HOMOSALATE

Ultraviolet radiation is the leading cause of skin damage, such as burns, premature aging, and the development of skin cancer. Organic sunscreens are widely used in the cosmetics industry due to their ability to absorb ultraviolet radiation and dissipate it as heat. These compounds can be susceptible to photochemical instability, which compromises their effectiveness over time and also poses environmental risks, particularly in aquatic ecosystems. This study investigated the electronic properties, absorption spectra, and solvent effects of five widely used organic UV filters: Avobenzone, Homosalate, Octisalate, Octocrylene, and Bemotrizinol. The analyses were performed through DFT and TD-DFT calculations. Solvent effects were evaluated using an implicit solvent model and complemented by molecular dynamics simulations in an aqueous environment.

A critical element for understanding measured concentrations and predicting exposure levels of UV filters (UVFs) in recreational waters relates to mass released from sunscreen products applied to skin during swimming and bathing. A probabilistic mass transfer kinetic model was developed to estimate distributions of the mass of five organic UVFs released during individual swim events with sunscreen. The model incorporates the ratios of different demographics and distributions of their total skin areas, adjusted to account for body areas to which sunscreens are not typically applied or do not contact water. The resulting distribution of skin areas is combined with distributions of sunscreen application rates and UVF levels in sunscreen products to generate a distribution of UVF masses on skin that are exposed to water with the fraction released to water calculated using a first-order equation describing the kinetics of release. The predicted median mass released during a swim event was 112 mg for oxybenzone, 32.6 mg for avobenzone, 23.5 mg for octocrylene, 47.7 mg for homosalate, and 7.59 mg for octisalate. As proof of principle, the model was used to repeat previous modeling at Prophète Beach, which resulted in predicted median values for oxybenzone and avobenzone within a factor of three of the reported measured environmental concentrations.

Micro- and nanoplastics (MNPs) can enhance the toxicity of co-occurring chemicals via a proposed "Trojan horse" effect, yet the underlying mechanisms remain unclear. Here, we investigated the estrogenic effects of coexposure of ultraviolet filter homosalate (HMS) and polystyrene nanosphere (PNS) using ovariectomized mice (HMS: 0.1 and 1 mg/kg; PNS: 2.5 mg/kg) and human cell models (HMS: 0.01 - 1 μM; PNS: 1 mg/L). In mice, HMS-PNS coexposure significantly increased uterine weight, promoted mammary gland proliferation, and upregulated estrogen receptor 1 and its downstream targets amphiregulin and progesterone receptor. Integrated metabolomic and transcriptomic analyses identified endogenous 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) as a key mediator of these effects in mammary glands. In MCF-7 cells, HMS-PNS coexposure elevated 15(S)-HETE levels, promoting cell proliferation via the estrogen receptor alpha-arachidonate 15-lipoxygenase (ERα-ALOX15) axis. At a concentration of 100 nM 15(S)-HETE, pharmacological inhibition of phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) abrogated cell proliferation and serum and glucocorticoid-regulated kinase 1 (SGK1) activation. Moreover, immunoprecipitation and docking analyses suggested a direct interaction between 15(S)-HETE and SGK1. Knockdown of ALOX15, or PI3K/AKT inhibition, suppressed HMS-PNS-induced cell proliferation. Taken together, these results demonstrated that HMS-PNS coexposure amplifies estrogenic responses through ERα-ALOX15-dependent 15(S)-HETE production and PI3K/AKT/SGK1 signaling. Our findings uncover a mechanistic pathway beyond the canonical "Trojan horse" effect, providing new insight into how MNPs modulate endocrine-disrupting activity of co-occurring contaminants and informing future risk assessment of combined environmental exposures.

As emerging global environmental contaminants, organic ultraviolet absorbers (OUVAs) are widely used in personal care formulations and exhibit environmental persistence and potential bioaccumulation. Among these compounds, 2-ethylhexyl salicylate (EHS) and homosalate (HMS) are the most frequently used salicylate-type UV filters in cosmetic formulations. Although an increasing number of studies have demonstrated their environmental hazards, little is known about the molecular mechanisms underlying their cytotoxicity in mammalian systems, a fundamental knowledge gap for both human health protection and the development of more environmentally friendly consumer goods. In this study, we used mouse embryonic fibroblasts (MEFs, 3T6) and zebrafish as models to assess the toxicological phenotypes of EHS and HMS in vitro and in vivo, respectively. We found that both EHS and HMS induced cellular damage characterized by oxidative stress, disrupted intracellular calcium homeostasis, mitochondrial impairment, and DNA damage. Importantly, molecular analyses further suggested the concurrent activation of two distinct regulated cell death programs: pyroptosis, as suggested by Caspase-11 -mediated GSDMD cleavage, and necroptosis, as suggested by ZBP1-RIPK3-Caspase-8 -mediated MLKL phosphorylation. The in vitro data have been partially validated at the level of gene expression and in developmental toxicity in the zebrafish model, providing some in vivo phenotypic and molecular correlates. While the upstream events were experimentally verified, the causal links among them remain to be further elucidated. Taken together, this work suggested that OUVA-induced toxicity is not limited to isolated oxidative damage, but may also involve the activation of two different cell death programs. These findings provide important molecular clues to understanding the potential health and ecological risks of widely used UV filters and offer a scientific basis for their more environmentally friendly safety evaluation and regulatory management, which are crucial for advancing more sustainable chemistry and safer consumer goods.

Sea salt increasingly harbors organic contaminants from personal care products, yet current monitoring methods lack spatial resolution and require destructive sampling. This study introduces an innovative analytical framework integrating Laser-Induced Fluorescence (LIF) Hyperspectral Imaging (HSI) with machine learning for the rapid, non-destructive detection of sunscreen residues on salt crystals. To simulate contamination, seawater from the Mediterranean coast (Alexandria, Egypt) was spiked to achieve a 10 mg/L sunscreen concentration within the seawater matrix prior to crystallization; this formulation contained Ethylhexyl Methoxycinnamate, Homosalate, and Ethylhexyl Salicylate. A SOC710 HS camera (128 bands) acquired fluorescence data under 450 nm laser excitation. Raw data underwent preprocessing and dimensionality reduction via Sparse Principal Component Analysis (Sparse PCA, λ = 0.5, k = 4 components, 73.4% sparsity). A Support Vector Machine (SVM) with an RBF kernel was trained on these sparse features. Performance evaluation employed tenfold stratified cross-validation, an 80-20 holdout test on ROI-based spectra, and independent sample validation against manually annotated pixel-wise ground-truth masks. While ROI-based tests yielded near-perfect accuracy under ideal conditions, full-image evaluation achieved ≈96% pixel-wise accuracy (precision ≈ 0.99, recall ≈ 0.95, F1 ≈ 0.97), providing a realistic estimate under heterogeneous conditions. Full-image classification mapped widespread contamination (57.8% of pixels), whereas an independently prepared clean salt sample produced zero false positives. The integrated Sparse PCA-SVM framework transforms fluorescence-imaging data into spatio-chemical maps, simultaneously revealing contaminant presence and spatial distribution on salt surfaces, thereby offering a powerful paradigm for the interpretable monitoring of organic pollutants in food materials.

The release of chemicals into marine environments from coastal human activities has raised growing concern about pollution. Among these chemicals, organic ultraviolet filters (oUVFs), widely used in personal care products and industrial applications, have recently been identified as pollutants of emerging concern. Their extensive use and persistence highlight the need to assess their occurrence and potential impacts on aquatic ecosystems. This study aimed to optimize and apply an analytical methodology for the determination of eleven oUVFs in zooplankton matrices. Microwave-assisted extraction (MAE) was employed for sample preparation, while ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) enabled the identification and quantification of the target compounds. Extraction parameters, including solvent, temperature, and time, were systematically optimized to enhance recovery and ensure accuracy and precision in complex biological samples. The method achieved limits of detection (MLOD) between 1.47 and 5.98 ng g -1 dry weight (d.w.) and method limits of quantification (MLOQ) between 4.900 and 19.92 ng g -1 d.w. Recovery efficiencies were low, ranging from 28 to 63 %, reflecting the diverse physicochemical properties of oUVFs and the strong matrix effects associated with zooplankton heterogeneity. Application of the validated method to zooplankton collected around Madeira Island (Portugal) revealed the presence of six oUVFs. Homosalate was the most frequently detected compound (53 % of samples), while octocrylene exhibited the highest concentrations, ranging from 24.01 to 1029 ng g -1 d.w. These findings demonstrate the relevance of zooplankton as bioindicators of oUVF contamination and support the need for regulatory monitoring and ecological risk assessments in coastal ecosystems.

UV filters used in personal care products are increasingly recognised as emerging contaminants due to their persistence and ecological risks. Detected in aquatic systems at concentrations from ng L -1 to μg L -1 , their monitoring is essential for environmental risk assessment but challenging because of their diverse physicochemical properties, requiring sensitive analytical methods. This study optimised a solid-phase extraction gas chromatography-tandem mass spectrometry (SPE-GC-MS/MS) method for the simultaneous determination of twelve UV filters in marine waters. The method showed suitable linearity, precision, and recoveries, with detection limits below 1 ng L -1 . Seawater samples collected along the Adriatic coast (Rimini and Riccione, Italy) during peak recreational activity were analysed. All twelve UV filters were detected, with octocrylene (up to 23,100 ng L -1 ), homosalate (up to 16,400 ng L -1 ), and ethylhexyl salicylate (up to 10,900 ng L -1 ) being most abundant. Trans-2-Ethylhexyl methoxycinnamate (E-EHMC, the trans isomer of octinoxate, 13-1474 ng L -1 ) occurred consistently with its isomer Z-EHMC (cis-octinoxate), contributing 18-64 % of total (E + Z)-EHMC, suggesting in situ photochemical conversion, since the cis form is negligible in cosmetic products. Benzophenone, ethylhexyl dimethyl PABA, 4-methylbenzylidene camphor, benzyl salicylate, and isoamyl methoxycinnamate were found at lower yet relevant concentrations. UV filters banned under European regulations, such as menthyl anthranilate and etocrylene, were absent or barely detected. This work provides the first data on sunscreen UV filters in Adriatic coastal waters and the first quantitative evidence of Z-EHMC in environmental waters, highlighting its in situ formation and contributing to understanding their environmental fate and risks.

The present work investigates the in vitro hepatic metabolism of six commonly used sunscreen UV filters: oxybenzone, avobenzone, octocrylene, octinoxate, octisalate, and homosalate, using human liver microsomes. In vitro-in vivo extrapolation was performed to predict key metabolic parameters, including hepatic clearance (CL H ) and hepatic extraction ratio (E H ), providing valuable insights into the potential systemic persistence of these compounds after dermal or oral absorption. Additionally, reaction phenotyping was conducted for the first time to characterize the human liver enzymes involved in the metabolism of these sunscreen UV filters, with carboxylesterases (CES) playing a key role in the biotransformation of ester-containing compounds such as octocrylene and octinoxate. Furthermore, oxybenzone is predominantly metabolized by CYP2C19 and CYP1A2, while avobenzone is primarily metabolized by CYP2C19, CYP2C9, and CYP1A2. The results showed significant variability in metabolic stability and systemic clearance, with compounds like octocrylene exhibiting relatively higher half-lives, suggesting potential for bioaccumulation. The findings highlight the importance of understanding the kinetic profiles of sunscreen UV filters for more accurate risk assessments, particularly in the context of prolonged human exposure.

This study aims to evaluate the potential of green-synthesized titanium dioxide (TiO₂) nanoparticles (NPs) derived from herbal extracts-namely Camellia sinensis (Green Tea), Eclipta prostrata (Bhringraj), Glycyrrhiza glabra (Licorice), and Cinnamomum zeylanicum (Cinnamon)-for enhancing the Sun Protection Factor (SPF) in sunscreen formulations. Addressing the environmental and toxicity concerns associated with conventionally synthesized TiO₂ NPs, this eco-friendly approach offers a sustainable and effective alternative for cosmetic applications without compromising efficacy. The synthesized nanoparticles were characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), and then incorporated into oil-in-water emulsions containing 5% homosalate. In vitro SPF was measured using the Labsphere UV-2000S system, while formulation stability was assessed via pH monitoring, rheological behavior, and accelerated centrifugation using the LUMiSizer. Statistical analysis, including one-way ANOVA and effect size metrics (η 2 , Cohen's d), confirmed significant SPF enhancement, particularly in formulations using Green Tea and Cinnamon-derived TiO₂ NPs, which showed 3.12-fold and 3.11-fold improvements, respectively. Notably, smaller crystallite size (30.2 nm in Green Tea-derived TiO₂) correlated with higher SPF (14.97 ± 0.31). All formulations exhibited excellent physical and thermal stability. These findings underscore the promise of plant-mediated TiO₂ NPs as a viable, sustainable solution for next-generation sunscreen products, with further investigation warranted for scale-up and in vivo validation.

Ultraviolet filters (UVFs), widely used in industrial and personal care products, are emerging environmental contaminants of great concern because of their persistence, bioaccumulation and toxicity. Sediments are generally considered the reservoir and secondary source of UVFs, yet knowledge of the occurrence of these emerging contaminants in coastal sediments on a large geographical scale remains unknown. In this study, 31 out of 37 target UVFs were detected in 91 sediment samples collected from 43 coastal cities of China. Benzophenone UVFs exhibited the highest mean total concentration of 5374.8 pg/g, followed by benzotriazole (3298.3 pg/g), salicylate (3094.1 pg/g) and triazin UVFs (61.2 pg/g), respectively. Spatial analysis revealed significantly higher UVF concentrations ranging from 1839 pg/g to 82,308 pg/g in coastal sediments from the Yellow Sea compared with those of the South China Sea, the East China Sea and the Bohai Sea (p < 0.05). Source apportionment indicated that the emissions from industrial productions, cosmetics and personal care products are major contributors to UVF contamination. A nationwide mass inventory identified the Liaodong Peninsula, Yangtze River Estuary, Pearl River Estuary, and north-east Hainan Province as UVF accumulation hotspots, influenced by tourism, industrial activities, and ocean currents. Ecological risk assessment showed that seven UVFs, including Benzophenone-7 (BP-7), 2-(benzotriazol-2-yl)-4-tert-butylphenol (UV-PS), 2-tert-butyl-6-(5-chlorobenzotriazol-2-yl)-4-methylphenol (UV-326), 2,4-ditert-butyl-6-(5-chlorobenzotriazol-2-yl) phenol (UV-327), 2-(benzotriazol-2-yl)-4-(2,4,4-trimethylpentan-2-yl) phenol (UV-329), 2-Ethylhexyl salicylate (EHS) and Homosalate (HMS), posed significant ecological risks (RQ > 0.1) in coastal sediments. This work delivers the first nationwide assessment of four classes of UVFs contamination in coastal sediments of China, providing critical data for their environmental mitigation and management.