The HallStar Company, a manufacturer of esters and polyesters, has been researching, developing, manufacturing and marketing ingredients specifically for the sun care market since the 1990s. Although novel and innovative ingredients developed by HallStar’s laboratories are found in sun and skin care products of pharmaceutical and cosmetic companies worldwide, we have a particular interest in sunscreens produced for the US. That’s because it is especially challenging for formulators to make superior performance products for this market. Why? One major reason: A limited palette of allowed sunscreen active ingredients (called UV filters in many other countries, and in the rest of this article) are available. The US has only 16 UV filters approved for use, while the European Union (EU) has 27, Japan has 34, and South Africa has a whopping 49. Plus, there are restrictions in the US around what combinations of those 16 UV filters may be used. Another reason: Some of the authorized UV filters, such as avobenzone (also known as butyl methoxydibenzoylmethane) are inherently unstable…in sunlight! Formulators know they face a challenge when necessary ingredients are unstable (labile) in their intended conditions of use.
Many have petitioned, and continue to lobby, the US Food and Drug Administration (FDA) for a broader array of approved UV filters. Data packages that present the established safety and efficacy for eight additional UV filters allowed elsewhere in the world have been submitted to the FDA for regulatory review. Some of these submissions date back more than 10 years, with more information requested and all still under consideration.
In the absence of additional authorized UV filters, HallStar has launched new products aimed specifically at remedying the photolability of available UV filters, most notably avobenzone. This is the primary non-mineral UV filter used in the US to protect skin from the aging and cancer causing UVA rays of the sun. HallStar’s SolaStay products enable photoprotection through stabilization of avobenzone and other anti-aging skin care active ingredients that degrade when exposed, unprotected, to sunlight.
36 Years and Counting
When the FDA first started looking at sunscreens through an Advanced Notice of Proposed Rulemaking in 1978, the focus was almost exclusively on preventing sunburn, which is caused by shorter wavelength, higher energy UVB rays. That is how sunscreens were marketed in the US for decades, based on SPFs (sun[burn] protection factors) that informed the consumer how many times more sun exposure a person could experience when using a product, before the first hint of skin redness (measured as the minimal erythemal dose; MED). At the same time, ongoing research was demonstrating that not only UVB rays, but also UVA rays, adversely impact skin health. Indeed, just as UVB rays were known as the “burning” rays of the sun, UVA rays were becoming known as the “aging” rays. Other geopolitical zones (e.g., Japan and the EU) were early adopters of guidelines for the measure of UVA protection to be delivered by sunscreens. Eventually this matter was taken up by the FDA and, after a false start in 2007 (a Proposed Amendment of Final Monograph), a standard for UVA protection was finally established in 2011 (a Final Rule), taking full effect at the start of 2014.
Some of the key questions regarding monograph-compliant US sunscreens, now answered for the consumer on the packaging, include:
- What is the SPF?
- Is the sunscreen “broad spectrum”?
- Will the product, used as directed, decrease the risk of skin cancer and of early skin aging?
- Is the product water resistant after 40 or 80 minutes of exposure?
- What are its active ingredients (UV filters)?
- What are its inactive ingredients?
- What warnings regarding usage apply?
- What are the directions for use?
Another change to sunscreen packaging is the explicit directive that “sweatproof” and “waterproof” claims (“sunblock,” too) are false and misleading for a sunscreen, thereby rendering products labeled this way as incorrect and misbranded. The FDA now requires every sunscreen, water resistant or not, to state that the product is to be applied liberally 15 minutes before sun exposure and to be reapplied at least every 2 hours (sooner if classified as water resistant, and the user is sweating or swimming).
While not at the top of the list of things to look for on a sunscreen label for most consumers (even though they are at the top of the Drug Facts listed on the product label), active ingredients (the UV filters) and their levels continue to be listed. Importantly, farther down the label all inactive ingredients contained in the formulation must also be listed alphabetically. Why is this important? These “inactive” ingredients often have a direct impact on product performance.
Using our FDA-provided label, here are some examples of inactive ingredients and their function/use: polyglyceryl-3 distearate and sorbitan isostearate with water form a lotion of the UV filters; stearic acid and carbomer with triethanolamine thicken and stabilize the lotion, making it less prone to separation; dimethicone improves the lotion’s spreadability while reducing “soaping” (whitening) during product application; disodium EDTA ties up common environmental metal ions, such as calcium, magnesium, and iron, helping to keep the product free of microbial growth (methylparaben and propylparaben further assist in this area); and octadecene/MA copolymer imparts water resistance to the product. Thus these “inactive” ingredients and the labeling guidelines are an important part of the product and information available to consumers.
As already noted, some UV filters are not stable in sunlight, most notably avobenzone (a strong and cost effective UVA filter, when stabilized). Further, when avobenzone and octinoxate (also known as ethylhexyl or octyl methoxycinnamate, a strong and cost effective UVB filter) are combined without an appropriate stabilizer, both become unstable in sunlight, resulting in an ongoing loss in sunscreen performance across the entire UV spectrum as sun exposure continues.
The traditional approach to dealing with this instability has been to incorporate an excess of UV filters so that sufficient performance remains at the end of the FDA mandated testing procedures to achieve the desired sun protection on the sunscreen’s label. The use of SolaStay stabilizers, though, allows two options: the use of less octinoxate and avobenzone, or the ability to market a higher SPF level sun protection product if the UV filter use levels are left unchanged. To know whether these stabilizers are in such a sunscreen, look for ethylhexyl methoxycrylene or polyester-25 among the “inactive” ingredients.
What about sunscreens where avobenzone is used in the absence of octinoxate? Ethylhexyl methoxycrylene or polyester-25 retain full efficacy. A number of related, but not as powerful, stabilizers are also effective in these less challenging formulations. These include undecylcrylene dimethicone and polyester-8, which would appear among inactive ingredients, and octocrylene, which would appear among the active ingredients.
The earliest sunscreens focused on simply preventing summer sunburn from the UVB rays of the sun, but a growing understanding of the effects of the sun on skin— which extend from sunburn, to premature aging, and increased cancer risks—have resulted in the sun protection products evolving from beach products to everyday skin care creams, anti-aging products, and even color cosmetics. The benefits to consumers of the FDA’s revised performance and labeling requirements for sunscreens (products that claim sun protection for the skin) have been presented and are clearly evident. Even in the absence of an enlarged palette of UV filters with which to work, formulators continue to receive new tools useful in the delivery of sunscreens for the US consumer that provide better protection of the skin from aging, burning and cancer, and the evidence is on the newly mandated labels. Take a look, a close look, and benefit from the progress that has been made.
More info: Gary Neudahl, The HallStar Company, Bedford Park, IL. Tel: 708-594-5058; E-mail: firstname.lastname@example.org;