refine the system every five years.”
More on Ingredients
While filters and blocks are the primary defenses against UV radiation, Stefan Baenziger of Rahn Cosmetics said that adding cosmetic actives to formulations can reduce detrimental secondary damage, provide a second line of defense and offer new claims, including protection against free radicals, as well as cell, DNA and stem cell protection, and age spot reduction.
Symposium attendees had the opportunity to visit with dozens of industry suppliers in the exhibition hall.
To prevent radical oxidative stress, Rahn has created a material from rosmarinic acid, rutin and barley extract that counteracts oxidative stress and prevents cell damage. To protect cells and DNA, Rahn markets a material that combines ethylferulate to neutralize oxygen radicals, carnosolic acid to combat free radicals and uridine monophosphate, which supports DNA repair. To protect stem cells, the company developed a material with the INCI name: Helianthus annuus (sunflower) seed oil, ethyl ferulate, polyglyceryl-5 trioleate, rosmarinus officinalis (rosemary) leaf extract, water, disodium uridine phosphate. To reduce age spots, Rahn offers a material that combines stabilized vitamin C with zinc PCA and oleuropein.
Finally, Rahn has created a sun protection concept that provides five-fold protection for skin (UV protection, stem cell and DNA protection, dryout protection and protection from light-induced skin aging), by combining UV filters and cosmetic actives along with oils, glycerin or aloe vera gel for hydration.
Merck’s Thomas Rudolph provided new insights into the photochemistry of avobenzone, noting that molecular modeling helps chemists better understand photochemical processes. Rudolph reminded the audience that UV filters, whether photostable or not, can be photoreactive. Finally, he noted that complete photostability is achievable with triplet quenchers, specific antioxidants and regenerators.
In light of the recent actions by FDA, John Staton of Dermatest took a closer look at zinc oxide to see if it could stand on its own as an active ingredient in formulation. He concluded that the new in-vitro UVA broad-spectrum test is valid for zinc oxide. However, in thin film, zinc oxide is subject to both physical and chemical changes. Finally, it is possible to modify the behavior of the active in order to improve performance.
“Don’t abandon zinc oxide. It is still a very efficacious active ingredient,” he concluded. “But we’ve shown that there are changes taking place in this inert ingredient.”
Robert Coots of Colonial Chemical explained how the benefits of replacing ethoxylated emulsifiers with sorbitan oleate decylglucoside crosspolymers. The materials are safe, green and naturally derived, have low irritation and can be easily formulated into a wide array of cosmetic products. According to Coots, eliminating ethoxylated emulsifiers will appeal to consumers who want to minimize possible contact with suspected carcinogens.
Erica Babson of Active Concepts detailed the use of enzymes to modulate repair and augment sunscreen formulas for added protection. For example, T4 Endonuclease is an enzyme that induces single-stranded breaks in UV-irradiated DNA. Histone deacetylases are enzymes that remove acetyl groups from certain histone amino acids. DNA is wrapped around histones and deacetylases help control DNA expression, according to Babson, who told the audience that new DNA repair treatment sunscreens that contain enzymes reduce DNA damage by 45% and increase UV protection by 300%.
“Enzymes in sunscreens not only repair, but also prevent damage,” she concluded.
The Symposium’s final speaker, Jürgen Vollhardt of DSM, reviewed the critical factors that significantly affect high performance sunscreens. These factors include the proper level of UVA filters with good coverage of the spectral region, stabilization of avobenzone, film quality on the skin, and the addition of a UVB block such as titanium dioxide to the formula.