title: Comparing quantitative measures of erythema, pigmentation and skin response using reflectometry.
abstract: We measured a number of pigmentation and skin response phenotypes in a sample of volunteers (n=397) living in State College, PA. The majority of this sample was composed of four groups based on stated ancestry: African-American, European-American, Hispanic and East Asian. Several measures of melanin concentration (L*, melanin index and adjusted melanin index) were estimated by diffuse reflectance spectroscopy and compared. The efficacy of these measures for assessing constitutive pigmentation and melanogenic dose-response was evaluated. Similarly, several measures of erythema (a*, erythema index and adjusted erythema index) were compared and evaluated in their efficacy in measuring erythema and erythemal dose-response. We show a high correspondence among all of the measures for the assessment of constitutive pigmentation and baseline erythema. However, our results demonstrate that evaluating melanogenic dose-response is highly dependent on the summary statistic used: while L* is a valid measure of constitutive pigmentation it is not an effective measure of melanogenic dose-response. Our results also confirm the use of a*, as it is shown to be highly correlated with the adjusted erythema index, a more advanced measure of erythema based on the apparent absorbance. Diffuse reflectance spectroscopy can be used to quantify the constitutive pigmentation, melanogenic dose-response at 7 d and erythemal dose-response at both 24 h and 7 d postexposure.
authors.affiliation: Department of Anthropology, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Wagner
authors.forename: Celina
authors.initials: C
authors.lastname: Jovel
authors.forename: Heather L
authors.initials: HL
authors.lastname: Norton
authors.forename: Esteban J
authors.initials: EJ
authors.lastname: Parra
authors.forename: Mark D
authors.initials: MD
authors.lastname: Shriver
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004817:Epidermis / Q000378:metabolism / Q000528:radiation effects*; D004890:Erythema / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008543:Melanins / Q000096:biosynthesis / Q000528:radiation effects*; D008875:Middle Aged; D010858:Pigmentation / Q000502:physiology / Q000528:radiation effects*; D011930:Reaction Time / Q000502:physiology; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D008543:Melanins