Photochemistry and Photobiology

Continuous-wave (CW) 450 nm blue diode-laser irradiation was evaluated as a physical seed-priming treatment for improving lettuce (Lactuca sativa L.) germination and early seedling establishment under reduced water availability. Dry seeds were irradiated at 50-250 mW for 2 min and at 100 mW for 0.5-10 min; each condition included three independent Petri-dish replicates with 100 seeds per replicate, and the replicates were monitored for 72 h. Laser treatment produced a dose-dependent biological response. The optimized condition, 100 mW for 2 min, increased final germination from approximately 65-70% to 90-95%, increased the germination speed index, and promoted root elongation more strongly than shoot elongation. Longer exposures reduced germination and seedling growth. Under reduced water availability (0.5-6 ml per Petri dish), laser-treated seeds germinated earlier, maintained final germination of 83-93% compared with 57-72% in controls, and produced better-developed seedlings. The relative benefit increased as water availability decreased, indicating that optimized blue laser priming partially compensated for low water supply during germination and early establishment. These results identify CW blue laser priming as a contactless, chemical-free approach for improving lettuce seed performance and early seedling vigor under limited water availability.

Germicidal UV devices offer a promising solution to mitigate surface-mediated pathogen transmission, providing effective disinfection without material corrosion. This study evaluated the surface inactivation kinetics of two bacteria and two bacteriophages using a low-pressure (LP) mercury UV lamp (254 nm) and a filtered krypton chloride (KrCl*) excimer lamp (222 nm). Three deposition methods (Spray, Spread, and Pipette) and two extraction methods (Swab and Elute) were compared. The UV dose response on surfaces followed a two-region non-linear model due to shielding from dried deposition constituents, primarily through UV absorption. KrCl* excimer exhibited similar bacterial inactivation but slightly lower viral inactivation than LP UV lamp (maximum inactivation [~] 1 log lower), but its safety profile makes it compelling in occupied spaces. Compared to aqueous conditions, bacteria were more UV sensitive on surfaces, whereas viruses were more resistant. The deposition methods affected the inactivation results, with the Spray method resulting in higher bacteria inactivation. While the extraction methods had limited effect on inactivation efficacy, the Swab method provided higher inactivation detection limits ([~] 2 log higher) and more consistent extraction efficiency. This study provides mechanistic insights into the effects of deposition conditions, UV wavelengths, and microbial characteristics on UV surface disinfection and contributes to standardization of testing methods. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/734141v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@11db511org.highwire.dtl.DTLVardef@15aa3faorg.highwire.dtl.DTLVardef@1c39ac9org.highwire.dtl.DTLVardef@e726ed_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundPersonal light dosimeters enable exposure assessment under free- living conditions, but sensors are rarely positioned near the eyes--the relevant site for visual and non-visual responses. Chest and wrist placement may improve adherence and scalability, yet placement-dependent error and its consequences for derived outcomes remain insufficiently characterised. ObjectiveTo quantify how chest and wrist placement affects time-resolved estimates of eye-level light exposure across naturalistic contexts and derived exposure metrics. MethodsWe analysed concurrent 10-s melanopic equivalent daylight illuminance measurements from identical dosimeter models at the glasses, chest, and wrist across eight sites in seven countries. Melanopic equivalent daylight illuminance was compared at two analytical scales. Generalised additive mixed models quantified time-resolved placement error across contexts (N=787 participant-days), and mixed- effects models compared 54 daily metrics (N=604 participant-days). Hierarchical bootstrap resampling quantified the precision of population-average metric bias across participant numbers and monitoring durations. ResultsBody-worn dosimeters generally underestimated eye-level exposure. Across categorical contexts, estimated mean errors ranged from -23.1% to -4.2% at the chest and from -54.7% to -30.3% at the wrist, with larger errors generally observed at night. Nineteen of 54 chest-derived and 27 of 54 wrist-derived metrics differed nominally from glasses. Among these, median absolute bias was 5% at both placements, but maxima reached 50% and 84%, respectively. Timing outcomes were comparatively insensitive, whereas level and temporal-dynamics outcomes were more sensitive. With seven days per participant, the class-median bias standard deviation reached the 5% precision tolerance with 2-16 participants for all classes except temporal dynamics, which required 33 at the chest and 59 at the wrist. SignificanceDosimeter-placement validity depends on analytical scale and exposure construct. Chest placement can support scalable studies focused on aggregated timing or duration outcomes, whereas wrist placement introduces greater and less predictable bias. Near-eye measurement remains preferable for small- sample studies, time-resolved exposure levels and temporal-dynamics analyses.

Light reaching the retina is a primary regulator of human circadian physiology, acting largely through melanopsin-expressing retinal ganglion cells with peak short-wavelength sensitivity. Delivering known, repeatable retinal doses outside the laboratory is difficult because conventional light sources leave viewing geometry, gaze, and ambient conditions uncontrolled. Consumer extended-reality (XR) glasses fix a bright binocular display in constant geometry relative to the eye, but their suitability as calibrated photic stimulators has not been established. Here we validate a commercial micro-OLED XR display (VITURE Luma Ultra) for controlled retinal photostimulation. A purpose-built host application renders exact 8-bit RGB stimuli while independently controlling hardware brightness and logging all intensity-determining state; spectral radiance was measured at the retinal position of a 3D-printed phantom head with an open-source miniature spectroradiometer, anchored to absolute units by a luminance transfer calibration. The blue primary peaks at 461 nm (FWHM 43 nm), is spectrally invariant across a >10-fold intensity range, and at maximum output delivers an estimated 299 lx melanopic equivalent daylight illuminance, above consensus daytime recommendations, while remaining roughly two orders of magnitude below photobiological safety limits. The red primary is visually effective with minimal melanopic drive (melanopic DER 0.10), enabling spectrally shifted evening stimulation. Unlike the immersive virtual-reality headsets previously used for calibrated light delivery, the see-through form factor preserves the wearer's view of the surroundings--relevant for clinical monitoring in supervised settings such as the intensive care unit. These results show that consumer XR glasses can serve as a dose-calibrated platform for wearable photostimulation using an open-source measurement chain, and provide groundwork for application-layer dose-response studies.

Ultraviolet-C (UV-C) radiation can be highly damaging to plants, yet its effects on gibberellin (GA) homeostasis are not well understood. In this study, we show that short daily UV-C pulse treatments (12 s, 1,200 J m-2) applied for seven days reduce plant height and delay flowering in Arabidopsis thaliana. Endogenous levels of the GA biosynthesis precursors GA12, GA53, GA15, and GA24, the bioactive GA4, and the GA catabolites GA34 and GA110 are all lower in UV-C treated plants than in untreated controls. These changes were accompanied by lower transcript levels of the GA biosynthesis genes KS, GA13ox1, GA20ox1, and GA3ox1, together with opposing changes in the expression of GA2ox genes. Exogenous GA4 restores growth in UV-C-treated plants, suggesting that reduced GA availability contributes to UV-C-induced growth inhibition. Consistent with this finding, the GA-signalling mutant gdella and the GA-biosynthesis mutants kao1 and kao2 show strongly reduced UV-C responses. Together, these findings highlight the importance of GA metabolism and signalling in the developmental response to repeated UV-C exposure, and suggest that exposure regimen influences the dynamics of UV-C-induced hormonal responses.

The time of day of UV exposure impacts both erythema and cancer development. To investigate whether UV-relevant clock-controlled gene expression can be modulated pharmacologically, we treated human skin explants with a combination of a cryptochoursome inhibitor and REV-ERB antagonist and then examined changes in gene expression of a limited number of core clock and clock-regulated genes. mRNA levels of both the DNA repair factor XPA and cell cycle checkpoint kinase WEE1 were found to be significantly increased by treatment. This pilot study suggests that clock-controlled gene expression can be altered pharmacologically to possibly alter skin responses to UV radiation.

Bacterial survival after ultraviolet (UV) exposure is shaped not only by the extent of DNA damage but also by the physiological state-dependent capacity for DNA repair. Here, we examined the mechanisms underlying growth phase-dependent UV resistance in Escherichia coli K-12 exposed to 262 nm UV irradiation. Stationary-phase cells required higher UV fluence for log inactivation than exponential-phase cells, whereas the levels of UV-induced DNA damage, assessed by cyclobutane pyrimidine dimer staining and real-time PCR, did not differ markedly between the two growth phases. Deletion of nucleotide excision repair (NER) genes, including uvrA, uvrB, uvrC, and uvrD, markedly reduced survival after UV irradiation, indicating that NER is essential for the high UV resistance of stationary-phase cells. Quantitative real-time reverse transcription PCR showed stronger UV-induced expression of several DNA repair and UV resistance genes, including uvrA, uvrB, cho, umuC, and umuD, in stationary-phase cells than in exponential-phase cells. Furthermore, deletion of the DNA cytosine methyltransferase gene dcm increased UV resistance and enhanced the expression of uvrB, cho, umuC, umuD, and sulA in stationary-phase cells. These findings suggest that DNA cytosine methylation modulates UV resistance in E. coli, at least in part by influencing NER- and SOS-associated gene expression.

Background: A subset of uveal melanomas can be treated using either enucleation or proton beam therapy (PBT), which offer similar oncological outcomes. The most appropriate treatment depends on a patient's preference. To allow patients to genuinely determine their preference, it is recommended to describe options as neutrally as possible. This study assesses to what extent ocular oncologists use and perceive non-neutral framing behaviour, and if it is related to patient satisfaction with decision-making. Methods: Consultations of ocular oncologists with patients newly-diagnosed with uveal melanoma were audio recorded, transcribed verbatim, and coded for ocular oncologists' explicit and implicit non-neutral framing behaviours. Explicit non-neutral framing was defined as: explicitly mentioning a preferred option at least once, without relating it to the patient. Implicit non-neutral framing was defined as: describing an option (un)favourably, without providing a medically substantive clarification alongside. Results: 110 patients provided consent for the audio recordings. Non-neutral framing was found in 84% (n=92/110) of consultations. We found explicit behaviour in 38% (42/110) and implicit behaviour in 76% (84/110, median=1, range, 0-4) of consultations. The most frequent implicit framing was presenting options by positively or negatively emphasizing one option. Non-neutral framing behaviours were not significantly related to patient satisfaction with decision-making. Conclusion: This study shows that in most consultations some non-neutral framing was present, which did not impact patients' satisfaction with decision-making. Nonetheless, ocular oncologists should be aware that how they describe options may influence preferences in ways that do not align with the patient's values.

Blue light using Flavin (BLUF) proteins are microbial photoreceptors that are involved in various physiological responses. Their occurrence and biochemical properties in fungi remain poorly understood. Here, we investigated a putative BLUF photoreceptor from the corn-smut fungus Mycosarcoma maydis (MmBLUF). Domain analysis, multiple sequence alignment of BLUF core regions, and structural modelling indicated conserved canonical BLUF fold and flavin-pocket residues. However, when heterologously expressed, UV-visible and fluorescence spectroscopy revealed different spectral behaviour than canonical BLUF protein. Further, we tested the role of extended N-terminus in modulation of chromophore binding by expressing N-terminus truncated protein variants. Our results suggest that the unusual spectral behaviour is not linked to the truncation construct (extended N-terminus), which also showed similar spectral features, indicating that the extended N-terminus is unlikely to account for an unusual photodynamics characteristics. Our findings support MmBLUF as a structurally conserved putative fungal BLUF-like photoreceptor with different photochemical properties. Further studies are required to establish its chromophore identity, photocycle and function of this unusual BLUF-like domain from fungal system.

Purpose: To analyze the effect of radiotherapy timing relative to surgery on patients' survival and mortality rates in uveal melanoma (UM). Design: Retrospective cohort study using registry data from the Surveillance, Epidemiology, and End Results (SEER) database. Subjects: A total of 1,198 patients with UM were extracted from the SEER database and divided into three groups: preoperative radiotherapy, intraoperative radiotherapy (IORT), and postoperative radiotherapy. Methods: UM cases were extracted from the SEER database. Survival curves were generated based on the Kaplan-Meier method. An extended Cox regression was used to estimate the cancer-specific and all-cause mortality. Main Outcome Measures: Overall survival (including median survival) and hazard reductions for cancer-specific and all-cause mortality. Results: Preoperative radiotherapy revealed the highest median survival (4.93 years), followed by postoperative radiotherapy (4.76 years), and IORT (4.02 years). The preoperative strategy reduced the hazard of all-cause mortality by 42%, 50%, and 60% at 5-, 7-, and 10-year follow-up, respectively, compared with IORT. Findings were consistent in the cancer-specific sensitivity analysis (45%, 53%, and 62% reductions at the same time points). However, postoperative radiotherapy did not significantly reduce the cancer-specific mortality in comparison to IORT. Conclusions: Preoperative radiotherapy was associated with higher median overall survival and lower all-cause and cancer-specific mortality than IORT over 10 years of follow-up. Postoperative radiotherapy showed intermediate outcomes that did not differ significantly from IORT. Prospective studies with more detailed data on the temporal relation of radiotherapy timing and surgery are needed to confirm these findings.

Reactive nitrogen species (RNS), particularly peroxynitrite generated from the reaction of superoxide and nitric oxide, are implicated in thermally-induced oxidative stress but remain difficult to resolve in live coral cells. We optimized fluorescent dye strategies to directly quantify superoxide, nitric oxide, and peroxynitrite production in thermally stressed Pocillopora acuta cell suspensions. Thermal stress was associated with an increase in intracellular peroxynitrite concentration, but not in its precursors, nitric oxide and superoxide, highlighting challenges with the application of fluorescent probes and their controls to live coral cells. Compounds developed for mammalian systems often translate poorly to non-model systems such as corals: strong endogenous fluorescence and multiple membrane barriers within the coral symbiocyte, for instance, limited the function of the nitric oxide probe, DAF-2DA. Despite these limitations, the detection of peroxynitrite in live, thermally stressed P. acuta cells represents a step forward in understanding the mechanism of coral bleaching. We also outline strategies for improving the performance of commercial dyes in non-model systems, including media optimization with EDTA treatment to preserve both cell viability and probe performance.

Germline pathogenic or likely pathogenic variants (GPVs) in BRCA-1 Associated Protein 1 (BAP1) are associated with a spectrum of tumors, including uveal melanoma (UM). Currently, UM patients with BAP1 GPVs are treated as high-risk class 2 tumors based on mostly empiric data. In the current study, we examined the clinical phenotype of a cohort of 29 UM patients with BAP1 GPVs. We also carried out a systematic review of the literature of UM patients with BAP1 GPVs. We observed that UM patients with BAP1 GPVs have significantly lower median age of diagnosis compared to median age reported in UM patients in the Surveillance, Epidemiology, and End Results Program (SEERS) database. Metastatic risk and overall survival in the UM BAP1 GPVs cohort were statistically significant from those in patients with class 1 tumors, but were comparable to those observed in UM patients with class 2 tumors. In UM BAP1 GPVs treated with radiation (n=12), no secondary cancers were observed in the field of radiation in a median 26.5 months (range, 4-119 months) follow up period. One patient experienced a separate growth of UM at a distinct location within the same eye. These data support managing UM in patients with BAP1 GPVs as aggressive class 2 tumors, following the currently established standard of care for these high-risk tumors.

Reported relative biological effectiveness (RBE) values for low-energy X-rays disagree, assays scoring initial DNA double-strand breaks (DSBs) returning about 1.1 and chromosome-level assays 2 to 4. Whether radiation quality varies within the diagnostic range, and how its comparison with a megavoltage reference depends on target scale, has not been quantified on a tube-potential series. A tungsten-anode tube with 1 mm Be and 2.5 mm Al filtration, with copper added in some cases, was modelled in PHITS for 40 to 200 kV. The spectra were transported into a water phantom in which absorbed dose, lineal-energy densities and cluster size distributions were scored for target diameters of 3 nm to 1 micrometre against a cobalt-60 reference; DSB yields were computed in the electron track-structure mode with the PHITS DNA damage tally. Between 40 and 120 kV the depth-dose ratio changed by a factor of 5.7 and the tube output by a factor of 42, whereas the dose-mean lineal energy varied by 2.5 % at 1 micrometre and 1.2 % at 3 nm against a reproducibility of 0.3 %. Relative to cobalt-60 it was 2.05 times larger at 1 micrometre but only 1.08 times larger at 3 nm, while DSB yields per unit dose were 5 to 7 % higher and constant across the range within the 2 % bound set by the statistics. Tube potential therefore changes the amount and distribution of dose but not its physical quality, and a stated RBE is incomplete without the target scale implied by the endpoint.

Introduction Anatomical endoscopic enucleation of the prostate (AEEP) techniques, including bipolar enucleation (B-TUEP), holmium laser enucleation (HoLEP), thulium laser enucleation (ThuLEP), and thulium fibre laser enucleation (ThuFLEP), demonstrate comparable clinical outcomes for benign prostatic hyperplasia. As clinical equivalence is increasingly established, cost becomes a key determinant of modality selection. We performed a cost minimisation analysis comparing index procedural costs across AEEP modalities from an institutional perspective. Methods A cost minimisation model was developed from the institutional perspective, incorporating amortised capital costs, maintenance, and consumables. In addition to the base-case scenario of 180 cases per year, we modelled two additional case volume scenarios: low (50 cases/year) and high (500 cases/year) volume. Thu:YAG laser fibres were modelled on two scenarios: disposable single-use, and reusable fibres (up to 10 cases per fibre). Breakeven analysis determined the threshold volume at which each laser modality achieves cost parity with B-TUEP, and one-way sensitivity analysis was performed on key cost parameters. Analysis was limited to index procedural costs calculated in Singapore dollars. Results At the base case of 180 cases per year, B-TUEP had the lowest index procedure cost (SGD 1,018), followed by ThuFLEP (SGD 1,584), ThuLEP (1,599), and HoLEP (SGD 1,655). Breakeven analysis demonstrated that HoLEP, ThuLEP, and ThuFLEP can never achieve cost parity with B-TUEP when laser fibres are single-use, as laser modalities carry higher costs on both capital and per-case dimensions. ThuLEP with reusable fibres (10 uses per fibre) was the only modality to cross below B-TUEP, at a breakeven volume of 198 cases per year. At 500 cases per year with reusable fibres, ThuLEP achieved the lowest cost (SGD 847), representing a 15.4% saving over B-TUEP. Sensitivity analysis identified annual case volume and B-TUEP loop cost as the most influential parameters. Conclusion Index procedural costs in AEEP are strongly influenced by case volume and consumable strategy. While B-TUEP remains cost-efficient at low volume, high-volume practice combined with reusable Thu:YAG fibre technology enables cost parity and potential cost advantage for laser enucleation. These findings highlight the importance of economies of scale and device utilisation in technology adoption.

Background: Autonomous ultraviolet-C (UV-C) disinfection systems are increasingly used to supplement manual environmental cleaning, yet evidence-based guidance defining pathogen-specific UV-C dose requirements across representative surfaces remains limited. Aim: To characterize operational UV-C dose requirements for clinically relevant pathogens across diverse high-touch and healthcare surfaces and determine how experimentally derived microbial inactivation can inform operational exposure parameters. Methods: SARS-CoV-2, adenovirus, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, Candida auris, and Clostridioides difficile spores were exposed to defined UV-C doses on representative high-touch materials or stainless steel under standardized conditions, including a 10% fetal bovine serum organic soil challenge. Microbial inactivation was quantified by viable recovery. Dose-response analysis and operational modelling were used where supported by the experimental data. Findings: UV-C exposure significantly reduced viable recovery of all pathogens, with substantial differences in the exposure conditions associated with microbial inactivation. SARS-CoV-2 exhibited substantial inactivation at doses as low as 2.6 mJ/cm2, whereas the highest evaluated doses were 1,800 mJ/cm2 for C. difficile spores and 3600 mJ/cm2 for C. auris. For C. auris, multi-dose data estimated that approximately 1,410 mJ/cm2 was associated with a 2-log10 reference reduction, enabling distance-dependent exposure-time predictions. Conclusion: Experimentally quantified UV-C exposures produced substantial microbial inactivation across diverse pathogen classes and surfaces. Integrating delivered dose with microbial reduction provides a quantitative framework for translating laboratory efficacy into operational parameters for autonomous UV-C disinfection.

The rise of antimicrobial resistance has intensified interest in antimicrobial photodynamic inactivation (aPDI) and antimicrobial blue light (aBL) as alternatives or adjuvants to conventional antibiotics. However, whether chemically distinct photodynamic treatments elicit a shared bacterial response remains unclear. Here, we integrated transcriptomic profiles of Escherichia coli BW25113 exposed to five short-term, sub-lethal photodynamic treatments: antimicrobial blue light (aBL), aBL combined with 5-aminolevulinic acid (aBL+ALA), rose bengal (RB), new methylene blue (NMB), and the cationic porphyrin TMPyP. Intersection analysis identified 891 conserved core genes differentially expressed across all treatments, of which approximately 98% changed in a consistent direction despite differences in photosensitizer chemistry and activating wavelength. Random-effects meta-analysis and robust rank aggregation prioritized 88 high-confidence genes, revealing induction of envelope stress and cytoplasmic protein quality control pathways alongside repression of acid resistance, hydrogen metabolism, molybdate transport, and biofilm formation. Regulon enrichment indicated that heat-shock sigma factor {sigma}32/RpoH and the envelope-stress regulators CpxR, BaeR, {sigma}24/RpoE, and PspF were enriched among induced genes, whereas GadW/GadX/GadE, Fur, and {sigma}38/RpoS were enriched among repressed genes. Functional validation using selected single-gene Keio knockouts confirmed that deletion of conserved-core genes sensitized E. coli to photodynamic treatment and delayed post-treatment recovery in a modality-dependent manner. Moreover, RT-qPCR analysis of selected transcriptional responses confirmed the direction and overall pattern of RNA-seq-derived expression changes. Together, these findings define a unified conserved early survival program in E. coli after chemically distinct photodynamic treatments and identify stress-response modules that may serve as targets for potentiating aPDI. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=126 SRC="FIGDIR/small/744726v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@dbbadaorg.highwire.dtl.DTLVardef@1c85538org.highwire.dtl.DTLVardef@152d699org.highwire.dtl.DTLVardef@18705a6_HPS_FORMAT_FIGEXP M_FIG C_FIG

Fluorescent voltage-sensitive dyes (VSDs) enable non-invasive, high-throughput optical measurement of membrane potential in living cells, but the analytical reliability of such measurements depends critically on whether the dye and associated imaging conditions perturb the system under study. Here, we systematically characterise the photophysical performance and cell-perturbing effects of FluoVolt, a widely adopted VSD, across cancer cell lines (GIN31 glioblastoma and SK-MEL-30 melanoma) and primary human macrophages. Photobleaching kinetics were strongly cell-type-dependent, with SK-MEL-30 cells exhibiting complete fluorescence loss within 400 seconds under standard widefield conditions. FluoVolt staining combined with laser excitation caused an approximately 2.5-fold increase in cell detachment relative to unstained controls, and dual-wavelength excitation (488 + 405 nm) reduced GIN31 cell viability by approximately 17.5%. Critically, morphological changes, a transition from elongated to amoeboid-like phenotypes, were detected under staining conditions alone, prior to any laser exposure, indicating baseline dye-induced perturbation independent of phototoxicity. Halving dye concentration and loading time significantly attenuated these effects while preserving measurable fluorescence signal. These findings identify FluoVolt staining and excitation as previously uncharacterised sources of systematic measurement artefact and provide practical, actionable guidance for protocol design, control selection, and data interpretation in optical membrane potential imaging.

Occupational ocular injuries are a preventable yet neglected public health problem, particularly in low- and middle-income countries. Maintenance workers are exposed to diverse ocular hazards daily, yet compliance with protective measures is consistently poor. A descriptive cross-sectional study was conducted among 85 maintenance workers at the Maintenance and Essential Services Organization (MESO) of Kwame Nkrumah University of Science and Technology (KNUST), Ghana, recruited through stratified convenience sampling across seven occupational sections. A structured questionnaire assessed knowledge of ocular hazards and protective equipment, attitudes toward ocular safety, and safety practices. Data were analyzed using IBM SPSS version 26 (IBM Corp., Armonk, NY, USA); chi-square and Fishers exact tests assessed associations (p < 0.05). Participants were predominantly male (84/85, 98.8%), with a mean age of 44.5 {+/-} 10.4 years. Overall knowledge was good (mean 9.40 {+/-} 1.59 out of 11), but attitude and practice scores were average (2.78 {+/-} 0.92 and 3.27 {+/-} 0.93, respectively). Most workers correctly identified goggles and face shields as protective, but only about half recognized that ordinary sunglasses and spectacles offer inadequate protection. Although 97.6% (83/85) recognized the need for ocular protection, only 7.1% (6/85) reported consistent protective eyewear use, and fewer than half (45.9%, 39/85) had received formal ocular safety training. Routine general protective equipment use was significantly associated with ocular protection use (Fishers exact test, p = 0.011). Sand and dust particles were the leading causes of injury and only 25% (5/20) of injured workers sought formal care. Workers demonstrated good knowledge but poor attitudes and practices toward ocular safety, suggesting that knowledge alone does not translate into protective behaviour even within a relatively well-resourced institutional setting. Findings suggest that limited access to task-appropriate protective eyewear may represent an important institutional barrier. Institutional PPE supply and section-specific safety training are essential to bridge this knowledge-practice gap.

Human skin colors occupy a characteristic banana-shaped region in CIE L*a*b* space, but why skin color coordinates are restricted to this region and how they relate to melanin and blood remain incompletely understood. We developed a physics-based framework linking skin chromophore content to colorimeter-derived skin color coordinates using two complementary three-layer light transport models. Across physiologic ranges of epidermal melanosome volume fraction and dermal blood volume fraction, simulated reflectance spectra were converted to CIE L*a*b* coordinates and compared with human skin color measurements from the International Skin Spectra Archive. Physiologic variation in melanin and blood reproduced the observed banana-shaped locus and revealed distinct chromophore-specific trajectories. Iso-melanin trajectories became progressively more linear as melanin increased, whereas iso-blood trajectories retained the curvature of the skin color locus. As melanin increased, perceptible color differences from blood volume changes were reduced, providing a mechanistic explanation for reduced erythema visibility in highly pigmented skin. These relationships were stable across plausible variations in layer thickness and tissue oxygenation and agreed with external validation data. The framework also identified when the Individual Typology Angle is confounded by blood or distorted by dermal melanin. Together, these findings establish a mechanistic optical basis for interpreting colorimeter-derived skin color coordinates.

While exposure to volatile organic compounds such as ethylene dichloride and vinyl chloride monomer is a well-established cause of liver disease, particularly hepatic hemangiosarcoma, characterizing real-world exposure profiles in communities surrounding industrial centers remains challenging. Calvert City, Kentucky (population ~2,500), provides a unique setting characterized by both active industrial emissions and legacy sources of air toxics. To address these complexities, this method paper describes the framework for the Biomonitoring and Environmental Assessment for Community Outreach and Neighborhood Safety (BEACON) study. By utilizing a novel, multi-dimensional exposure assessment strategy, BEACON aims to characterize air toxic exposures and provide actionable data for community health and safety. For the BEACON study, we will leverage Kentucky Department of Air Quality measures of air toxics, analyze urine samples in a small cohort of community volunteers, analyze community urine via wastewater in an adjacent community, geocode citizen odor reporting, assess blood markers in wildlife, survey small and large animal veterinarians in the area for anomalies in morbidity and mortality, and work with the regional health system to enhance vigilance for health issues associated with toxicants present in the area. In addition, blood samples will be collected at three time points and biobanked for future analyses. Efforts will be made to link this study to additional large-scale long-term cohorts where possible. Throughout the project, community engagement will play a critical role by raising awareness, fostering collaboration, and ensuring that the voices of affected residents are heard.