A precise analysis of the relative contribution of UVA1 and visible light colour domains in solar light-induced skin pigmentation.

BACKGROUND: Solar light induces or aggravates hyperpigmentation issues. The contribution of UVA1, as well as visible light (VL), especially high-energy blue-violet visible (HEV) light, is now clearly established. OBJECTIVES: This work aimed at determining the relative contribution of UVA1, HEV and VL wavelength bands and their sub-domains in pigmentation induction. METHODS: Two clinical studies using solar simulators equipped with specific bandpass physical filters were carried out. Volunteers (FSPT III-IV) were exposed on the back to UVA1 + HEV (350-450 nm), UVA1 (350-400 nm), HEV (400-450 nm) or part of UVA1 + HEV (370-450 nm) in Study 1 (n = 27) and to VL (400-700 nm), HEV (400-450 nm), Blue (400-500 nm), Green (500-600 nm) and Green+Red (500-700 nm) domains in Study 2 (n = 25). Pigmentation level was assessed by visual scoring and colorimetry at different time points postexposure, up to Day 43. RESULTS: Induced pigmentation was detected in all exposed conditions, peaking at 2 h and thereafter progressively decreasing but remaining persistent up to Day 43. In Study 1, UVA1 showed an additive effect with HEV, with a significant contribution coming from the Longest UVA1 rays (370-400 nm). Study 2 demonstrated that 24 h postexposure, the Blue domain accounted for 71% of VL-induced pigmentation, the HEV one for 47%, the Green one for 37% and the Green+Red one for 36%, confirming no significant effect for Red light. CONCLUSIONS: Altogether, these results underline the need for UVA1 photoprotection up to 400 nm and highlight the importance of protecting the skin from solar VL wavelengths and especially from HEV, Blue and Green light, to limit induced pigmentation.

Novel laser hair removal in all skin types.

BACKGROUND: Laser has been long accepted as a solution for excess or unwanted hair growth yet traditional lasers are not always ideal for safe and effective outcome for all skin types and hair characteristics. A diode laser module combining three wavelengths (755, 810, and 1064 nm) in a single pulse was developed to provide a fast and long-term solution for subjects with various profiles. AIMS: To evaluate the safety and efficacy of a Triple wavelength diode laser module for hair removal treatment in all skin types (Fitzpatrick I-VI). SUBJECTS AND METHODS: This was a prospective, dual centered, single-arm study. Subjects were treated with a novel diode laser module. Thirty-six subjects were enrolled, sixteen with Fitzpatrick skin types I-IV (46%) and twenty with Fitzpatrick skin types V-VI (54%). Treatment areas were axilla and bikini lines. Subjects underwent 4 treatment sessions at 6 weeks ± 5 days intervals and attended a follow-up visit 3 months after the last treatment session. 2D digital photographs were taken at baseline and at the follow-up visit, and a hair count was conducted by three blinded evaluators. RESULTS: A significant reduction in hair count between baseline and the 3-month follow-up visit was observed in both axilla and bikini lines for all skin types. The mean hair reduction was 41.5 ± 19.4% and 48.1 ± 20.9% in the axilla and bikini line, respectively. A significant hair reduction was also observed within skin type groups; mean hair reduction 45.5 ± 16.9% and 40.3 ± 17.2% in skin types I-IV and V-VI, respectively, indicating similar efficacy for both light and dark skin types. No serious adverse events were reported. CONCLUSIONS: This study demonstrates that the Soprano Titanium laser platform is safe and effective for hair removal treatment in all skin types.

The potential role of antioxidants in mitigating skin hyperpigmentation resulting from ultraviolet and visible light-induced oxidative stress.

Oxidative stress is an integral element that influences a variety of biochemical reactions throughout the body and is known to play a notable role in melanogenesis. Exogenous triggers of oxidative stress, such as ultraviolet radiation (UVR) and visible light (VL), lead to pigment formation through somewhat different pathways, but both share a common endpoint-the potential to generate cosmetically undesirable hyperpigmentation. Though organic and inorganic sunscreens are available to protect against the UVR portion of the electromagnetic spectrum, coverage is lacking to protect against the VL spectrum. In this manuscript, we review the phases of tanning, pathways of melanogenesis triggered by UVR and VL, and the associated impact of oxidative stress. We also discuss the known intrinsic mechanisms and paracrine regulation of melanocytes that influence their response to UVR. Understanding these mechanisms and their role in UVR-induced hyperpigmentation should potentially lead to identification of useful targets that can be coupled with antioxidant therapy to alleviate this effect.

La seguridad de las lámparas emisoras de radiación ultravioleta de uso cosmético desde el punto de vista de su regulación legal / Safety of UV lamps for cosmetic use: regulatory considerations

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Immediate pigment darkening and persistent pigment darkening as means of measuring the ultraviolet A protection factor in vivo: a comparative study.

BACKGROUND: Persistent pigment darkening (PPD) is a widely used in vivo method for measurement of ultraviolet (UV) A protection factor (UVAPF). However, with increased emphasis on UVA protection and sunscreen products with higher UVAPF gaining popularity, the immediate pigment darkening (IPD) method is drawing attention again. Furthermore, only about a quarter of the recommended quantity of sunscreen is used during daily activities. However, there is as yet no clearly defined relationship between the UVAPF and the amount of sunscreen applied. OBJECTIVES: To analyse the differences between the IPD and PPD methods, and to establish a relationship between the quantity of sunscreen application and the UVAPF. METHODS: Different doses of sunscreen were applied on the back of 15 healthy volunteers, and the UVAPF was measured using both the IPD and the PPD methods. RESULTS: Both methods proved to be effective for measuring the UVAPF. However, all the UVAPF values determined by the PPD method were lower than those determined by the IPD method. Additionally, an exponential relationship between the amount of sunscreen applied and the UVAPF was observed. CONCLUSIONS: The IPD method can also be used as an appropriate endpoint in the determination of UVA protection. It is time saving, and thus considerably lowers the risk of UV exposure, particularly when testing sunscreen products with higher UVAPF. We further state that in order to achieve the desired protective effect of the sunscreen, the quantity of application is also very important.

The physiological and phenotypic determinants of human tanning measured as change in skin colour following a single dose of ultraviolet B radiation.

Experimental study of the in vivo kinetics of tanning in human skin has been limited by the difficulties in measuring changes in melanin pigmentation independent of the ultravioletinduced changes in erythema. The present study attempted to experimentally circumvent this issue. We have studied erythemal and tanning responses following a single exposure to a range of doses of ultraviolet B irradiation on the buttock and the lower back in 98 subjects. Erythema was assessed using reflectance techniques at 24 h and tanning measured as the L* spectrophotometric score at 7 days following noradrenaline iontophoresis. We show that dose (P < 0.0001), body site (P < 0.0001), skin colour (P < 0.0001), ancestry (P = 0.0074), phototype (P = 0.0019) and sex (P = 0.04) are all independent predictors of erythema. Quantitative estimates of the effects of these variables are reported, but the effects of ancestry and phototype do not appear solely explainable in terms of L* score. Dose (P < 0.0001), body site (P < 0.0001) and skin colour (P = 0.0365) or, as an alternative to skin colour, skin type (P = 0.0193) predict tanning, with those with lighter skin tanning slightly more to a defined UVB dose. If erythema is factored into the regression, then only dose and body site remain significant predictors of tanning: therefore neither phototype nor pigmentary factors, such as baseline skin colour, or eye or hair colour, predict change in skin colour to a unit erythemal response.

Telomere-mediated effects on melanogenesis and skin aging.

UV-induced melanogenesis (tanning) and "premature aging" or photoaging result in large part from DNA damage. This article reviews data tying both phenomena to telomere-based DNA damage signaling and develops a conceptual framework in which both responses may be understood as cancer-avoidance protective mechanisms.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 25-31; doi:10.1038/jidsymp.2009.9.

Trends in UV irradiance of tanning devices in Norway: 1983-2005.

Indoor tanning increases skin cancer risk, but the importance of different parts of the UV spectrum is unclear. We assessed irradiance of tanning devices in Norway for the period 1983-2005. Since 1983, all tanning models needed approval before being sold or used. UV Type 3 limits were valid from late 1992 (<0.15 W m(-2) for CIE-weighted, i.e. erythemally weighted, short and long wave irradiances). We analyzed data from 90% of the approved tanning models (n = 446 models) and two large inspection surveys in 1998/1999 and 2003 (n = 1,341 tanning devices). Mean CIE-weighted short wave irradiance of approved models increased from 0.050 W m(-2) (95% confidence interval [CI] 0.045-0.055) in 1983-1992 to 0.101 W m(-2) (95% CI 0.098-0.105) in 1993-2005, and mean long wave from 0.091 W m(-2) (95% CI 0.088-0.095) to 0.112 W m(-2) (95% CI 0.109-0.115), respectively. Inspection surveys revealed short wave irradiances much higher than that approved. In 1998-1999, only 28% (293/1034) of the devices were equipped with correct sunlamps and only 1 out of 130 inspected establishments fulfilled all requirements. In 2003, corresponding numbers were 59% (180/307) of devices and 2 out of 52 establishments. Mean short and long wave irradiances of the inspected tanning devices in 2003 were 1.5 and 3.5 times, respectively, higher than the irradiance of natural summer sun in Oslo. In conclusion, the short wave irradiance has increased in indoor tanning devices in Norway over the last 20 years. Due to the high long wave irradiance throughout this period, the percentage of short wave irradiance was much lower than for natural sun.