Abstract
This review delves into the insights presented in Volume 14 of the Advances in Neurotoxicology series, aptly titled “Neurotoxicity of Solvents.” This pivotal volume is expertly curated by Prof. Dr Christoph van Thriel, the Head of the Research Group on Neurotoxicology and Chemosensation at the Leibniz Research Centre for Working Environment and Human Factors (IFADO) in Dortmund, Germany. The print edition made its debut in the latter part of July 2025, while the eBook version was launched on July 1, 2025.
This extensive volume, encompassing roughly 250 pages, offers a thorough and contemporary examination of the effects of organic solvents on the nervous system. It reflects the latest advancements in research, featuring insightful chapters that delve into specific topics such as the influence of toluene on cognitive functions, particularly memory retention. The book also investigates the neurotoxic effects of ethanol and propylene glycol ethers, shedding light on their implications for human health.
In addition to these focused studies, the text provides an ecotoxicological perspective on various solvents, addressing their broader environmental impact and potential risks. A significant section synthesizes previously disjointed findings on how organic solvents affect olfactory processes and their connections to neurodegenerative diseases, offering a cohesive view of this critical area of research. A detailed review of propylene glycol ethers adds further depth, discussing their chemical properties and health implications.
Moreover, the volume is equipped with valuable neurobehavioral methods, designed to assist occupational health professionals and regulatory experts in assessing and mitigating risks associated with solvent exposure in various work environments. This comprehensive resource serves as an essential guide for those seeking to understand the intricate relationship between organic solvent exposure and neurological health.
Prof. Dr Christoph van Thriel convenes a diverse array of 18 distinguished experts hailing from various countries, specifically 5 specialists each from Brazil and the United States, along with 2 from Turkey, Switzerland, Mexico, and Germany—the latter being Prof. Thriel’s homeland. The well-structured table of contents reflects a dual focus on mechanistic insights as well as applied and occupational themes related to solvent exposure.
The first section delves into the impact of toluene on cognitive functions, particularly examining its effects on memory retention and recall. In another segment, the neurotoxicological mechanisms associated with various alcohols are thoroughly explored, shedding light on how they affect neural pathways and brain function. Additionally, the volume introduces innovative neurobehavioral methodologies designed for studying the effects of solvents, providing researchers with effective tools to assess solvent exposure’s impact on behavior.
Further, the collection addresses the relationship between solvent exposure and neurodegenerative diseases, offering valuable perspectives on how these substances may contribute to conditions like Alzheimer’s and Parkinson’s disease. Another chapter focuses on propylene glycol ethers (PGEs), detailing their chemical properties and potential neurotoxic effects. This is complemented by a comprehensive discussion on solvents from an ecotoxicological standpoint, emphasizing their environmental impacts and implications for public health.
Lastly, the book takes an intriguing look at the olfactory system, positing it as a significant target for solvent toxicity and exploring the mechanisms through which solvent exposure can disrupt sensory processing and neural health. Through this multifaceted approach, the edited volume aims to provoke thought and inspire further research in the field of neurotoxicology.
The volume is divided into 7 chapters as follows:
Chapter 1, written by Sergio Montes and Nayeli Páez-Martinez, is titled “Effect of Toluene on Memory: A Focus on Humans, Experimental Models, and Treatment Approaches” (pp. 1-40). This chapter combines findings from clinical neuropsychology, including deficits in attention and working memory, with animal research on hippocampal plasticity as well as the regulation of dopamine and glutamate. It also discusses mitigation strategies such as abstinence, pharmacological treatments, and environmental enrichment. The authors provide a clear mechanistic explanation for the cognitive decline observed in workers exposed to toluene.
Chapter 2, authored by Yousef Tizabi, Bruk Getachew, Michael Aschner, and Michael A. Collins, is titled “Role of Glial Cells in the Neurotoxicological Effects of Alcohol (Ethanol)” (pp. 41-73). This chapter explores the activation of microglia caused by ethanol, the dysfunction of astrocytes, and the resulting neuroinflammation. It also examines the impact on the blood-brain barrier and the subsequent cognitive and emotional outcomes. Furthermore, the chapter includes translational notes on potential anti-inflammatory targets and provides a citable map of glia-mediated neurotoxic pathways that extend Chapter 3, authored by Yousef Tizabi, Bruk Getachew, Michael Aschner, and Michael A. Collins, which is titled “Role of Glial Cells in the Neurotoxicological Effects of Alcohol (Ethanol)” (pp. 41-73). This chapter explores ethanol-induced microglial activation, astrocyte dysfunction, and the resulting neuroinflammation. It also examines the impact on the blood-brain barrier and the subsequent cognitive and emotional outcomes. Furthermore, the chapter includes translational notes on potential anti-inflammatory targets and provides a citable map of glia-mediated neurotoxic pathways that extend beyond central nervous system (CNS) depression.
Chapter 4, titled “Organic Solvents and Neurodegenerative Diseases: Exploring a Possible Link,” by Mary Beth Genter, spans pages 115 to 130. This chapter discusses the epidemiology of neurodegenerative diseases and various mechanisms that may be involved, including oxidative stress, α-synuclein, and mitochondrial effects. It establishes a connection between solvent exposure and potential neurodegenerative risks. Understanding this relationship is essential for recognizing long-latency outcomes and identifying areas where data are particularly significant.
Chapter 5, written by Hélène P. De Luca and Nancy B. Hopf, is titled “Neurotoxic Effects of Propylene Glycol Ethers: Potential Risk to Human Health” (pp. 131-162). This chapter provides a comprehensive overview of propylene glycol ethers (PGEs). It examines data from both human and animal studies, compares the metabolism of PGEs with different chain lengths, and discusses their derivatives. The information presented is valuable for product stewardship, particularly in cases where PGEs are used as carriers or solvents. These data can also support in-house evaluations of alternative products.
Chapter 6, authored by Daiana Silva Ávila, Marcell Valandro Soares, Lisiane Martins Volcão, Marcelo Dutra Arbo, and Flávio Manoel Rodrigues Silva-Junior, is titled “An Ecotoxicological View on Solvents’ Neurotoxicity” (pp. 163-186). This chapter explores cross-species evidence, emphasizing the uptake of solvents driven by lipophilicity and their targeting of the nervous system. It also evaluates ecological endpoints that reveal neurotoxic mechanisms in mammals. Overall, this chapter provides valuable narratives on environmental risks and supports read-across arguments with mechanistic data from various taxa.
Chapter 7, authored by Sabine Werner and Christoph van Thriel, is titled “Solvent Toxicity: The Olfactory System” (pp. 187-250). This chapter investigates the olfactory pathway as a target for solvent exposure. It discusses the transport of solvents across the olfactory epithelium, the vulnerability of neurons, and the clinical symptoms associated with anosmia and hyposmia. Additionally, it outlines various testing methods. This information is essential for effectively justifying olfactory endpoints in risk assessments and monitoring.
This volume acts as a well-organized and current scientific reference on solvent neurotoxicity, linking traditional occupational findings with newer research areas such as olfaction and neurodegeneration hypotheses. It provides a strong foundation for evidence-based risk assessments and briefing memos, and it is clearly written and up to date. While the book offers limited discussion on mixtures and low-dose chronic exposures, and does not include a detailed regulatory framework, it remains an impressive scholarly review of the field. It is a valuable resource for anyone working with solvents who needs to understand the mechanisms and outcomes of exposure.
Industrial hygienists and toxicologists working on solvents like toluene, xylene, and glycol ethers will find a wealth of scientific insights in this volume. It’s an invaluable resource for developing compelling risk narratives. Additionally, product safety and stewardship teams will receive essential mechanistic explanations to improve their communications. A must-read for anyone in the field!