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Skin pigmentation kinetics after exposure to ultraviolet A.
Acta Derm Venereol. 2009; 89(4):357-63.AD

Abstract

Multiple exposures to ultraviolet radiation (UVR) are the norm in nature and phototherapy. However, studies of the kinetics of pigmentation following UVA exposure have included only fair-skinned persons. The aim of this study was to investigate steady-state pigmentation and fading in 12 Scandinavians and 12 Indians/Pakistanis after 6 and 12 exposures on the back using broadband UVA and UVA1 with equal sub-minimal melanogenic doses (individually predetermined). Pigmentation was measured by skin reflectance at 555 and 660 nm. The UV dose to minimal pigmentation was higher in dark-skinned persons after a single broadband UVA exposure, but independent of pigmentation/skin type after single and multiple UVA1 exposures. To elicit minimal melanogenic doses after 6 and 12 exposures, every dose is lowered by a factor of 2 and 3, respectively, but the cumulative dose increases three- and four-fold, respectively. The absolute increase in pigmentation was independent of pre-exposure pigmentation; therefore the percentage increase in pigmentation was higher in fair-skinned subjects. The absolute increase in pigmentation was higher and it took 2-3 days longer to reach steady-state after 12 UV exposures compared with 6 UV exposures. Days to steady-state pigmentation and fading were independent of pre-exposure pigmentation, and fading took 5-6 months. Comparing data from a narrowband UVB source and a Solar Simulator, it was shown that pigmentation built up faster and increased more after 12 UVA exposures (16 days) than with the Solar Simulator (21 days).

Authors+Show Affiliations

Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, DK-2400 Copenhagen NV, Denmark.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19688146

Citation

Ravnbak, Mette H., et al. "Skin Pigmentation Kinetics After Exposure to Ultraviolet A." Acta Dermato-venereologica, vol. 89, no. 4, 2009, pp. 357-63.
Ravnbak MH, Philipsen PA, Wiegell SR, et al. Skin pigmentation kinetics after exposure to ultraviolet A. Acta Derm Venereol. 2009;89(4):357-63.
Ravnbak, M. H., Philipsen, P. A., Wiegell, S. R., & Wulf, H. C. (2009). Skin pigmentation kinetics after exposure to ultraviolet A. Acta Dermato-venereologica, 89(4), 357-63. https://doi.org/10.2340/00015555-0635
Ravnbak MH, et al. Skin Pigmentation Kinetics After Exposure to Ultraviolet A. Acta Derm Venereol. 2009;89(4):357-63. PubMed PMID: 19688146.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Skin pigmentation kinetics after exposure to ultraviolet A. AU - Ravnbak,Mette H, AU - Philipsen,Peter A, AU - Wiegell,Stine R, AU - Wulf,Hans C, PY - 2009/8/19/entrez PY - 2009/8/19/pubmed PY - 2009/9/15/medline SP - 357 EP - 63 JF - Acta dermato-venereologica JO - Acta Derm Venereol VL - 89 IS - 4 N2 - Multiple exposures to ultraviolet radiation (UVR) are the norm in nature and phototherapy. However, studies of the kinetics of pigmentation following UVA exposure have included only fair-skinned persons. The aim of this study was to investigate steady-state pigmentation and fading in 12 Scandinavians and 12 Indians/Pakistanis after 6 and 12 exposures on the back using broadband UVA and UVA1 with equal sub-minimal melanogenic doses (individually predetermined). Pigmentation was measured by skin reflectance at 555 and 660 nm. The UV dose to minimal pigmentation was higher in dark-skinned persons after a single broadband UVA exposure, but independent of pigmentation/skin type after single and multiple UVA1 exposures. To elicit minimal melanogenic doses after 6 and 12 exposures, every dose is lowered by a factor of 2 and 3, respectively, but the cumulative dose increases three- and four-fold, respectively. The absolute increase in pigmentation was independent of pre-exposure pigmentation; therefore the percentage increase in pigmentation was higher in fair-skinned subjects. The absolute increase in pigmentation was higher and it took 2-3 days longer to reach steady-state after 12 UV exposures compared with 6 UV exposures. Days to steady-state pigmentation and fading were independent of pre-exposure pigmentation, and fading took 5-6 months. Comparing data from a narrowband UVB source and a Solar Simulator, it was shown that pigmentation built up faster and increased more after 12 UVA exposures (16 days) than with the Solar Simulator (21 days). SN - 1651-2057 UR - https://www.unboundmedicine.com/medline/citation/19688146/Skin_pigmentation_kinetics_after_exposure_to_ultraviolet_A_ L2 - https://www.medicaljournals.se/acta/content/abstract/10.2340/00015555-0635 DB - PRIME DP - Unbound Medicine ER -