B L Diffey’s research while affiliated with Newcastle University and other places

Objective To propose a strategy for using sunscreens that optimizes the balance between skin health and adverse effects to humans and the environment. Methods A model was developed to explore the relationship between sunscreen usage and personal sun exposure throughout the year in populations resident at different latitudes. Results There is little biological justification in terms of skin health for applying sunscreen over the 4–6 winter months at latitudes of 45° N and higher, whereas year‐round sunscreen is advised at latitudes of 30° N and lower. Avoiding sunscreen application at times when it is biologically unnecessary results in an annual reduction in sunscreen use of 25%. Furthermore, using products containing UV filters over the winter months at more northerly latitudes could lead to a higher number of people with vitamin D deficiency. The single largest use of sunscreen is on a sun‐seeking holiday and encouragement to make more use of clothing and shade would appreciably reduce the sunscreen burden to the environment. Conclusion We need to use sunscreens wisely so that we gain the health benefit from their use while at the same time limiting possible harm to ourselves and the environment.

Beach holidays in areas of strong sunlight are popular and sunscreen is often the primary means of photoprotection favored by many people. The object of this study was to estimate how effective sunscreen is in preventing sunburn under high ultraviolet (UV) levels. We used a computational model to determine how the quantity, frequency, substantivity, and labeled SPF of applied sunscreens impact on the predicted erythemal response in unacclimatized skin over the course of a 7-day holiday in a high-solar environment. Our results indicated that sunscreen on its own may be insufficient to prevent sunburn in white skin on a sun-seeking holiday that combines prolonged exposure with high UV levels. Nevertheless, sunscreens have a valuable role to play on a beach holiday especially if an SPF30 or higher is chosen, the product is applied liberally and uniformly, application is started early into the sun exposure period and repeated at 2-hourly intervals throughout the day, and the product binds well to the skin. The main limitation of our investigation is that it is not an observational study but rather a computational model and while all models are wrong, some, including this one, are useful.

Background Evidence on validation of surrogates applied to evaluate the personal exposure levels of solar ultraviolet radiation (UVR) in epidemiological studies is scarce. Objectives To determine and compare the validity of three approaches, including (i) ambient UVR levels, (ii) time spent outdoors, and (iii) a modelling approach integrating the aforementioned parameters, to estimate personal UVR exposure over a period of six months among indoor and outdoor workers and in different seasons (summer/winter). Methods This validation study was part of the EU ICEPURE project and was performed between July 2010 and January 2011 in a convenience sample of indoor and outdoor workers in Catalunya - Spain. We developed linear regression models to quantify the variation in the objectively measured personal UVR exposure that could be explained, separately, by the ambient UVR, time spent outdoors, and modelled UVR levels. Results Our 39 participants – mostly male and with a median age of 35 years- presented a median daily objectively measured UVR of 0.37 standard erythemal doses (SEDs). The UVR dose was statistically significantly higher in summer and for outdoor workers. The modelled personal UVR exposure and self-reported time spent outdoors could reasonably predict the variation in the objectively measured personal UVR levels (R²= (0.75, 0.79)), whereas ambient UVR was a poor predictor (R²=0.21). No notable differences were found between seasons or occupation. Conclusions Time outdoors and our modelling approach were reliable predictors and of value to be applied in epidemiological studies of the health effects of current exposure to UVR.

The development of a computational model is described that allows time‐varying erythema and acclimatization to be determined following repeated exposure to solar ultraviolet (UV) radiation. Good agreement was observed between experimental data and model predictions. Results are presented that illustrate how daily, adventitious sun exposure over the course of a year can result in occasional erythema generally in the late spring/early summer, whilst at the same time showing how the photoadaptive response of the skin changes throughout the year at different latitudes and for different sun reactive skin types. The model is predicated on three physiological responses; the erythemal response as a function of increasing UV dose, and the time courses of erythema and adaptation in response to a single UV exposure. Mathematical models complement observational data and the outputs from the model may help in planning future experimental studies, as well as providing insights into mechanistic responses.

Correction for ‘A library of action spectra for erythema and pigmentation’ by Alois W. Schmalwieser et al. , Photochem. Photobiol. Sci. , 2012, 11 , 251–268, DOI: 10.1039/c1pp05271c.

In the early 1970s, environmental conservationists were becoming concerned that a reduction in the thickness of the atmospheric ozone layer would lead to increased levels of ultraviolet (UV) radiation at ground level, resulting in higher population exposure to UV and subsequent harm, especially a rise in skin cancer. At the time, no measurements had been reported on the normal levels of solar UV radiation which populations received in their usual environment, so this lack of data, coupled with increasing concerns about the impact to human health, led to the development of simple devices that monitored personal UV exposure. The first and most widely used UV dosimeter was the polymer film, polysulphone, and this review describes its properties and some of the pioneering studies using the dosimeter that led to a quantitative understanding of human exposure to sunlight in a variety of behavioral, occupational, and geographical settings.

Sun protection behaviour studies are almost exclusively carried out in populations with fair skin for the obvious reason that people with unpigmented skin are more susceptible to the health impacts of excess solar ultraviolet radiation exposure. In a dataset of 1,271 Black South Africans, we analysed factors related to sun protection applied when spending time outdoors including awareness of skin cancer, gender, age, and Living Standards Measure (LSM) where 1-4 equates to the lowest, 5-7 intermediate and 8-10 the highest LSM status. The most important driver for Black South Africans to use sun protection was whether they were aware of skin cancer (OR: 2.6 for those who were aware versus those who were not, p<0.0001). Sunscreen was preferred by respondents in LSM 8-10 whereas people in the lowest group (LSM 1-4) favoured shade, umbrellas and hats. One in two respondents claimed to use some form of sun protection which appears to be higher than deeply-pigmented populations in other countries.

One of the many environmental factors affecting the health of both farmed and wild fish is exposure to solar ultraviolet radiation (UVR). These rays penetrate to biologi‐cally relevant depths in natural waters and cause changes ranging from embryo mal‐function to the production of heat‐shock proteins. As suppression of cell‐mediated immunity has been shown to follow irradiation of mammals, the possibility of UVR‐induced modulation in immune responses in fish is considered in this review. It is sug‐gested that, after adsorption of UV photons by surface chromophores, dendritic‐like cells may be activated by immune mediators, leading to the generation of T‐ and B‐cell subsets with down‐regulatory activity. A limited number of studies involving in‐fection of irradiated fish with bacteria, nematodes and protozoa have demonstrated an increased microbial load and lack of clearance, with associated changes in a vari‐ety of immune parameters. These preliminary results indicate that exposure of fish to solar UVR leads to less effective control of infections. Strategies evolved by fish to avoid overexposure to UVR include photoenzymatic repair, nucleotide excision repair, pigments, mycosporine‐like amino acids and habitat selection. The welfare of farmed fish is of concern currently. The detrimental effects of excessive sun expo‐sure on the health of fish require recognition, and procedures put in place to minimize such consequences.