New trends on personalized sunscreens.

BACKGROUND/PURPOSE: Nowadays, there are emerging trends in customized and personalized photoprotection, focusing on the innovative approaches to enhance sun protection efficacy tailored to individual needs. METHODS: We conducted an electronic search of the following databases: MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Cochrane Skin Group Specialised Skin Register, and TESEO. Specific search terms related to personalized photoprotection and the variables of age, genetic predisposition, skin phototype, photodermatosis, and physiological conditions such as pregnancy, as well as lifestyle habits were used. RESULTS/CONCLUSION: The article highlights the challenges and opportunities in adopting personalized photoprotection strategies, aiming to promote skin health and prevent the harmful effects of UV radiation in the era of precision medicine.

A systematic review of the risk of cutaneous malignancy associated with ultraviolet nail lamps: what is the price of beauty?

Gel manicures have become part of a popular personal care service in the last two decades due to increased longevity of the polish and the added strength to the nail plate. Prolonged exposure to nail ultraviolet (UV) lamps is required to cure the gel polish. Despite the increased use of UV nail lamps, there is limited consensus in the literature on the risk of skin malignancy associated with UV nail lamps. The objective of this article was to provide a systematic review of the risk of skin malignancy associated with the use of UV nail lamps and to synthesize evidence-based recommendations on their safe usage. A systematic review of the literature was conducted on the databases, Medline and Embase, in accordance with PRISMA guidelines. The search yielded 2,331 non-duplicate articles. Nine were ultimately included, of which three were case reports, one was a cross-sectional study, and five were experimental studies. The risk of bias per the Joanna Briggs Institute guidelines was high or unclear, likely due to the number of case reports included. Prolonged and repeated exposure to UV nail lamps may pose a low risk of skin cancer. It is important to note that the available evidence is weak, and patients should be informed about the limited data to make their own decisions. Dermatologists and other healthcare providers should be updated with the latest evidence to address patients' concerns about gel manicures and suggest practices which can effectively reduce the risk of cutaneous malignancy associated with gel manicures, such as the use of UV-blocking gloves or properly applied sunscreens.

Biomonitoring of benzophenones in guano samples of wild bats in Poland.

Benzophenones (BPs) are substances used in the production of sunscreens, cosmetics, and personal care products. However, there is a lack of knowledge of BPs in wild animals. Therefore, the study aimed to assess the concentration of selected BPs commonly used in the cosmetic industry in guano samples collected from 4 colonies of greater mouse-eared bats (Myotis myotis). Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to determine guano concentrations of benzophenone 1 (BP-1), benzophenone 2 (BP-2), benzophenone 3 (BP-3) and benzophenone 8 (BP-8). BP-1 levels above the method quantification limit (MQL) were noted in 97.5% of samples and fluctuated from <0.1 ng/g to 259 ng/g (mean 41.50 ng/g, median 34.8). The second most common was BP-3, which fluctuated from <0.1 ng/g to 19 ng/g (mean 6.67 ng/g, median 5.05), and its levels higher than MQL were observed in 40% of samples. BP-2 and BP-8 concentrations did not exceed the method detection limit (0.04 ng/g) in any analyzed sample. There were visible differences in the BP-1 and BP-3 levels among the studied bat colonies. Mean BP-1 concentration fluctuated from 11.23±13.13 ng/g to 76.71±65.51 ng/g and differed significantly between the colonies. Mean BP-3 concentration fluctuated from 5.03±6.03 ng/g to 9.18±7.65 mg/g, but it did not differ significantly between the colonies. The results show that guano is a suitable matrix for the assessment of wildlife exposure to BPs. This could be particularly advantageous in protected species, where not disturbing and stressing the animals are crucial.

Assessing the Fate of Benzophenone-Type UV Filters and Transformation Products during Soil Aquifer Treatment: The Biofilm Compartment as Bioaccumulator and Biodegrader in Porous Media.

The fate of selected UV filters (UVFs) was investigated in two soil aquifer treatment (SAT) systems, one supplemented with a reactive barrier containing clay and vegetable compost and the other as a traditional SAT reference system. We monitored benzophenone-3 (BP-3) and its transformation products (TPs), including benzophenone-1 (BP-1), 4,4'-dihydroxybenzophenone (4DHB), 4-hydroxybenzophenone (4HB), and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB), along with benzophenone-4 (BP-4) and avobenzone (AVO) in all involved compartments (water, aquifer sediments, and biofilm). The reactive barrier, which enhances biochemical activity and biofilm development, improved the removal of all detected UVFs in water samples. Among monitored UVFs, only 4HB, BP-4, and AVO were detected in sediment and biofilm samples. But the overall retained amounts were several orders of magnitude larger than those dissolved. These amounts were quantitatively reproduced with a specifically developed simple analytical model that consists of a mobile compartment and an immobile compartment. Retention and degradation are restricted to the immobile water compartment, where biofilm absorption was simulated with well-known compound-specific Kow values. The fact that the model reproduced observations, including metabolites detected in the biofilm but not in the (mobile) water samples, supports its validity. The results imply that accumulation ensures significant biodegradation even if the degradation rates are very low and suggest that our experimental findings for UVFs and TPs can be extended to other hydrophobic compounds. Biofilms act as accumulators and biodegraders of hydrophobic compounds.

Investigation on the Validity of in vitro Sun Protection Factor and Ultraviolet-A Protection Factor Evaluation Method for Sunscreen Samples.

Factors affecting the in vitro Sun Protection Factor (SPF) and Ultraviolet-A Protection Factor (UVA-PF) of sunscreens were analyzed for verifying the validity and reliability of the ISO24443 evaluation method. UV absorbance measurements by different spectrophotometers did not lead to the large difference in in vitro SPF/UVA-PF, although the UV absorbance determined by each spectrophotometer exhibited relatively large difference when it was larger than 2. On the other hand, relatively large difference was found in in vitro SPF/UVA-PF by utilizing European Cosmetic and Perfumery Association (Colipa) 1994 or UV-solar simulated radiation (UV-SSR) for the spectral irradiance. Appropriateness of employing the coefficient of adjustment for the determination of in vitro UVA-PF was also found to be reexamined.

Efficacy of a facial-aging web app on sun protection behaviors among primary school students in Iran: a randomized controlled trial.

BACKGROUND: Skin cancers resulting from excessive exposure to solar ultraviolet (UV) radiation are on the rise. This study aims to investigate the impact of facial-aging app intervention on promoting safe and healthy behaviors and its influence on reducing students' UV exposure. METHOD: Utilizing a Pretest-Posttest repeated-measures design, we developed a theory-guided web app on the WhatsApp platform, named the Sunshine and Skin Health app. This app allows users to visualize their altered faces in three stages of adolescence, middle age, and old age based on sun protection behavior. The intervention continued within WhatsApp, incorporating 27 health messages grounded in the PMT theory, eight educational files, and a skin cancer video clip. The primary outcome is the change in sun protection behavior between the two groups (intervention and control) immediately after the intervention (T2) and the secondary outcome is the change in sun protection behavior between the two groups at 3 months follow-up (T3). The data are analyzed in SPSS 22 and a significance level of 0.05 is considered. RESULTS: The results revealed no significant difference between the two groups before the intervention. However, in the intervention group, there were significant differences in the utilization of sunglasses, hats, and sunscreen in the last month, as well as sunscreen reapplication after washing their hands and face, both immediately after the intervention and at the 3-month follow-up, compared to the control group (P = 0.001). Furthermore, a significant intervention effect, time effect, and interaction effect between group and time were observed in behaviors related to using sunscreen in the last month and sunscreen reapplication after washing hands and face (P = 0.001). Specifically, the intervention group exhibited a significant difference from Time 1 to 2 and from Time 1 to 3 (p = 0.001), but no significant difference from Time 2 to 3. In contrast, the control group did not show any significant differences over time. CONCLUSIONS: This study indicated that the Facial-Aging web app can effectively encourage safe behaviors in sunlight. To ensure the maintenance and sustainability of these behaviors over the long term, it is crucial to consider implementing booster sessions. TRIAL REGISTRATION: Iranian Registry of Clinical Trials IRCT20200924048825N1. Registered prospectively on 8 February 2021.

BSA Adsorption on Titanium Dioxide Nanoparticle Surfaces for Controlling Their Cellular Uptake in Skin Cells.

Nanoparticles (NPs) are continuously being developed for many applications including imaging, biomedicine, and everyday products. It is difficult to avoid contact with NPs such as titanium dioxide (TiO2) NPs, which are widely used in sunscreens. However, the safety of TiO2 NPs for skin contact and inhalation remains controversial. If NPs cannot penetrate the skin, they will be unable to circulate in the bloodstream, accumulate in the body, or cause side effects, ensuring their safety. Therefore, this study aimed to modify TiO2 NP surfaces to inhibit their uptake in skin cells. Inspired by protein corona studies, bovine serum albumin (BSA) was chosen to functionalize TiO2 NP surfaces via physical adsorption. The maximum BSA adsorption occurred at pH 5.0. The physicochemical properties (size, ζ-potential, morphology, ultraviolet (UV) absorption efficiency, and sun protection factor (SPF)) of TiO2-BSA NPs were comparable to those of TiO2 NPs, indicating that these properties did not affect cellular uptake. In the safety evaluation, TiO2 NPs and TiO2-BSA NPs exhibited high biocompatibility with skin cells and no phototoxicity after UVA and UVB irradiation. In the efficacy evaluation, both NPs possessed the same photoprotection abilities, reducing membrane damage and DNA breakage after UVA irradiation. Compared with TiO2 NPs, TiO2-BSA NPs showed substantially reduced skin penetration in Franz diffusion cells (91%) and human immortalized keratinocyte (HaCaT) cells (89%). A qualitative cellular uptake study using transmission electron microscopy and confocal laser scanning microscopy confirmed that TiO2 NPs were more abundant than TiO2-BSA NPs inside the HaCaT cells. These findings indicate that TiO2 surface functionalization with BSA inhibits cellular uptake in skin cells while maintaining safety and UV protection efficacy, which might be extended to other NP-based sunscreens.

Current safeguards, risk mitigation, and transparency measures of large language models against the generation of health disinformation: repeated cross sectional analysis.

OBJECTIVES: To evaluate the effectiveness of safeguards to prevent large language models (LLMs) from being misused to generate health disinformation, and to evaluate the transparency of artificial intelligence (AI) developers regarding their risk mitigation processes against observed vulnerabilities. DESIGN: Repeated cross sectional analysis. SETTING: Publicly accessible LLMs. METHODS: In a repeated cross sectional analysis, four LLMs (via chatbots/assistant interfaces) were evaluated: OpenAI's GPT-4 (via ChatGPT and Microsoft's Copilot), Google's PaLM 2 and newly released Gemini Pro (via Bard), Anthropic's Claude 2 (via Poe), and Meta's Llama 2 (via HuggingChat). In September 2023, these LLMs were prompted to generate health disinformation on two topics: sunscreen as a cause of skin cancer and the alkaline diet as a cancer cure. Jailbreaking techniques (ie, attempts to bypass safeguards) were evaluated if required. For LLMs with observed safeguarding vulnerabilities, the processes for reporting outputs of concern were audited. 12 weeks after initial investigations, the disinformation generation capabilities of the LLMs were re-evaluated to assess any subsequent improvements in safeguards. MAIN OUTCOME MEASURES: The main outcome measures were whether safeguards prevented the generation of health disinformation, and the transparency of risk mitigation processes against health disinformation. RESULTS: Claude 2 (via Poe) declined 130 prompts submitted across the two study timepoints requesting the generation of content claiming that sunscreen causes skin cancer or that the alkaline diet is a cure for cancer, even with jailbreaking attempts. GPT-4 (via Copilot) initially refused to generate health disinformation, even with jailbreaking attempts-although this was not the case at 12 weeks. In contrast, GPT-4 (via ChatGPT), PaLM 2/Gemini Pro (via Bard), and Llama 2 (via HuggingChat) consistently generated health disinformation blogs. In September 2023 evaluations, these LLMs facilitated the generation of 113 unique cancer disinformation blogs, totalling more than 40 000 words, without requiring jailbreaking attempts. The refusal rate across the evaluation timepoints for these LLMs was only 5% (7 of 150), and as prompted the LLM generated blogs incorporated attention grabbing titles, authentic looking (fake or fictional) references, fabricated testimonials from patients and clinicians, and they targeted diverse demographic groups. Although each LLM evaluated had mechanisms to report observed outputs of concern, the developers did not respond when observations of vulnerabilities were reported. CONCLUSIONS: This study found that although effective safeguards are feasible to prevent LLMs from being misused to generate health disinformation, they were inconsistently implemented. Furthermore, effective processes for reporting safeguard problems were lacking. Enhanced regulation, transparency, and routine auditing are required to help prevent LLMs from contributing to the mass generation of health disinformation.

Effects of benzophenone-3 and its metabolites on the marine diatom Chaetoceros neogracilis: Underlying mechanisms and environmental implications.

The wide application of benzophenones (BPs), such as benzophenone-3 (BP3), as an ingredient in sunscreens, cosmetics, coatings, and plastics, has led to their global contamination in aquatic environments. Using the marine diatom Chaetoceros neogracilis as a model, this study assessed the toxic effects and mechanisms of BP3 and its two major metabolites (BP8 and BP1). The results showed that BP3 exhibited higher toxicity on C. neogracilis than BP8 and BP1, with their 72-h median effective concentrations being 0.4, 0.8 and 4 mg/L, respectively. Photosynthesis efficiencies were significantly reduced after exposure to environmentally relevant concentrations of the three benzophenones, while cell viability, membrane integrity, membrane potential, and metabolic activities could be further impaired at their higher concentrations. Comparative transcriptomic analysis, followed by gene ontology and KEGG pathway enrichment analyses unraveled that all the three tested benzophenones disrupted photosynthesis and nitrogen metabolism of the diatom through alteration of similar pathways. The toxic effect of BP3 was also attributable to its unique inhibitory effects on eukaryotic ribosome biosynthesis and DNA replication. Taken together, our findings underscore that benzophenones may pose a significant threat to photosynthesis, oxygen production, primary productivity, carbon fixation, and the nitrogen cycle of diatom in coastal waters worldwide.

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.

Design of Bombyx mori (B. mori) Silk Fibroin Microspheres for Developing Biosafe Sunscreen.

Sunscreens play a crucial role in protecting the skin from ultraviolet (UV) damage. However, present commercial sunscreens have a tendency to generate free radicals in the UV window, resulting in serious inflammatory responses and health problems. In this study, we demonstrate that silk fibroin microspheres (SFMPs) assembled from regenerated silk fibroin (SF) could scavenge free radicals while preventing UV irradiation and thus present a promising sunscreen. The SFMP reflected more UV light than SF and presented a higher stability than that of organic commercial sunscreens. In vitro analysis proved that SFMP could more efficiently scavenge the hydroxy radical and reduce the intracellular reactive oxygen than titanium dioxide (TiO2). In vivo experiments exhibited that SFMP provided stronger skin protection against UV irradiation than commercial sunscreens and TiO2. Furthermore, SFMP treatment significantly inhibited the skin inflammatory response. This work suggests that the SFMP has great potential to be developed into a biosafe sunscreen.

Rural-urban differences in meeting of physical activity recommendations by sun exposure and protection behaviors in the United States.

OBJECTIVE: To examine associations between sun protection behaviors and physical activity (PA) by rural and urban residence in the United States. METHODS: We analyzed data from the National Health and Nutrition Examination Survey (2013-2018), restricting to participants ages 20-59 with sun behavior data. Sunburns, sun exposure, and sun protection measures were dichotomized (yes/no): ≥1 sunburn in the past year, 2+ hour outside during workdays or non-workdays, and never/rarely/sometimes using sunscreen, wearing long sleeves, and staying in the shade. Meeting PA recommendations (yes/no) was defined as ≥150 min of vigorous/moderate or ≥ 75 min vigorous PA per week. Associations between sun behaviors and PA were analyzed using logistic regression models, which accounted for survey-weights and potential confounders, and stratified by rural-urban status. RESULTS: Rural and urban individuals meeting PA recommendations had greater odds of spending 2+ hour outside during workdays (OR: 2.26 [1.88, 2.74] and 3.95 [2.72, 5.73]) and non-workdays (OR: 2.06 [1.78, 2.38] and 3.33 [2.47, 4.46]). Among urban residents, odds of staying in the shade were lower among those who met PA recommendations (OR: 0.78 [0.66, 0.92]). We did not observe differences in sunburns or other sun behaviors by PA status, regardless of rurality. CONCLUSIONS: Meeting PA recommendations was associated with greater sun exposure in both rural and urban populations. Additional exercise location (indoors/outside) data is needed to inform PA and skin cancer prevention interventions to reduce unintended increases in sun exposure and reductions in PA, respectively, especially among rural populations.

In vitro Evaluation Method of UV Protecting Ability of Sunscreens: Clarifying and Overcoming Problems to Develop New Method.

Factors influencing on in vitro evaluation of UV protecting ability of sunscreens were analyzed. It was found that any factors making the sunscreen layer spatially inhomogeneous, such as directional viscous fingering during the sunscreen application, dewetting of applied sunscreen layer, and the surface roughness of the standard PMMA plate, alter the UV transmittance. New application procedure and new type of flat hydrophilic plate were developed for inhibiting the generation of spatial inhomogeneity in applied sunscreen layer. The method created by the combination of these newly developed technologies succeeded in providing reliable and reproducible in vitro evaluation of UV protecting ability.

Effects of the sunscreen ultraviolet filter oxybenzone (benzophenone-3) on the seagrass Posidonia oceanica (L.) Delile and its associated N2 fixers.

Oxybenzone/benzophenone-3 (BP-3) is one of the most detrimental organic ultraviolet filters for marine biota, leading to legislative measures banning its presence in commercial sunscreen formulations of several countries. It remains poorly explored how this contaminant is currently threatening the persistence of critical ecosystems for conservation in the Mediterranean, such as Posidonia oceanica meadows, but it is essential for promoting sustainable coastal tourism. Our investigation aimed to determine the effects of BP-3 on P. oceanica under a short-term laboratory setup, recreating summer conditions while testing three environmentally relevant concentrations for Mallorca, Spain (minimum: 53.6 ng L-1, maximum: 557.5 ng L-1 and increased: 1115 ng L-1) and a control (0 ng L-1). Primary productivity was unaffected by the treatments, however, a reduction in leaf chlorophyll content and nitrogen fixation activity associated with rhizomes was evidenced under BP-3 addition. This may be related with oxidative damage, as reactive oxygen species production and catalase activity in P. oceanica leaves were the highest even at minimum BP-3 concentrations. Alkaline phosphatase rates showed inverted trends between old leaves and rhizomes, being enhanced in the former under BP-3 addition and reduced in the latter. These results are of great relevance for the future management of P. oceanica meadows, elucidating that even minimum concentrations of BP-3 reported in coastal waters of Mallorca can induce elevated levels of oxidative stress in the seagrass, that lead to impairments in its photosynthetic pigments production and supply of essential nutrients through belowground tissues.

Skin Protection by Carotenoid Pigments.

Sunlight, despite its benefits, can pose a threat to the skin, which is a natural protective barrier. Phototoxicity caused by overexposure, especially to ultraviolet radiation (UVR), results in burns, accelerates photoaging, and causes skin cancer formation. Natural substances of plant origin, i.e., polyphenols, flavonoids, and photosynthetic pigments, can protect the skin against the effects of radiation, acting not only as photoprotectors like natural filters but as antioxidant and anti-inflammatory remedies, alleviating the effects of photodamage to the skin. Plant-based formulations are gaining popularity as an attractive alternative to synthetic filters. Over the past 20 years, a large number of studies have been published to assess the photoprotective effects of natural plant products, primarily through their antioxidant, antimutagenic, and anti-immunosuppressive activities. This review selects the most important data on skin photodamage and photoprotective efficacy of selected plant carotenoid representatives from in vivo studies on animal models and humans, as well as in vitro experiments performed on fibroblast and keratinocyte cell lines. Recent research on carotenoids associated with lipid nanoparticles, nanoemulsions, liposomes, and micelles is reviewed. The focus was on collecting those nanomaterials that serve to improve the bioavailability and stability of carotenoids as natural antioxidants with photoprotective activity.

Characterization and Anti-Ultraviolet Radiation Activity of Proanthocyanidin-Rich Extracts from Cinnamomum camphora by Ultrasonic-Assisted Method.

The ultrasonic-assisted extraction (UAE) method was employed to separate Cinnamomum camphora proanthocyanidin-rich extracts (PCEs). This extraction process was optimized by the Box-Behnken design, and the optimal conditions, on a laboratory scale, were as follows: an ethanol concentration of 75%, a liquid-to-solid ratio of 24 mL/g, an ultrasonic time of 39 min, and an ultrasonic power of 540 W. Under the obtained conditions, the PCE yield extracted by UAE was higher than that from heat reflux extraction and soaking extraction. An ultra-performance liquid chromatography-tandem mass spectrometry analysis was employed to characterize the phloroglucinolysis products of the C. camphora PCEs, by which epigallocatechin, catechin, epicatechin, and (-)-epigallocatechin-3-O-gallate were identified as the terminal units; epigallocatechin, epicatechin, and (-)-epigallocatechin-3-O-gallate were recognized as extension units. The C. camphora PCEs possessed higher anti-ultraviolet activity in vitro compared with the commercially available sunscreen additive of benzophenone with respect to their ethanol solutions (sun protection factor of 27.01 ± 0.68 versus 1.96 ± 0.07 at a concentration of 0.09 mg/mL) and sunscreens (sun protection factor of 17.36 ± 0.62 versus 14.55 ± 0.47 at a concentration of 20%). These results demonstrate that C. camphora PCEs possess an excellent ultraviolet-protection ability and are promising green sunscreen additives that can replace commercial additives.

Effect of Ag and Ni-Doped Cerium Oxide Nanoparticles on the Formation of ROS and Evaluation as an Alternative Physical Sunscreen Material.

CeO2 nanoparticles (nanoceria) were proposed as an alternative physical sunscreen agent with antioxidant properties and comparable UV absorption performance. Green synthesis of nanoceria with Ag and Ni dopants resulted in doped nanoceria with lower catalytic activity and biologically-safe characteristics. The doped nanoceria was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Rancimat Instrument, and UV-Vis Spectrophotometer for SPF (Sun Protection Factor) determination. XRD and TEM analysis showed that nanoceria had been successfully formed in nanoscale-sized with a change in crystallite size due to the crystal defect phenomenon caused by dopant addition. While the Rancimat test and band gap energy analysis were conducted to evaluate the oxidative stability and reactive oxygen species formation, it was confirmed that dopant addition could decrease catalytic activity of material, resulting in Ni-doped Ce with a longer incubation time (11.81 h) than Ag-doped Ce (10.58 h) and non-doped Ce (10.30 h). In-vitro SPF value was measured using the thin layer technique of sunscreen prototype with Virgin Coconut Oil (VCO)-based emulsion, which yielded 10.862 and 5.728 SPF values for 10% Ag-doped Ce and 10% Ni-doped Ce, respectively. The dopant addition of nanoceria could reduce catalytic activity and give a decent in vitro UV-shielding performance test; thus, Ag and Ni-doped nanoceria could be seen as promising candidates for alternative physical sunscreen agents.

Rural-Urban Differences in Sun Exposure and Protection Behaviors in the United States.

BACKGROUND: Evidence regarding whether rural residence is a risk factor for skin cancer is mixed. We compared sun exposure and protection behaviors between rural and urban residents by ethno-racial group in the United States. METHODS: We analyzed data from three (2013-2018) National Health and Nutrition Examination Survey cycles. We compared self-reported sun exposure and protection measures (sunburn, time spent outside, sunscreen use, wearing long sleeves, staying in shade) by rural-urban residential status using survey-weighted logistic regression models stratified by ethno-racial group, adjusting for age, sex, income, education, body mass index, and smoking. RESULTS: Hispanic rural versus urban residents more often reported sunburns in the past year [41.6% vs. 31.2%, adjusted OR (aOR): 1.46 (1.15-1.86)]. White rural versus urban residents more often spent 2+ hours outside on workdays [42.9% vs. 29.1%, aOR: 1.60 (1.27-2.01)] and non-workdays [72.2% vs. 64.8%, aOR: 1.45 (1.12-1.88)] and less often used sunscreen [26.0% vs. 35.1%, aOR: 0.74 (0.59-0.93)] and stayed in the shade [21.7% vs. 26.7%, aOR: 0.72 (0.57-0.89)]. Black rural versus urban residents stayed in the shade less often [31.6% vs. 43.9%, aOR: 0.60 (0.39-0.91)] but less often spent 2+ hours outside on non-workdays [47.6% vs. 56.8%, aOR: 0.67 (0.51-0.90)]. CONCLUSIONS: Across all ethno-racial groups included, rural residents reported greater sun risk behaviors than urban residents, with some nuances by ethno-racial identity, suggesting rural residence is a potential risk factor for skin cancer. IMPACT: Sun protection promotion programs should consider rural-urban settings while also accounting for ethno-racial identities.

Identification, Organic Synthesis, and Sensitive Analysis of a cis-Homosalate-Specific Exposure Biomarker.

Homosalate (HMS) is an organic UV filter used in sunscreens and personal care products. Despite its widespread use and detection in environmental matrices, little is known regarding its exposure in humans. HMS is used as a mixture of cis- and trans-isomers, and we recently revealed major differences in human toxicokinetics, indicating the need to consider these isomers separately in exposure and risk assessments. In the course of these previous investigations of human HMS toxicokinetics, we identified two trans-HMS-specific and one cis-HMS-specific biomarker candidates. However, the latter lacks sensitivity due to only low amounts excreted in urine, prompting the search for another cis-HMS-specific biomarker. Our toxicokinetic investigations revealed a total of five isomers of HMS carboxylic acid metabolites (HMS-CA). Of these, only one was specifically formed from cis-HMS (HMS-CA 5), but its full identity in terms of constitution and configuration had, so far, not been elucidated. Here, we describe the synthesis of three HMS-CA isomers, of which the isomer (1R,3S,5S)/(1S,3R,5R)-3-((2-hydroxybenzoyl)oxy)-1,5-dimethylcyclohexane-1-carboxylic acid turned out to be HMS-CA 5. Taken together with two previously synthesized HMS-CA isomers, we were able to identify the constitution and configuration of all five HMS-CA isomers observed in human metabolism. We integrated the newly identified cis-HMS-specific metabolite HMS-CA 5 into our previously published human biomonitoring LC-MS/MS method. Intra- and interday precisions had coefficients of variation below 2% and 5%, respectively, and the mean relative recovery was 96%. The limit of quantification in urine was 0.02 µg L-1, enabling the quantification of HMS-CA 5 in urine samples for at least 96 h after sunscreen application. The extended method thus enables the sensitive and separate monitoring of cis- and trans-HMS in future human biomonitoring studies for exposure and risk assessment.

Reducing Gut Dissolution of Zinc Oxide Nanoparticles by Secondary Microplastics with Consequent Impacts on Barnacle Larvae.

The environmental impact of sunscreen is a growing concern, yet the combined effects of its components on marine animals are poorly understood. In this study, we investigated the combined effects of sunscreen-extracted zinc oxide nanoparticles (nZnO) and microplastics (MPs) on the development of barnacle larvae, focusing on the different roles played by primary microplastics (PMPs) and secondary microplastics (SMPs) generated through the phototransformation of PMPs. Our findings revealed that a lower concentration of nZnO (50 µg/L) enhanced molting and eye development in barnacle larvae, while a higher concentration (500 µg/L) inhibited larval growth. Co-exposure to PMPs had no significant effect on larval development, whereas SMPs mitigated the impact of nZnO by restricting the in vivo transformation to ionic Zn. Accumulated SMPs reduced gut dissolution of nZnO by up to 40%, lowering gut acidity by 85% and buffering the in vivo dissolution of nZnO. We further identified a rough-surfaced Si-5 fragment in SMPs that damaged larval guts, resulting in decreased acidity. Another Si-32 resisted phototransformation and had no discernible effects. Our study presented compelling evidence of the impacts of SMPs on the bioeffect of nZnO, highlighting the complex interactions between sunscreen components and their combined effects on marine organisms.