The Relationship among Minimal Erythema Dose,Minimal Delayed Tanning Dose,and Skin Color

The relationship among minimal erythema dose (MED), minimal delayed tanning dose (MDTD), and skin color was examined in 16 healthy volunteers using three different spectra. The subjects were exposed to UVB, UVA+B, and UV+Visible light (UV+Visible) with a xenon arc solar simulator as a light source. The MEDs for UVB and UVA+B were less than the MDTDs, whereas the MED for UV+Visible was higher than the MDTD. There was no significant correlation between the MED and the MDTD for UVB or UVA+B. The MED for UV+Visible was significantly correlated to the MDTD (p<0.01). Skin color significantly correlated with MEDs for UVB and UVA+B (p<0.01), but not for UV+Visible. There was no significant correlation between skin color and the MDTD for any spectra. From these results, it is suggested that the relationship between erythemal and melanogenic responses is dependent on spectral bands of the light source and that skin color is a predictor of UV-induced erythema.     

118例志愿者紫外线最小红斑量值测定

目的 测定118例志愿者长波紫外线(UVA)和中波紫外线(UVB)的最小红斑量(MED)正常值。方法 以SUV1000型日光紫外模拟仪为光源,测定118例健康志愿者和非炎症性皮肤病患者UVA-MED和UVB-MED正常值。结果 UVA-MED均值男性为55J/cm²(18-95J/cm²),女性40J/cm²(15-100J/cm²);UVB-MED均值男性31mJ/cm²(12-95mJ/cm²),女性29mJ/cm²(8-95mJ/cm²)。男性UVA-MED显著高于女性(P<0.05),UVB-MED两性间差异无统计学意义(P>0.05)。皮肤光反应类型为Ⅲ型的受试者UVA-MED和UVB-MED均显著低于Ⅳ型(两种类型皮肤UVA-MED:在男性、女性均P<0.05;UVB-MED:在男性P<0.05,女性P<0.01)。女性的年龄与MED值无关;30-49岁男性UVB-MED低于其他年龄组,UVA-MED与年龄无关。遮光部位测得的UVA-MED和UVB-MED与户外停留时间长短无关。结论 皮肤光反应类型是决定MED的重要因素。     

中波高能紫外线最小红斑量值测定

目的探讨中波高能紫外线最小红斑量值(MED)范围及其与年龄、性别、皮肤日光反应类型的关系。方法以Dualight targeted Phototherapy System UV120-2的UVB作为照射光源,测定73名健康志愿者和35例白癜风患者腹部正常皮肤的MED值范围。结果108名受试者MED值为(189.17±56.156)mJ/cm2,范围为90～330mJ/cm2;Ⅲ型皮肤为(155.88±34.996)mJ/cm2(90～210mJ/cm2),Ⅳ型皮肤为(218.95±54.957)mJ/cm2(120～330mJ/cm2),Ⅲ型显著低于Ⅳ型(P<0.01)。男性受试者中,Ⅲ型为(154.29±39.443)mJ/cm2(90～210mJ/cm2),Ⅳ型为(224.4±54.854)mJ/cm2(150～330mJ/cm2),男性Ⅲ型显著低于Ⅳ型(P<0.01)。女性受试者中,Ⅲ型为(157±32.179)mJ/cm2(90～210mJ/cm2),Ⅳ型为(214.69±55.532)mJ/cm2(120～330mJ/cm2),女性Ⅲ型也显著低于Ⅳ型(P<0.01)。两性别组间和各年龄组间比较无统计学差异(P>0.05)。结论中波高能紫外线的MED值与性别和年龄无直接关系,皮肤日光反应类型是影响其重要因素。     

Sun protection factor measurement of sunscreens is dependent on minimal erythema dose

This study investigates the influence of skin colour and minimal erythema dose (MED) on the in vivo determination of sunscreen sun protection factors (SPFs). The MEDs of groups of 10-20 subjects were measured on the lower back with a 1000-W solar-simulated xenon arc lamp. Five sunscreens, with commercially measured SPFs ranging from 4 to 30 + were then tested on the different groups, and their SPFs were correlated with volunteers' MEDs. We found that the sunscreens had higher SPF values when tested on subjects with lower MEDs and paler skin. The SPF values obtained with our ultraviolet (UV) source were lower than the SPF values reported with commercially used solar simulators. We conclude that while SPF tests with artificial UV sources and pale-skinned volunteers can and should be used to rank the efficacy of various sunscreens in preventing sunburn, they should not be interpreted as measures of a sunscreen's absolute level of sun protection. Factors such as the differences in skin colour and MED between subjects used for SPF testing and the general population, the spectral differences between sunlight and artificial UV, as well as the tendency of the public to apply only small amounts of sunscreen and to re-apply it infrequently, mean that laboratory and sunlight SPFs may be markedly different.     

Skin typing, sun exposure, and sunscreen use in a population of Japanese

Distribution of Japanese skin types (JSTs), sun-exposure habits, and sunscreen use were surveyed in 379 new outpatients. The largest number of subjects belonged to JST class J-II (65%), J-I was second (24%), and J-III was third (11%). Eighty-eight percent of those studied had occasional or habitual sun exposure during the summer, and many were exposed for more than three hours per exposure day (80% of those with occasional exposure; 62% of those with habitual exposure). More younger persons had occasional sun exposure than older persons. More males had habitual sun exposure than females. Sunscreens were used by 41% of the subjects, but 77% of these used them without accurate understanding of the definition of the sun protection factor. More J-I subjects used sunscreens than J-II and J-III subjects. More females than males used them.     

An analysis of cumulative lifetime solar ultraviolet radiation exposure and the benefits of daily sun protection

ABSTRACT:  Cumulative exposure to ultraviolet radiation (UVR) increases the risk of developing skin cancer, particularly squamous cell carcinoma and basal cell carcinoma. Thus, the need for protection from the sun is widely advocated, but consumers generally associate such protection with the occasional extreme exposure and tend to ignore the risk of long-term exposure. In fact, a sun exposure model predicts that over a lifetime, a person will receive tens of thousands of minimal erythema doses worth of UVR through normal, daily, incidental exposure. The cumulative effect of casual sun exposure over the years underscores the need for everyday basic UVR protection in which even low level (SPF 4–10) sunscreens are shown to offer significant benefit. Analysis shows that daily protection can reduce lifetime exposure by 50% or more.     

广州地区102例正常人紫外线最小红斑量测定

目的:测定广州地区正常人紫外线最小红斑量(MED)的正常值范围,探讨其与性别、年龄、皮肤日光类型的关系。方法:以SUV1000型日光紫外模拟器作为照射光源,测定102名健康志愿者腹部正常皮肤的MED值(Ⅲ型、Ⅳ型皮肤)。结果:102名受试者MED均值:UVA为50.0 J/cm2,UVB为43.0 m J/cm2。不同皮肤类型间,Ⅲ型皮肤MED均值:UVA为38.5 J/cm2,UVB为36.1 m J/cm2;Ⅳ型皮肤MED均值:UVA为50.0 J/cm2,UVB为47.0 m J/cm2,Ⅳ皮肤MED均值均明显大于Ⅲ型皮肤(P值均<0.01)。不同性别间,男性MED均值:UVA为50.0 J/cm2,UVB为43.0 m J/cm2;女性:UVA为50.0 J/cm2,UVB为43.0 m J/cm2,不同性别间差异均无统计学意义(P值均>0.05)。不同性别的不同年龄阶段间UVA、UVB MED均值差异均无统计学意义(P值均>0.05);UVA-MED的正常值范围为≥30 J/cm2,UVBMED的正常值范围为≥29.1 m J/cm2。结论:紫外线MED的影响因素与皮肤日光反应类型有关,Ⅲ型皮肤UVA-MED、UVB-MED均明显低于Ⅳ型皮肤(P<0.01)。本组受试者MED与性别和年龄无直接关系。     

Skin phototyping in a Chinese female population: analysis of four hundred and four cases from four major cities of China

BACKGROUND/PURPOSE: The sun-reactive skin types in 404 Chinese females living in different cities were investigated in this study. METHODS: A questionnaire was designed according to the original concept of skin types proposed by Fitzpatrick and the investigation was conducted in two ways: self-administered reporting and then a personal interview. Minimal erythema dose (MED) and minimal persistent pigmentation dose (MPPD) were also measured in part of the volunteers with a standard solar simulator. RESULTS: The results show that in the way of personal interview, the predominant skin type of the investigated group is type III (71.4%), and then type II (14.7%) and type IV (14.2%), while in the self-reporting manner, the result is as follows: type III, 74.3%, type II, 25.6% and type IV, 1%. There are no skin type I, V or VI in the studied group. MED and MPPD from the same population show some relevance to the skin types, e.g. with the change of skin type from Type II to IV, the mean value of MED increases gradually and the MPPD decreases slightly. CONCLUSIONS: From the study we concluded that the skin types of the investigated Chinese females are principally type III (more than 70%), and then type II and type IV. The different ways of answering the questionnaire did not affect the results remarkably. The measurements of photobiology parameters confirmed that there is a certain correlation between skin types and MED or MPPD determined in this group of volunteers.     

A new method of phototesting before narrowband UVB therapy

Narrowband UVB therapy is versatile and generally preferred to broadband sources. Recently, a convenient device has been described which gives 10 different doses simultaneously to the forearm to determine the minimal erythema dose (MED). It is known there is no relation between sun reactive skin type and MED. Twenty-four individuals were tested using 26% increments giving a range of MED of between 0.38 J/cm2 and over 1.5 J/cm2. When compared to conventional window testing in 15 cases, it was found to be identical or within one increment.     

Topographic measurement of skin color by narrow-band reflectance spectrophotometer and minimal erythema dose (MED) in Koreans

Background/aims: Narrow-band reflectance spectrophotometer is one of the objective and quantitative devices for measuring the skin colors. There has been some controversy concerning the relationship between the objectively measured skin color and cutaneous responsiveness to ultraviolet radiation, including minimal erythema dose (MED). The aims of this study were to compare the color of Korean brown skin with that of Caucasians by objective measurement with the narrow-band reflectance spectrophotometer, and to determine whether the skin color has any correlation with MED in Koreans, and demonstrate differences in this correlation according to the anatomical sites. Methods: With narrow-band reflectance spectrometer, skin colors were measured at 17 body sites of 20 healthy Korean male volunteers after measuring MED for the same subjects. Results: The constitutional skin color, as measured by the melanin index of the nonexposed sites, showed a statistically significant correlation with MED values, whereas the facultative skin color did not. The Korean brown skin showed higher melanin index and lower erythema index compared with that of Caucasians. Conclusions: We confirmed significant differences in the correlation between MED and melanin indices, depending on the anatomic sites. This suggests that selection from various sites, even among the nonexposed sites, is quite important and deserves further evaluation.     

UV transmission and UV protection factor (UPF) measured on split skin following exposure to UVB radiation — correlation with the minimal erythema dose (MED)

In this study the ultraviolet (UV) transmission of split skin exposed to UVB radiation and of non-exposed skin was compared in the 280-390 nm wavelength range and quantified. In addition, the correlation between the increase in the minimal erythema dose (MED) associated with a defined exposure to UVB and the ultraviolet protection factor (UPF) calculated from the transmission data was investigated. The study population consisted of 12 patients. Two pieces of split skin of the same thickness (0.3 mm) were taken from the right thigh of each patient. One specimen was removed from an area of non-exposed healthy skin and the other from an area which had been exposed to UVB radiation for a period of 12 days in which the initial dose of 1/3 MED was raised by 1/3 MED every 4 days. The split skin specimens were stretched over a special frame; subsequently, the UV transmission was determined with a spectrophotometer. The mean values obtained for UV transmission were all significantly below the initial data for non-exposed split skin. In the UV range of 280--390 nm, the transmission measured in the exposed specimens was 49.1% of the value measured in the non-exposed split skin (P<0.05). The corresponding values for the UVA range (315--390 nm) and the UVB range (280--315 nm) were 50.1% and 29.5%, respectively (P<0.05), based on the initial transmission data obtained from non-exposed skin. The clinical determination of MED after 12 days of exposure to UVB yielded mean values that were 3.2 times the initial values. Moreover, the mean UPFs calculated from the transmission data measured at the end of the 12-day exposure period were also about three times the initial values. The present study has thus established a significant correlation between the clinical MED values and the UPFs calculated from the transmission data measured following exposure to UVB.     

Minimal erythema dose and minimal melanogenesis dose relate better to objectively measured skin type than to Fitzpatricks skin type

Background: Fitzpatrick skin type (FST I–IV) is a subjective expression of ultraviolet (UV) sensitivity based on erythema and tanning reactivity after a single exposure. Pigment protection factor (PPF) is an objective measurement of skin sensitivity in all skin types after a single exposure. Methods: The aim was to compare FST and PPF with clinically determined minimal erythema dose (MED) and minimal melanogenesis dose (MMD) in 84 persons with skin types I–V both after single and multiple exposures (one, four, five, six, or 12) to buttock and back skin. Results: FST was better correlated to MED than to MMD, and FST correlated better to constitutive than to facultative pigmented areas after multiple exposures rather than to a single exposure. PPF was generally much better correlated to MED and MMD than FST especially after a single exposure and multiple exposures with steady‐state pigmentation. Multiple regression analyses showed that MED was the only significant, or most important determinator, of both FST and PPF. The correlation coefficient was highly significant for PPF (r²=82). Conclusions: PPF is a better predictor of the individual UV sensitivity (linear relation) than FST (only 4 grades) and PPF can substitute FST.     

The importance of using broad spectrum SPF 30+ sunscreens in tropical and subtropical climates

BACKGROUND/PURPOSE: To evaluate the Sun Protection Factors (SPF) of six sunscreens sold in Australia, using an ultraviolet (UV) spectrum which mimics sunlight as closely as possible, and by using volunteers with a range of skin types to reflect the Australian population. METHODS: Open prospective study. Seventy-five volunteers of skin types 1-3 were tested in a dermatology research laboratory in a major metropolitan teaching hospital in Sydney, Australia in the years 2000-2001. Sunscreen SPF's were measured using a solar simulator and procedures which complied with the Australian Standard. RESULTS: Sun Protection Factors, as measured by a solar simulator more approximating to natural sunlight than commercial simulators, and using individuals of skin type 1-3, were shown to be approximately between 50% and 80% of their labelled value. Sunscreen application method can also affect SPF measurement. CONCLUSION: For a number of reasons, Sun Protection Factors are often overestimated. In addition, many individuals use less than half the amount of sunscreen recommended. Those living in tropical or subtropical climates should be encouraged to use only broad spectrum SPF 30+ sunscreens to achieve adequate protection from the sun.     

华北、华东和华南地区人群皮肤颜色与年龄的关系

目的探讨华北、华东和华南三大地区中国人不同年龄段人群皮肤颜色差异,以选择适合用于美白功效评价的测试部位。方法利用同一型号色差测试仪测量该三大地区各200名(分为四个年龄段)受试者的额头、左脸颊、左手臂内侧和手背等四个部位的皮肤颜色。采用L*a*b*色度系统测量值计算得出每一个志愿者的个人类型角(individual type angle,ITA°)。结果三个受试地区人群额头、左脸颊和左手背的皮肤颜色随着年龄增加而逐渐加深。各个地区受试人群的额头、左脸颊和左手背的皮肤颜色均显示出了与年龄有较强的相关性。随着年龄的增长,其额头和左脸颊皮肤颜色差异均有统计学意义(P均<0.05)。结论不同年龄段人群肤色存在差异,皮肤颜色会随着年龄的增长而逐渐加深。左手臂内侧受年龄与环境的影响不明显,肤色相对稳定,适合作为美白功效评价的受试部位。     

硬皮病皮损CTGF,COL-Ⅰ Ⅲ的检测及意义

目的研究硬皮病(SD)发病与结缔组织生长因子(CTGF)及Ⅰ,Ⅲ型胶原(COL-Ⅰ,Ⅲ)表达的关系,探讨硬皮病可能的发病机制。方法采用免疫组化SP法检测72例SD患者皮损中CTGF蛋白及COL-Ⅰ,Ⅲ蛋白表达,18例正常人皮肤组织作为正常对照组。结果①CTGF在SD患者皮损的表达强于对照组,在系统性硬皮病(SSc)表达高于局限性SD(P均<0.001);②COL-Ⅰ在SD患者皮损的表达强于对照组,但在SSc组、局限性SD组间表达无明显差异(P>0.05);COL-Ⅲ在SD患者皮损的表达与对照组相近(P>0.05);相关分析表明COL-Ⅰ与CTGF的表达呈正相关(r5SC=0.728,rSD=0.71,P均<0.01)。结论COL-Ⅰ与CTGF在SD患者皮肤硬化过程中起一定作用,可能与SD的病理纤维化形成有关。     

黄芪甲苷乳膏对光老化小鼠皮肤组织MDA含量及SOD、GSH-px活力的影响

目的研究皮肤外用黄芪甲苷对紫外线照射引起的小鼠光老化皮肤的影响。方法BACB/C小鼠随机分成6组:正常对照组(A)、模型组(B)、模型+基质组(C)、模型+黄芪甲苷低剂量组(D)、模型+黄芪甲苷中剂量组(E)、模型+黄芪甲苷高剂量组(F)。模拟UV长期照射,造成皮肤光老化小鼠模型。给药组照射同时外用黄芪甲苷乳膏。用组织切片HE染色观察皮肤结构改变;以生化分析方法测定MDA含量及SOD、GSH-px活性;测定UVB最小红斑量,计算日光防护系数(SPF)值。结果模型组小鼠皮肤组织MDA含量明显增加,SOD、GSH-px活性明显降低(P0.01),病理切片呈现光老化状态;与模型组比较,黄芪甲苷高剂量组可显著降低MDA含量,提高SOD、GSH-px活性,(P0.01);随着外用黄芪甲苷乳膏时间延长,最小红斑量不断增高,90d时SPF=25。结论黄芪甲苷乳膏对紫外线照射引起的小鼠皮肤光老化具有保护作用。其机制可能一方面是黄芪甲苷本身具有清除自由基的作用;另一方面黄芪甲苷可以通过提高SOD、GSH-px活力来达到抗氧化的目的。     

Comparison of three techniques for evaluating skin erythemal response for determination of sun protection factors of sunscreens: high resolution laser Doppler imaging, colorimetry and visual scoring

BACKGROUND/PURPOSE: Sun protection factor (SPF) measurement is based on the determination of the minimal erythema dose (MED). The ratio of doses required to induce a minimal erythema between product-treated and untreated skin is defined as SPF. The aim of this study was to validate the conventionally used visual scoring with two non-invasive methods: high resolution laser Doppler imaging (HR-LDI) and colorimetry. Another goal was to check whether suberythemal reactions could be detected by means of HR-LDI measurements. MATERIALS AND METHODS: Four sunscreens were selected. The measurements were made on the back of 10 subjects. A solar simulator SU 5000 (m.u.t., Wedel, Germany) served as radiation source. For the visual assessment, the erythema was defined according to COLIPA as the first perceptible, clearly defined unambiguous redness of the skin. For the colorimetric determination of the erythema, a Chromameter CR 300 (Minolta, Osaka, Japan) was used. The threshold for the colorimetry was chosen according to the COLIPA recommendation as an increase of the redness parameter delta a* = 2.5. For the non-contact perfusion measurements of skin blood flow, a two-dimensional high resolution laser Doppler imager (HR-LDI) (Lisca, Link?ping, Sweden) was used. For the HR-LDI measurements, an optimal threshold perfusion needed to be established. RESULTS: For the HR-LDI measurements basal perfusion +1 standard deviation of all basal measurements was found to be a reliable threshold perfusion corresponding to the minimal erythema. Smaller thresholds, which would be necessary for detection of suberythemal responses, did not provide unambiguous data. All three methods, visual scoring, colorimetry and HR-LDI, produced similar SPFs for the test products with a variability of < 5% between methods. The HR-LDI method showed the lowest variation of the mean SPF. Neither of the instrumental methods, however, resulted in an increase of the sensitivity of SPF determination as compared with visual scoring. CONCLUSION: Both HR-LDI and colorimetry are suitable, reliable and observer-independent methods for MED determination. However, they do not provide greater sensitivity and thus do not result in lower UV dose requirements for testing.     

Change in ultraviolet (UV) transmission following the application of vaseline to non-irradiated and UVB-exposed split skin

BACKGROUND: Topical preparations such as emollients used in combination with phototherapy can interfere with such treatment. OBJECTIVES: This study was performed to investigate the impact of vaseline on the ultraviolet (UV) transmission of non-irradiated split skin and on split skin previously exposed to UVB radiation. METHODS: Split-skin specimens were obtained from 20 patients. In each case, one sample was taken from an area of non-irradiated skin, while the second was taken from an area that had been previously exposed to UVB. The transmission was spectrophotometrically measured with split skin placed in specially designed quartz glass cuvettes before and after the application of two different amounts of vaseline (2.5 and 17.5 mg cm-2). RESULTS: Application of vaseline to skin previously exposed to UVB caused significant (P < 0.0001) changes in UV transmission in certain wavelength ranges. In the UVA range, a greater increase in transmission was achieved with 2.5 mg cm-2 vaseline, whereas in the UVB range, a greater increase was achieved with 17.5 mg cm-2 vaseline. The thicker the layer of vaseline applied, the lower was the difference in transmission between non-irradiated split skin and UVB-exposed split skin. CONCLUSIONS: Application of the correct amount of vaseline can enhance transmission in either the UVA or UVB range, and would enable dose reduction during a course of phototherapy.