Vitamin D in health and disease

Background/purpose: Investigations have revealed that vitamin D plays an important role in many areas of health and disease. Questions over whether sun avoidance and sunscreen use will decrease vitamin D levels may concern clinicians when counseling patients at risk for vitamin D insufficiency. A review of the role of vitamin D in health and disease, the impact of photoprotection and skin type on vitamin D levels, and recommendations for adequate vitamin D intake is provided to aid clinicians in counseling patients regarding these issues. Results: Review of the literature indicates that adequate vitamin D intake is associated with decreased risk of falls and bone fractures in the elderly, breast and gastrointestinal cancer risk, cardiovascular disease, and possibly all cause mortality, diabetes, and multiple sclerosis. While skin type does affect vitamin D levels, regular use of sunscreen is not associated with vitamin D insufficiency. Conclusions: Adequate intake of vitamin D is important for maintenance of good health, and may be achieved through diet and oral supplementation. Intentional or prolonged exposure to ultraviolet light should not be used as a means of obtaining vitamin D.     

Sun exposure behavior and protection practices in a Mediterranean population: a questionnaire-based study

Objective: Skin cancer campaigns have only recently been implemented in a wide scale in Greece. In order to better target those individuals at risk, we aimed to explore sun exposure behaviors in a sample of the Greek population.
Methods: A total of 802 subjects, randomly selected among the residents of the two largest Greek cities, underwent a questionnaire-based telephone interview, assessing the degree of sun exposure patterns and knowledge of skin cancer risk factors.
Results: Females more commonly (90%) used sunscreens compared with males (67.5%), and among sunscreen users, only 8% used products with SPF <10. Almost half of the participants (48%) preferred going to the beach during the midday hours. Over exposure to the sun was mostly reported by individuals with phototypes III/IV and of younger age (18–35 years). Most participants were aware of sun exposure as a cause of skin cancer, but among those who did not, 41% were younger than 34 years of age.
Conclusions: In our survey, significant differences in age, sex and phototypes were observed with regard to sun exposure patterns and sunscreen use. Educational campaigns should focus more on younger age groups, encouraging a more complete set of photoprotective measures. However, potential trial limitations inherent in self-reported measures should be taken into account.     

Analysis of titanium dioxide and zinc oxide nanoparticles in cosmetics

There have been rapid increases in consumer products containing nanomaterials, raising concerns over the impact of nanoparticles (NPs) to humankind and the environment, but little information has been published about mineral filters in commercial sunscreens. It is urgent to develop methods to characterize the nanomaterials in products. Titanium dioxide (TiO₂) and zinc oxide (ZnO) NPs in unmodified commercial sunscreens were characterized by laser scanning confocal microscopy, atomic force microscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that laser scanning confocal microscopy evaluated primary particle aggregates and dispersions but could not size NPs because of the diffraction limited resolution of optical microscopy (200 nm). Atomic force microscopy measurements required a pretreatment of the sunscreens or further calibration in phase analysis, but could not provide their elemental composition of commercial sunscreens. While XRD gave particle size and crystal information without a pretreatment of sunscreen, TEM analysis required dilution and dispersion of the commercial sunscreens before imaging. When coupled with energy-dispersive X-ray spectroscopy, TEM afforded particle size information and compositional analysis. XRD characterization of six commercial sunscreens labeled as nanoparticles revealed that three samples contained TiO₂ NPs, among which two listed ZnO and TiO₂, and displayed average particle sizes of 15 nm, 21 nm, and 78 nm. However, no nanosized ZnO particles were found in any of the samples by XRD. In general, TEM can resolve nanomaterials that exhibit one or more dimensions between 1 nm and 100 nm, allowing the identification of ZnO and TiO₂ NPs in all six sunscreens and ZnO/TiO₂ mixtures in two of the samples. Overall, the combination of XRD and TEM was suitable for analyzing ZnO and TiO₂ NPs in commercial sunscreens.     

When to apply sunscreen: a consensus statement for Australia and New Zealand

Introduction : Cancers of the skin are the most common cancers in humans, with Australia and New Zealand having the world’s highest incidence. Primary prevention campaigns advise people to apply sunscreen to exposed body sites when outdoors. However, despite growing evidence that cumulative sub‐erythemal exposures cause mutational damage, and trial data demonstrating benefit from daily sunscreen use, current policies do not consider the hazards of incidental (everyday) sun exposure. Thus, a Sunscreen Summit was convened to review the evidence and update the policies for people living in Australia and New Zealand. Results : After reviewing the benefits and risks of sunscreen application, the policy group concluded that people living in Australia and New Zealand should be advised to apply sunscreen to the face/head/neck and all parts of the body not covered by clothing on all days when the ultraviolet index is forecast to reach three or greater, irrespective of their anticipated activities. For planned outdoors activities, sunscreen should be used alongside other sun protection measures. Conclusions : People living in Australia and New Zealand are now advised to apply sunscreen every day when the UV index is predicted to reach 3 or above. Implications for public health : Increased use of sunscreen as part of the daily routine to reduce incidental sun exposure will lead to decreased incidence of skin cancer in the future.     

Insect repellents and sunscreen: implications for personal protection strategies against mosquito-borne disease

Objective: To determine the protection times provided by insect repellent and sunscreen in combined formulations against biting mosquitoes. To determine if concurrent use of repellent and sunscreen influenced protection times.
Methods: Insect repellent containing comparable concentrations of N, N-diethyl-3-methylbenzamide (DEET) with and without sunscreen were tested on human skin to determine the mean protection time (MPT) against Aedes aegypti (L.) in the laboratory. Further trials were undertaken to determine the effect on MPT of sunscreen reapplication over repellent every two hours.
Results: There was no significant difference in the MPT provided by 80% DEET with (MPT±SE=770±54.8 minutes) and without (MPT±SE=830±20.2 minutes) sunscreen or 7.14% DEET with (MPT±SE =240±15.5 minutes) and 6.98% DEET without (MPT±SE =230±18.4 minutes) sunscreen. Reapplication of sunscreen resulted in a significantly lower MPT of a 17.0% DEET formulation when sunscreen was reapplied concurrently (MPT±SE=330±25.2 minutes), compared with DEET alone (MPT±SE =400±12.7 minutes).
Conclusions: When combined in a single formulation with sunscreen, the MPT provided by both high and low concentrations of DEET is not reduced. However, if sunscreen is reapplied over insect repellent, protection times can be reduced significantly.
Implications: In areas of endemic mosquito-borne disease, the reapplication of a low concentration repellent and sunscreen formulation may provide the most effective protection from biting mosquitoes while minimising the risk of overexposure to DEET.     

30种中草药化学成分的防晒潜能研究

目的：为从中草药化学成分中寻找天然防晒剂提供依据。方法：采用紫外分光光度法在280—400nm对30种中草药化学成分样品液进行扫描,并进行紫外吸收特性的比较分析。结果：其中17种中草药化学成分具有防晒潜能。结论：中草药化学成分作为天然防晒剂的开发具有广阔的前景,紫外吸收特性考察作为天然防晒剂的初筛方法简便快捷。     

Sunscreen use and intentional exposure to ultraviolet A and B radiation: a double blind randomized trial using personal dosimeters

A previous randomized trial found that sunscreen use could extend intentional sun exposure, thereby possibly increasing the risk of cutaneous melanoma. In a similarly designed trial, we examined the effect of the use of sunscreens having different sun protection factor (SPF) on actual exposure to ultraviolet B (UVB) and ultraviolet A (UVA) radiation. In June 1998, 58 European participants 18-24 years old were randomized to receive a SPF 10 or 30 sunscreens and were asked to complete daily records of their sun exposure during their summer holidays of whom 44 utilized a personal UVA and UVB dosimeter in a standard way during their sunbathing sessions. The median daily sunbathing duration was 2.4 hours in the SPF 10 group and 3.0 hours in the SPF 30 group (P = 0.054). The increase in daily sunbathing duration was paralleled by an increase in daily UVB exposure, but not by changes in UVA or UVB accumulated over all sunbathing sessions, or in daily UVA exposure. Of all participants, those who used the SPF 30 sunscreen and had no sunburn spent the highest number of hours in sunbathing activities. Differences between the two SPF groups in total number of sunbathing hours, daily sunbathing duration, and daily UVB exposure were largest among participants without sunburn during holidays. Among those with sunburn, the differences between the two groups tended to reduce. In conclusion, sunscreens used during sunbathing tended to increase the duration of exposures to doses of ultraviolet radiation below the sunburn threshold.     

A graded work site intervention program to improve sun protection and skin cancer awareness in outdoor workers in Israel

Objectives: A graded worksite intervention program to improve sun protection and skin cancer awareness of outdoor workers was implemented and evaluated longitudinally over a period of 20 months. Methods: Outdoor male workers (144/213 recruits) from geographically separated units of the Israel National Water Company were allocated to complete (n = 37), partial (n = 72) or minimal (n = 35) intervention groups. Subsequent to the assignment and training of local safety officers, an educational and medical screening package was provided to the corresponding groups either once, or repeatedly a year later. Personal sun protective gear was provided upon repeated intervention. Outcome measures were evaluated through self-response questionnaires administered prior to the first intervention pulse, and 8 months after the first and second interventions. Results: A 15–61% improvement in sun-protection habits was noted in the entire study population 8 months after initialization, compared to no sunscreen use, 20% sun-exposed skin area and highest mean occupational exposure dose of 1.68 MED/day at pre-test. An even greater use of sunscreen was evident 1 year later in the complete and partial intervention groups, + 80% and + 52%, respectively. The baseline rate of self-examination of the skin in the same two groups (49%) increased significantly at post-test (+ 71% and + 53%, respectively). Conclusions: This integrated intervention program led to significantly improved sun protection and skin cancer awareness. Repeated intervention combined with the supply of sun-protective gear contributed to an even greater impact.     

Primary prevention of skin cancer: a review of sun protection in Australia and internationally

The incidence of skin cancer is increasing worldwide. Protecting the skin from the sun by wearing protective clothing, using a sunscreen with appropriate sun protection factor, wearing a hat, and avoiding the sun are recommended as primary preventive activities by cancer agencies. In this paper the recent data relating to skin cancer primary preventive behaviour in Australia and other countries is reviewed. Comparison of the studies in a table format summarizing the methods, objectives, participants, findings and implications may be obtained from the corresponding author. The sun protection knowledge, attitudes and behaviour patterns observed in Australia are similar in other countries, although Australian studies generally report higher knowledge levels about skin cancer and higher levels of sun protection. The findings suggest that sunscreen is the most frequent method of sun protection used across all age groups, despite recommendations that it should be an adjunct to other forms of protection. While young children's sun protective behaviour is largely influenced by their parents' behaviours, they are still under protected, and sun protective measures such as seeking shade, avoiding the sun and protective clothing need to be emphasized. Adolescents have the lowest skin protection rates of all age groups. Within the adult age range, women and people with sensitive skin were most likely to be using skin protection. However, women were also more likely than men to sunbath deliberately and to use sun-tanning booths. The relationship between skin protection knowledge and attitudes, attitudes towards tanning and skin protection behaviour needs further investigation. Further studies need to include detailed assessments of sunscreen use and application patterns, and future health promotion activities need to focus on sun protection by wearing clothing and seeking shade to avoid increases in the sunburn rates observed to date.