Field Of Toxicology Research Articles

The alcohol exposome.

Science is now in a new era of exposome research that strives to build a more all-inclusive, panoramic view in the quest for answers; this is especially true in the field of toxicology. Alcohol exposure researchers have been examining the multivariate co-exposures that may either exacerbate or initiate alcohol-related tissue/organ injuries. This manuscript presents selected key variables that represent the Alcohol Exposome. The primary variables that make up the Alcohol Exposome can include comorbidities such as cigarettes, poor diet, occupational hazards, environmental hazards, infectious agents, and aging. In addition to representing multiple factors, the Alcohol Exposome examines the various types of intercellular communications that are carried from one organ system to another and may greatly impact the types of injuries and metabolites caused by alcohol exposure. The intent of defining the Alcohol Exposome is to bring the newly expanded definition of Exposomics, meaning the study of the exposome, to the field of alcohol research and to emphasize the need for examining research results in a non-isolated environment representing a more relevant manner in which all human physiology exists.

Drug combination assays using Caenorhabditis elegans as a model system.

The C. elegans drug combination assay evaluates the effects of drug combinations in the nematode Caenorhabditis elegans, serving as a valuable tool to assess the efficacy of pharmaceutical agents and natural compounds. Using C. elegans as a model organism, this method allows for the efficient screening of the combined effects of different drugs and evaluation of synergistic effects in drug combinations, which reduces the risk of developing drug resistance. Combination therapy, involving commercial drugs, new agents, or natural products, broadens treatment effectiveness by targeting multiple pathways, effectively managing complex diseases with minimized side effects. The method focuses on discovering effective drug combinations, such as anthelmintic drugs, streamlining early-stage drug discovery to save time and resources. Additionally, its versatility allows for application across most areas of pharmacology and toxicology, extending its usefulness beyond anthelmintic treatments. In the experiments, synchronized worms are exposed to different drug concentrations to evaluate behavioral changes, mostly alterations in worm locomotion. Concentration-response curves for changes in behavior are generated and EC50 or IC50 values determined for the individual drugs. To determine whether the effects of a drug combination are synergistic, additive, or antagonistic, at least three different concentration ratios must be tested. These combinations are then analyzed using specialized drug combination analysis software. This methodology ensures consistent and precise outcomes and evaluates drug impacts on worm behavior parameters crucial for effective pharmacological activity. In conclusion, the C. elegans drug combination assay provides critical insights for developing successful market formulations applicable across a wide range of pharmacological treatments. Its ability to efficiently screen for synergistic, additive, or antagonistic effects makes it a valuable tool for identifying effective therapeutic strategies, potentially reducing drug resistance and improving treatment outcomes in various medical and toxicological fields.

The Role of Faculty in Assessment: Traditional vs. CompetencyBased Medical Education in Toxicology Learning

Toxicology is a very important subject in medical science which deals with the study of poisons and their effects in all aspects. Teaching of toxicology in medical school must be evaluated and assessed effectively to know the actual delivery of content and understanding of students. Faculty plays a critical role in the assessment of toxicology education, influencing the effectiveness and outcomes of both traditional and Competency-Based Medical Education (CBME) models. This article compares the roles and responsibilities of faculty in traditional and CBME frameworks within toxicology learning. It highlights specific examples of assessments and discusses various types of faculty training required to excel in these educational models. The analysis underscores the need for faculty development to adapt to the evolving demands of toxicology education. In Indian medical colleges, CBME has already been adopted and now it is time to create an excellent faculty development program to enhance assessment levels, particularly in the field of toxicology.

Evaluation of rewarding effects of nitazene analogs: results from conditioned place preference tests and in vivo microdialysis experiments in mice

In illicit drug markets, the most recently expanding new synthetic opioid subclass is benzimidazoles, also known as nitazenes, which were originally developed as analgesics in the 1950s. The emergence of this classical, potent drug family has attracted extensive research interest in the field of forensic toxicology; however, information on their psychological and physical dependence is very limited. Herein, we evaluated the rewarding effects of four nitazene analogs using a battery of in vivo experiments, with a positive control drug (isotonitazene). The four test materials, metonitazene, etodesnitazene, metodesnitazene, and flunitazene, were administered to male C57BL/6J mice by i.p. administration at 0.5, 2, 20, and 20 mg/kg, respectively. In comprehensive behavioral observation tests, representative opioid-related physiological and behavioral states, including analgesia, stereotypic circling behavior, hyperlocomotion, and Straub tail response, were observed. A set of conditioned place preference tests revealed that all the four analogs induced palatability in mice. Furthermore, measurements of dopamine levels in the nucleus accumbens shell by in vivo microdialysis resulted in significant elevations in all test material-treated groups, suggesting that the nitazenes elicit the rewarding effect through a neural circuit originating from the μ-opioid receptor activation at the ventral tegmental area. Our findings add important data regarding the psychological dependence of nitazenes and highlight the abuse potential of these four materials and other prevailing nitazene analogs.

Evaluation of Respiration with a Clark-Type Electrode in Isolated Mitochondria, Intact and Permeabilized Cells, and Explants from Animal Tissues.

Evaluation of mitochondrial function in aerobic cells is crucial for understanding the conditions that can potentially compromise their physiology. From the fields of Toxicology to Oncology, various approaches involving freshly isolated fractions of mitochondria, permeabilized cells, intact cells, or animal tissues have been employed to investigate metabolism through oxygen consumption.Several techniques are available for measuring oxygen consumption in liquids. These include polarography with oxygen electrodes, which can employ chemical, electrochemical, or optical detection methods, as well as the use of fluorescent or luminescent probes. In this chapter, we will review the concepts previously discussed in earlier editions, focusing on Clark-type electrodes for electrochemical detection. Additionally, we will explore other approaches that involve intact cells and tissue explants with minimal plasmatic membrane alterations. These techniques provide an integrated view of Glycolysis, Krebs Cycle and Oxidative Phosphorylation. Despite being a classical and cost-effective system, this elegant technique continues to amaze us with its versatility and generation of reliable data.

Zebrafish: A Cost-Effective Model for Enhanced Forensic Toxicology Capabilities in Low- and Middle-Income Countries.

Low- and middle-income countries (LMICs) are increasingly challenged by the rising burden of medicolegal cases. Traditional forensic infrastructure and in vivo rodent models often have significant limitations due to high costs and ethical concerns. As a result, zebrafish (Danio rerio) are gaining popularity as an attractive alternative model for LMICs because of their cost-effectiveness and practical advantages. Zebrafish have a lower acquisition cost, require less demanding husbandry, and have rapid development cycles, all of which facilitate faster and more economical toxicological studies, even in limited laboratory space. Additionally, the optical transparency of zebrafish embryos and larvae allows for non-invasive in vivo observations, reducing the need for extra resources. Research has shown that zebrafish can effectively investigate the behavioral, developmental, and cardiotoxic effects of various novel psychoactive substances (NPSs), including synthetic opioids, cathinones, and hallucinogens. They also excel in metabolic profiling, producing a broader range of metabolites than other models, with significant overlap in human metabolism. The presence of mammalian-like metabolic enzymes further positions zebrafish as a valuable tool for understanding human NPS metabolism and predicting potential effects. Notably, they can identify metabolites that traditional models may not detect, underscoring their potential for novel metabolite discovery. Despite these advantages, standardizing data collection protocols and addressing interlaboratory variability are crucial challenges that must be overcome for the widespread adoption of the zebrafish model. However, ongoing global efforts are paving the way to address these limitations and ensure the successful integration of zebrafish models into the field of forensic toxicology. This review highlights the potential of zebrafish as a cost-effective and versatile model for LMICs, emphasizing their growing application in NPS research and forecasting broader adoption in forensic toxicology.

Mechanisms of influence of cadmium salt on postembryonic hemopoiesis in red bone marrow

This review examines the mechanisms by which cadmium salts affect the lineages of blood cells during postembryonic hematopoiesis in the bone marrow, as well as the disruptions that arise due to cadmium exposure, based on recent researches. Cadmium is a highly toxic heavy metal that, as proven by numerous scientific studies, can enter the human body from the environment and cause various diseases. The article analyzes the impact of cadmium compounds on the cellular composition of the bone marrow, especially on the hematopoietic process and cell differentiation. It illustrates the ways in which cadmium disrupts hematopoiesis by triggering cellular stress responses, apoptosis and inflammatory processes. As blood, being the primary liquid medium of the body, participates in regulating all ongoing processes, understanding the impact of cadmium on hematopoiesis and the balance of blood cells is crucial for public health. The article is relevant both scientifically and practically due to the rising concentrations of heavy metal in the environment. The research findings provide insights into the mechanisms of cadmium toxicity at the molecular and cellular levels, which in turn can serve as a basis for disease prevention, diagnosis, and the development of new therapeutic strategies in medical practice. This research work presents valuable information in the fields of biology, ecology, medicine, and toxicology, contributing to the assessment of cadmium’s risk to human health.

Nuclear Magnetic Resonance Spectroscopic Characterization and Determination of the New Psychoactive Substance Benzylone: Application in a Biological Fluid.

New psychoactive substances (NPS)-designed to mimic various legal or illegal substances-are an emerging worldwide health problem. Their identification and quantification in either complex seized samples or powders are critical; moreover, their determination in biological fluids is an intriguing goal in the forensic toxicology field. Synthetic cathinones are one of the most important groups among NPS. The current paper was designed as a pilot study to investigate the application of NMR techniques to identify and quantify unknown NPS compounds in deuterated dimethyl sulfoxide (DMSO-d6) and in urine using the synthetic cathinone benzylone (3,4-methylenedioxy-N-benzylcathinone, BMDP) as a pilot compound. In the first part of our study, nuclear magnetic resonance (NMR) spectroscopic characterization was performed using 1D and 2D homonuclear and heteronuclear NMR spectroscopic methods as long as diffusion ordered spectroscopy (DOSY). Following the above, the assignment of benzylone in DMSO-d6 was performed, and a distinct spectroscopic pattern was proposed. In the second part of our study, a NMR spectroscopic approach was applied for benzylone identification and quantification in a spiked with benzylone urine. Following the above, the assignment of benzylone in spiked urine was performed. A distinct pattern of the H11, H14, H15, and H8 signals on the 1H NMR spectra was observed and suggested as a "NMR spectroscopic pattern/signature" enabling the identification of benzylone moieties in urine. On the other hand, the applied NMR techniques showed low sensitivity in quantitating benzylone in spiked urine. Overall, our results are promising in using NMR for structure determination of unknown compounds in urine.

Overview of Computational Toxicology Methods Applied in Drug and Green Chemical Discovery.

In the field of computational chemistry, computer models are quickly and cheaply constructed to predict toxicology hazards and results, with no need for test material or animals as these computational predictions are often based on physicochemical properties of chemical structures. Multiple methodologies are employed to support in silico assessments based on machine learning (ML) and deep learning (DL). This review introduces the development of computational toxicology, focusing on ML and DL and emphasizing their importance in the field of toxicology. A fine balance between target potency, selectivity, absorption, distribution, metabolism, excretion, toxicity (ADMET) and clinical safety properties should be achieved to discover a potential new drug. It is advantageous to perform virtual predictions as early as possible in drug development processes, even before a molecule is synthesized. Currently, there are numerous commercially available and free web-based programs for toxicity prediction, which can be used to construct various predictive models. The key features of the QSAR method are also outlined, and the selection of appropriate physicochemical descriptors is a prerequisite for robust predictions. In addition, examples of open-source tools applied to toxicity prediction are included, as well as examples of the application of different computational methods for the prediction of toxicity in drug design and environmental toxicology.

Bridging organ transcriptomics for advancing multiple organ toxicity assessment with a generative AI approach

Translational research in toxicology has significantly benefited from transcriptomic profiling, particularly in drug safety. However, its application has predominantly focused on limited organs, notably the liver, due to resource constraints. This paper presents TransTox, an innovative AI model using a generative adversarial network (GAN) method to facilitate the bidirectional translation of transcriptomic profiles between the liver and kidney under drug treatment. TransTox demonstrates robust performance, validated across independent datasets and laboratories. First, the concordance between real experimental data and synthetic data generated by TransTox was demonstrated in characterizing toxicity mechanisms compared to real experimental settings. Second, TransTox proved valuable in gene expression predictive models, where synthetic data could be used to develop gene expression predictive models or serve as “digital twins” for diagnostic applications. The TransTox approach holds the potential for multi-organ toxicity assessment with AI and advancing the field of precision toxicology.

The AI-assisted Traditional Design Methods for the Construction Sustainability: A Case Study of the Lisu Ethnic Minority Village

In recent decades, economic and technical advancements have surged tremendously, accompanied by non-regulatory and unsustainable use of non-renewable assets. The ecological field of toxicology has garnered considerable focus on elucidating the impact of harmful substances on people's wellness. Environmental hazardous chemicals induce many illnesses, posing a heightened danger to youngsters, pregnant women, the elderly, and anyone with preexisting health conditions. Air pollution adversely impacts human health, leading to heightened morbidity and death, necessitating intensified toxicological investigations on industrial air pollution affecting the general populace. It is necessary to develop a computerized Ecological Toxicology-based Air Pollution Management System. Constructive social development is driven by cultural education. It can guarantee a sustainable future, protect national history, and unleash community potential. This study examines Chinese architects' perspectives and understanding of sustainability in village revitalization and conservation. It incorporates traditional Lisu building techniques and materials in Hunan, China. To close research gaps, this study looks at the contributions made by architects to traditional practice integration and environmentally conscious architectural design. This study proposes an IoT-enabled Environmental Toxicology platform for air pollution surveillance, utilizing artificial intelligence (AI) techniques to mitigate the limits of standard monitoring systems and lower total costs, enhancing human wellness. The research examined the intricate interaction between architects' understanding of sustainability, Lisu building techniques and materials, and sustainable architectural designs in village preservation and revitalization programs using path analysis on data from 326 architects in Hunan Province. Lisu building practices and materials strongly correlate with architects' awareness of and attitudes toward sustainability. According to the research, these characteristics are necessary for sustainable architectural solutions that support village revival and preservation. This study has significant theoretical and practical ramifications for academics, lawmakers, and architects. To evaluate the air quality monitoring efficacy of the suggested approach, a comprehensive series of simulation analyses is conducted, and the results are assessed at durations of 5, 15, 30, and 60 minutes. The experimental results demonstrate the superior efficacy of the suggested model compared to current methodologies. These findings could lead to the creation of sustainable design solutions that advance rural development. A thorough overview of upcoming studies on sustainable design approaches in Chinese contexts rounds out this talk.

Predictive, integrative, and regulatory aspects of AI-driven computational toxicology – Highlights of the German Pharm-Tox Summit (GPTS) 2024

The 9th German Pharm-Tox Summit (GPTS) and the 90th Annual Meeting of the German Society for Experimental and Clinical Pharmacology and Toxicology (DGPT) took place in Munich from March 13–15, 2024. The event brought together over 700 participants from around the world to discuss cutting-edge developments in the fields of pharmacology and toxicology as well as scientific innovations and novel insights. A key focus of the conference was on the rapidly increasing role of computational toxicology, artificial intelligence (AI), and machine learning (ML) into the field, marking a shift away from traditional methods and allowing the reduction of animal testing as primary tool for toxicological risk assessment. Tools such as Toxometris.ai showcased the potential of AI-based risk assessments for predicting carcinogenicity, offering more ethical and efficient alternatives. Additionally, computer-driven models like computer-aided pattern analysis (C@PA) for drug toxicity prediction were presented, emphasizing the growing role of chem- and bioinformatic applications in computational sciences. Throughout the summit, there was a strong focus on the need for regulatory innovation to support the adoption of these advanced technologies and ensure the safety and sustainability of chemical substances and drugs.

Development of a TBXT-EGFP iPS cell model for screening the early developmental toxicity of typical environmental pollutants

In our daily lives, we are inevitably exposed to a variety of environmental pollutants in numerous ways. Fortunately, recent years have witnessed significant advancements in the field of stem cell toxicology, which have provided new opportunities for research in environmental toxicology. Applying stem cell technology to environmental toxicology, overcomes some of the limitations of traditional screening methods and we can more accurately predict the toxicity of environmental pollutants. However, there are still several aspects of stem cell toxicology models that require improvement, such as increasing the throughput of detection and simplifying detection methods. Consequently, we developed an environmental pollutant toxicity detection model based on TBXT-EGFP iPS cells and screened the developmental toxicity of 38 typical environmental pollutants. Our results indicate that TBBPA-BDBPE, TBBPA-BHEE, DG, and AO2246 may interfere with the expression of TBXT, a critical marker gene for early human embryo development, implying that these environmental pollutants could lead to developmental abnormalities.

Simple and Highly Sensitive Electrochemical Sensor for Sunset Yellow Detection Based on Co3O4/g‐C3N4 Nanocomposite Modified Gold Electrode

AbstractSunset Yellow (SY) is an azo dye used in various food and pharmaceutical industries that deserves special attention because of its allergic and carcinogenic properties. Recently, electrochemical techniques have come to the spotlight because of their high sensitivity, simplicity and rapidity as compared to other techniques. In this work, we have developed a cost‐effective and stable electrochemical sensor by a simple method using Vitamin B12‐derived cobalt oxide coupled with g‐C3N4 (V12‐CoO/gCN) modified Au electrode. The composite prepared for the sensor was characterized using techniques such as FTIR, Powder XRD, SEM analysis, EDAX, and mapping. For electrochemical sensing of the dye Sunset Yellow, CV, DPV, and LSV techniques have been used, out of which DPV shows a better detection limit of 1.39 nM followed by LSV and CV that displayed detection limits of 3.3 nM and 4.14 nM respectively. When 5 real samples obtained from the local market are analyzed using the DPV technique, the detection limit is obtained in the range between 2.1 nM and 6.9 nM. This method leads to the development of an electrochemical sensor for the detection of Sunset Yellow to get a lower detection limit that can be used in food toxicology and related fields.

Adverse Outcome Pathways Mechanistically Describing Hepatotoxicity.

Adverse outcome pathways (AOPs) describe toxicological processes from a dynamic perspective by linking a molecular initiating event to a specific adverse outcome via a series of key events and key event relationships. In the field of computational toxicology, AOPs can potentially facilitate the design and development of in silico prediction models for hazard identification. Various AOPs have been introduced for several types of hepatotoxicity, such as steatosis, cholestasis, fibrosis, and liver cancer. This chapter provides an overview of AOPs on hepatotoxicity, including their development, assessment, and applications in toxicology.

OMIP-107: 8-color whole blood immunophenotyping panel for the characterization and quantification of lymphocyte subsets and monocytes in swine.

We developed this whole blood immunophenotyping panel with the aim to monitor and quantify major lymphocyte subsets (CD4+, CD8+, CD4+CD8+ αβ T cells, γδ-T cells, B and NK cells) and monocytes in pigs. The panel involved the use of commercially available reagents, avoiding secondary antibody staining or in-house antibody conjugations, with the aim to make the assay accessible and reproducible across laboratories. The assay is accurate, robust and represents a useful tool for immune monitoring of swine in the pharmacology and toxicology fields, or to monitor the immune status in response to vaccination and diseases.

Hydrophilic interaction liquid chromatography: An efficient tool for assessing thorium interaction with phosphorylated biomimetic peptides

In the field of nuclear toxicology, the knowledge of the interaction of actinides (An) with biomolecules is of prime concern in order to elucidate their toxicity mechanism and to further develop selective decorporating agents. In this work, we demonstrated the great potential of hydrophilic interaction liquid chromatography (HILIC) to separate polar thorium (Th) biomimetic peptide complexes, as a key starting point to tackle these challenges. Th4+ was used as plutonium (Pu4+) analogue and pS16 and pS1368 as synthetic di- and tetra-phosphorylated peptides capable of mimicking the interaction sites of these An in osteopontin (OPN), a hyperphosphorylated protein. The objective was to determine the relative affinity of pS16 and pS1368 towards Th4+, and to evaluate the pS1368 selectivity when Th4+ was in competition complexation reaction with UO22+ at physiological pH. To meet these aims, HILIC was simultaneously coupled to electrospray ionization mass spectrometry (ESI-MS) and inductively coupled plasma mass spectrometry (ICP-MS), which allowed to identify online the molecular structure of the separated complexes and quantify them, in a single step. Dedicated HILIC conditions were firstly set up to separate the new dimeric Th2(peptide)2 complexes with good separation resolution (peptide = pS16 or pS1368). By adding pS16 and pS1368 in different proportions relatively to Th4+, we found that lower or equal proportions of pS16 with respect to pS1368 were not sufficient to displace pS1368 from Th2pS13682 and pS16 proportion higher than pS1368 led to the formation of a predominant ternary complex Th2(pS16)(pS1368), demonstrating preferential Th4+ binding to the tetra-phosphorylated peptide. Finally, online identification and quantification of the formed complexes when Th4+ and UO22+ were mixed in equimolar ratio relatively to pS1368 showed that in spite of pS1368 has been specifically designed to coordinate UO22+, pS1368 is also Th4+-selective and exhibits stronger affinity for this latter than for UO22+. Hence, the results gathered through this approach highlight the impact of Th4+ coordination chemistry on its interaction with pS1368 and more widely to its affinity for biomolecules.

A REVIEW ON VISHAVILWADI AGADA

Kerala has a proven unique background in the field of toxicology (Visha chikitsa). Many eminent Visha vaidyas in Kerala managed snake bites and other poisonous stings/ bites. Rather than classical Ayurvedic texts, many books were written by the Visha Vaidyas of Kerala based on their practical knowledge. Kriyakoumudi is one such book which describes many yogas which contain herbal and herbo-mineral drugs for the treatment of Visha as well as its complications. Many formulations mentioned in this book, once used as first-line management of poisonous bites and stings, are now being neglected and forgotten. Vishavilwadi agada is one such antitoxic formulation. In the present day, only a few antitoxic formulations and practices are used for the management of poisoning, the reason for the same being the non-availability of the drugs, the controversy regarding the identity of the ingredients of the formulations mentioned in the classical texts and the lack of knowledge about the traditional treatment procedures and formulations. Vishavilwadi agada, once practised as a lifesaving medicine, remains unrecognized.

Heterogeneous Organohydrogel Toward Automated and Interference-Free Gradient Feeding of Drugs in Cell Screening.

Cell-based microarrays are widely used in the fields of drug discovery and toxicology. Precise gradient generation and automated drug feeding are essential for high-throughput screening of live cells in tiny droplets. However, most existing technologies either require sophisticated robotic equipment or cause mechanical/physiological interference with cells. Here, a heterogeneous organohydrogel is presented for automated gradient drug feeding, while ensuring minimal interference with cells. The heterogeneous organohydrogel comprises three crucial components. The bottom surface can automatically generate gradients functioning as a gradient generator, the organohydrogel bulk allows unidirectional transport of drugs without backflow, and the top surface with hydrophilic arrays can firmly anchor the cell-based droplet array to evaluate the concentration-dependent bioeffects of drugs accurately. Such a unique structure enables universal screening of different cell types and drugs dissolved in different solvents, requiring neither additional accessories nor arduous drug functionalization. The heterogeneous organohydrogel with unprecedented automation and non-interference possesses the enormous potential to be a next-generation platform for drug screening.

Unlocking the Potential of Clustering and Classification Approaches: Navigating Supervised and Unsupervised Chemical Similarity.

The field of toxicology has witnessed substantial advancements in recent years, particularly with the adoption of new approach methodologies (NAMs) to understand and predict chemical toxicity. Class-based methods such as clustering and classification are key to NAMs development and application, aiding the understanding of hazard and risk concerns associated with groups of chemicals without additional laboratory work. Advances in computational chemistry, data generation and availability, and machine learning algorithms represent important opportunities for continued improvement of these techniques to optimize their utility for specific regulatory and research purposes. However, due to their intricacy, deep understanding and careful selection are imperative to align the adequate methods with their intended applications. This commentary aims to deepen the understanding of class-based approaches by elucidating the pivotal role of chemical similarity (structural and biological) in clustering and classification approaches (CCAs). It addresses the dichotomy between general end point-agnostic similarity, often entailing unsupervised analysis, and end point-specific similarity necessitating supervised learning. The goal is to highlight the nuances of these approaches, their applications, and common misuses. Understanding similarity is pivotal in toxicological research involving CCAs. The effectiveness of these approaches depends on the right definition and measure of similarity, which varies based on context and objectives of the study. This choice is influenced by how chemical structures are represented and the respective labels indicating biological activity, if applicable. The distinction between unsupervised clustering and supervised classification methods is vital, requiring the use of end point-agnostic vs. end point-specific similarity definition. Separate use or combination of these methods requires careful consideration to prevent bias and ensure relevance for the goal of the study. Unsupervised methods use end point-agnostic similarity measures to uncover general structural patterns and relationships, aiding hypothesis generation and facilitating exploration of datasets without the need for predefined labels or explicit guidance. Conversely, supervised techniques demand end point-specific similarity to group chemicals into predefined classes or to train classification models, allowing accurate predictions for new chemicals. Misuse can arise when unsupervised methods are applied to end point-specific contexts, like analog selection in read-across, leading to erroneous conclusions. This commentary provides insights into the significance of similarity and its role in supervised classification and unsupervised clustering approaches. https://doi.org/10.1289/EHP14001.