Sunscreen Use Research Articles

Exploring the Preventive Potential of Vitamin D against Respiratory Infections in Preschool-Age Children: A Cross-Sectional Study.

Recent studies hypothesized that vitamin D supplementation and subsequent higher 25(OH)D serum levels could protect against respiratory infections in children. This cross-sectional study, conducted from May 2022 to December 2023 in Timisoara, Romania, aimed to evaluate the potential influence of vitamin D supplementation on the incidence of respiratory infections among preschool-age children. This study examined 215 children over 18 months who were split into a group of patients with recurrent respiratory infections (n = 141) and another group of patients with only one respiratory tract infection in the past 12 months (n = 74). Patients were evaluated based on their serum vitamin D levels 25(OH)D, demographic characteristics, and health outcomes. The study identified that preschool-age children with recurrent infections had significantly lower mean vitamin D concentrations (24.5 ng/mL) compared to the control group (29.7 ng/mL, p < 0.001). Additionally, a higher proportion of vitamin D deficiency was observed among children with recurrent infections in the past 12 months. Notably, vitamin D supplementation above 600 IU/week significantly reduced the likelihood of respiratory infections, evidenced by an odds ratio of 0.523 (p < 0.001), indicating that preschool-age children receiving a dose of vitamin D higher than 600 IU/week were about half as likely to experience respiratory infections compared to those who did not. Furthermore, no significant associations were found between sun exposure, daily sunscreen use, and the incidence of respiratory infections. Conclusively, this study underscores the potential role of vitamin D in helping the immune system against respiratory infections in preschool-age children. The observed protective effect of vitamin D supplementation suggests a potential public health strategy to mitigate the incidence of respiratory infections in preschool children on top of the already known benefits.

A Summarized Review of Formulation, in Vitro Evaluation of Sunscreen

The efficacy and safety of sunscreens are diminished when their agents permeate the skin, resulting in systemic circulation and unidentified negative effects. The filters in sunscreens muster main on the skin's surface with minimal penetration through the dermis in order to preserve their safety and efficacy. Sunscreen should always be worn, even in the event that filters manage get through. Damage like as erythema, the production of free radicals, aging of the skin, and skin cancer brought on by UV radiation. Research is being done to limit skin penetration, assess sun protection factor (SPF), and improve formulation properties and stability in order to target potential negative effects caused by topical absorption of sunscreens. In vitro or in vivo investigations are used in current assays to determine sunscreen penetration since they mimic the physiological conditions of use. This review objectives are to reexamine data on sunscreen skin penetration over the last ten years and identify variables that may increase skin penetration or boost sunscreen efficacy. Sunburn is caused by ultraviolet B radiation, but ultraviolet A may be more damaging to the skin. Sunscreens should ideally block both wavebands. A sunscreen sun protection factor is mostly determined by how well it blocks ultraviolet B. The efficiency of preventing ultraviolet A is not measured. Sunscreens may be organic or inorganic chemicals. If metal oxide sunscreens are made into nanoparticles, their cosmetic acceptance might increase. It doesn’t seem that absorbing organic sunscreens and nanoparticles has any appreciable systemic effects. Frequent use of sunscreen prevents melanoma, squamous cell carcinoma, and actinic keratosis from developing.

The risk of skin cancer in women who carry BRCA1 or BRCA2 mutations

BackgroundIt has not been clearly established if skin cancer or melanoma are manifestations of BRCA1 or BRCA2 mutation carrier status. Estimating the risk of skin cancer is an important step towards developing screening recommendations.MethodsWe report the findings of a prospective cohort study of 6,207 women from North America who carry BRCA1 or BRCA2 mutations. Women were followed from the date of baseline questionnaire to the diagnosis of skin cancer, to age 80 years, death from any cause, or the date of last follow-up.ResultsDuring the mean follow-up period of eight years, 3.7% of women with a BRCA1 mutation (133 of 3,623) and 3.8% of women with a BRCA2 mutation (99 of 2,584) reported a diagnosis of skin cancer (including both keratinocyte carcinomas and melanoma). The cumulative risk of all types of skin cancer from age 20 to 80 years was 14.1% for BRCA1 carriers and 10.7% for BRCA2 carriers. The cumulative risk of melanoma was 2.5% for BRCA1 carriers and 2.3% for BRCA2 carriers, compared to 1.5% for women in the general population in the United States. The strongest risk factor for skin cancer was a prior diagnosis of skin cancer.ConclusionThe risk of non-melanoma skin cancer in women who carry a mutation in BRCA1 or BRCA2 is similar to that of non-carrier women. The risk of melanoma appears to be slightly elevated. We suggest that a referral to a dermatologist or primary care provider for BRCA mutation carriers for annual skin examination and counselling regarding limiting UV exposure, the use of sunscreen and recognizing the early signs of melanoma might be warranted, but further studies are necessary.

Urinary benzophenone-3 concentrations and ovarian reserve in a cohort of subfertile women

ObjectiveTo evaluate the association between urinary benzophenone-3 concentrations and measures of ovarian reserve (OR) among women in the Environment and Reproductive Health (EARTH) Study seeking fertility treatment at Massachusetts General Hospital in Boston, Massachusetts. DesignProspective cohort study. MethodsWomen from the EARTH cohort contributed spot urine samples before assessment of OR outcomes. Antral follicle count (AFC) and day-3 follicle stimulating hormone (FSH) levels were evaluated as part of standard infertility workups during unstimulated menstrual cycles. Quasi-Poisson and linear regression models were used to evaluate the association of specific gravity (SG)-adjusted urinary benzophenone-3 concentrations with AFC and FSH, respectively, with adjustment for age and physical activity. In secondary analyses, models were stratified by age. Sensitivity analyses assessed for confounding by season by restricting to women with exposure and outcome measured in the same season and stratifying by summer vs. non-summer months and for confounding by sunscreen use by restricting to women who filled out product questionnaires and adjusting for and stratifying by average sunscreen use score. ResultsThe study included 142 women (mean age ± SD, 36.1 ± 4.6; range, 22-45 years) enrolled between 2009 and 2017 with both urinary benzophenone-3 and AFC and 57 women with benzophenone-3 and FSH measurements. Most women were white (78%) and highly educated (49% with a graduate degree). Women contributed a mean of 2.7 urine samples (range, 1-10) with 37% contributing 2 or more samples. Benzophenone-3 was detected in 98% of samples. Geometric mean (GM) SG-corrected urinary benzophenone-3 concentration was 85.9 μ g/L (geometric standard deviation 6.2). There were no associations of benzophenone-3 with AFC and day-3 FSH in the full cohort. In stratified models, a 1-unit increase in log GM benzophenone-3 was associated with AFC 0.91 (95% CI, 0.86, 0.97) times lower among women ≤35 years old and was associated with FSH 0.73 (95% CI, 0.12, 1.34) IU/L higher among women >35 years old. Effect estimates from models stratified by season and sunscreen use were null. ConclusionIn main models, urinary benzophenone-3 was not associated with OR. However, younger may be vulnerable to potential effects of benzophenone-3 on AFC. Further research is warranted.

Development of Cosmetic Formulations Containing Olive Extract and Spirulina sp.: Stability and Clinical Efficacy Studies

Cosmetic formulations with natural antioxidants can reduce the oxidative stress caused by solar radiation and pollution. In this context, the aim of this study was to develop and evaluate the clinical efficacy of cosmetic formulations containing olive extract (OE) and Spirulina sp. (SP). For this, rheological behavior, texture, and sensory properties were evaluated. In addition, 31 healthy women with an age of 39 to 60 years, with skin phototypes II and III, and the presence of signs of photoaging on the face were recruited and divided in Group 1 (vehicle formulation) and Group 2 (vehicle with active substances) for this clinical efficacy study. Both groups applied sunscreen daily during the day. The formulations showed non-Newtonian pseudoplastic behaviors and good sensory properties. The clinical evaluation using instrumental measurements showed an increase in skin hydration, an improvement of the skin barrier, and morphological characteristics of the epidermis after 12 weeks of application of the formulations. There was a significant increase in the brightness of the stratum corneum, which suggested a film-forming effect. In addition, both groups had an improvement in the dermis echogenicity, due to the use of sunscreens. Finally, the proposed formulation was effective in protecting the skin and reducing skin changes related to photoaging.

Characterization of the effects of vitamin D synthesis and sunburn in the population due to solar radiation exposure using PROBIT methodology

The main objective of this work is to present a set of equations that relates exposure time to solar radiation, the ultraviolet index (UVI), and its effects, both positive (vitamin D synthesis) and negative (sunburns), including the influence of repeated doses and the incorporation of protective factors. To do so, expressions are proposed for both effects and a time range is specified where repeated doses can be applied. Moreover, we propose expressions (PROBIT equations) that relate the percentage of a population that would reach the recommended daily amount of vitamin D and the repeated dosage to which the population is exposed for skin types I to IV. For all the cases studied, protective factors, such as the use of clothes or sunscreens, were taken into account. Additionally, comparisons were made based on skin types between the generation of daily vitamin D and the onset of sunburn, being able to establish a percentage of those who would suffer from first-degree sunburns when this population reached the recommended daily amount of vitamin D. Thus, it can be noted that when a large percentage of a population wants to obtain the recommended daily allowance of vitamin D of 2000 IU or more, and by exposing a small portion of skin to solar radiation, a considerable percentage of that population would suffer from first-degree sunburn as vitamin D generation is related to the area of exposed skin. Therefore, by increasing the area of skin that is exposed to solar radiation, vitamin D needs can be safely met even with higher daily amounts.

Dangers of Oxybenzone in Sunscreens on Coral Reefs: Proposed Policy Approaches

Sunscreen was developed to combat the harmful effects of skin exposure to ultraviolet radiation, but organic UV filters like oxybenzone pose a threat to coral reefs by promoting bleaching incidents, damaging coral DNA, and interfering with coral larvae. Oxybenzone has also been found to cause a wide range of reproductive and developmental harm within other marine organisms, like fish and invertebrates. While there are alternative sunscreens that are less detrimental to coral such as mineral-based products, toxic oxybenzone-based sunscreens are still popular among cosmetic companies and consumers. Scientific findings in the past decade have demonstrated a connection between high concentrations of chemical UV filters and the destruction of marine ecosystems. This knowledge has prompted some governments in coastal regions to pass legislation aiming to limit the use of sunscreens containing these chemicals. These regulations provide beneficial case studies that can be used to develop further effective policies to federally ban these products in the United States. The jurisdictions of Hawaii, the US Virgin Islands, and Key West are model examples of successful implementation of such laws domestically. Based on efforts from such coastal communities, our suggested best practices to eliminate the threat posed by harmful sunscreens are to promote alternative sunscreen use, to define ‘reef-safe’ within the Federal Trade Commission’s Green Guides, and to impose a nationwide ban on oxybenzone. These recommendations provide a comprehensive plan to protect the United States’ fragile marine ecosystems.

Sunscreen Use, Awareness And Lifestyle Among Young Adult In Makassar

Sunscreens function as a barrier to block UV radiation. The harmful effects of UV can be prevented by using sunscreen and modifying lifestyle. The aim of this study is to find a correlation between sunscreen use, sunscreen awareness, and lifestyle in young adults. The study was an observational analysis with a cross-sectional design and was conducted in Makassar, Indonesia. Participants were young adults aged 18 to 35 years old and willing to fill out questionnaires. The data were analyzed with the Spearman test. There were 85 participants, they were 23.9 years old on average (SD = 3.99), female (83.5%), college students (52.9%), and employees (35.3%). Participants mostly answer very often for sunscreen use (43.5%). There was a correlation between sunscreen use and factors such as awareness due to benefits (p &lt; 0.001), preventive objectives (p &lt; 0.001), activity (p &lt; 0.001), and finances (p = 0.048). A correlation was found between the use of sunscreen and drinking enough water (p = 0.031). In general, lifestyle is not yet healthy, but sunscreen use and drinking enough water showed sufficient awareness of improving health.

The importance of using sunscreen correctly for patients with Melasma

Melasma is a hyperpigmentation disorder that mainly affects women. Factors such as chronic exposure to ultraviolet radiation, visible light, hormonal stimulation and genetic factors have been identified in its pathogenesis. It is characterized by reticulated, irregular, brown spots on areas of the skin exposed to the sun. The methodology used was a literature review with an exploratory qualitative approach, using academic platforms and bibliographies: SCIELO, PUB MED and GOOGLE ACADEMICO. The inclusion criteria were articles from recent years in Portuguese and English. The correct use of sunscreens can prevent the appearance of melasma, which in turn prevents skin cancer. Sunscreen helps block solar radiation, preventing dischromic spots that ultraviolet rays cause on the skin, and there are different factors for each skin type; always reapply every two hours and it is important to know that the use of sunscreen begins in childhood, as damage accumulates on the skin, causing complications in adulthood, such as skin cancer. It can be concluded that the use of accessories such as hats, umbrellas and sunscreens help prevent dyschromia.

Perceptions of Sun Protection, Skin Tone, Colorism, and Dermatologic Care Among South Asians in the USA.

South Asians (SAs) are among the fastest growing populations in the USA. Colorism - the system of inequality that views lighter skin as more advantageous in society - is prevalent in SA culture. This study evaluates motivations of sun protection use, attitudes of colorism, and skin lightening (SL) practices among SA Americans. Two-hundred-four participants recruited from online forums and ResearchMatch completed a questionnaire. Over half (111/204) reported use of sunscreen, of which 39.6% (44/111) reported daily or frequent use. Nearly half of respondents (98/204) believed that they are not at risk for skin cancer, with 37.7% (77/204) reporting minimal knowledge of skin cancers and only 4.9% (10/204) receiving a total body skin exam. One-third (65/204) reported being more concerned about prevention of tanning than skin cancer. In total, 38.2% (78/204) of respondents reported use of SL products, of which 33.3% (26/78) reported hydroquinone-based products and 26.9% (21/78) were unaware of the ingredients in their SL product. Only 16.7% (13/78) consulted a medical professional before using SL products. While many agreed that SA culture places high importance on light skin with regards to beauty standards (82.3%, 168/204), less noted that lighter skin is more beautiful (37.0%, 74/204). SL users more strongly agreed with colorism attitudes than non-users. Limitations include a small sample size with younger participants. Dermatologists must be mindful of the cultural motivations for skin tone preferences, sun protection habits, and SL behaviors and provide culturally relevant education on sunscreen, skin cancer, and risks of SL for the SA community.

Extensive extra genital Csillag’s disease: a rare case report

Lichen sclerosus et atrophicus (LSA), also called as Csillag’s disease, is characterized by small, shiny, porcelain white, sclerotic papules, plaques and atrophic patches that can occur at any site on the skin including the mucosa. Most commonly found in genitalia, rarely occurring on extragenital skin. Predominantly seen in women with bimodal age distribution. Predominantly an interface dermatoses histopathologically consisting of epidermal atrophy, sclerosis /homogenization of collagen fibers and lichenoid inflammatory infiltrates in dermis. No effective treatment till date although topical steroids, calcineurin inhibitors, topical retinoids and systemic agents like hydroxychloroquine, mexthotrexate, PUVA shows varying inconsistent results. Here we report a case of 36-year-old female having LSA with extensive extra vulval involvement including face. No any other co-existing skin disorders. She showed partial improvement use of physical sunscreens, systemic antimalarials, oral methotrexate and antioxidants.

Basal Cell Carcinoma: Diagnosis, Management and Prevention

Basal cell carcinoma (BCC) is a slow-growing, locally aggressive, rarely metastasizing, low-grade cutaneous neoplasm that arises from the epidermal basal layer and invades the adjoining tissues. It is the most common skin cancer. It is fairly common in fair Caucasians and quite uncommon in dark-skinned populations. It contributes to 65–75% of cutaneous malignancies in whites and 20–30% in Asian Indians. The most important causal factors appear to be radiation exposure and genetic predisposition. It may present as a nonhealing lesion that occasionally bleeds or as a pruritic lesion with no symptoms. Tumours rarely spread to regional lymph nodes. The clinical appearances and morphology of BCC are diverse. Clinical types include nodular, cystic, superficial, pigmented, morphoeaform, (sclerosing), keratotic and fibroepithelioma of Pinkus. Most of the lesions appear on the head and neck, usually above the line joining the tragus and the angle of the mouth. A biopsy should be performed on all lesions suspected of BCC. The primary aim of treatment is the complete excision of the tumour tissue. Other treatment modalities include cryotherapy, immunomodulatory drugs, laser treatment or locally applicable chemotherapeutic agents. Prevention consists of lifestyle changes such as avoiding sunburn, tanning beds and prolonged direct sun exposure, shade seeking, sunscreen application on the skin, and physical barrier methods such as protective clothing, hats and sunglasses. Regular sunscreen use in childhood and adolescence seems more beneficial than in adulthood.

311 Low Referral Rates to Dermatology and Relationship to Knowledge and Sunscreen Use in Patients with End Stage Kidney Disease (ESKD)

311 Low Referral Rates to Dermatology and Relationship to Knowledge and Sunscreen Use in Patients with End Stage Kidney Disease (ESKD)

Actinic Reticuloid: A Literature Review of a Case

Actinic reticuloid is a chronic inflammatory skin condition that primarily affects elderly individuals and is associated with chronic sun exposure. It is characterized by the presence of papules, plaques, and fine lines that form a reticular pattern on sun-exposed areas, such as the face, neck, and extremities. Histologically, lichenification and dermal alterations are observed, suggesting a chronic response to sun exposure. Actinic reticuloid is often diagnosed clinically, but confirmation may require a skin biopsy. Managing this condition involves measures to protect the skin from the sun, such as the use of sunscreens and protective clothing. Topical and systemic treatments, such as corticosteroids and ultraviolet light therapy, may also be beneficial in some cases. Although the actinic reticuloid is not malignant, its chronic course and the aesthetic changes it produces can have a significant impact on patients' quality of life. Therefore, it is important for doctors to properly recognize and manage this condition in order to provide effective relief to affected patients.

Prevalence and biological characteristics of acne in adult women employees of a university

Background: Increasingly observed in adulthood, adult female acne is considered a common chronic inflammatory disease of the pilosebaceous unit, presenting polymorphic lesions, risk of sequelae and negative impact on quality of life. This is a disease that may persist from adolescence (persistent acne) or manifest de novo in adulthood (late onset acne). Its etiology is multifactorial, and most of patients don’t have any abnormality in plasma androgen levels. Objectives: To investigate the prevalence and biological characteristics of acne in adult women, over 25 years, employees of a university in Sao Paulo, Brazil. Material and Methods: Project approved by Institutional Review Board. All participants signed online Consent Form and Authorization for Photography. This was a cross-sectional online study by using a questionnaire which was uploaded at the intranet of the university. It was sent and visualized by 2560 women employees, but just 241 filled the 59 questions. The data are presented in a descriptive way, in number and percentage. Results: We’ve received 9.4% of responses (241/2560); acne was reported by 94.2% (227/241) and 87.2% (198/227) were still suffering from acne. The real prevalence of acne in that population may be estimated in 7.7% (198/2560); 96% of patients reported inflammatory lesions; 58% on face; 68.7% persistent and 8.5% late onset acne. Regarding the severity, 48.5% were mild, 44.9% moderate and 6.6% severe. Familial history of acne was present in 79% of the patients with persistent acne and 81% late onset acne. Polycystic ovary syndrome was observed in 35% of women with persistent acne, 15% have already been treated or were under treatment; on the contrary 21% presented late onset acne and 64% were treated. Psychological impact was reported by 39% of women with persistent acne and 46% used antidepressants. On the other hand, 8% of women with late onset declared psychological disturbances and 30% were in use of antidepressants. Stress was reported by 51% of women with late onset acne. Additionally, 54% and 68% of women with persistent and late onset acne, respectively, reported sleep disturbances. Our study showed that 60% and 55% of women with persistent and late onset, respectively, consumed a diet featuring a high glycemic load, preferably including sweets. Results about the use of skin care during the treatment (persistent X late onset acne) were quite similar: regular use of sunscreen (50% X 58%); moisturizers (30% X 43%) and cleanser for oily skin (42% X 47%). In addition, 32% X 26% were submitted to chemical peeling; 55% X 41% used oral antibiotic, 28% X 26% combined oral contraceptive, 11% X 19% oral spironolactone, and 22% X 13% oral isotretinoin. Conclusions: The prevalence of acne among adult women employees at a university from Sao Paulo, Brazil is high, and the biological characteristic of the disease corroborates many previous studies. It is important to highlight the predominance of persistent acne, mild to moderate, inflammatory lesions, frequent report of ovary polycystic syndrome with low level of medical care and sleep disturbances. The excessive use of oral antibiotics instead of hormonal treatment point out the need of medical education for the management of this disease that causes important negative impact in women’s quality of life.

NLC-Based Sunscreen Formulations with Optimized Proportion of Encapsulated and Free Filters Exhibit Enhanced UVA and UVB Photoprotection.

The topical use of sunscreens is recommended for avoiding the damaging effects of UV radiation. However, improvements are still needed in the existing products to enhance their photoprotection effectiveness and safety. This involves minimizing the use of chemical UV filters while providing enhanced and prolonged photoprotection. This work investigated novel sunscreen formulations and their UV protection effects by encapsulating Uvinul® A, Tinosorb® S, and Uvinul® T150 into nanostructured lipid carriers (NLCs) based on bacuri butter and raspberry seed oil. First, the impact of critical formulation and process parameters on NLCs' particle size was evaluated using a 22 Face Centered Central Composite Design. Then, formulations were evaluated in terms of critical quality factors, in vitro skin permeation, and in vitro and in vivo photoprotection activities. The developed NLCs-containing formulations exhibited appropriate size (122-135 nm), PdI (<0.3), encapsulation efficiency (>90%), and drug content (>80%), which were preserved for at least 90 days under different stability conditions. Moreover, these NLCs-based formulations had equivalent skin permeation to emulsion-based controls, and the addition of NLCs into sunscreen cream bases in the optimum proportion of 20% (w/w) resulted in enhanced UVA and UVB photoprotection levels, despite a 10% reduction in the total filters content. Altogether, these results describe the application of nanoencapsulated organic UV filters in innovative sunscreen formulations to achieve superior photoprotection and cosmeceutical properties.

Sunscreen Safety and Efficacy for the Prevention of Cutaneous Neoplasm.

Sunscreen is widely used for ultraviolet radiation protection. Studies validate sun protection factors (SPFs) to prevent ultraviolet (UV)-induced skin changes such as melanoma and squamous cell carcinoma (SCC). Few studies examine sunscreen's impact on endocrine and immune system dysregulation, the production of radical oxygen species, and whether the ingredients deteriorate under prolonged exposure. We present an investigation of sunscreen labels and how ingredients impact sun safety and human health. A review of the literature was conducted using Embase and PubMed to examine sunscreen safety, efficacy, and use to prevent UV-induced skin damage. Increasing sunscreen reapplication, wearing protective clothing, and limiting exposure can reduce the incidence of skin cancer. Inorganic sunscreens form barriers to block UV light, but without titanium dioxide (TiO2), they may not be advantageous due to their low UVA protection. Organic sunscreens absorb into the skin and provide a better feeling after application. Octocrylene and avobenzone are stable and provide UVA and UVB protection with minimal adverse effects. Oxybenzone is harmful to the neuroendocrine system and should be avoided. Titanium dioxide works for broad-spectrum UV protection and offers minimal adverse effects. Octocrylene and avobenzone are organic sunscreen ingredients that also provide a better feeling on the skin after application, which enables higher rates of use. Oxybenzone should be avoided.

Natural Stabilizers and Nanostructured Lipid Carrier Entrapment for Photosensitive Compounds, Curcumin and Capsaicin.

Capsaicin and curcumin, the active components of chili and turmeric, are prone to instability when exposed to light. Therefore, this research aimed to enhance the photostability of both extracts via the use of antioxidants, natural sunscreen, and nanostructured lipid carriers (NLCs). NLCs were chosen for this this study due to their advantages in terms of stability, drug loading capacity, occlusive effect, skin penetration, and controlled release. The photostability of each extract and extracts mixed with antioxidants, including grape seed extract, tea extract, and chlorogenic acid, were determined. Chlorogenic acid can enhance the photostability of capsaicin from 6.79 h to 16.50 h, while the photostability of curcumin increased from 9.63 h to 19.25 h. In addition, the use of natural sunscreen (sunflower oil) also increased the photostability of capsaicin and curcumin. The mixed extracts were then loaded into NLCs. The particle size of the formulation was 153.73 nm with a PDI value of 0.25. It exhibited high entrapment efficiency (more than 95%). In addition, it effectively reduced the decomposition of capsaicin and curcumin. Importantly, the natural stabilizers chosen for NLC fabrication significantly improved the photostability of curcumin and capsaicin by 600% and 567% compared to the unstabilized counterparts. This improvement contributes to the sustainability and bioavailability of these compounds in both cosmeceutical and pharmaceutical products.

Toxicokinetics of homosalate in humans after dermal application: applicability of oral-route data for exposure assessment by human biomonitoring

Homosalate (HMS) is a UV filter used in sunscreens and personal care products as a mixture of cis- and trans-isomers. Systemic absorption after sunscreen use has been demonstrated in humans, and concerns have been raised about possible endocrine activity of HMS, making a general population exposure assessment desirable. In a previous study, it was shown that the oral bioavailability of cis-HMS (cHMS) is lower than that of trans-HMS (tHMS) by a factor of 10, calling for a separate evaluation of both isomers in exposure and risk assessment. The aim of the current study is the investigation of HMS toxicokinetics after dermal exposure. Four volunteers applied a commercial sunscreen containing 10% HMS to their whole body under regular-use conditions (18–40 mg HMS (kg bw)−1). Parent HMS isomers and hydroxylated and carboxylic acid metabolites were quantified using authentic standards and isotope dilution analysis. Further metabolites were investigated semi-quantitatively. Elimination was delayed and slower compared to the oral route, and terminal elimination half-times were around 24 h. After dermal exposure, the bioavailability of cHMS was a factor of 2 lower than that of tHMS. However, metabolite ratios in relation to the respective parent isomer were very similar to the oral route, supporting the applicability of the oral-route urinary excretion fractions for dermal-route exposure assessments. Exemplary calculations of intake doses showed margins of safety between 11 and 92 (depending on the approach) after single whole-body sunscreen application. Human biomonitoring can reliably quantify oral and dermal HMS exposures and support the monitoring of exposure reduction measures.

Predictors of sunscreen use in United States high-school students.

Predictors of sunscreen use in United States high-school students.