Erythema Dose Research Articles

High Oral Vitamin D3 Intake Does Not Protect Against UVR-induced Squamous Cell Carcinoma in Mice.

The effect of vitamin D on skin carcinogenesis is unclear. Vitamin D derivatives may protect against ultraviolet radiation (UVR)-induced DNA damage, immune suppression, and skin carcinogenesis. However, some epidemiological studies have reported an increased incidence of skin cancer associated with high serum vitamin D levels. We investigated the effect of vitamin D supplementation on serum, skin, and tumor vitamin D levels and on skin cancer development in hairless immunocompetent mice. Female C3.Cg-Hrhr/TifBomTac immunocompetent mice (n=125) were randomly separated into five groups. Two groups received a high vitamin D3 diet (4.5 μg/day/mouse). One group received a medium vitamin D3 diet (2.3 μg/day/mouse). Two groups received a standard diet (0.045 μg/day/mouse). Three standard erythema doses of UVR were given three times per week to three groups. Animals on a high vitamin D3 diet had ~150-fold higher serum vitamin D3 levels (p=0.00016) and 3-fold higher serum 25-hydroxyvitamin D3 [25(OH)D3] levels (p=0.00016) than those on a standard diet. For mice on the medium vitamin D3 diet, serum vitamin D3 and 25(OH)D3 levels were 18-fold and 2.3-fold higher than for the standard diet, respectively (p=0.00016). All UVR-exposed mice developed tumors. Vitamin D3 levels were lower in the tumor than the skin (p<0.0001). High and medium supplementation with vitamin D3 did not affect tumor development (p>0.05). In mice, vitamin D levels in the serum, skin, and tumors were augmented by supplementation, but this did not affect the development of UVR-induced skin tumors.

Role of conjunctival ultraviolet autofluorescence device, as an indicator of ocular ultraviolet radiation exposure in pterygium and pinguecula among outdoor workers in Southern India

Background: Objective of the study was to evaluate conjunctival ultraviolet autofluorescence (CUVAF) device, as an indicator of ocular ultraviolet (UV) radiation exposure in pterygium and pinguecula among outdoor workers.Methods: Subjects above 21 years of age engaged in outdoor work were enrolled based on inclusion criteria. A standardized questionnaire was administered to assess the lifetime UV exposure and erythemal UV dose were noted from the tropospheric emission monitoring internet service (TEMIS). Autofluorescence photographs of the nasal and temporal conjunctiva were taken using CUVAF tool and were assessed for presence of damage with exposure to UV radiation. Logistic regression was done to estimate the risk.Results: A total of 229 participants, among them 205 (89.5%) were males and 24 (10.4%) were females. This included 75 (32.7%) with pterygium in one or both eyes, 69 (30.3%) with pinguecula and 85 (37.1%) normal. Median conjunctival damage in pterygium was 45.3 mm2 (IQR 35.1), in pinguecula was 17.9 mm2 (IQR 16.0) and in normal was 11.1 mm2 (IQR 25.2) demonstrating significant difference between the groups (p&lt;0.001). The conjunctival damage was positively associated with pterygium OR: 1.12 (95% CI: 1.05-1.71, p&lt;0.001) and pinguecula OR: 1.10 (95% CI: 1.07-1.49, p=0.01). Rural location, literacy status were the significant risk factors for development of pterygium with odds of 2.97 (95% CI: 1.46-6.05, p=0.003) and 4.84 (95% CI: 1.86-12.73, p=0.001) respectively.Conclusions: Increasing conjunctival damage was found to be associated with prevalent pterygium.

Correlation between Objective Measures of Sun Exposure and Self-Reported Sun Protective Behavior and Attitudes in Predominantly Hispanic Youth.

Melanoma incidence is increasing, with poor prognosis cases growing faster in California Hispanics than in non-Hispanic whites. Ultraviolet Radiation (UVR) exposure as a child has been found to disproportionately increase the risk of melanoma. To determine correlates of UVR exposure in this high-risk population, we conducted a study in predominately Hispanic 4th and 5th grade classrooms in Los Angeles County, a high UVR environment, during the spring. To address potential reporting bias, electronic UV dosimeters were utilized to objectively measure the association between UVR exposure and constructs (acculturation, sun protective behavior and knowledge, family interventions) obtained on baseline questionnaires (n = 125). Tanning attitude (wanting to get a tan) was associated with lower median time spent outside (1.73 min versus 22.17, AUC 82.08, Sensitivity 0.78, Specificity 0.73) and standard erythemal dose (SED) on weekends, but positively associated with sun protective knowledge. Sun protective knowledge and family discussion of sunscreen were also inversely associated with objectively measured time outside. Students spent a median 30.61 (IQR 19.88) minutes outside per day (SED 0.30, IQR 0.20), with only 35.70% of it occurring in nonschool hours. We determined the majority of UVR exposure in this population occurs at school, providing valuable guidance for future interventions.

The comprehensive assessment of epigenetics changes during skin development

Epigenetic regulation is critical to multiple physiological and pathological processes. However, little is known regarding the epigenetic changes during neonatal skin development and skin aging, and in response to ultraviolet (UV) exposure. The transcriptomes of human skin samples from different ages or irradiated with different types and doses of UV light were analyzed using R (version 4.0.3) software. The epigenetic landscape of the skin, including histone modifications, genetic imprinting and m6A modification, which are mainly involved in collagen formation, extracellular matrix organization, immune function and keratinization, underwent significant changes during neonatal to adult development. Epigenetic effectors such as IGF2BP2, GATA2, GATA3, CPA4 and CDK1 were significantly correlated with extracellular matrix organization, and VEGFA, CDK1 and PRKCB with skin immune function. The m6A readers such as IGF2BP2, IGF2BP3, HNRNPA2B1 and EIF3G showed significant correlation with extracellular matrix organization, metabolism, or antigen processing and presentation. Small doses of UV exposure only induced changes in the expression levels of some epigenetic effectors, without any significant effect on the overall epigenetic landscape. However, the minimal erythema dose of UV exposure altered multiple epigenetic effectors regulating extracellular matrix organization, cell-matrix adhesion, innate immune response, mitochondrial function and mRNA processing. In addition, epigenetic changes following UV exposure were more pronounced in the elderly skin compared to the younger skin. In conclusion, histone modifications, genetic imprinting and m6A modification play critical roles during skin development, and a large dose of UV exposure can significantly change the expression of multiple epigenetic effectors.

Modeling acute and cumulative erythemal sun exposure on vulnerable body sites during beach vacations utilizing behavior-encoded 3D body models

Vacationers in a high-solar-intensity beach setting put themselves at risk of ultraviolet radiation (UV) over-exposure that can lead to acute and chronic health consequences including erythema, photoaging, and skin cancer. There is a current gap in existing dosimetry work on capturing detailed time-resolved anatomical distributions of UV exposure in the beach vacation setting. In this study, a radiative transfer model of the solar conditions of Tampa Bay, St. Petersburg, Florida, USA (27.8°N, 82.8°W) is combined with an in silico three-dimensional body model and data on typical beach vacation behaviors to calculate acute and cumulative body-site-specific UV exposure risk during a beach vacation. The resulting cumulative UV exposure calculated for a typical mix of clothing choices, settings, and activities during a week-long (7-day) beach vacation is 172.2 standard erythemal doses (SED) at the forearm, which is comparable with the average total annual UV exposure of European and North American residents and consistent with existing dosimetry studies. This model further estimates that vacationers choosing to spend a full day exclusively in the beach or pool setting can experience UV exposure in excess of 50 SED a day at multiple body sites. Such exposure indicates that significant sun protective measures would be required to prevent sunburn across all skin types in this setting. This work clarifies the significant role that beach vacations play in UV exposure and corresponding acute and cumulative health risks and highlights the importance of behavioral choices (including clothing, activity and photoprotection) as crucial factors in differentiating personal solar exposure risks.Graphical abstract

Solar UV Measured under Built-Shade in Public Parks: Findings from a Randomized Trial in Denver and Melbourne.

Reducing exposure to ultraviolet radiation (UV) is crucial for preventing UV-induced diseases of the skin and eyes. Shade may offer significant protection from UV. More empirical research to quantify the UV protection offered from built shade is needed to guide disease prevention practices and confidence in investment in shade. This study quantified UV levels under built-shade relative to unshaded passive recreation areas (PRAs) over summer months in parks in two cities. In a randomized controlled trial, n = 1144 UV measurements were conducted at the center and periphery of PRAs in a total sample of 144 public parks as part of pretest and posttest measures of use of the PRAs by park visitors for three recruitment waves per city during 2010 to 2014. Following pretest, 36 PRAs received built-shade and 108 did not. Regression analyses modelled pre-post change in UV (Standard Erythemal Dose (SED) per 30 min) at PRAs; and environmental predictors. Mean UV at the center of built-shade PRAs decreased from pretest to posttest ( = 3.39, = 0.93 SED), a change of = −3.47 SED relative to control PRAs (p < 0.001) adjusting for the covariates of ambient SED, (cosine) solar elevation and cloud cover. Clouds decreased and solar elevation increased UV levels under shade. No significant differences in UV by shade design occurred. A substantial reduction in exposure to UV can be achieved using built-shade with shade cloth designs, offering considerable protection for shade users. Supplementary sun protection is recommended for extended periods of shade use during clear sky days.

Diacetylene-Zinc(II)-Zinc Oxide Nanocomposites for Colorimetric Detection of Ultraviolet-A Light

Polydiacetylenes (PDAs) have received widespread attention as chromatic sensors of various stimuli. The utilization of PDA materials for detecting ultraviolet-A (UVA) light, however, is quite rare. This study introduces a facile approach for enhancing the UVA-responsive property of PDAs. The incorporation of zinc oxide (ZnO) nanoparticles into the assemblies of diacetylene monomers, 10,12-pentacosadiynoic acid (PCDA), creates PCDA/Zn2+/ZnO nanocomposites. We have found that the nanocomposites change from colorless to blue upon exposure to UVA light. The intensity of blue color systematically increases with the UVA dose. The sensitivity to UVA light can be enhanced by increasing the ZnO ratios within the nanocomposites. Various types of UVA colorimetric sensors can be fabricated by incorporating the nanocomposites into a filter paper, hydrogel, and coconut oil. Interestingly, coconut oil-based sensors exhibit a color transition from colorless to blue with increasing UVA dose in sunlight from 0 to 50 J/cm2. This property allows their utilization for colorimetric detection of minimal erythema dose of UVA light, 33.27 J/cm2, for all skin types of normal people. The preparation of the nanocomposites is simple and cheap, suitable for large-scale production. The nanocomposites can be further developed for colorimetric detection of UVA radiation from sunbeds tanning, phototesting, and UV curing applications.

STUDY OF ULTRAVIOLET SOLAR RADIATION IN DUHOK CITY UNDER CLEAR SKY CONDITIONS

This work focused on the UV solar radiation measurements under clear sky conditions for typical days in months (April to July) when the UV radiation is expected to have the highest values in Duhok city. Two types of UV, (UVA and UVB) were measured from April to July under clear sky conditions. The maximum UVA (wavelength 315-400 nm) irradiance (38 and 37) W/m2 was measured at noon in June and July, respectively. The minimum UVA of 30 W/m2 was recorded at April noon. In July, the hourly UVA ranged between 2.6 W/m2 at 6:00 pm to 37 W/m2 at 12:00 pm; maximum UVB (wavelength 280-315 nm) irradiance of 1.9 W/m2 was measured in July noon’s, and a minimum of 1.4 W/m2 at April noon. The effect of the atmosphere (solar zenith angle) on the UVB clearness index was investigated and a functional relationship between them was developed. Finally, the time required for UVB minimum erythemal dose was estimated.

Exposure to solar UV radiation of Polish teenagers after the first COVID-19 lockdown in March–April 2020

In Poland, schools were closed from March to June 2020 due to the COVID-19 epidemic. During the lockdown (March–April), everyone was advised to stay at home. From May, students were allowed to spend time outdoors. We examine their exposure to solar UV radiation during the period of virtual learning at schools (May–June), vacations (July–August) and the first month of typical learning (September). Primary and high school students aged 12–18 completed a questionnaire on the details of their outdoor activities and the weather at the exposure site. A total of 146 anonymous questionnaires were registered for the study. The survey responses provided input to a radiative transfer model to estimate erythemal and vitamin D doses obtained by teenagers during outdoor activities. The results from 48% of the questionnaires indicated that students’ exposure exceeded 1 minimal erythema dose (MED) during the day. Corresponding doses of sun-synthesized vitamin D, in excess of 1000 international units (IU) and 2000 IU, were found in 77% and 66% of the surveys, respectively. Only 12% of the teenagers declared that they use sunscreen. The overexposure (> 1 MED) increased with age. It was found in 72% and 26% of surveys among the students aged 17–18 and 12–14, respectively. Teenagers seem to have tried to compensate for the lack of sunlight during the lockdown by engaging in outdoor activities permitted since May. While those activities could have improved their vitamin D levels, they also put them at a higher risk of developing erythema.

A predictive model of the requisite minimal erythema dose between 308-nm monochromatic excimer light and 311-nm narrowband Ultraviolet-B light.

There are limited data in the relationship between the minimal erythema dose (MED) of 308-nm monochromatic excimer light (MEL) and 311-nm Narrowband UVB (NB-UVB). To establish a predictive model of the relationship between MEDs of both wavelengths. An MED test was performed on the back of 40 healthy Thai volunteers. One side was irradiated with 308-nm MEL, and the opposite side was irradiated with 311-nm NB-UVB. The correlation and a predictive model of the relationships were then analyzed. There was a positive correlation in the MED of both wavelengths (r=0.82, p < 0.001). A predicted MED of 308-nm MEL was based on Y=62.421 + 0.439X, where Y and X were a predicted MED of 308-nm MEL and an actual 311-nm NB-UVB, respectively. This model could predict an MED of 308-nm MEL by using an actual MED of 311-nm NB-UVB with a root mean square difference of 13.64%, and a mean bias difference of 0.63%. All volunteers were Fitzpatrick's skin phototype type IV. The predictive model might not generalize to other skin phototypes. We established a predictive model of the relationship between MED of 308-nm MEL and 311-nm NB-UVB with acceptable accuracy.

Reconstruction and variability of high daily erythemal ultraviolet doses and relationship with total ozone, cloud cover, and albedo in Novi Sad (Serbia)

AbstractIn this paper, a method previously developed for reconstructing daily erythemal ultraviolet (UVery) doses in Novi Sad (Serbia) was improved and used for estimating daily UVery over the period 1971–2018. The proposed new method uses reanalysed total ozone column (TOC) data and snow cover as an input and is based on the empirical relationship between relative sunshine duration and relative UVery doses. Introducing reanalysed TOC data and snow cover data significantly improved the quality and accuracy of the reconstructed UVery time series, particularly in the winter season. The reconstructed time series revealed the statistically significant increase in summer and winter UVery in the 1980s and the first half of the 1990s (+8.78% and + 13.14% per decade, respectively), which was linked to the statistically significant decline in TOC (−4.13 and −7.36% per decade, respectively). The study focuses on days with high erythemal UV dose (highUVery), which is defined based on the 90th percentile of the daily UVery for each month. Moreover, the influence of low TOC, low cloud cover conditions, and high surface albedo on highUVery was analysed on a seasonal basis. The results of this study show that highUVery days increased from the 1980s, particularly strongly in the period of TOC depletion. A fraction of highUVery days in the last two decades was large (12.29%), which is higher than in the previous periods (6.97 and 8.68% in the period before and during TOC depletion, respectively). The occurrence of highUVery days was influenced mostly by low cloud cover (89.71% of days), and low TOC (82.23% of days). In the winter season, high surface albedo influenced the appearance of 19.18% of highUVery days. However, overall the interaction of low cloud cover and low TOC in all seasons most often led to the appearance of highUVery days.

Innovative digital solution supporting sun protection and vitamin D synthesis by using satellite-based monitoring of solar radiation.

Public health campaigns advise minimising UV radiation (UVR)exposure to prevent skin cancer and precancer,e.g. actinic keratosis (AK). A 3-day clinical field study, in Brazil, was performed to evaluate the mobile app Sun4Health® by siHealth Ltd. The app performs real-time monitoring of both erythemal and vitamin D-effective solar radiation doses using satellite data, enabling personalised recommendations on optimal sun exposure time and sunscreen use. When coupled to a wearable device, the app also provides body-site specific recommendations ("3D" version). 59 healthy volunteers were randomised into 3 groups, each given a different app providing: (1) ultraviolet indexonly (control app), (2) personalised recommendations and sun overexposure alerts (Sun4Health® app), (3) as (2) but connected via Bluetooth to a wearable device to monitor sun exposure in 3D (Sun4Health®-3D app). Participants were offered sunscreens (SPF 30 and 50) to use at their discretion. Erythema, quantified by reflectance spectroscopy, was assessed daily in the mornings and evenings on six body sites. Serum vitamin D (25(OH)D3) was measured before and after the study. Mean increase of erythema (Mexameter® units ± SD) of all exposed body sites combined over 3days showed 55.76 ± 47.47 for group 1, 40.27 ± 37.91 for group 2 and 37.12 ± 30.69 for group 3 (p < 0.05 for all groups). Mean increase of serum 25(OH)D3 (nmol/l ± SD) showed 1.32 ± 36.49 for group 1, 6.38 ± 21.19 for group 2 and 18.68 ± 35.45 for group 3 (p > 0.05 for all groups). The results show that the Sun4Health® app is safe to use and can modify behaviour to reduce skin erythema (sunburn) yet not decreasing vitamin D status.

In vitro safety evaluation of sunscreen formulation from nanostructured lipid carriers using human cells and skin model

There is a risk of toxicological reactions due to systemic absorption and photo-instability of sunscreens. The study aimed to investigate the safety profile (cytotoxicity, phototoxicity, photostability, UV filter release profile, and skin irritation properties) of sunscreen (NLC-TRF sunscreen) produced from nanostructured lipid carriers (NLCs) and tocotrienol-rich fraction (TRF). The cytotoxicity and phototoxicity of the sunscreen were evaluated on normal human dermal fibroblast (NHDF) and skin irritation properties was tested on skin model. Besides, the photoprotection in pre- and post-UV irradiation were analysed to determine the photostability. Additionally, the release profile for UV filters (diethylamino hydroxybenzoyl hexyl benzoate (DHHB) and ethylhexyl triazone (EHT)) were evaluated. The NLC-TRF sunscreen demonstrated no cytotoxicity and skin irritation to cause cell death. It showed no phototoxic effect and high photostability up to 10 Minimal Erythema Dose (MED) to ensure high SPF value above 50 and broad-spectrum of UV absorption. The NLC-TRF sunscreen implies its safety for topical application with sustainable release profile for UV filter (cumulative release of 28% for DHHB and 40% for EHT after 8 h) due to the application of NLCs. The results suggest that the NLC-TRF sunscreen is an advanced formulation with improved stability and is safe for topical delivery.

Dynamic visualization of ultraviolet dose on skin with sunscreen applied using minimum erythema dose.

Visualizing the ultraviolet (UV) dose on skin serve as an intuitive approach to ensure appropriate sunscreen usage and reduce the risk of erythema. UV dose is determined by a number of external factors, such as properties of sunscreens, weather, and type of outdoor activity. We propose a framework for visualizing UV doses that considers various external factors. First, the skin of a three-dimensional human model was represented using triangular meshes, and various static postures and dynamic motions were simulated to express outdoor activities. Then, we evaluated the persistency and insufficiency properties of sunscreen, which are time dependent and directly affect the effectiveness of the sunscreen skin protection factor (SPF) during UV exposure. Finally, to calculate the UV dose in real time, we tracked the trajectory of the sun and motion of the skin while considering the time-dependent properties of sunscreen. An S/W system was implemented based on the proposed framework to visualize the distribution of UV doses through dynamic color changes in exposed skin areas. The color types include true colors, which represent the minimum erythema dose (MED), and pseudo colors representing states before 1 MED is reached. We devised various examples to discuss the usability of the proposed framework. The system conveniently displays the MED according to an individual's skin phototype. When the properties of a wide range of commercial sunscreens are added to the system database, it is expected that the rate of appropriate sunscreen usage by customers will increase.

UVR Exposure and Prevention of Street Construction Workers in Colombia and Germany.

(1) Solar ultraviolet radiation (UVR) poses a major risk factor for developing skin cancer after years of chronic exposure. The irradiation is strongly dependent upon the activity or occupation carried out, but also on the climate conditions at the workplace. Knowledge of both has been tested within the occupational group of road construction workers in Colombia and Germany. (2) The GENESIS-UV measurement system has been used at both locations for consistency. A number of workers in both countries wore an electronic data logging dosimeter for several months to deliver detailed information on UVR exposure. (3) It was found that in a tropical climate, UVR exposure remains constant throughout the year, while in a temperate climate seasonal effects are visible, superimposed by behavioural aspects e.g., in springtime. The daily distribution of the radiation shows a distinct dip, especially in the Colombian data. Derived data show the high fraction of working days exceeding a threshold set by the skin type. (4) Road construction work involves high UVR exposure. In both countries, preventive measures are required to reduce the personal exposure to a minimum. Exceedance of the minimal erythema dose (MED) suggests a possible enhancing effect, especially in fair skinned people. Intercomparison of UVR exposure at workplaces is possible between countries and climate zones, emphasizing efforts for global action against skin cancer.

Modulating effects of oral administration of Lycii Fructus extracts on UVB-induced skin erythema: A Randomized, placebo-controlled study.

Severe UV exposure induces skin inflammation, causing erythema. Lycii Fructus (Lycium barbarum and Lycium chinense) is a potential antioxidant agent with a high content of polyphenols, including rutin and chlorogenic acid. This study examined the effects of Lycii Fructus extract (LFE) on UVB-induced skin erythema in humans. Healthy volunteers were randomly assigned to one of two groups and received UVB irradiation at 1.5 minimal erythemal dose (MED) on day 0 at three designated sites on their backs, and the skin color was measured until day 7. After an 8-week treatment with LFE (900 mg/day) or placebo, UVB irradiation (l.5 MED) was applied again at different sites on day 63. Skin color was continuously measured in each group until day 69. LFE tablet administration for 8 weeks significantly inhibited UVB-induced erythema formation and increased the MED by 13%. Erythema formation peaked on the first day after UVB irradiation, but gradually dissipated over the next several days. LFE tended to accelerate erythema disappearance. To determine the polyphenol responsible for the protection against UVB-induced skin damage, the effects of LFE-derived polyphenols and their metabolites on UVB-induced cytotoxicity were examined in vitro. The major intestinal metabolite of rutin and LFE significantly attenuated phototoxicity and in human keratinocyte HaCaT cells. Quercetin enhanced intracellular glutathione levels in HaCaT cells, even though LFE did not increase it. Together, the results showed that LFE inhibited erythema formation and accelerated erythema dissipation, possibly through its direct antioxidative action.

Photoprotective and Antiaging Effects of a Standardized Red Orange (Citrus sinensis (L.) Osbeck) Extract in Asian and Caucasian Subjects: A Randomized, Double-Blind, Controlled Study.

The increase in solar ultraviolet radiation (UVR) that reaches the Earth’s surface should make us reflect on the need to develop new approaches in protecting the skin from UVR exposure. The present study aims to evaluate the photoprotective and antiaging efficacy of a red orange extract (100 mg/day) in both Asian and Caucasian subjects. A randomized, double-blind, controlled study was carried out in 110 Asian and Caucasian subjects. Product efficacy was measured as follows: (1) the photoprotective effect was measured by the minimal erythema dose (MED) assessment; (2) the efficacy in decreasing the UVA+B-induced skin redness was measured by colorimetry; (3) the antioxidant efficacy was measured by the ferric-reducing antioxidant power (FRAP) and the malondialdehyde (MDA) assay; and (4) skin moisturization, skin elasticity, skin radiance, the intensity of melanin staining, transepidermal water loss (TEWL), and wrinkles were measured to assess the antiaging efficacy. The intake of the product for 56 days was effective in improving the skin reaction to UV exposure; in increasing the skin antioxidant capacity as well as in decreasing UVA-induced lipid peroxidation; in increasing the skin moisturization, skin elasticity, and skin radiance; and in decreasing TEWL, the intensity of melanin staining inside dark spots, and wrinkle depth. Our results suggest that the test product is effective in counteracting both the harmful effects of UVR exposure and aging signs.

Ultraviolet radiation-induced degradation of dermal extracellular matrix and protection by green tea catechins: a randomized controlled trial.

BackgroundLoss and remodelling of the dermal extracellular matrix (ECM) are key features of photodamaged human skin. Green tea catechins (GTCs) have been explored for their anti‐inflammatory and chemopreventive properties, but data on the impact of GTCs on ultraviolet radiation (UVR)‐induced changes to the dermal ECM are lacking.AimTo investigate the effect of an inflammatory dose of solar‐simulated UVR on human dermal ECM and potential for protection by GTCs in a double‐blind randomized controlled trial.MethodsIn total, 50 healthy white (Fitzpatrick skin type I–II) adults aged 18–65 years were randomized to a combination of GTCs 540 mg plus vitamin C 50 mg or to placebo twice daily for 12 weeks. The impact of solar‐simulated UVR at 3 × minimal erythema dose on the dermal collagen and elastic fibre networks was assessed by histology and immunohistochemistry in all participants at baseline. The impact of GTC supplementation on UVR‐induced effects was compared between the groups post‐supplementation.ResultsThe area of papillary dermis covered by collagen and elastic fibres was significantly lower (P < 0.001) in UVR‐exposed skin than in unexposed skin. Significantly lower levels of fibrillin‐rich microfibrils (P = 0.02), fibulin‐2 (P < 0.001) and fibulin‐5 (P < 0.001) were seen in UVR‐exposed than unexposed skin, while procollagen‐1 deposition was significantly higher in UVR‐exposed skin (P = 0.01). Following GTC supplementation, the UVR‐induced change in fibulin‐5 was abrogated in the active group but not the placebo group, with no difference between the two groups for other components.ConclusionsAcute UVR induced significant changes in the human dermal collagen and elastic fibre networks, whereas oral GTCs conferred specific UVR protection to fibulin‐5. Future studies could explore the impact of GTCs on the effects of repeated suberythemal UVR exposure of human skin.

Kolmogorov Complexity Analysis and Prediction Horizon of the Daily Erythemal Dose Time Series

Influenced by stratospheric total ozone column (TOC), cloud cover, aerosols, albedo, and other factors, levels of daily erythemal dose (Her) in a specific geographic region show significant variability in time and space. To investigate the degree of randomness and predictability of Her time series from ground-based observations in Novi Sad, Serbia, during the 2003–2012 time period, we used a set of information measures: Kolmogorov complexity, Kolmogorov complexity spectrum, running Kolmogorov complexity, the largest Lyapunov exponent, Lyapunov time, and Kolmogorov time. The result reveals that fluctuations in daily Her are moderately random and exhibit low levels of chaotic behavior. We found a larger number of occurrences of deviation from the mean in the time series during the years with lower values of Her (2007–2009, 2011–2012), which explains the higher complexity. Our analysis indicated that the time series of daily values of Her show a tendency to increase the randomness when the randomness of cloud cover and TOC increases, which affects the short-term predictability. The prediction horizon of daily Her values in Novi Sad given by the Lyapunov time corrected for randomness by Kolmogorov is between 1.5 and 3.5 days.

The dynamic behaviour of sunscreens under in-service conditions.

Discussion continues over various aspects of sunscreen science: regulation, test methods, sun protection factor (SPF), labelling claims, potentially harmful components, among others. In this paper the UV transmission properties of a number of commercial sunscreens have been determined at constant sunscreen film thickness under different local UV Index conditions. The data demonstrate difficulties facing the public and the sunscreen industry as a whole, even though SPF values and other data stated on the sunscreen packaging are assumed to be correct according to standard testing methods. This work has shown that at realistic application rates the critical factors are the intensity of the incident solar radiation and the accumulated erythema UV dose transmitted over time. In one example, on 'Extreme' UV Index days, an SPF 30 sunscreen under test transmitted one minimal erythema dose (MED) of UV in only 35min. In another example, although it should not, in theory, transmit one MED until several hours of exposure, this level was reached in 1h by an SPF 50 sunscreen under these typical Australian summer conditions (UV Index 12) in Wollongong, NSW (34.4°S). Such properties could have severe consequnces if these sunscreens were used by individuals with Fitzpatrick Skin Type 1, organ transplant recipients or other immuno-compromised individuals.