As I write this column, the weather in the U.K. is far from summery but many of us will be taking vacations to sunnier climates. Sun-safe behavior is important at home as well as on vacation if we are to avoid sunburn and the risk of serious, long-term skin disease. And a key element of that behavior, after seeking shade and covering up, is the use of sunscreen.
Today, we take the effectiveness of sunscreen products for granted, and if you’ve ever missed a small area when applying sunscreen, you know painfully well how effective today’s products are. As the industry knows, this performance is not simply a happy coincidence but the culmination of a whole program of research and development that involves many different experts. We review the steps in this program here and consider where questions may arise both from the experts and consumers.
The Making of a Sunscreen
Setting the brief: At the outset, the manufacturer will decide what product is to be developed and marketing experts will analyze its intended place in the market. This may be cream, lotion or spray product, and it may be intended to provide high, medium or low protection against UVB with a goal of a specific sun protection factor (SPF). The product also should provide adequate broad spectrum protection against UVA; in the EU, a product with this efficacy in indicated by a UVA logo in a circle on the product label.
Additionally, the product may be marketed for the entire family to use, or targeted to a specific market segment or age demographic, e.g., children; in the latter case, the product may be colored to show whether the product application has been carried out completely. The product may provide prolonged protection, sometimes incorrectly called “once-a-day” protection, or it may be water-resistant. Once all these attributes have been defined, R&D will have a brief to work toward.
UV filters: The first stage is to ensure the targeted SPF and UVA protection are likely to be achieved, so the UV filters must be decided upon. This requires great skill and knowledge because the palette of available filters and levels at which they can be used are not infinite. Furthermore, the efficacy of a filter is influenced to some extent by the base formulation in which it is used.
Products intended for the international market have the added complication of working with various sets of national restrictions on allowed filters, disallowed ingredients, etc., not all of which are fully compatible. Past experiences in the field are invaluable in making the right choice at this stage to increase the likelihood of success.
Parallel testing: Importantly, the manufacturer also will embark upon a series of tests that are carried out in parallel with the formula development. These check to ensure that all is on track to deliver the anticipated SPF and UVA protection for the finished final product. If such interim tests during development indicate the product may not ultimately deliver, a brainstorming session is required immediately rather than pressing ahead.
As the initial formulation is refined to meet the ever more exact brief, problems may arise at any time due to incompatibilities between one or more ingredients and the UV filters. This could be due to poor dispersion of the filters throughout the product, separation or settling during storage, and possible—although rare—degradation of the filters themselves; or even a product whose spreadability is inconsistent or interacts with the packaging materials. The end result, in each case, would be failure to achieve the desired sun protection performance.
If all is well, the interim testing will show a consistent and satisfactory level of performance in the key SPF and UVA protection areas, whilst also meeting the other elements of the brief, including: color, viscosity, skin feel, fragrance, price, packaging, ease of manufacture, stability, microbiological resistance and, of course, safety.
Additional testing: Toward the end of the R&D program, the new product will be sent for SPF and UVA testing at an accredited laboratory using the internationally standardized test methods. Although there are some small differences in the way these are conducted around the world, they are all closely based on the tests proposed by the International Standards Organization and each will produce similar outcomes.
However, this is not to say the SPF test will not raise some issues. The test is based on human responses and as such, has an inherent level of variability. Close attention to detail during the test can minimize variability but cannot remove it.
Questions in Testing
The question is sometimes raised as to whether a single SPF test carried out in isolation has been subjected to insufficient variability, rendering the final results unreliable. This tends to occur when consumer organizations pick products at random and test their efficacy, criticizing any that appear to fall short of the advertised SPF. It is in these cases where the many corroborating tests carried out during development show their value—because if the final SPF test result is consistent with the results obtained previously, during the development program, the confidence in that final test result is high.
If there is a great discrepancy—whether higher or lower—between the final SPF test result and previous results, confidence is lowered. Of course, if you don’t have access to such a series of test data gathered during product development, but have the single test results in isolation, you cannot be sure that the test was not one of those rare, but not unknown, cases where the accuracy of the results simply cannot be trusted.
Some might argue a sunscreen product should be formulated to ensure it always passes the SPF test no matter how questionable the result is in an individual test. However, I believe this is not in the public’s best interest. In effect, if you had to develop products to be SPF 50 but labeled them as SPF 30 to ensure they always delivered an SPF 30 or more, even in a questionable study, the costs will rise due to the use of additional materials. The higher SPF formulation also is more difficult to achieve, and fewer options are available for different product types.
Furthermore, the consumer would begin to use the product differently as they got used to the extra margin of protection provided, and would be at risk if they changed to a product that delivered a true SPF 30 rather than an SPF 50 labeled SPF 30. Such over-labeling might even post legal issues in some countries.
Bound to Safety
As consumers, we all know we should reapply sunscreen frequently, especially after swimming, sweating or towel-drying. Of course, when at the beach or by a pool, reapplying sunscreen can be inconvenient. Nonetheless, the industry has developed products that are more resistant to being washed off than ever before—although they are not waterproof. This is achieved by some clever formulation, which increases the affinity of the product and especially the UV filters to the skin. Such products require some application time prior to sun exposure for them to be the most effective. In essence, they need time for the ingredients to “bind” to skin.
This trend has been pushed further, and innovations have provided products that deliver extended protection; although to call such products “once-a-day” sun protection might give a false sense of security. Certainly outdoor workers and sports enthusiasts who find reapplication every two hours or so impossible to achieve may find such products a boon.
The emphasis in these formulas has been to ensure the UV filters remain stable on the skin even under some duress. Of course, there are compromises. Extended wear and water-resistant sunscreens may be more visible on the skin or leave a residual feeling of slight stickiness, compared with their less-resistant counterparts; but for some, this is worthwhile in order to gain the other benefits. In time, new formulations will evolve to improve even these aspects.
Today, thanks to skillful research and development scientists, the sun care market provides consumers with highly effective sunscreen products tailored to meet a range of needs, from ease of use to enhanced durability. There is no need to suffer from the skin health risks associated with sunburn.