Atrazine (ATZ) is a widely used and environmentally persistent chlorinated herbicide that has been implicated in various adverse effects in mammals, including cellular toxicity in red blood cells (RBCs) from various species. Human RBCs in particular are a proxy for systemic toxicity whose susceptibility to ATZ remains largely unexplored. In this study, RBCs purified from whole blood were treated with 0.01–1.0 mM of ATZ, and several toxic endpoints were subsequently investigated using photometric, potentiometric, cytofluorimetric, and microscopic techniques. ATZ elicited concentration-dependent hemolysis that resulted in lactate dehydrogenase and K+ leakage due to membrane pore formation, which was resealed by polyethylene glycol 8,000 (PEG). Additionally, ATZ significantly increased phosphatidylserine translocation and free radicals and decreased forward scatter without an appreciable Ca2+ increase. The hemolytic activity of ATZ was ameliorated by urea and sucrose, whereas phosphatidylserine exposure was reversed by urea and extracellular Ca2+ deprivation. Moreover, co-treatment of cells with ATZ and ATP, SB203580, or L-NAME significantly inhibited ATZ-induced cell death. In conclusion, this study shows, for the first time, that ATZ elicits eryptosis and hemolysis in RBCs mediated by osmotic membrane rupture, PS translocation, loss of ionic regulation and cellular volume, oxidative stress, metabolic exhaustion, extracellular Ca2+ availability, and p38 MAPK/nitric oxide synthase stimulation. The insights presented herein highlight the potential systemic effects of ATZ, which inform toxicological assessments critical for refining human health regulations.
Sodium hypochlorite (NaOCl) is a biocidal substance widely used in household bleaching products and industrial applications. However, repeated, or long-term dermal exposure poses risks to human health. To address these concerns, the present study evaluated the potential dermal toxicity of sodium dodecanoyloxybenzenesulfonate (LOBS), which was developed as an alternative to NaOCl as a disinfectant and bleaching agent. This 13-week repeated dermal toxicity study was conducted in compliance with Organisation for Economic Co-operation and Development (OECD) Test Guideline 411. LOBS was administered dermally for 13 weeks and no treatment-related mortality or systemic toxicity was observed. No toxicologically meaningful changes were detected in body weight, food consumption, hematological or clinical chemistry parameters. Furthermore, no alterations were observed in organ weights, or gross and histopathological examinations of major organs. Local reactions observed at the injection site and on the skin were mild and reversible, and were not considered adverse effects related to the test substance. Based on these findings, the no observed adverse effect level for LOBS was determined to be 1000 mg/kg/day for both males and female SD rats. The results indicate that LOBS has an acceptable toxicological profile following repeated dermal exposure. Additionally, this study provides safety data supporting its use as a disinfectant and bleaching agent.
Ethyl hexyl salicylate (EHS) is a salicylate derivative commonly used as a UV filter in cosmetic products at concentrations up to 5
In recent years, New Approach Methodologies (NAMs) are rapidly emerging as a central paradigm for advancing human-relevant approaches in toxicology, biomedical research, and environmental health science. In respiratory toxicology, traditional two-dimensional cell cultures have limited capacity to reflect human physiological responses, structural complexity, and relevant inhalation exposure environments. Additionally, in vivo models not only present ethical challenges but also lack sufficient human relevance to reliably predict human responses. Recent advances in three-dimensional in vitro models, particularly organoids and microphysiological systems such as organ-on-chip platforms, offer promising alternatives that better recapitulate the structural, molecular, and functional features of the human respiratory system. Lung organoids derived from pluripotent or adult stem cells provide multicellular architecture, lineage diversity, and regenerative capacity suitable for evaluation of toxic mechanisms. Meanwhile, organ-on-chip systems enable dynamic exposure environments, including airflow, mechanical stretch, and air–liquid interface (ALI) conditions, improving the relevance of inhalation exposure modeling. This review summarizes current advances in lung organoid and organ-on-chip models as NAMs for respiratory toxicity testing, discusses their application potential and limitations, and outlines future directions to accelerate their translation into predictive, regulatory-relevant toxicology frameworks.
Lead (Pb) and hypertension (HTN) frequently coexist in the environment, yet the impact of their co-exposure on social impairment remains poorly understood. We found that co-exposure to Pb and hypertension significantly exacerbated social impairment in mice, accompanied by nuclear hyperchromasia and structural damage in the hypothalamic paraventricular nucleus (PVN). Moreover, co-exposure significantly exacerbated microglial polarization imbalance in the PVN, as reflected by elevated expression of the M1 markers iNOS and COX2, coupled with reduced expression of the M2 marker Arg-1. Crucially, co-exposure induced a profound downregulation of TREM2 in the PVN, whereas TREM2 overexpression through intracerebral stereotactic injection not only alleviated the M1/M2 imbalance and mitigated neuronal injury but also improved social behavior. Mechanistically, we demonstrate that TREM2 exerts its neuroprotective effects by sustaining the expression of insulin-like growth factor-1 (IGF-1). Notably, the therapeutic benefits of TREM2 overexpression were abolished by concurrent IGF-1 knockdown, confirming that IGF-1 acts as an obligatory downstream mediator of TREM2-regulated microglial polarization. Collectively, our findings demonstrate that the TREM2/IGF-1 axis serves as an essential pathway mediating microglial polarization and social impairment following co-exposure to Pb and hypertension, underscoring a viable therapeutic strategy for neurobehavioral disorders linked to environmental and vascular insults.
Airborne nanoplastics (NPs) are increasingly recognized as an emerging respiratory health concern because their small size enables deposition in the distal lung, where they can interact directly with the alveolar microenvironment. However, the sequence of mechanisms linking their initial physicochemical interactions to chronic pulmonary outcomes remains insufficiently defined. This review integrates recent evidence to propose a mechanistic framework connecting early biophysical barrier disruption with intracellular stress signaling and progressive lung pathology. We discuss how inhaled NPs may destabilize lung surfactant (LS) structure and function and acquire biological coronas that modify their cellular interactions and uptake. We then examine how lysosomal dysfunction, impaired mitophagy, and mitochondrial damage amplify oxidative stress and promote the release of mitochondrial danger signals, leading to activation of cGAS-STING and the NLRP3 inflammasome. These events contribute to sterile inflammation, pyroptotic signaling, ferroptotic cell death, and profibrotic remodeling. Particular attention is given to epithelial injury, fibroblast metabolic reprogramming, and immune dysregulation as key processes that may underlie asthma exacerbation and pulmonary fibrosis. Finally, we highlight current knowledge gaps, including the limited relevance of short-term high-dose models to chronic low-dose inhalation scenarios, and discuss priorities for future research, biomarker development, and mechanism-based intervention strategies.
The respiratory tract is continuously exposed to airborne chemicals, particles, and pathogens, underscoring the growing need for predictive, human-relevant approaches to inhalation toxicity and pulmonary safety assessment. Conventional animal models and static in vitro cultures frequently fall short because of species differences and their inability to reproduce key lung microenvironmental cues, such as the air–liquid interface (ALI), vascular perfusion, and breathing-like mechanical strain. Microphysiological systems (MPS), including lung- and airway-on-a-chip platforms, help address these limitations by integrating multicellular co-culture, controlled transport, and biomimetic mechanical stimulation to emulate airway and alveolar physiology. This review summarizes recent engineering advances in respiratory MPS, including platform architectures, membranes and extracellular matrix, cell sources, and biomimetic inputs. Furthermore, we discuss fit-for-purpose endpoint selection and exposure modalities for drug safety assessment and environmental and industrial chemical toxicology. We highlight emerging directions, including immune-competent models, quantitative dosimetry for ALI aerosol exposure, and multi-organ coupling, which may further improve the mechanistic and translational value of respiratory MPS. Finally, we outline current regulatory signals and industrial adoption trends, and emphasize the need for standardized performance metrics, integrated quality control frameworks, and clearly defined contexts of use to support broader qualification and regulatory confidence in respiratory MPS data. Collectively, respiratory MPS are gaining importance as promising human-relevant approaches for more mechanistically informative and translationally relevant respiratory toxicity assessment.
Bisphenol A (BPA) is a high-volume industrial chemical used in polycarbonate plastics and epoxy resins that has become a pervasive environmental contaminant. Human exposure occurs primarily through diet, with inhalation and dermal routes as secondary pathways. After absorption, BPA rapidly enters systemic circulation and traverses the blood–placenta and blood–brain barriers, raising concern for fetal and neonatal vulnerability. Toxicologically, BPA acts as an endocrine-disrupting chemical with estrogenic, anti-androgenic, and thyroid-disrupting activities, binding nuclear and membrane receptors to perturb hormonal homeostasis. Accumulating evidence links chronic exposure to endocrine-related disorders (e.g., infertility, breast cancer, obesity, and ADHD), neurotoxicity with adverse neurodevelopmental and cognitive outcomes, and metabolic dysregulation including hepatic steatosis. While human biomonitoring studies, murine in vivo models, and in vitro assays have characterized exposure, mechanisms, and health endpoints, much less is known about BPA in companion animals that share human environments. Emerging data in dogs (and to a lesser extent cats) demonstrate short-term internal exposure and acute biological responses—such as altered serum BPA level, endocrine changes, and microbiome shifts—but the long-term consequences, epigenetic alterations, immune and stress-response markers, and multigenerational effects remain insufficiently defined. Framed within a One Health perspective, this review synthesizes current evidence across humans, experimental animals, and cells, and critically appraises the nascent literature in companion animals. We highlight key knowledge gaps and propose a research agenda emphasizing standardized exposure assessment, longitudinal cohorts, species-appropriate biomarkers, and integrative omics to strengthen causal inference and risk assessment. Understanding BPA’s impacts in companion animals living alongside humans may yield sensitive sentinels and translational insights to guide public-health policy and mitigation strategies.
Pancreatic β-cell function defects are responsible for the pathology of both type 1 and type 2 diabetes. The sensitivity of mTOR Complex 1 (mTORC1) to insulin and nutrients suggests its importance in β-cell function. To assess the effect of mTOR signaling in mouse β-cells, we specifically deleted the mTOR gene in this cellular compartment. These mice display glucose intolerance and do not secrete insulin in response to a glucose challenge. Similarly, depletion of mTOR via siRNA in INS-1 cells demonstrated that the kinase is necessary for glucose-stimulated insulin secretion (GSIS). The effects of mTOR on GSIS were dependent on mTORC1, not mTORC2, and resulted in a selective reduction of NeuroD1 expression, with no impact on PDX1. These findings on NeuroD1 expression were also observed in the islets of diabetic patients. Overall, mTOR signaling regulates insulin secretion and production in β-cells through mTORC1 and NeuroD1.
While the prognosis of thyroid cancer is generally favorable effective therapeutic options remain limited for its advanced or metastatic stages. In this study, we investigated the anti-cancer effects of amiodarone, a widely prescribed anti-arrhythmic agent, in SNU-790 human thyroid cancer cells. Cell viability and cytotoxicity were evaluated using the water-soluble tetrazolium salt-8 assay, which demonstrated a concentration-dependent reduction in cell viability following amiodarone treatment, and the half-maximal inhibitory concentration value was determined accordingly. Flow cytometric analysis revealed that amiodarone induced G1-phase cell-cycle arrest, indicating suppression of thyroid cancer cell proliferation. In addition, a trans-well migration assay showed that amiodarone significantly inhibited cell migration in a concentration-dependent manner, suggesting a potential anti-metastatic effect. Intracellular and mitochondrial reactive oxygen species levels were assessed using 2’,7’-dichlorofluorescein diacetate and MitoSOX™ Red staining, respectively, and both were increased in the amiodarone-treated groups. Additionally, mitochondrial membrane potential was evaluated using JC-10 staining, which revealed a significant decrease. Furthermore, the apoptotic cell population was evaluated by Annexin V/propidium iodide staining, which demonstrated a significant increase in the induction of apoptosis in amiodarone-treated cells. Autophagic responses were further examined by acridine orange staining, which revealed an increase in acidic vesicular organelles, and Western blot analysis confirmed the accumulation of microtubule-associated protein 1 light chain 3B, indicating activation of autophagy in the SNU-790 cells. In conclusion, this study confirmed that amiodarone inhibits the proliferation and migration of thyroid cancer cells and induces apoptosis. Furthermore, we observed that amiodarone induces biochemical changes, including activation of autophagy and mitochondrial dysfunction, suggesting its potential as a repositioned therapeutic agent for thyroid cancer.
Bisphenol A (BPA) is an environmental pollutant with toxic effects associated with disruption of redox balance and activation of inflammatory cascades. This study investigated the protective efficacy of carbocisteine (S-carboxymethylcysteine (SCMC)), a cysteine derivative with established antioxidant and cytoprotective properties, against BPA-induced kidney damage. Adult male rats were orally exposed to BPA and/or SCMC for 28 consecutive days. BPA elevated serum creatinine, BUN, uric acid, and Kim-1, in parallel with histological alterations and excessive collagen deposition in renal tissue. BPA exposure markedly enhanced lipid peroxidation, upregulated NF-κB p65 and pro-inflammatory cytokines, and suppressed GSH, SOD, catalase, and IL-10. Additionally, BPA provoked endoplasmic reticulum (ER) stress and apoptotic signaling, as evidenced by upregulated CHOP, GRP78, GRP75, and cleaved caspase-3. Co-administration of SCMC ameliorated BPA-induced renal dysfunction, preserved tissue architecture, attenuated oxidative damage, and mitigated inflammatory responses. SCMC further alleviated ER stress and apoptosis by downregulating CHOP, GRP78, GRP75, and cleaved caspase-3. SCMC suppressed Keap1 while enhancing Nrf2 and HO-1. In conclusion, these findings demonstrate that SCMC confers protection against BPA-induced nephrotoxicity by restoring antioxidant capacity, activating Nrf2/HO-1 signaling, and inhibiting inflammatory response, ER stress, and apoptosis. SCMC may therefore represent a promising therapeutic candidate for preventing kidney injury associated with BPA and related environmental toxicants.
Biotin, also known as vitamin B7, has been used as a skin- and hair-conditioning agent in cosmetic products. In acute oral toxicity studies, the lethal dose 50 (LD50) exceeded 10 g/kg in mice, indicating low acute toxicity. Dermal and eye irritation studies in rabbits showed that biotin was non-irritant. Guinea pig maximization test demonstrated no sensitizing potential of biotin. In a 28-day repeated-dose oral toxicity study in rats, dietary administration with over 0.08
Benzophenone-3 (also known as oxybenzone) is an ultraviolet filter commonly used in sunscreen formulations and personal care products. Given its systemic exposure through dermal and oral absorption, the toxicity of benzophenone-3 has been widely studied. In rodents, dietary exposure to high experimental doses of benzophenone-3 was associated with mild systemic toxicity, including reduction in body weight gain, increase in liver and kidney weights, and signs of nephropathy. While benzophenone-3 was shown to be non-irritating and non-skin sensitizing following ocular instillation and dermal application in animal studies, it has been recognized as a cause of photoallergic contact dermatitis in clinical studies. Mild reproductive and developmental effects have also been reported, including reduced offspring body weight, slightly reduced litter size, and altered sperm parameters. Benzophenone-3 was non-mutagenic in genotoxicity assays, and a lifetime dietary exposure study in rodents suggested equivocal evidence of carcinogenic activity. The endocrine-disrupting potential of benzophenone-3 is of concern because it binds to estrogen receptors. Although in vitro and in vivo assays have shown inconsistent results, the potential risk to humans remains a concern. For the safety assessment, a no-observed-adverse-effect level of 1,000 ppm (67.9 mg/kg/day) was selected from a reproductive and developmental toxicity study in which a reduced number of spermatocytes per seminiferous tubule was observed in male F1 offspring. The systemic exposure dose, calculated based on the daily usage amount for the Korean population, was 0.6732 mg/kg/day when used at 2.4
Trace elements play essential roles in neural homeostasis by modulating energy metabolism, redox balance, neurotransmitter synthesis, and synaptic plasticity, processes directly related to cognition and mood. Elements such as zinc, iron, copper, selenium, iodine, and phosphorus act as enzymatic cofactors and regulators of neuronal excitability, while their imbalance has been associated with cognitive impairment, affective alterations, and increased vulnerability to neurodegenerative diseases. In contrast, heavy metals such as lead, mercury, cadmium, arsenic, aluminum, and bismuth are neurotoxic agents capable of triggering oxidative stress, neuroinflammation, mitochondrial dysfunction, and alterations in neurotransmission, thereby contributing to memory deficits, executive dysfunction, and symptoms of anxiety and depression. Given the need for methods capable of detecting early chemical alterations associated with metal dyshomeostasis, Raman spectroscopy has emerged as a promising analytical tool, as it enables the noninvasive identification of vibrational signatures related to biomolecules and metal–protein interactions in tissues and biofluids. In addition, surface-enhanced Raman spectroscopy (SERS) increases the sensitivity of the technique through metallic nanostructures, enabling detection at ultralow concentrations. The integration of Raman spectroscopy with machine learning methods has the potential to improve spectral pattern discrimination and to enable biomarkers capable of reflecting dysfunctional neurochemical states prior to clinical onset. Thus, Raman and SERS represent innovative approaches for investigating and monitoring the interface between metals, neurotoxicity, cognition, and mental health.
The prevalent use of combination antiretroviral therapy (cART) in the treatment and as a preventative prophylaxis in HIV-exposed individuals has raised concern for its neurotoxicity. The diabetogenic effect of cART and alcohol consumption also warrants that cART cerebellar neurotoxicity be evaluated for its impact in a diabetic state. Therefore, the cerebellar effects of the interaction of cART and alcohol in diabetic disease conditions were assessed using a diabetic male Sprague Dawley rat model. Forty-eight adult male Sprague Dawley rats were divided into eight groups of six rats; untreated group (NC), cART alone group (AV), alcohol alone (AL), diabetes (DB), cART and alcohol treated (AVAL), diabetic cART treated group (AVDB), diabetic alcohol treated group (ALDB), and diabetic alcohol and cART treated group (AVALDB), treated for 90 days and then terminated, brains excised, and homogenized. Cerebellar samples were analysed for MDA Elisa, Caspase 3, Bcl2 and Occludin qPCR while Giemsa stain histology and Caspase 3 and cyclophilin A immunohistochemistry were also carried out on sectioned cerebellar tissue. Our results reveal increased oxidative stress and Caspase 3 mRNA in all treated groups, with elevated immunohistochemical Caspase 3 expression in Bergmann and cerebellar nuclei glial cells, but depleted cyclophilin A expression in these cells with AV and AVAL treatments. The AL, DB, AVDB, and AVALDB groups showed depleted occludin mRNA and elevated cyclophilin A expression in glial cells, while apoptotic Caspase 3 expression is observed mostly in the cerebellar nuclei neurons and Purkinje neurons of the diabetic groups (DB, AVDB, ALDB and AVALDB). These results indicate the potential of cART and alcohol interaction to impair cerebellar nuclei and cortex glial cells but in combination with diabetes induces Purkinje and dentate nucleus apoptosis with depleted cyclophilin A expression. Therefore, these crucial cells for cerebellar homeostasis and coordination function should be monitored where these factors co-occur.
Household insecticides are frequently used in combination indoors; however, the inhalation-relevant toxicological consequences of such co-exposure remain unclear. Therefore, in this study, we investigated whether co-exposure to hydramethylnon and representative pyrethroid insecticides (tetramethrin, prallethrin, and imiprothrin) induces synergistic toxicity in BEAS-2B human bronchial epithelial cells and explored a metabolic mechanism involving cytochrome P450 (CYP) inhibition. Cell viability was quantified via water-soluble tetrazolium salt-1 assay after 24 h exposure, and the half-maximal inhibitory concentration (IC50) of individual chemicals were used to define toxic units for mixture design. Mixture interactions were evaluated by comparing experimentally observed mixture concentration–response relationships with predictions from concentration addition (CA) or independent action (IA) using the Open Mixture Risk Assessment (OpenMRA) platform, with interaction classification based on the model deviation ratio (MDR). Analyses of chemical category and mode of action (MoA) revealed that hydramethylnon mechanistically differed from pyrethroid insecticides, supporting the application of the IA model for mixture toxicity evaluation. Although mixtures containing only pyrethroids showed additive effects consistent with the CA model (MDR, 0.95), every mixture containing hydramethylnon exhibited significant synergism, with MDRs of 2.62–5.80 under the IA model. Mechanistically, hydramethylnon significantly reduced CYP3A4 and CYP3A5 mRNA expression levels in BEAS-2B cells and inhibited recombinant CYP3A4 activity in a dose-dependent manner (IC50, 3.30 µg/mL). Molecular docking further confirmed stable binding of hydramethylnon within CYP3A4/3A5 active sites. Collectively, these findings suggest that hydramethylnon acts as a synergy-inducing co-exposure factor for pyrethroid mixtures in the bronchial epithelium, possibly via suppression of CYP-mediated detoxification, underscoring the need to incorporate metabolic interactions into inhalation-relevant mixture risk assessment.
Hexachlorophene is a topical antiseptic historically used for skin cleansing and preoperative skin disinfection, but its use today is tightly restricted due to neurotoxicity risks. However, its underlying mechanisms are still not fully understood. Here, we investigated hexachlorophene-induced stress responses and cell death pathways in human neuroblastoma SH-SY5Y cells. Hexachlorophene treatment induced G3BP stress granule assembly factor 1 (G3BP1)–positive stress granules (SGs) in a time- and dose-dependent manner, along with increased eIF2α phosphorylation at serine 51, indicating activation of canonical translational repression. In addition, inhibition of G3BP1 using the selective inhibitor FAZ-3532 effectively suppressed SG formation but worsened hexachlorophene-induced cytotoxicity, suggesting that SGs serve a protective function under chemical stress. Despite SG suppression, eIF2α phosphorylation remained elevated. Collectively, these results demonstrate that SGs are adaptively formed in response to hexachlorophene and act to mitigate neuronal toxicity. Disruption of SG assembly sensitizes neuronal cells to stress, and the enhanced cytotoxicity was mediated through apoptosis, highlighting the functional importance of SGs in hexachlorophene mediated neurotoxic contexts.
p-Tert-butylphenol (ptBP) is widely used in polymer resin synthesis and industrial applications, and workers are potentially exposed to it during manufacturing and handling. ptBP induces vitiligo and is associated with skin depigmentation and endocrine-disrupting effects mediated by oxidative stress. These toxicological concerns extend beyond local irritation to systemic health risks and underscore the need to establish scientifically derived reference values and occupational safety standards to protect workers. Key data was selected from animal and human biomonitoring studies. Reference values were derived for the dermal and inhalation routes using internationally accepted methodologies. Worker exposure was estimated by the ECETOC TRA model. Hazard quotients (HQs) were calculated by comparing the predicted exposure levels with derived reference values. Reference values were determined as 0.196 mg/kg bw/day for dermal exposure and 0.5 mg/m3 for inhalation. Predicted chronic dermal exposures ranged from 1.71E-03 to 6.86E-01 mg/kg bw/day, while inhalation exposures were between 1.50E-04 to 4.73E+00 mg/m3. The HQs exceeded one in several processes, particularly dermal exposure, with four processes being problematic even after accounting for workplace conditions. Inhalation risks are generally low because of the closed-system operations. This study provided a comprehensive evaluation of the occupational risks of ptBP and offers scientific evidence to support exposure limits and regulatory strategies.
Methylene bis-benzotriazolyl tetramethylbutylphenol (MBBT) is a UV filter and UV absorber used in cosmetics. In this study, the acute toxicity, repeated dose toxicity, skin irritation, ocular irritation, skin sensitization, reproductive, and developmental toxicity, genotoxicity, carcinogenicity, toxicokinetics, and dermal absorption of MBBT were evaluated. The oral and dermal LD50s of non-nanoform MBBT in rats were 2 g/kg. The LC50 of nanoform MBBT in rats was 0.488 mg/L. Neither 20
Diethylamino hydroxybenzoyl hexyl benzoate (DHHB) is a UVA filter widely used in cosmetic formulations. The present study evaluated the toxicological profile and conducted a human health risk assessment of DHHB based on available toxicological and exposure data. Overall, the available studies indicate low acute toxicity, no evidence of genotoxicity, and minimal skin irritation or sensitization potential. For risk characterization, the maternal no-observed-adverse-effect level (NOAEL) of 200 mg/kg bw/day derived from a reproductive and developmental toxicity study in rats was selected as the point of departure because it represents the most relevant endpoint for systemic exposure. Human exposure was estimated using the cosmetic exposure assessment approach recommended by the Ministry of Food and Drug Safety (MFDS). The systemic exposure dose (SED) was calculated assuming daily use of sunscreen products (17 g/day), a maximum DHHB concentration of 10
