共查询到20条相似文献,搜索用时 31 毫秒
1.
Haywood R 《Photochemistry and photobiology》2006,82(4):1123-1131
With the continued rise in skin cancers worldwide there is a need for effective skin protection against sunlight damage. It was shown previously that sunscreens, which claimed UVA protection (SPF 20+), provided limited protection against UV-induced ascorbate radicals in human skin. Here the results of an electron spin resonance (ESR) investigation to irradiate ex vivo human skin with solar-simulated light are reported. The ascorbate radical signal in the majority of skin samples was directly proportional to the irradiance over relevant sunlight intensities (0.9-2.9 mW cm(-2)). Radical production (substratum-corneum) by UV (wavelengths < 400 nm) and visible components (> 400 nm) was approximately 67% and 33% respectively. Ascorbate radicals were in steady state concentration at low irradiance (approximately 1 mW cm(-2) equivalent to UK sunlight), but at higher irradiance (approximately 3 mW cm(-2)) decreased with time, suggesting ascorbate depletion. Radical protection by a four star-rated sunscreen (with UVA protection) was optimal when applied as a thin film (40-60% at 2 mg cm(-2)) but less so when rubbed into the skin (37% at 4 mg cm(-2) and no significant protection at 2 mg cm(-2)), possibly due to cream filling crevices, which reduced film thickness. This study validates ESR determinations of the ascorbate radical for quantitative protection measurements. Visible light contribution to radical production, and loss of protection when sunscreen is rubbed into skin, has implications for sunscreen design and use for the prevention of free-radical damage. 相似文献
2.
We are assured by responsible scientific and governmental organizations that sunscreens should be routinely worn to reduce skin cancer risk. We are also advised that wearing sunscreens will not hinder our ability to produce sufficient previtamin D3 (preD3) from casual sunlight exposure. We report the examination of a series of 166 solar spectra, obtained on different days throughout a year, evaluated for erythemic and preD3 effectiveness and the relative effects of recommended Sun protection factor (SPF) 15 sunscreen. The results show that the sunscreen is much more effective in blocking the formation of preD3, than its labeled SPF for preventing sunburn. In fact with sunscreen applied only miniscule amounts of preD3 are predicted to be made outdoors even with extensive exposure. This raises important questions regarding the safest way to use sunlight exposure to promote healthy vitamin D3 levels and suggests the need to modify the public safety "Safe Sun" messages. 相似文献
3.
Irradiation from an artificial solar simulator that matches the relative cumulative erythema effectiveness (RCEE) of sunlight is used for in vivo sun protection factor (SPF) testing, whereas irradiation that matches the spectrum of natural sunlight (NS) is generally used for in vitro SPF testing. This study was designed to clarify whether this difference is important. Eight sunscreens spread on artificial substrates and several optical filters as sunscreen mimics were used. Their in vitro SPF values were evaluated using RCEE-compliant and NS spectrum-matching light sources in calculation. The calculated in vitro SPF values obtained using NS light (SPF [NS]) were lower than those obtained using RCEE light (SPF [RCEE]). The in vitro SPF (RCEE) values showed a better correlation and better agreement with in vivo SPF values, as compared with the in vitro SPF (NS) values. A marked difference between in vitro SPF values obtained with the two light sources in calculation was found for sunscreens showing low transmittance in the ultraviolet B region. To obtain in vitro SPF values that correspond well to in vivo SPF values measured with currently accepted methodology, it is important to use an RCEE-compliant light source. 相似文献
4.
A Review of Sunscreen Safety and Efficacy 总被引:9,自引:0,他引:9
Francis P. Gasparro Mark Mitchnick J. Frank Nash 《Photochemistry and photobiology》1998,68(3):243-256
The use of sunscreen products has been advocated by many health care practitioners as a means to reduce skin damage produced by ultraviolet radiation (UVR) from sunlight. There is a need to better understand the efficacy and safety of sunscreen products given this ongoing campaign encouraging their use. The approach used to establish sunscreen efficacy, sun protection factor (SPF), is a useful assessment of primarily UVB (290–320 nm) filters. The SPF test, however, does not adequately assess the complete photoprotective profile of sunscreens specifically against long wavelength UVAI (340–400 nm). Moreover, to date, there is no singular, agreed upon method for evaluating UVA efficacy despite the immediate and seemingly urgent consumer need to develop sunscreen products that provide broad-spectrum UVB and UVA photoprotection. With regard to the safety of UVB and UVA filters, the current list of commonly used organic and inorganic sunscreens has favorable toxico-logical profiles based on acute, subchronic and chronic animal or human studies. Further, in most studies, sunscreens have been shown to prevent the damaging effects of UVR exposure. Thus, based on this review of currently available data, it is concluded that sunscreen ingredients or products do not pose a human health concern. Further, the regular use of appropriate broad-spectrum sunscreen products could have a significant and favorable impact on public health as part of an overall strategy to reduce UVR exposure. 相似文献
5.
Lee K. Robertst Donathan G. Beasley Douglas B. Learn Lori D. Giddens John Beard Joseph W. StanfieW 《Photochemistry and photobiology》1996,63(6):874-884
Acute exposure to UV radiation causes immunosuppression of contact hypersensitivity (CH) responses. Past studies conducted with unfiltered sunlamps emitting nonsolar spectrum UV power (wavelengths below 295 nm) or using excessive UV doses have suggested sunscreens may not prevent UV-induced immunosuppression in mice. This study was thus designed to evaluate critically the effects of different UV energy spectra on the immune protection capacity of sunscreen lotions. Minimum immune suppression doses (MISD), i.e. the lowest UV dose to cause~50% suppression of the CH response to dinitrofluorobenzene in C3H mice, were established for three artificial UV sources. The MISD for each UV source was 0.25 kJ/m2 for unfiltered FS20 sunlamps (FS), 0.90 kJ/m2 for Kodacel-filtered FS20 sunlamps (KFS), which do not emit UV power at wavelengths <290 nm, and 1.35 kJ/m2 for a 1000 W filtered xenon arc lamp solar simulator. Using MISD as baseline, sunscreens with labeled sun protection factors (SPF) of 4, 8, 15 and 30 were tested with each UV source to establish their relative immune protection factors. The immune protection factor of each sunscreen exceeded its labeled SPF in tests conducted with the solar simulator, which has a UV power spectrum (295–400 nm) similar to that of sunlight. Conversely, sunscreen immune protection factors were significantly less than the labeled SPF in tests conducted with FS and KFS. Comparison of the immunosuppression effectiveness spectra showed that relatively small amounts of nonsolar spectrum UV energy, i.e. UVC (200–290 nm) and/or shorter wavelength UVB (between 290 and 295 nm), produced by FS and KFS contributes significantly to the induction of immunosuppression. For example, 36.3% and 3.5% of the total immunosuppressive UV energy from FS and KFS, respectively, lies below 295 nm. Sunscreen absorption spectra showed that transmission of immunosuppressive UV energy below 295 nm for FS was at least eight-fold higher than that for KFS. Compared to the solar simulator UV spectrum the transmission of nonsolar immunosuppressive UV energy through sunscreens was >15-fold higher for FS and ≥1.5-fold higher for KFS. These data demonstrate that relevant evaluations of sunscreen immune protection can only be obtained when tests are conducted with UV sources that produce UV power spectra similar to that of sunlight and UV doses are employed that are based on established MISD. 相似文献
6.
Evaluation of sunscreen protection in human melanocytes exposed to UVA or UVB irradiation using the alkaline comet assay 总被引:4,自引:0,他引:4
Jean S De Méo M Sabatier AS Laget M Hubaud JC Verrando P Duménil G 《Photochemistry and photobiology》2001,74(3):417-423
The in vivo assessment of sunscreen protection does not include the photogenotoxicity of UVA or UVB solar radiation. Using the comet assay we have developed a simple and rapid technique to quantify sunscreen efficacy against DNA damage induced by UV light. Cutaneous human melanocytes from primary cultures were embedded in low-melting point (LPM) agarose and exposed to UVA (0.8 J/cm2) or to UVB (0.06 J/cm2) through a quartz slide covered with 10 microL volumes of sunscreens. DNA single-strand breaks induced directly by UVA at 4 degrees C and indirectly through nucleotide excision repair by UVB following a 35 min incubation period at 37 degrees C were quantified using the comet assay. Tail moments (TM) (tail length x %tail DNA) of 100 cells/sample were determined by image analysis. DNA damage was evaluated with a nonlinear regression analysis on the normalized distribution frequencies of TM using a chi 2 function. The coefficients of genomic protection (CGP) were defined as the percentage of inhibition of DNA lesions caused by the sunscreens. Twenty-one sunscreens were evaluated, and the calculated CGP were compared with the in vivo sun protective factor (SPF) and with the protection factor UVA (PFA). Nonlinear relationships were found between SPF and CGPUVB and between PFA and CGPUVA. 相似文献
7.
De Villa D Nagatomi AR Paese K Guterres S Cestari TF 《Photochemistry and photobiology》2011,87(2):457-460
The sun protection factor (SPF) of sunscreens is determined using samples applied with a thickness of 2 mg cm(-2). Sunscreen users, however, typically apply sunscreen nonuniformly and in smaller amounts. The objective of our study was to verify whether sunscreen reapplication increases the amount and regularity of the product on the skin. Volunteers were asked to apply an SPF 6 sunscreen on their forearms and reapply it 30 min later on one forearm. Tape-strips were used to collect five samples from two different sites on each forearm. The concentration of benzophenone-3 in the samples was measured and the total amount of sunscreen was estimated using high-performance liquid chromatography. The median amount of sunscreen film was 0.43 mg cm(-2) (0.17-1.07) after one application and 0.95 mg cm(-2) (0.18-1.91) after two applications (P = 0.002). No significant difference was found in the film uniformity. Though sunscreen reapplication increases the amount of product on the skin, levels are still lower than the recommended amount, confirming that the protection level is less than the product-stated SPF. Our results are the first in the literature to support the recommendation for reapplying sunscreens. Based on our results, we recommend that sunscreens be labeled using qualitative measures. 相似文献
8.
Effective Photoprotection of Human Skin against Infrared A Radiation by Topically Applied Antioxidants: Results from a Vehicle Controlled,Double‐Blind,Randomized Study
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Susanne Grether‐Beck Alessandra Marini Thomas Jaenicke Jean Krutmann 《Photochemistry and photobiology》2015,91(1):248-250
Infrared A radiation (IRA) from solar sunlight contributes to photoaging of human skin, e.g. by upregulating MMP‐1 expression in dermal fibroblasts, indicating the need for photoprotection of human skin against IRA. Up to now, however, there has been no controlled study to show that effective protection of human skin against IRA radiation is possible. Here, we have conducted a randomized, controlled, double‐blinded prospective study in 30 healthy volunteers to assess the capacity of an SPF 30 sunscreen versus the same sunscreen supplemented with an antioxidant cocktail containing grape seed extract, vitamin E, ubiquinone and vitamin C to protect human skin against IRA radiation‐induced MMP‐1 upregulation. As expected, exposure to IRA radiation significantly upregulated MMP‐1 expression, as compared to unirradiated skin, and this response was significantly reduced, if the SPF30 sunscreen plus the antioxidant cocktail had been applied prior to IRA radiation. In contrast, treatment of human skin with the SPF30 sunscreen alone did not provide significant protection. These results indicate that topically applied antioxidants effectively protect human skin against IRA radiation and that regular sunscreens need to be supplemented with specific antioxidants in order to achieve IRA photoprotection. 相似文献
9.
Mouret S Bogdanowicz P Haure MJ Castex-Rizzi N Cadet J Favier A Douki T 《Photochemistry and photobiology》2011,87(1):109-116
Evaluation of the photoprotection provided by sunscreens is performed either through the induction of erythema and expressed as the sun protection factor (SPF), or by the UVA-mediated persistent pigment darkening (PPD). None of these two endpoints has a link with skin cancer, the most deleterious consequence of excess exposure to solar UV radiation. We thus set up a complementary approach to evaluate the protection provided by sunscreens to the genome of human skin. This is based on the quantification of the thymine cyclobutane dimer (TT-CPD), the main DNA lesion induced by both UVB and UVA radiations. Irradiations were performed ex vivo on human skin explants and the level of TT-CPD in DNA was determined by HPLC associated with tandem mass spectrometry. The technique was first optimized and validated with three standard sunscreens. The study was then extended to the evaluation of a commercial high SPF sunscreen exhibiting efficient UVA photoprotection. The DNA protecting factor was found to reflect the ratio between UVB and UVA photoprotection, although the absolute values of the genomic protection were, as a general trend, lower than either SPF or PPD. These data show the usefulness of the proposed approach for the evaluation of the genoprotection afforded by sunscreens. 相似文献
10.
Widely used polymethylmethacrylate substrates for in vitro sun protection factor (SPF) testing of sunscreens do not mimic the rough surface structure of skin, and in addition, sample loading is less than that used in in vivo SPF testing (2.00 mg cm(-2)). We have developed a skin-mimicking substrate (SMS), which has furrows and ridges on its surface, like human skin. A comparison of the photodegradation profiles of sunscreens on commercially available substrates (including SMS) at the recommended application amounts, and on SMS at various application amounts showed that the photodegradation rate of photounstable sunscreen was dependent on the application amount being higher at lower application amounts. SMS at the recommended application amount of 2.00 mg cm(-2) provided in vitro SPF values that were comparable with in vivo SPF values. Our results confirm that, in order to develop a reliable in vitro SPF method, which is consistent with in vivo SPF determination, it is important to use the same application amount of sample as in the in vivo method, in order to take proper account of sunscreen photostability. 相似文献
11.
R.P. Stokes B.L. Diffey 《Journal of photochemistry and photobiology. B, Biology》1999,50(2-3):137-143
We have carried out ex vivo studies to examine the feasibility of using fluorescence spectroscopy as an in vivo quantitative technique to assess sunscreen substantivity in terms of skin surface thickness and/or photoprotection. We found that the majority of sunscreens produced insufficient natural fluorescence and so we have attempted to increase the fluorescent signal by adding various fluorescing agents to the sunscreens. However, none of these substances is ideal; either they do not bind sufficiently strongly to sunscreen products, or their fluorescence is quenched by the active ingredients contained within sunscreens. The feasibility of using fluorescence spectroscopy for in vivo quantitative assessments of sunscreen substantivity therefore remains unproved and is dependent on a suitable fluorescent agent being found. Such an agent would have to be non-toxic, mix readily with sunscreens and be excited by visible wavelengths. 相似文献
12.
Rosenstein BS Phelps RG Weinstock MA Bernstein JL Gordon ML Rudikoff D Kantor I Shelton R Lebwohl MG 《Photochemistry and photobiology》1999,70(5):798-806
Sun exposure histories were obtained from a series of patients age 35 or younger following diagnosis and removal of a basal cell carcinoma (BCC). The DNA was extracted from tumor biopsy samples derived from BCC of 10 patients who reported that they did not use sunscreens during youth (age 18 or younger) and 10 patients who routinely employed sunscreens during this age period. Exons 5-9 of the p53 gene were then amplified in three fragments from these samples using a nested polymerase chain reaction (PCR) approach and screened for mutations using an RNA heteroduplex assay. All PCR products displaying evidence of a mutation were sequenced. It was found that 6 of the 10 patients who were not routine sunscreen users displayed mutations in these p53 exons. All of the mutations were located at dipyrimidine sites, five of the six were C-->T transitions and one mutation was a tandem double mutation, consistent with a role for solar UVB in BCC formation. In contrast, only one p53 mutation was detected in the group of 10 patients who routinely employed sunscreens during childhood and adolescence. Hence, a significantly (P = 0.029) lower level of p53 mutations was detected in the BCC obtained from sunscreen users compared with tumors derived from nonusers. These findings suggest that the mechanisms involved in the etiology of skin carcinogenesis differ in sunscreen users compared with people who did not routinely employ sunscreens. These data are also indicative of a protective effect associated with sunscreen use against the formation of p53 mutations. It is possible that the patients who were diagnosed with BCC despite their use of sunscreens possessed a genetic susceptibility for skin cancer formation and developed BCC through a p53-independent pathway. Alternatively, solar UVA wavelengths, that were generally not blocked by the suncare products employed by the sunscreen users, may have played a significant role in BCC development through induction of a mutation(s) in an oncogene and/or a tumor suppressor gene, other than p53, for these patients. 相似文献
13.
There remains an unmet need for skin tissue-based assays for the measurement of the UVA protection and efficacy of sunscreens. Here we describe development of a novel electron paramagnetic resonance assay that uses the photogeneration of reactive melanin radical as a measure of UV light penetration to melanocytes in situ in skin. We have used areas of focal melanocytic hyperplasia in the skin of Monodelphis domestica to model the human nevus. We show that we are able to use this assay to determine the monochromatic protection factors (mPF) of research and commercial sunscreens at specific narrow wavebands of UVB, UVA and blue visible light. Both commercial sunscreens, a sun protection factor (SPF) 4 and an SPF 30 product, had mPFs in the UVB range that correlated well with their claimed SPF. However, their mPF in the UVA ranges were only about one-third of claimed SPF. This technique can be used to design and assay sunscreens with optimally balanced UVA and UVB protection. 相似文献
14.
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16.
We describe an in vitro approach to assessing the potential genotoxicity of illuminated sunscreens. The photomutagenic sunscreen Padimate-O attacks DNA on illumination with simulated sunlight, producing strand breaks and lesions that are labile to N, N'-dimethylethy-lenediamine but few, if any, cyclobutane dimers or other direct photoproducts. The damage can be completely suppressed by the free radical quenchers Tris, ethanol, mannitol and dimethylsulfoxide, which is commonly used as a solvent in conventional photomutagenicity assays. Using a genetic reversion assay that depends on regenerating P-galactosidase activity in photodamaged plas-mids we find that GC base pairs are particularly susceptible to attack by Padimate-O. 相似文献
17.
Abstract The trans to cis photoisomerization of urocanic acid (UCA) in skin is considered to play an important role in the mechanism of immunosuppression. We have investigated the effects of skin type and various sunscreens with low sun protection factor (SPF) on the UV-induced cis -UCA formation in human skin after exposure to artificial IJV light. The rate of cis -UCA formation depends little on the skin type and is reduced by topical application of sunscreens. The rate of cis -UCA formation decreases with increasing SPF and only broad-spectrum, highly protective sunscreens offer protection against the UV-induced formation of cis -UCA, which accumulates in the stratum corneum after multiple UV exposures. A theoretical approach to estimate the distribution of cis -UCA after irradiation indicates that this compound may diffuse into the deeper layers of the epidermis with D ∼ 10−17 m2 /s, and that its elimination from the stratum corneum is mainly due to desquamation. 相似文献
18.
L Dubertret D Serraf-Tircazes M Jeanmougin P Morlière D Averbeck A R Young 《Journal of photochemistry and photobiology. B, Biology》1990,7(2-4):251-259
As part of an international cooperative study of the photophysical, photomutagenic and photocarcinogenic properties of bergamot oil and the effect of UVA and UVB sunscreens, the phototoxic properties of model perfumes containing 5, 15 and 50 ppm 5-methoxypsoralen (5-MOP) in bergamot oil with and without a sunscreen have been investigated on human skin. It has been confirmed that the photosensitivity of human skin is maximal 2 h after perfume application. Interestingly the addition of a UVA sunscreen is more efficient for decreasing the phototoxic properties of bergamot oil than is a UVB sunscreen. The addition of sunscreens in a model perfume containing 50 ppm 5-MOP in bergamot oil can reduce the phototoxic properties of this perfume to a toxicity equivalent to that produced by the application of a model perfume containing 15 ppm 5-MOP without sunscreens. However, despite their promising protective effect in vitro, UVB and UVA sunscreens at low concentration (0.5%-1%) in perfumes cannot suppress the phototoxicity of bergamot oil on human skin. 相似文献
19.
D L Bissett J F McBride D P Hannon L F Patrick 《Journal of photochemistry and photobiology. B, Biology》1991,9(3-4):323-334
To determine the time dependence of sunscreen protection against chronic photodamage in hairless mice, the time was varied (0-8 h) between topical sunscreen treatment and UVB radiation exposure. Sunscreen products with labeled sun protection factor (SPF) values of 2, 4 and 8 were evaluated; these values were verified in a guinea pig model for SPF determinations. When applied immediately prior to UVB radiation exposure, these sunscreen products were very effective in prevention of skin wrinkling and tumor formation. Onset of photodamage was delayed, the delay being greater with higher SPF values. However, the sunscreen actives were rapidly lost from the skin surface, and their protective effect diminished strikingly as the time between treatment and irradiation increased. For daily protection against chronic photodamage, this suggests a need for photoprotectants with greater substantivity to achieve a high level of protection throughout the day. 相似文献
20.
Sunscreen isn't enough. 总被引:2,自引:0,他引:2
B Diffey 《Journal of photochemistry and photobiology. B, Biology》2001,64(2-3):105-108
Topical sunscreens act by absorbing or scattering UV radiation and are widely available for general public use as a consumer product. Surveys carried out in the UK find that sunscreen use is regarded as the most important, and by implication the most effective, sun protection measure. But is perception borne out by reality? Sunscreens applied at the thickness tested by manufacturers need only possess an SPF of 15 to prevent sunburn even for all day exposure in tropical sunshine. Yet behavioural studies show that high SPF (>15) sunscreens do not always prevent sunburn. That the protection achieved is often less than that expected depends upon a number of factors: application thickness and technique; type of sunscreen applied; resistance to water immersion and sand abrasion; and when, where and how often sunscreen is re-applied. These factors provide ample evidence that the numerical measure of protection indicated on the product pack is generally higher than achieved in practice. This mismatch between expectation and realisation may be one contributing factor why sunscreens have been reported to be a risk factor in melanoma. 相似文献