Chemical Irritants Research Articles

The evolving role of mast cells in wound healing: insights from recent research and diverse models.

Chronic wounds significantly burden health care systems worldwide, requiring novel strategies to ease their impact. Many physiological processes underlying wound healing are well studied but the role of mast cells remains controversial. Mast cells are innate immune cells and play an essential role in barrier function by inducing inflammation to defend the host against chemical irritants and infections, among others. Many mast cell-derived mediators have proposed roles in wound healing; however, in vivo evidence using mouse models has produced conflicting results. Recently, studies involving more complex wound models such as infected wounds, diabetic wounds and wounds healing under psychological stress suggest that mast cells play critical roles in these processes. This review briefly summarizes the existing literature regarding mast cells in normal wounds and the potential reasons for the contradictory results. Focus will be placed on examining more recent work emerging in the last 5 years that explores mast cells in more complex systems of wound healing, including infection, psychological stress and diabetes, with a discussion of how these discoveries may inspire future work in the field.

"Construction Chemical Irritant Exposure Controls in Relation to Prevalence of Symptoms of Skin Diseases in Zambia"

"Construction Chemical Irritant Exposure Controls in Relation to Prevalence of Symptoms of Skin Diseases in Zambia"

Silk fibroin-based wearable SERS biosensor for simultaneous sweat monitoring of creatinine and uric acid

Sweat biomarkers have the potential to offer valuable clinical insights into an individual's health and disease condition. Current sensors predominantly utilize enzymes and antibodies as biometric components to measure biomarkers present in sweat quantitatively. However, enzymes and antibodies are susceptible to interference by environmental factors, which may affect the performance of the sensor. Herein, we present a wearable microfluidic surface-enhanced Raman scattering (SERS) biosensor that enables the non-invasive and label-free detection of biomarkers in sweat. Concretely, we developed a bimetallic self-assembled anti-opal array structure with uniform hot spots, enhanced the Raman scattering effect, and integrated it into a silk fibroin-based sensing patch. Utilizing a silk fibroin substrate in the wearable SERS sensor imparts desirable properties such as softness, breathability, and biocompatibility, which enables the sensor to establish close contact with the skin without causing chemical or physical irritation. In addition, introducing microfluidic channels enables the controlled and high temporal resolution management of sweat, facilitating more efficient sweat collection. The proposed label-free SERS sensor can offer chemical ‘fingerprint’ information, enabling the identification of sweat analytes. As an illustration of the feasibility, we have effectively monitored the creatinine and uric acid levels in sweat. This study presents a versatile and highly sensitive approach for the simultaneous detection of biomarkers in human sweat, showcasing significant potential for application in point-of-care monitoring.

Comparing the Pulmonary-Spirometry In Laboratory Workers Who Wear Acchadana® and KN95® Masks

BACKGROUND : The upper respiratory tract is susceptible to inflammation caused by exposure to airborne contaminants, particularly chemical irritants. Inhaled irritant gases can lead to various symptoms and adverse reactions in the respiratory tract. Laboratory workers are at a high risk of respiratory tract inflammation due to exposure to volatile chemicals. The use of personal protective equipment (PPE), such as masks, is essential to prevent inflammation and protect the respiratory tract. Lung function tests using spirometry, including Forced Vital Capacity (FVC), Forced Expiratory Volume in One Second (FEV1.0), and Peak Expiratory Flow (PEF), can help identify abnormalities in lung function. AIMS : The primary objective of this investigation is to juxtapose the pulmonary conditions of laboratory workers before and after the utilization of KN95® masks and Acchadana® masks. METHOD : The study design was a Randomized Control Trial, and the subjects were divided into two groups: the control group wearing KN95 masks and the treatment group wearing Acchadana® herbal masks. Spirometry measurements were taken before and after using the masks, and statistical analysis was conducted to compare the results. RESULT : The results showed that both mask groups experienced improvements in lung function parameters after using the masks. However, the KN95 mask group showed better lung conditions compared to the Acchadana® mask group. CONCLUSION : Spirometry tests conducted on lab workers revealed improved lung function metrics (including FVC, FEV1.0, and PEF) following the usage of KN95 masks and Acchadana® herbal masks. The KN95 mask users exhibited superior respiratory health compared to the other group in this investigation.

Topical retinoids: Novel derivatives, nano lipid-based carriers, and combinations to improve chemical instability and skin irritation.

Retinoids, defined as synthetic or natural derivatives of vitamin A, have been extensively studied as anti-aging molecules that are widely applied in cosmetics. However, due to their physicochemical property, retinoids are highly unstable and extremely sensitive to light, oxygen, and temperature. Moreover, topical application of retinoids often leads to cutaneous irritation. These instabilities and irritant properties of retinoids limit their application in cosmetic and pharmaceutical products. Our study aimed to provide a systematic review to summarize the mechanisms underlying the instability and irritant properties of retinoids, as well as recent developments in addressing these challenges. A comprehensive PubMed search was conducted using the following keywords: retinoids, chemical instability, skin irritation, retinoid derivatives, nano lipid-based carriers, liposomes, penetration-enhancer vesicles, ethosomes, niosomes, nanoemulsions, solid lipid nanoparticles, vitamins, soothing and hydrating agents, antioxidants and metal chelator and retinol combinations. Relevant researches published between 1968 and 2023 and studies related to these reports were reviewed. The development of new retinoid derivatives, the utilization of new delivery systems like nano lipid-based carriers and the combination with other compounds like vitamins, soothing agents, antioxidants and metal chelator have been explored to improve the stability, bioavailability, and toxicity of the retinoid family. Through advancements in formulation techniques, structure modification of retinoid derivatives and development of novel nano lipid-based carriers, the chemical instability and skin irritation of retinoids has been mitigated, ensuring their efficacy and potency over extended periods.

GC/HRMS Analysis of E-Liquids Complements In Vivo Modeling Methods and can Help to Predict Toxicity.

Tobacco smoking is a major risk factor for disease development, with the user inhaling various chemicals known to be toxic. However, many of these chemicals are absent before tobacco is "burned". Similar, detailed data have only more recently being reported for the e-cigarette with regards to chemicals present before and after the e-liquid is "vaped." Here, zebrafish were dosed with vaped e-liquids, while C57-BL/6J mice were vaped using nose-cone only administration. Preliminary assessments were made using e-liquids and GC/HRMS to identify chemical signatures that differ between unvaped/vaped and flavored/unflavored samples. Oxidative stress and inflammatory immune cell response assays were then performed using our in vivo models. Chemical signatures differed, e.g., between unvaped/vaped samples and also between unflavored/flavored e-liquids, with known chemical irritants upregulated in vaped and unvaped flavored e-liquids compared with unflavored e-liquids. However, when possible respiratory irritants were evaluated, these agents were predominantly present in only the vaped e-liquid. Both oxidative stress and inflammatory responses were induced by a menthol-flavored but not a tobacco-flavored e-liquid. Thus, chemical signatures differ between unvaped versus vaped e-liquid samples and also between unflavored versus flavored e-liquids. These flavors also likely play a significant role in the variability of e-liquid characteristics, e.g., pro-inflammatory and/or cytotoxic responses.

Prison overcrowding and ill-treatment: sentence reduction as a reparation measure. A view from Latin America and Europe.

In recent years mass protest movements have taken to the streets in many countries across the world. Despite strong international and domestic legal protections for the right to freedom of peaceful assembly and other fundamental human rights, entire assemblies are frequently labelled violent and less lethal weapons are used to disperse them. This article examines the weapons often used by police against public assemblies. Focusing on striking weapons (batons), chemical irri-tants, kinetic impact projectiles and stun grenades, the article uses examples from various countries to illustrate how these weapons are being used and the associated human rights and health impacts. Re-sults: Worrying trends identified include the use of dangerous or untested equipment, such as thermal foggers to deploy chemical irritants; the use of inherently abusive weapons, such as whips or sjam-boks; and the increasing use of certain types of munitions, specifically indiscriminate kinetic impact projectiles. The article seeks to support medical and legal professionals becoming more familiar with the weapons being used in the countries they practice in, the effects of those weapons, and clinical aspects in the presentation and care of those exposed.

Chitosan Alginate Nanoparticles of Protein Hydrolysate from Acheta domesticus with Enhanced Stability for Skin Delivery.

This study aimed to develop chitosan alginate nanoparticles (CANPs) for enhanced stability for dermal delivery of protein hydrolysate from Acheta domesticus (PH). CANPs, developed using ionotropic pre-gelation followed by the polyelectrolyte complex technique, were characterized for particle size, polydispersity index (PDI), and zeta potential. After the incorporation of PH into CANPs, a comprehensive assessment included encapsulation efficiency, loading capacity, morphology, chemical analyses, physical and chemical stability, irritation potential, release profile, skin permeation, and skin retention. The most optimal CANPs, comprising 0.6 mg/mL sodium alginate, 1.8 mg/mL calcium chloride, and 0.1 mg/mL chitosan, exhibited the smallest particle size (309 ± 0 nm), the narrowest PDI (0.39 ± 0.01), and pronounced negative zeta potential (-26.0 ± 0.9 mV), along with an encapsulation efficiency of 56 ± 2%, loading capacity of 2.4 ± 0.1%, release of 40 ± 2% after 48 h, and the highest skin retention of 12 ± 1%. The CANPs induced no irritation and effectively enhanced the stability of PH from 44 ± 5% of PH remaining in a solution to 74 ± 4% after three-month storage. Therefore, the findings revealed the considerable potential of CANPs in improving PH stability and skin delivery, with promising applications in cosmetics and related fields.

Knowledge and Attitudes of Female Adolescents on the Causes, Effects and Prevention of Vaginal Candidiasis in the Adenta Municipality of the Greater Accra Region of Ghana

Introduction: Among every four women, at least, three of them experience vaginal candidiasis caused by Candida albicans. People with dysfunctional immune system such as the aged, very young children, altered pH and sugar content in vaginal secretions as a result of pregnancy, HIV/AIDS, diabetes, hormonal fluctuations, smoking, black race, oral-contraceptives, obesity and use of broad-spectrum antibiotics increases the frequency to acquiring infection and are therefore vulnerable to fungal infections. Poor hygiene, chemical irritants and the presence of foreign body in the vagina can also cause vaginal candidiasis Objective: This study sought to access the knowledge and attitudes regarding causes, effects and prevention of vaginal candidiasis among female adolescent in the Adenta Municipality. Methods: A cross-sectional design and a multi-stage sampling technique was used to obtain a sample of 403 female adolescents within the Adenta Municipality using a structured questionnaire. The data collected from respondents were collected and entered into Epi Data Entry Client v4.0.2.4.9 and was exported into Stata 14.0 for analysis. All numerical data was analyzed using descriptive statistics. Chi-square, p-values were used to establish the associations between variables. Logistic regression of less than 0.05 were considered statistically significant at 95% confidence interval. Results were presented in tables and graphs. Result: The study revealed that the overall knowledge of respondents was good (54.7%). Majority (57.7%) of the respondents knew poor hygiene to be the major cause of vaginal candidiasis and it can easily be transmitted through sexual intercourse (67.8%). About 97% of the respondents most agreed that sugar intake was a major risk factor of vaginal candidiasis with (39.9%) of them knowing infertility as a major effect of vaginal candidiasis if not treated. Friends (47.5%) and school (41.1%) were seen to be the major source of information regarding vaginal candidiasis. The attitude towards the prevention of candidiasis among female adolescents was good (58.9%). Though, more than 50% of the respondents agreed that candidiasis infection was dangerous, majority (82.7%) of them were unsure of symptoms and therefore (87.6%) agreed that people infected with candidiasis must seek for treatment from the hospital. Having a good knowledge on vaginal candidiasis [AOR=2.56 (95% Cl: 1.57– 4.15), p<0.001] and a good attitude towards it prevention [AOR=1.83 (95% Cl: 1.12–2.99), p<0.015] were positively associated with the effects of vaginal candidiasis. These participants were 3 and 2 times respectively more likely to have good attitudes towards the effects of vaginal candidiasis respectively. Also, the participants who were in a relationship with the opposite sex was statistically significant such that those who were in a relationship were 3 times more likely to be knowledgeable about candidiasis [AOR=2.96 (95% Cl: 1.14 – 7.84), p<0.025] as compared with those who were not in a relationship. In conclusion, female adolescents in the Adenta Municipality had good knowledge on the causes and effects of vaginal candidiasis. Those aged 10-15 years exhibited poor knowledge and attitudes regarding the causes, effects and prevention of vaginal candidiasis. Programs aimed at increasing the knowledge, attitudes of female adolescents on vaginal candidiasis should be implemented and more attention should be given to the adolescents between the ages of 10 and 15 years. The responses given by respondents was seen to be influenced by the socio-demographic characteristics such as age, level of education, religion and ethnic group.

Research progress in the development of 3D skin models and their application to in vitro skin irritation testing.

Toxicological assessment of chemicals is crucial for safeguarding human health and the environment. However, traditional animal experiments are associated with ethical, technical, and predictive limitations in assessing the toxicity of chemicals to the skin. With the recent development of bioengineering and tissue engineering, three-dimensional (3D) skin models have been commonly used as an alternative for toxicological studies. The skin consists of the subcutaneous, dermis, and epidermis. All these layers have crucial functions such as physical and biological protection and thermoregulation. The epidermis is the shallowest layer protecting against external substances and media. Because the skin is the first contact point for many substances, this organ is very significant for assessing local toxicity following skin exposure. According to the classification of the United Nations Global Harmonized System, skin irritation is a major potentially hazardous characteristic of chemicals, and this characteristic must be accurately assessed and classified for enhancing chemical safety management and preventing and reducing chemical accidents. This review discusses the research progress of 3D skin models and introduces their application in assessing chemical skin irritation.

Irritant and repellent behaviors of sterile male Aedes aegypti (L.) (Diptera: Culicidae) mosquitoes are crucial in the development of disease control strategies applying sterile insect technique.

The mosquito Aedes aegypti, known to transmit important arboviral diseases, including dengue, chikungunya, Zika and yellow fever. Given the importance of this disease vector, a number of control programs have been proposed involving the use of the sterile insect technique (SIT). However, the success of this technique hinges on having a good understanding of the biology and behavior of the male mosquito. Behavioral responses of Ae. aegypti male populations developed for SIT technology were tested under laboratory conditions against chemical and natural irritants and repellents using an excito-repellency (ER) chamber. The results showed that there were no significant behavioral escape responses in any of the radiation-sterilized male Ae. aegypti test populations when exposed to citronella, DEET, transfluthrin, and deltamethrin, suggesting that SIT did not suppress the expected irritancy and repellency (avoidance) behaviors. The type of information reported in the current study is vital in defining the effects of SIT on vector behavior and understanding how such behavior may influence the success of SIT technology with regard to other vector control interventions.

Esophageal cancer in an adult with congenital esophageal stenosis: a case report

BackgroundCongenital esophageal stenosis (CES) is a rare condition. We encountered a case of esophageal cancer that developed in an adult with persistent CES. Although many studies have investigated the therapeutic outcomes and performed surveillance for symptoms after treatment for CES, few have performed long-term surveillance or reported on the development of esophageal cancer. We report this case because it is extremely rare and has important implications.Case presentationA 45-year-old woman with worsening dysphagia was transferred to our hospital. The patient was diagnosed with CES at 5 years of age and underwent surgery at another hospital. The patient underwent esophageal dilatation for stenosis at 36 years of age. Esophagoscopy performed at our hospital revealed a circumferential ulcerated lesion and stenosis 15–29 cm from the incisors. Histological examination of the biopsy specimen revealed squamous cell carcinoma. Computed tomography (CT) revealed abnormal circumferential wall thickening in parts of the cervical and almost the entire thoracic esophagus. 18F-fluorodeoxyglucose-positron emission tomography-CT revealed increased uptake in the cervical and upper esophagus. No uptake was observed in the muscular layers of the middle or lower esophagus. Based on these findings, the patient was diagnosed with clinical stage IVB cervical and upper esophageal cancer (T3N1M1 [supraclavicular lymph nodes]). The patient underwent a total esophagectomy after neoadjuvant chemotherapy. The esophagus was markedly thickened and tightly adhered to the adjacent organs. Severe fibrosis was observed around the trachea. Marked thickening of the muscular layer was observed throughout the esophagus; histopathological examination revealed that this thickening was due to increased smooth muscle mass. No cartilage, bronchial epithelium, or glands were observed. The carcinoma extended from the cervical to the middle esophagus, oral to the stenotic region. Finally, we diagnosed the patient with esophageal cancer developing on CES of the fibromuscular thickening type.ConclusionsChronic mechanical and chemical irritations are believed to cause cancer of the upper esophagus oral to a persistent CES, suggesting the need for long-term surveillance that focuses on residual stenosis and cancer development in patients with CES.

Hand eczema: a common diagnosis in everyday practice

Hand eczema is one of the most common dermatoses at the doctor’s office during visits. There is some evidence that the prevalence rates reach almost 15% of the population. This disease greatly affects patients’ quality of life, work activities and other areas of life. The eczema pathogenesis is quite complex and is built up of genetic factors, environmental effects and various irritating agents. Disturbances of skin barrier also plays a significant role in the development of the disease. For example, patients with atopic dermatitis often suffer from hand eczema. Excessive hand hygiene (frequent washing and use of alcohol-based products) also increases the risk of developing this unpleasant dermatosis. Clinical features distinguish acute from chronic eczema. Acute eczema manifests as erythema, oedema, and vesicular rashes. The chronic course is characterized by skin thickening, peeling, erosion and cracks. Exacerbations occur 2 or more times per year. Hand eczema can be divided into irritant, which develops in response to contact with physical, mechanical, and chemical irritants, and allergic, which is provoked by contact with an allergen that induces type IV immune response. It is also common to distinguish protein contact dermatitis, which refers to a subtype of allergic eczema. Traditionally, moisturizers and topical corticosteroids are used for the treatment of hand eczema. Among topical corticosteroids, methylprednisolone aceponate (Advantan®) is especially worth noting. In addition to the pronounced therapeutic effect, the option to use it once a day is an undoubted advantage over many other drugs. This fact has a positive effect on therapy adherence. This topical corticosteroid is well tolerated and highly effective for the treatment of eczematous dermatitis, which is confirmed by many-year experience in using it.

Nonallergic Rhinopathy: A Comprehensive Review of Classification, Diagnosis, and Treatment

Chronic nonallergic rhinitis syndromes encompass various conditions, of which vasomotor rhinitis is the most common form, representing approximately 80% of patients, also referred to as nonallergic rhinopathy (NAR), nasal hyperreactivity, neurogenic rhinitis, or idiopathic rhinitis. Expert panels have recommended replacing vasomotor rhinitis terminology because it is more descriptive of this condition that is characterized by symptoms triggered by chemical irritants and weather changes through chemosensors, mechanosensors, thermosensors, and/or osmosensors activated through different transient receptor potential calcium ion channels. Elucidating the specific role of transient receptor potential vanilloid 1, triggered by capsaicin, has been an important advancement in better understanding the pathophysiology of NAR because it has now been shown that downregulation of transient receptor potential vanilloid 1 receptors by several therapeutic compounds provides symptomatic relief for this condition. The classification of NAR is further complicated by its association with allergic rhinitis referred to as mixed rhinitis, which involves both immunoglobulin E-mediated and neurogenic mechanistic pathways. Comorbidities associated with NAR, including rhinosinusitis, headaches, asthma, chronic cough, and sleep disturbances, underscore the need for comprehensive management. Treatment options for NAR include environmental interventions, pharmacotherapy, and in refractory cases, surgical options, emphasizing the need for a tailored approach for each patient. Thus, it is extremely important to accurately diagnose NAR because inappropriate therapies lead to poor clinical outcomes and unnecessary health care and economic burdens for these patients. This review provides a comprehensive overview of NAR subtypes, focusing on classification, diagnosis, and treatment approaches for NAR.

Single-Cell Analysis of Rohon-Beard Neurons Implicates Fgf Signaling in Axon Maintenance and Cell Survival.

Peripheral sensory neurons are a critical part of the nervous system that transmit a multitude of sensory stimuli to the central nervous system. During larval and juvenile stages in zebrafish, this function is mediated by Rohon-Beard somatosensory neurons (RBs). RBs are optically accessible and amenable to experimental manipulation, making them a powerful system for mechanistic investigation of sensory neurons. Previous studies provided evidence that RBs fall into multiple subclasses; however, the number and molecular makeup of these potential RB subtypes have not been well defined. Using a single-cell RNA sequencing (scRNA-seq) approach, we demonstrate that larval RBs in zebrafish fall into three, largely nonoverlapping classes of neurons. We also show that RBs are molecularly distinct from trigeminal neurons in zebrafish. Cross-species transcriptional analysis indicates that one RB subclass is similar to a mammalian group of A-fiber sensory neurons. Another RB subclass is predicted to sense multiple modalities, including mechanical stimulation and chemical irritants. We leveraged our scRNA-seq data to determine that the fibroblast growth factor (Fgf) pathway is active in RBs. Pharmacological and genetic inhibition of this pathway led to defects in axon maintenance and RB cell death. Moreover, this can be phenocopied by treatment with dovitinib, an FDA-approved Fgf inhibitor with a common side effect of peripheral neuropathy. Importantly, dovitinib-mediated axon loss can be suppressed by loss of Sarm1, a positive regulator of neuronal cell death and axonal injury. This offers a molecular target for future clinical intervention to fight neurotoxic effects of this drug.

A210 ESOPHAGEAL SQUAMOUS PAPILLOMATOSIS AFTER ENDOSCOPIC SUBMUCOSAL DISSECTION

Abstract Background Squamous papillomatosis is a rare benign epithelial finding, generally found incidentally in the distal esophagus. The pathophysiology is not well understood but felt to be secondary to reflux and chemical irritation leading to leukoplakia and verrucous hyperplasia of the epithelium and papilloma formation. Aims To present a case of esophageal squamous papillomatosis after endoscopic submucosal dissection (ESD) and radiofrequency ablation (RFA) of Barrett’s esophagus (BE) and early esophageal cancer. Methods Case report and review of the literature Results A 78-year-old male with C3M3 BE and previous band mucosectomy for nodular dysplasia was referred for ESD of an early esophageal cancer. ESD was successfully performed, with histopathology identifying a low-risk well-differentiated intramucosal adenocarcinoma without lymphovascular invasion and negative margins. Radiofrequency ablation was performed 3-months post-resection for residual BE. Subsequent surveillance gastroscopy 6 months post-resection identified extensive fleshy pink granulation tissue at the ESD scar, histopathology revealing SP. This was confirmed on subsequent repeat gastroscopy and biopsy. Compliance with double dose proton pump inhibitor therapy was confirmed. Conclusions To our knowledge, this is the first reported case of SP developing post-ESD and RFA; further expanding our knowledge of potential Barrett’s endotherapy-related adverse events. Funding Agencies None

Gene profiling in active dermatitis lesions strengthens the diagnosis of allergic contact dermatitis

BackgroundDistinguishing between allergic and non-allergic forms of Contact Dermatitis (CD) is challenging and requires investigations based on patch-testing. Early detection of allergy biomarkers in active CD lesions could refine and simplify the management of CD patients. ObjectiveTo characterize the molecular signatures of active CD lesions. MethodsWe studied the expression of 12 allergy biomarkers by qRT-PCR in active lesions of 38 CD patients. Allergic CD (ACD) was diagnosed based on patch-test (PT) results and exposure assessment. Molecular signatures of active lesions, as well as positive PT reactions, were compared with those of reference chemical allergens and irritants. Results19 of the 38 CD patients reacted positively upon patch-testing and exposure assessment confirmed ACD diagnosis for 17 of them. Gene profiling of active CD lesions revealed two distinct molecular patterns: patients harboring signatures similar to reference allergens (n=23) or irritants (n=15). Among the 23 patients with an “allergy signature”, we found the 17 patients with confirmed ACD, while no culprit allergen was identified for the 6 other patients. Interestingly, the 15 patients without biomarker induction had negative PT, suggesting that they developed non-allergic CD reactions. ConclusionMolecular signatures from active skin lesions may help to stratify CD patients and predict those suffering from allergic contact dermatitis.

Establishing short-term occupational exposure limits (STELs) for sensory irritants using predictive and in silico respiratory rate depression (RD50) models

Sensory irritation is a health endpoint that serves as the critical effect basis for many occupational exposure limits (OELs). Schaper 1993 described a significant relationship with high correlation between the measured exposure concentration producing a 50% respiratory rate decrease (RD50) in a standard rodent assay and the American Conference of Governmental Industrial Hygienists (ACGIH®) Threshold Limit Values (TLVs®) as time-weighted averages (TWAs) for airborne chemical irritants. The results demonstrated the potential use of the RD50 values for deriving full-shift TWA OELs protective of irritant responses. However, there remains a need to develop a similar predictive model for deriving workplace short-term exposure limits (STELs) for sensory irritants. The aim of our study was to establish a model capable of correlating the relationship between RD50 values and published STELs to prospectively derive short-term exposure OELs for sensory irritants. A National Toxicology Program (NTP) database that included chemicals with both an RD50 and established STELs was used to fit several linear regression models. A strong correlation between RD50s and STELs was identified, with a predictive equation of ln (STEL) (ppm) = 0.86 * ln (RD50) (ppm) − 2.42 and an R2 value of 0.75. This model supports the use of RD50s to derive STELs for chemicals without existing exposure recommendations. Further, for data-poor sensory irritants, predicted RD50 values from in silico quantitative structure activity relationship (QSAR) models can be used to derive STELs. Hence, in silico methods and statistical modeling can present a path forward for establishing reliable OELs and improving worker safety and health.

Environmental and Occupational Triggers of Dry Eye Symptoms in the Ahsa Region of Saudi Arabia: A Cross-Sectional Study.

This cross-sectional study aimed to investigate the associations between environmental and occupational factors and the prevalence of dry eye symptoms among participants from the Ahsa region of Saudi Arabia. Participants from urban, rural, and suburban areas seeking medical care at primary health centers were recruited through systematic random sampling. Data on demographics, exposures, and ocular health were captured using a structured questionnaire. Dry eye symptoms were evaluated using the Ocular Surface Disease Index (OSDI), Impact of Dry Eye on Everyday Life (IDEEL), and Symptom Assessment in Dry Eye (SANDE) questionnaires. Logistic regression analysis examined the relationships between environmental/occupational factors and the prevalence of dry eye symptoms. Key exposures included particulate matter (PM) (60%), low humidity (55%), wind/dust (50%), prolonged computer use (65%), and chemical irritants (45%). These factors were significantly associated with an increased prevalence of dry eye symptoms, with the following odds ratios (ORs): PM (1.85, 95% CI: 1.35-2.52), low humidity (1.45, 95% CI: 1.05-2.00), wind and dust (1.60, 95% CI: 1.20-2.14), prolonged computer use (2.10, 95% CI: 1.55-2.85), and chemical irritants (1.75, 95% CI: 1.30-2.35). All associations were statistically significant (p < 0.05). The use of protective equipment was associated with reduced odds of dry eye symptoms (OR 0.60, 95% CI: 0.42-0.85, p = 0.03). This study identifies significant associations between specific environmental and occupational exposures and the prevalence of dry eye symptoms. Reducing modifiable exposures through policy, workplace enhancements, and clinical preventative strategies is essential to mitigate the burden of dry eye symptoms related to modern lifestyles and technology.

Corneo‐conjunctival sensory neuron: Types, transduction channels and codification of nerve impulses

The cornea and the conjunctiva are innervated by the peripheral projections of a small number of primary sensory neurons whose somata are located at the ophthalmic region of the trigeminal ganglion. Most trigeminal neurons innervating the ocular surface are small and medium size, and contain neuropeptides such as SP and CGRP. Functionally, ocular surface neurons have been classified into five main neuronal types, based on their response to multiple modalities of stimuli (mechanical forces, heat, cold, H+, chemical substances, etc.). Polymodal nociceptors (activated by several modalities of stimulus, mechanical energy, heat, H+, and chemical irritants), mechanonociceptors (activated by mechanical energy), cold thermoreceptors (activated by temperature reductions and hyperosmolarity) are found in the cornea, the sclera and the conjunctiva. Besides, low‐threshold mechanoreceptors (activated by mechanical forces of low intensity) are found in the corneoscleral limbus and the lid border, and pruriceptors (activated by pruritogen substances) have been described in the tarsal conjunctiva, close to the lid margin.The ability to respond to the different modalities of stimulus lies in the types of transducing channels that each type of neuron expresses at its peripheral nerve endings. Sensory transduction involves the conversion of the physical or chemical stimuli acting on the nerve terminal into electrical energy, that is, into a local change of membrane potential that, if it is large enough, will generate action potentials that will travel along the axon to be processed by the CNS. So that, nerve terminals with TRPV1 channels are directly gated by heat, H+, and several chemical irritants such as capsaicin; nerve terminals with Piezo2 channels will be activated by mechanical forces; TRPM8 channels provide nerve terminals sensitivity to cold and osmolarity increases; et cetera.Ocular sensory neurons also express other ion channels that contribute to coding, that is to help the sensory neuron to establish a correspondence between the characteristics of the stimulus (intensity, temporal course, etc.) and specific parameters of the firing it induces. Voltage‐gated Ca2+, Na+ and K+ channels as well as cyclic nucleotide‐gated channels, among others, contribute to define the firing frequency and pattern to encode the traits of the stimulus. Thus, the ion channels present in the nerve terminals of each class of ocular sensory neuron provide the neurons the ability to detect and encode one or several modalities of stimulus, which constitutes the origin of the different sensations evoked on the ocular surface.(Supported by PID2020‐115934RB‐I00 from DOI: MCIN/AEI/10.13039/50110001103, and CIPROM/2021/48 from the Generalitat Valenciana, Spain)