Consumer product testing and procedures for implementing claims substantiation protocols are topics of increasing interest within the product development process. As this author previously has stated, the race to enhance, or at the very least match, a manufacturer’s on-package product claims to its competitors’ is of paramount importance to gain a crucial foothold in the relevant market and target demographic. This article follows neatly from a previous one regarding anti-wrinkle claims substantiation.1 Here, other related efficacy claims increasing in popularity are considered—including reducing age spots and hyperpigmentation, evening skin tone, skin lightening, and improving skin elasticity, firmness and cell turnover. Awareness of the testing procedures for these claims is lacking—but awareness is crucial to move forward, especially with heightened popularity for such products fueled by increased demand.
The Rise of ‘Anti-imperfection’ Claims
One of the reasons the modern cosmetics market continues to grow is the technology boom of the last 20 years. Before the ubiquity of the Internet and social media, the dissemination of images and advice relating to skin was only available through paper media, television or in-person interactions. However, the global uptake of the Internet and devices such as tablets and smart phones ensure that consumers can easily access countless sources of information, be it good or bad. This increase in curiosity, discussion and thus demand for “bigger and better” drives modern day capitalism in many markets, and skin care is no exception.
Although skin concerns date back throughout history—with clear, glowing and youthful skin indicating prosperity and health, and sallow, blemished skin portraying a toiling and stressful life (although the last century’s tanning craze has altered this perception)—skin concerns were merely a physical manifestation of the life the person led. Now, the need for an admirable complexion knows no social, economic or regional boundaries. In addition, the desired appearance is easily attainable and relatively affordable.
The compression of time and space for human interaction and attainability of desired solutions have produced a surge in, and shown the importance of, on-pack claims for cosmetics and personal care products. The visibility, popularity and dissemination of information are important for brands to succeed in this hungry and overcrowded market, but the final link to success is a perceived unique selling point from the consumer’s perspective. From this, desired claims increasingly have to do with achieving a homogenous and youthful complexion.
In an ideal world, every product development team member should understand the testing processes required to legitimize on-pack claims. Four individual tests can be undertaken to substantiate the areas of claims covered in this article. First, colorimetry analyzes pre- and post-product application skin tone, which substantiates claims such as improves luminosity, reduces uneven pigmentation, encourages even skin tone, reduces hyperpigmentation and reduces the appearance of age spots. A Cutometera or dermal torque meter (DTM)b measures the rate of skin extension pre- and post-product treatment to substantiate claims for skin-firming or improving skin elasticity. Finally, stratum corneum turnover tests and acute profilometry studies show the rate at which skin is renewed and the rate at which changes in the evenness of skin occur. These devices cover claims mainly for exfoliating products that relate to stimulating skin cell renewal, regenerating skin quicker and smoothing skin topography.
Skin Tone and Homogeneity Claims
Several instruments can be used in colorimetry. A spectrophotometer provides high precision analysis and accurate color management, although it is not currently the industry standard. Devices such as the Skin-Colorimeterc and Mexameterd provide more standardized protocols to determine the homogeneity of pigmentation. The former is a chromameter, and expresses skin color as a coordinate in the L*a*b* colorspace, described later. It can measure color changes resulting from the use of active ingredients or application of makeup. The latter specifically determines an index for melanin and erythema values, and gives the parameters of skin color very accurately.
As the industry standard, the chromameter will be explored here in depth. It measures color based on a tri-stimulus method to emulate the function of the human eye. In this approach, light, which is created by a flash and reflected by the skin, is measured by three sensors and represented by numerical values plotted in a colorspace characterized by the brightness, L*, and the color coordinates a* and b*, as defined in 1976 by the International Lighting Commission (Commission Internationale de l’Eclairage, or CIE).2
The effects of products on skin can be measured before and after application using these three values. If a product irritates the skin by causing a rash, the redness of the skin intensifies and the a* value increases. If a product has a soothing effect, redness is reduced; consequently a lower a* value would be expected. An increase in the b* value designates higher pigmentation, which also leads to a decrease in the brightness value L*. To minimize fluctuations in color, all measurements are conducted in triplicate and averaged by the device. This approach works similar to the albedo power of the Earth, moon, clouds, etc., to reflect and scatter solar radiation; the lighter and brighter the surface with which light comes into contact, the higher the percentage of initial radiation reflected.
Subjects and protocol: A statistically significant minimum of 30 subjects typically would be used for this study. Initially, pre-treatment chromameter assessments of the subjects’ upper inner arms would be taken to determine the reflectiveness of their skin. After initial assessments, the product in question would be applied to the same area and another measurement would be taken one hour after application. This procedure would be repeated at various stages throughout the duration of the trial to monitor the performance of the product over time. For a study like this, one can expect to pay between $12,000 and $15,000 for the full protocol.
Results and claims: Upon demonstrating statistically significant measured effects—as determined by p values typically at .05 or .01—the product can make the intended on-pack claim to the extent of the measured results. This often is expressed as a percentage of improvement in age spots, hyperpigmentation, etc. For example, a claim might state, “lightens the skin by X% over X weeks,” or the more generic, “shown to lighten skin tone.” As long as the test results support the intended claim, it can be used; however, the legitimacy of the claim’s extent and sensationalism of the language used to portray a product’s efficacy is at the discretion of advertising standards agencies.
Skin Firmness and Elasticity Claims
Two instruments typically are used to substantiate claims relating to skin firmness and elasticity: the Cutometer and DTM, both of which use similar concepts to facilitate measurements. The Cutometer uses suction to gently draw skin into the aperture of the probe, immediately releases the suction and counteracts with negative pressure, then measures the penetration depth and time it takes for skin to return to its original state. Elasticity refers to the skin’s ability to resist deformation and regain its normal position, thus a complete recovery corresponds to an elasticity value of 100%. These measurements can be graphed by plotting the theta (unknown) angle of the torque against time, which demonstrates the skin’s initial extensibility gradient when the vacuum is administered and then released—i.e., the rate of return.
The DTM functions similarly to the Cutometer, but its probe has an inner and outer chamber. Upon application, the inner chamber twists and applies a level of torque to the skin rather than using suction. In this case, it is the release from twisting the skin that provides a measurement of how quickly the skin returns to its original state.
Subjects and protocol: These studies also would typically use 30 subjects, normally with aging and/or non-firm skin. As with the skin tone study, a pre-assessment measurement would be taken before product application to capture a baseline value. Then, over a defined time period, the test product is applied and periodic assessments are made before the final measurement is taken, usually at eight weeks. After this, again after demonstrating statistical significance based on p values, the product can make the intended on-pack claim to the extent of the measured results; for example, “increases skin elasticity by X%” or “firms the skin.” Once again, a study like this could cost between $12,000 and $15,000 for a full protocol.
Turnover and Renewal Claims
The final methods described here are the stratum corneum turnover test and acute profilometry study. The former determines the regenerative ability and epidermal metabolic rate of the skin under the influence of a test sample by measuring increases in cell turnover.
Turnover: This method employs dansyl chloride as an epidermal stain, which is applied through a Finn chamber to the skin. The depth of stain penetration is assessed on non-test sites at the baseline by counting the number of adhesive tape-strippings required to remove the dye. The entire epidermis is replaced by new cell growth over a period of between 39 and 48 days; replacement of the stratum corneum alone takes around 14 to 28 days.3 However, each person’s turnover rate is different, and can even vary within individuals on a daily basis, which does not provide a strong basis for a hypothesis or baseline. Thus, the results of this approach are based on a comparison between the negative control site and test control sites.
A measurement of the number of days between the application of a fluorescent material and its cessation between two sites provides information about whether the cell turnover of the test site, situated close to the negative site due to the Finn chamber arrangement, has occurred quicker than at the negative site. If this occurs, claims for increased skin cell turnover can be substantiated and include the percentage of acceleration; for example, “regenerates the skin X% quicker” or “exfoliates the skin for faster skin renewal.” For this turnover test, a typical study would involve 20 subjects having regular assessments over the duration of 28 days. This test could cost between $8,000 and $12,000.
Profilometry: Acute profilometry provides a precise analysis of the topography of the epidermis using a three-dimensional (3D) documentation apparatus. For instance, the phase-shift rapid in vivo measurement of skin (PRIMOS) device uses digital fringe projection as an optical measuring technique. With this method, a set of parallel lines, referred to as the fringe pattern, is projected onto the surface of the skin and mapped on the charge-coupled device (CCD) chip of a camera. The 3D measurement achieved by the projected parallel lines is slightly deflected by any subtle unevenness in the epidermis, and this deflection constitutes a qualitative and quantitative measurement of the skin profile. This information is captured by the CCD camera, digitized and processed by a computer for quantitative analysis. The quantitative and qualitative results from PRIMOS studies provide the basis, after determining statistical significance, for substantiating exfoliating claims for smoothing the skin’s surface, such as “reduces wrinkles by X% over X weeks.” This test also could fetch fees of between $8,000 and $12,000.
The cosmetics industry is portrayed as glamorous, featuring products purporting to ease and improve skin ailments and conditions in many different ways. However, in this article and others,1, 4, 5 the author has examined the nuts and bolts upon which such glamour is built. Without a full understanding of how or if a claim can be legitimized, a product developer, brand manager or formulation chemist cannot diligently plan a product’s development from start to finish and incorporate function, aim, market position or price point to optimize profitability.
As this author has continued to state, a product can only work efficaciously for the consumer and gain the reputation the company desires if it is sold in the first place, which cannot happen if claims are made on package and not substantiated. The bottom line for obtaining brand trust is to formulate the best product possible, to test it diligently and to then be honest with the consumer about the results. With over-zealousness comes skepticism that is rarely surpassed or overridden, thus the stringency of testing should be viewed as an aid to product optimization rather than a hindrance to it.
- C McLeod, Testing tactics in skin: Anti-wrinkle claims substantiation, Cosm & Toil 128(11) 804 (Nov 2013)
- www.cie.co.at/publications/standards (Accessed Nov 13, 2013)
- I Hajime, Epidermal turnover time, J Derm Sci 8(3) 215–217 (1994)
- C McLeod, Testing tactics in skin: Moisturizing claims, Cosm & Toil 128(6) 390 (Jun 2013)
- C McLeod, Testing tactics in skin: Sun protection factor, Cosm & Toil 128(9) 624 (Sep 2013)