Self‐reported skin colour and erythemal sensitivity vs. objectively measured constitutive skin colour in an A frican population with predominantly dark skin

Solar Ultraviolet Radiation, Skin Cancer and Photoprotective Strategies in South Africa†

The most recent data relating to the incidence of, and mortality from, the three commonest forms of skin cancer, namely basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous melanoma (CM), in the Black African, Colored, Asian/Indian and White population groups in South Africa are reviewed. While exposure to solar ultraviolet radiation is the major environmental risk factor for BCC in all four groups, for SSC in the White and Asian/Indian groups and for CM in the White group, this is unlikely to be the case for most SCCs in the Black African group and for most CMs in the Black African and Asian/Indian groups. Strategies for practical personal photoprotection in South Africa are discussed with particular emphasis on people at heightened risk of skin cancer including the White population group, those with HIV or oculocutaneous albinism and outdoor workers.

Validity of self‐reported skin color by using skin color evaluation scale

INTRODUCTION

Although skin color has been suggested to be associated with the risk of some chronic disease, there has been no validated visual skin-color scale, with which subjects can self-report their skin color. Our objective was to develop a visual skin color evaluation scale for self-reporting that would be useful in large-scale epidemiological studies.

MATERIALS AND METHODS

Study participants were 99 university Japanese students aged 19-29. We developed a skin color evaluation scale consisting of six colors from light to dark. Participants were asked to choose one color that was the closest to their skin color. Their skin color was measured on the back of the hand and the inner upper arm by an examiner using a narrowband reflective spectrophotometer. Self-reported skin color was compared with the melanin and erythema indices.

RESULTS

Spearman's rank correlation coefficients of self-reported color with the melanin index after adjusted for age, temperature, and humidity were moderate but significant at both sites for both men and women. The correlation coefficients with the erythema index were significant only on the back of the hand for men. The higher melanin index was significantly associated with the darker skin color in both sexes for both sites. The erythema index showed such a significant trend only in men and not in women.

CONCLUSIONS

The validity of the skin color chart was moderate of melanin among Japanese people. It may be useful for large population studies examining the relationships between skin color and health outcomes.

GWAS Identifies Multiple Genetic Loci for Skin Color in Korean Women

Human skin color is largely determined by genetic factors. Recent GWASs have reported several genetic variants associated with skin color, mostly in European and African populations. In this study, we performed GWAS in 17,019 Korean women to identify genetic variants associated with facial skin color, quantitatively measured as CIELAB color index. We identified variants in three, one, and six genomic loci associated with facial skin color index L∗, a∗, and b∗ values, respectively, and replicated the associations (combined analysis P-value < 5.0 × 10^-8). The significant loci included variants in known genes (OCA2 rs74653330, BNC2 rs16935073, rs72620727 near KITLG, and SLC6A17 rs6689641) and to our knowledge previously unreported genes (SCARB1 rs10846744, SYN2 rs12629034, and LINC00486 rs6543678). This is GWAS to elucidate genetic variants of facial skin color in a Korean female population. Further functional characterizations of the investigated genes are warranted to elucidate their contribution to skin pigmentation-related traits.

The color of normal: How a Eurocentric focus erases pigmentation complexity

OBJECTIVES

Skin pigmentation is both a highly variable and highly visible human phenotypic trait. Investigations into the biology and origins of this variation have been the focus of research in the fields of dermatology, anthropology, and forensic science, among others. This manuscript explores how much of what we know about the biology, genetics, and evolutionary origins of pigmentation has been strongly influenced by investigations and applications that focus on lighter skin.

METHODS

I reviewed literature from the fields of dermatology, anthropology and evolutionary genetics, and forensic science to assess how perceptions of lighter skin as the "normal" state in humans can shape the ways that knowledge is gathered and applied in these fields.

RESULTS

This normalization of lighter skin has impacted common tools used in dermatology and shaped the framework of dermatological education. A strong Eurocentric bias has shaped our understanding of the genetic architecture of pigmentary traits, which influences the ways in we understand the evolutionary processes leading to modern pigmentation diversity. Finally, I discuss how these biases in pigmentation genetics work in combination with phenotypic systems that privilege predicting lighter pigmentation variation to impede accurate prediction of intermediate phenotypes, particularly in individuals with ancestry from multiple populations. This can lead to a disproportionate targeting of already over-policed populations with darker skin.

CONCLUSIONS

Potential changes to how we conceptualize clinical and basic pigmentation research may help to reduce existing health disparities and improve understanding of pigmentation genetic architecture and how this knowledge is applied in forensic contexts.

Research Techniques Made Simple: Cutaneous Colorimetry: A Reliable Technique for Objective Skin Color Measurement

Skin color evaluation contributes to assessment of an individual's cutaneous phenotype. Skin color changes provide important clues to disease progression or treatment response. Skin color is also a predictor of skin cancer risk. Melanin pigment, blood flow, skin thickness, and photoaging contribute to skin color. Melanin, hemoglobin, bilirubin, and carotene are the primary chromophores of skin color. Their concentrations vary depending on the individual's phenotype, anatomic location, external insults of chemical irritants and UVR, and physiological changes. The evaluation and perception of skin color are often subjective. Objective quantification of skin color can be achieved with colorimetric devices such as tristimulus colorimeters. These devices compute the intensity of light reflected from skin and correlate with pigmentation and erythema. Cutaneous color and color changes can be quantified under color organization systems, such as the CIELAB color space, which is standardized by the Commission Internationale de l'Eclairage (CIE). The CIELAB expresses color's lightness, red/green intensity, and yellow/blue intensity, as L*, a*, and b* values, respectively. Additionally, skin color's full spectral characteristics and cutaneous physiology can be measured with spectrophotometers. This article outlines basic principles of the CIELAB color system and how to optimally use colorimetric devices as a skin research tool.

Global data of unprotected skin minimal erythema dose relationship to Individual Typology Angle

BACKGROUND

Determination of the Minimal Erythema Dose (MED_u ) of unprotected skin is perhaps the most critical aspect of the Sun Protection Factor (SPF) value and disproportionately influences the SPF. Individual Typology Angle (ITA°), a skin reflectance measure of the skin's pigmentation, has been used by many clinical laboratories to estimate the MED_u values for SPF testing.

METHODS

Individual Typology Angle and unprotected MED_u data on 9931 individuals were received from 12 laboratories located on 5 continents to determine MED_u values in prospective sunscreen testing studies.

RESULTS

These data were compiled and normalized by laboratory (to account for differences in number of subjects within each laboratory). A polynomial regression best fits the relationship between ITA° and their MED_u and may be used to accurately predict the MED_u of an unknown test subject.

CONCLUSION

The regression data have been incorporated into the latest ISO24444 (Cosmetics - Protection test methods - in vivo determination of the sun protection factor (SPF), 2019) in vivo Sunscreen testing method that must be utilized to determine a subject's provisional MED_u for the testing procedure. Use of this common ITA°-MED_u relationship will help to minimize SPF variability between testing laboratories due to use of widely varying MED_u values.

Sunburn and sun protection in black skin

BACKGROUND

People with black skin are much less susceptible to sunburn than white-skinned individuals, yet there are scarce data on self-reported incidence of sunburn and sun protection measures in people with deeply-pigmented skin.

METHOD

An on-line survey tool was used to collect self-assessed data about demographic variables, sunburn incidence, and use of sun protection modalities.

RESULTS

Two-thirds of respondents with black skin living in the UK claimed never to have been sunburnt; a much higher proportion than those living in South Africa and Nigeria where 34 and 46%, respectively, reported never experiencing sunburn. Similar results were seen in the reported use of sun protection measures between the countries with two-thirds of black people living in the UK claiming they never used any form of sun protection compared with about one-third of Black Africans. Black people living in the UK were more likely to use sunscreen as a form of sun protection, whereas sunscreen was the least popular modality in the two African countries with shade being the most common form of limiting sun exposure.

CONCLUSION

The findings provide some insight into the complexities of skin color perception, incidence of sunburn, and sun protection use among people with deeply-pigmented skin living in three countries with large differences in the solar UV environment.

Solar ultraviolet radiation in Africa: a systematic review and critical evaluation of the health risks and use of photoprotection

The majority of the African continent experiences high solar UVB radiation throughout the year. The adverse consequences of this on the health of populations living in Africa are reviewed.