Features

Comparative Evaluation of Commercial SPF 100+ Sunscreen Products

By Olga V. Dueva-Koganov, Ph.D. and Nadim A. Shaath, Ph.D. , Integrated Botanical Technologies, LLC, Ossining, N.Y. Alpha Research and Development, White Plains, NY | November 23, 2010

More than three years ago, the FDA introduced a proposed rule that includes testing of sunscreen efficacy in vivo (SPF and UVA-PF) and in vitro (UVAI/UV ratio after pre-irradiation).1 The FDA requires U.S. sunscreen manufacturers to declare, in addition to SPF, the level of UVA protection provided by sunscreen product, based on the lowest result obtained using in vivo and in vitro UVA testing.

The FDA’s vision is to ensure and reward balanced and photostable UVA/UVB protection; according to the agency, both UVB and UVA radiation protection are equally important and more protection against UVA radiation damage is beneficial for consumers’ health. Others, however, have questioned the use of high SPF products.2

FDA also indicates its position regarding sunscreens with high SPF values. Data submitted to FDA show that the SPF test is accurate and reproducible for sunscreens with SPF up to 50. Thus, the agency proposes to allow labeled SPF values up to 50+ for the following reasons: to satisfy consumers who desire or need high levels of UV protection; help to compensate for inadequate application and/or re-application; provide additional sunburn protection during intense UV radiation conditions; help reduce cumulative UV radiation exposure; and generally provide consumers with incremental increases in sunburn protection.
 

FDA recognizes that future data may demonstrate that test variability may not be a problem for sunscreen products over SPF 50. It states that it will consider specific SPF values greater than 50 upon receipt of data demonstrating that accurate and reproducible results can be obtained from the SPF test for sunscreen products with SPF values over 50. According to FDA, allowing manufacturers to label sunscreens as “SPF 50+” may encourage further research into skin photobiology and the development of effective and safe sunscreen drug products with specific SPF values over 50.

Apparently, major U.S. sunscreen manufacturers followed this FDA encouragement by developing numerous commercial sunscreen products with SPF label values ranging from 100 to 110, which numerically are at least two times higher than the proposed limit of SPF 50+; all these products were introduced to the market in 2010 with description “new” on the packages.

From the technical point of view, the development of sunscreen products with 100+ SPF values using sunscreen actives selected from the current FDA approved list is a challenging task that requires creativity and utilization of optimized delivery systems in conjunction with:
• Photostabilizing technologies and ingredients, for example Helioplex,3 Avo- triplex,4 triplet combination of avobenzone, octocrylene and oxybenzone,5 and the use of sufficient levels of octocrylene to photostabilize avobenzone, etc.;
• SPF boosting technologies and ingredients, diethylhexyl syringylidenemalo- nate,6 styrene/acrylates copolymer microspheres,7 Triplet-Triplet and Singlet-Singlet quenchers8 and UV attenuating emollient butyloctyl salicylate;and
• Utilization of effective film-forming polymers, antioxidants, plant-derived ingredients and additional particulates (silica, modified silica) that help to improve overall product efficacy, sensorial profile and generate additional skin benefits.


Absorbance Spectra of Commercial SPF 100+ sunscreen products after pre-Irradiation
Currently, the FDA is still finalizing new regulations. In the event the FDA rules in the near future and confirms the allowed limit of SPF 50+, manufacturers will have substantial time to comply with new regulations. In the meantime, commercial SPF 100+ products will continue to be marketed. If the FDA abandons the proposed SPF 50+ limit, this will likely lead to the continuation of the development of SPF 100+ sunscreens, or so-called sunscreen race. In any scenario, the comparative evaluation of SPF 100+ commercial products using relevant in vitro test methods will help sunscreen consumers to better differentiate these products and provide formulators with useful information and data regarding commercial benchmarks.

Materials and Methods
Eight commercially available sunscreen products with label SPF waterproof (very water resistant) values ranging from SPF 100 to 110 are shown in the photo below. These products were evaluated in vitro according to the FDA proposed rule using Vitro Skin (N-19)9 as alternative substrate instead of roughened quartz plates, which FDA proposed for the in vitro portion of its UVA test method while requesting comments regarding the suitability of other possible substrates. The suitability of Vitro Skin (N-19) as an alternative substrate for evaluation of UVAI/UV ratio was demonstrated by Dueva-Koganov et al.10


Commercially available SPF 100+ sunscreen products
The required pre-irradiation step used a Solar Simulator 16S-300-002 with full spectrum sunlight (Air Mass 1.5) in conjunction with XPS 400—a precision current source, PMA2100 Radiometer with PMA2101 Detector (all from SolarLight Company, PA)11 and Peltier-cooled surface provided by SC25 Orbital Mixing Chilling / Heating Plate from Torrey Pines Scientific.12

The diffuse transmittance/absorbance measurements were conducted on the transmittance analyzer with integrated sphereLabsphere UV 2000S with Version 1.2 software to measure FDA proposed UVAI/ UV ratio.13 Pre-irradiation dose for each test product was calculated based on its actual SPF label value according to the formula: SPF 1 MED 2/3, where 1 MED = 200 J/m2-erythemally effective dose. Absorbance spectra of all test articles were within the dynamic range for Labsphere UV 2000S.13

Measurements of the contact angle of water to quantify the effects of test products on the surface properties of a skin-substitute substrate Vitro Skin (N-19) were conducted according to the test methodology described in a paper by Dueva-Koganov et al.14 where it was demonstrated that products producing relatively low contact angles tend to make more “light” and “non-greasy” sensory claims, while products that produce relatively high contact angles make more claims related to long-term moisturization. Contact angles were measured according to sessile drop method using Krüss EasyDrop analysis system with attached computer running Krüss DSA1 software for device control, image acquisition and analysis of drop shape images.15 In addition, it was previously shown that water resistant properties of sunscreen products correlate with the respective water contact angles (wettability) after their application in vitro on Vitro Skin (N-19)16 and in vivo on human skin—according to Hagens et al.17

In preparing the substrate and applying the product, Vitro Skin (N-19), Lot#0231 was pre-cut and pre-hydrated as described. The application dose of the test product in all in vitro tests was 2mg/sq. cm—similar to the application density used in the in vivo tests.

Results/Discussion
Detailed description of the test products, their UVAI/UV ratios, measured contact angles and absorbance spectra after pre-irradiation are presented in the graph above and the table on p. 52.Seven test products A, B, C, D, E, F and G contain identical composition of five sunscreen actives: avobenzone, 3.0%; homosalate, 15.0%; octisalate, 5.0%; octocrylene, 10.0%; and oxybenzone, 6.0%. Products A, B, C, D and F utilize Helioplex photostabilizing patented technology3 in conjunction with maximum allowed concentration of UVB sunscreen active octocrylene to further photostabilize avobenzone. Product G employs diethylhexyl syringylidenemalonate, a photostabilizer and SPF booster6 and maximum allowed concentration of octocrylene to further stabilize avobenzone.

Products A, B, C, D, E and G are oil-in-water emulsions; all contain styrene/acrylates copolymer microspheres, an effective SPF booster that also imparts smooth skin feel,7 additional particulates and polymers that contribute to product’s efficacy and performance. Products A and B both contain plant-derived natural ingredients glycine soja (soybean) seed extract, dipotassium glycyrrhizate and chrysanthemum parthenium (feverfew) leaf/flower/stem juice. Product E contains similar ingredients as product C, but listed in different order, with additional tocopheryl acetate, butylene glycol, ascorbyl palmitate and glycine soja (soybean) protein. Product H contains only three sunscreen actives: avobenzone, 2.5%; octocrylene, 8.0%; and oxybenzone 3.5%. These concentrations are lower than those in the other seven test products; it is a water in oil system and utilizes at least two patented photostabilizing/SPF boosting technologies, AvoTriplex4 and a triplet combination of avobenzone, octocrylene and oxybenzone5 together with particulates, polymers and emollients (including UV-attenuating butyloctyl salicylate), which likely contribute to the product’s high efficacy.

Experimental data show that UVAI/UV ratios of SPF 100+ sunscreen products launched in the U.S. in 2010 are in the narrow range of 0.8-0.85; all are photostable and belong to the proposed “High UVA Protection” category (three stars) while failing to fulfill the “Highest UVA Protection” criterion (four stars). Product H has highest UVAI/UV Ratio of 0.85 and product C the lowest at 0.80.

Products A and B generated similar contact angles of about 40 degrees, suggesting that their sensory properties are similar; products C, D and E are in the range of 52-57 degrees, indicating their possible sensorial similarities as well. Products A, B, C, D and E have combinations of “light” and/or “lightweight and/or non-greasy” claims, which are consistent with correlations, established earlier.14 Product G related contact angle value of 62.9 degrees predicts its good moisturizing potential14 that is actually confirmed by moisturization claim on its label. Product H generates contact angle value of 33.9 degrees; this is the lowest value ever found among more than 50 products evaluated so far under these test conditions14,16 and may indicate good sensory properties of this product, which currently does not have any relevant claims on the package. It was previously found that the majority of lotions with “non-greasy” and/or “lightweight” claims contain a certain particulate(s) or their combination: aluminum starch octenylsuccinate, silica, etc.;14 these findings are in agreement with current data—where seven SPF 100+ products that produce relatively low water contact angles contain spherical micro particles7 and other particulates, which are simultaneously contributing to achieving SPF 100+ and beneficial sensory profiles of these products. Test product F is an alcohol containing spray that generates a contact angle of 81.1 degrees; however, this is not a prohibitive value from having “non-greasy” and “lightweight” sensorial properties claimed for this product; it may also suggest its long term moisturization potential.14 Manufacturers also describe additional skin benefits for certain SPF 100+ products: their ability to counter skin damage on cellular level, prevent deep oxidative damage, prevent the appearance of discoloration and fine lines, protect collagen and elastin from breaking down (A and B); shields skin six layers deep from skin-aging UVA rays, combats free radicals that accelerate signs of aging (C); helps shield skin from environmental damage (E); moisturizing (H).

Table: Commercially available SPF 100+ products, their UVAI/UV ratios after pre-irradiation and contact angles of water on Vitro Skin (N-19) after product application.

Conclusions
Comparative evaluation of eight SPF 100+ commercial products launched in the U.S. in 2010 using in vitro test methods was conducted; study demonstrated that their photostability, UVAI/UV ratios in the range of 0.80-0.85 and good sensorial attributes can be considered beneficial to the consumer. However, all these products belong to the FDA proposed “High UVA Protection” category (three stars) while failing to fulfill the “Highest UVA Protection” criterion (four stars). Reaching the highest UVAI/UV ratio (four star) for sunscreens with SPF 100+ cannot be achieved with the use of sunscreen actives currently approved in the U.S. Measurements of the contact angle of water to quantify the surface modifying effects of test products on a skin-substitute substrate suggested similarities in sensorial profiles for certain SPF 100+ products. This study helps sunscreen consumers to better differentiate SPF 100+ commercial products while providing formulators with a useful testing approach to conduct in vitro benchmarking studies and optimize development of effective sunscreen products with good sensorial profile, moisturizing and other benefits.

Acknowledgement
We are grateful for the support of Steven G. Micceri and Art Duev of Integrated Botanical Technologies, LLC, Ossining, N.Y.
References:
1. Federal Register, 21 CFR Parts 347 and 352 Sunscreen Drug Products for Over-
The-Counter Human Use;Proposed Amendment of Final Monograph; Proposed Rule, 72(165), 49070-49122, §352.71, (2007)
2. Steven Q. Wang, The Sunscreen Race, HAPPI, 47 (1), 38-40 (January 2010)
3. US 6,444,195Coleet al. Sunscreen compositions containing a dibenzoylmethane derivative
4. US 7,014,842Dueva-Koganov et al. Sunscreen composition
5. US 7,285,262Lott.Natural sunlight photostable composition
6. Chaudhuri RK et al. Design of a photostabilizer having built-in antioxidant functionality and its utility in obtaining broad-spectrum sunscreen formulation. Photochem Photobiol 82 (3) 823–828 (May 2006)
7. http://www.dow.com/products/product_line_detail.page?product-line=1000072
8. Bonda et al. Singlet quenching proves faster is better for photostability. Cosmetics & Toiletries, February 2010, Vol. 125, No. 2, pp. 40-49
9.www.ims-usa.com/ittrium/ visit ?path = A1x66x1y xa0x1x65y1xc6x1x65y1xccx1x65
10. Dueva-Koganov et al. Addressing Technical Challenges Associated with FDA Proposed Rules for UVA In Vitro Testing Procedure. J. Cosmet. Sci., 60, 587-598 (2009)
11. www.solarlight.com/
12. www.torreypinesscientific.com/
13. www.labsphere.com/data/userFiles /UV2000s% 20Product%20Sheet.pdf
14. Dueva-Koganov et al. Correlating Water Contact Angles and Moisturization/Sensory Claims. Cosmetics & Toiletries, January 2007, Vol. 122, No. 1, pp. 20-27
15. www.kruss.de/en/products/contact-angle/easydrop.html
16. Dueva-Koganovet al. Importance of Polymers in the Development of Effective Water Resistant Sunscreens, In-Cosmetics, Munich, April 22, 2009
www.in-cosmetics.com/files/16.30_22 _April__Ciba.pdf
17. Hagens et al. Contact angle measurement - a reliable supportive method for screening water-resistance of ultraviolet-protecting products in vivo. International Journal of Cosmetic Science, 2007, 29, 283-291.

Related End-User Markets:

Related Raw Materials:

  • Get Ready, ‘Cause Here it Comes…

    Get Ready, ‘Cause Here it Comes…

    Christine Esposito, Associate Editor||November 1, 2016
    Skinphonic is a new brand created with a team of beauty experts and fronted by singer Smokey Robinson.

  • Hair for Me!

    Hair for Me!

    October 31, 2016
    Function of Beauty fulfills the promise of personalization in the beauty space—one bottle at a time.

  • Coming Clean on a Host of Issues

    Coming Clean on a Host of Issues

    October 17, 2016
    Cleaning Products Conference is set for Nov. 9-11, 2016 in Washington DC.

  • The World Comes to Orlando

    The World Comes to Orlando

    Tom Branna, Editorial Director||December 1, 2016
    More than 1,600 chemists traveled to Florida for the IFSCC Congress

  • Perform or Perish

    Perform or Perish

    Christine Esposito, Associate Editor||December 1, 2016
    Success in today’s skin care sector begins with active ingredients, formulated in products that address modern-day issues.

  • New Ingredients for  Household Cleaners

    New Ingredients for Household Cleaners

    Tom Branna, Editorial Director||November 2, 2016
    Here are ingredients introduced by suppliers during the past 12 months.

  • A-Okay!

    A-Okay!

    Imogen Matthews, For In-Cosmetics||November 2, 2016
    K-Beauty influences cosmetic development around the world.

  • Shine On

    Shine On

    Melissa Meisel, Associate Editor||November 2, 2016
    Oral care products are rising to the task with innovative components.

  • Next Gen  Antiseptics

    Next Gen Antiseptics

    Emily Kalal and Katherine S. Maka, RITA Corporation||November 2, 2016
    RITA researchers detail the benefits of 0.75% chlorhexidine gluconate (CHG) antiseptic handwash

  • Skin Care of One’s Own

    Skin Care of One’s Own

    Christine Esposito, Associate Editor||October 3, 2016
    Nu Skin’s ageLOC Me—which melds the worlds of smart-phone technology, efficacious ingredients and personalization

  • Proof Positive

    Proof Positive

    Christine Esposito, Associate Editor||October 3, 2016
    Testing service providers enable companies to back up their claims and stay in compliance with regulations.

  • Change Is in the Air

    Change Is in the Air

    Doreen Wang, BrandZ ||October 3, 2016
    Technology is changing the personal care market

  • Back to School

    Back to School

    Tom Branna, Editorial Director||September 1, 2016
    It may be September, but class was in session this summer during the Private Label Manufacturers Association’s Executive Educ

  • Silent Partners

    Silent Partners

    Christine Esposito, Associate Editor||August 1, 2016
    From research & development to logistics to confidentiality, savvy distributors help finished formulators achieve their goals

  • Sustainability is Omnipresent

    Sustainability is Omnipresent

    Christine Esposito , Associate Editor||July 1, 2016
    Industry stakeholders convene in New York City for Organic Monitor’s annual event

  • Preserve & Serve

    Preserve & Serve

    Melissa Meisel , Associate Editor||July 1, 2016
    Suppliers with innovative preservatives provide staying power for formulations.

  • Take Notice

    Take Notice

    Melissa Meisel , Associate Editor||June 1, 2016
    Packaging trends revolve around trendy artwork, eco-conscious materials—and portability is a plus too!

  • Virtual Reality

    Virtual Reality

    Christine Esposito, Associate Editor||June 1, 2016
    An update on nature-identical ingredients for cosmetics and personal care products.

  • Shiseido Advances in the US

    Shiseido Advances in the US

    Tom Branna, Editorial Director||June 1, 2016
    New facility in Windsor, NJ demonstrates its dedication to the US and other markets outside Japan.

  • April in Paris

    April in Paris

    Tom Branna, Editorial Director||June 1, 2016
    In-Cosmetics sets attendance record in its return to the City of Light.

  • Boxed Out?

    Boxed Out?

    Tom Branna, Editorial Director||May 2, 2016
    Salon sales outpace mass-market results in the highly competitive, highly fashionable and yes, highly-colorful hair color cat

  • Wacker Builds on Its Success

    Wacker Builds on Its Success

    Tom Branna, Editorial Director ||May 2, 2016
    The silicone maker had a good 2015 and expects the gains to continue in 2016, driven, in part, by success in the Americas and

  • I Want It All

    I Want It All

    Melissa Meisel , Associate Editor||May 2, 2016
    Skin care moves beyond the basics with pampering formulations with unique components and novel functions.

  • The New Spot For Acne Care

    The New Spot For Acne Care

    Tom Branna, Editorial Director||April 1, 2016
    Acne Treatment Research Center opens in Morristown, NJ.

  • The Scalp Microbiome

    The Scalp Microbiome

    Nava Dayan PhD, Dr. Nava Dayan LLC||April 1, 2016
    A review of recent findings and innovative approaches for treating scalp disorders.

  • Who Makes That?

    Who Makes That?

    Tom Branna, Editorial Director||April 1, 2016
    From concept and formulation to testing and filling, today’s contract manufacturers perform a range of services for marketers

  • Playing Doctor

    Playing Doctor

    Christine Esposito, Associate Editor||March 1, 2016
    The OTC aisle offers a wide array of no-prescription-needed treatments.

  • Shielding Skin from Airborne Antagonists

    Shielding Skin from Airborne Antagonists

    Shyam Gupta, Ph.D., John Stanek and Melinda Wochner, Bioderm Research and CoValence Laboratories, Inc.||March 1, 2016
    The enemy, it seems, is all around us. Researchers explain how to alleviate damage caused by a variety of villains.