Neurotoxicology is the field of study that focuses on the adverse effects of chemical substances on the structure or function of the nervous system. It involves the evaluation of the potential of various chemicals, including environmental pollutants, industrial chemicals, drugs, and pesticides, to induce neurotoxic effects. The nervous system includes the brain, spinal cord, and peripheral nerves, and neurotoxicity can manifest as a range of neurological disorders, impairments, or dysfunctions.

Here are the key aspects and areas of focus within neurotoxicology:

1. Neurotoxicity Testing: Neurotoxicity testing involves the assessment of the potential toxic effects of chemicals on the nervous system. It includes in vitro (cell-based) and in vivo (animal) studies to evaluate the impact of substances on neuronal cells, neural networks, and behavior. Neurotoxicity tests may involve assessing cell viability, neuronal morphology, neurotransmitter function, neurodevelopmental processes, synaptic activity, and cognitive or motor performance.
2. Acute and Chronic Neurotoxicity: Neurotoxicity can occur acutely, with immediate effects following exposure to a chemical, or chronically, with long-term or delayed effects. Acute neurotoxicity studies typically involve short-term exposure to high doses of a substance, while chronic neurotoxicity studies assess the effects of repeated or prolonged exposure over an extended period. These studies aim to identify the potential adverse effects on neuronal function, structure, or connectivity.
3. Neurodevelopmental Toxicity: Neurodevelopmental toxicity focuses on the potential effects of chemical exposure on the developing nervous system, particularly during critical periods of brain development. It investigates the impact of substances on neuronal differentiation, migration, synaptogenesis, myelination, and other key processes involved in brain development. Animal models are commonly used to assess neurodevelopmental toxicity, and the outcomes can include cognitive impairments, learning disabilities, and behavioral abnormalities.
4. Neurobehavioral Assessments: Neurotoxicology studies often include assessments of behavior to evaluate the functional consequences of chemical exposure on the nervous system. These assessments can involve a range of behavioral paradigms designed to evaluate cognitive functions, motor coordination, sensory perception, anxiety, depression, social behavior, and other aspects of neurological function. Behavioral tests provide valuable insights into the potential effects of chemicals on higher-order brain functions.
5. Mechanisms of Neurotoxicity: Understanding the mechanisms through which chemicals exert neurotoxic effects is a crucial aspect of neurotoxicology. Mechanistic studies investigate the pathways and processes involved in neuronal injury, oxidative stress, inflammation, excitotoxicity, disruption of neurotransmitter systems, impaired neuronal signaling, and other molecular and cellular mechanisms. Such studies help unravel the underlying biology and pathology of neurotoxicity and can guide the development of targeted interventions or preventive strategies.
6. Risk Assessment and Regulation: Neurotoxicology data play a significant role in risk assessment and the regulation of chemicals. Regulatory agencies, such as the US Environmental Protection Agency (EPA) and the European Chemicals Agency (ECHA), require neurotoxicity data for the registration and approval of chemicals. The results of neurotoxicity studies inform hazard classifications, exposure limits, risk management strategies, and the establishment of guidelines to protect human health and the environment.

Neurotoxicology is an interdisciplinary field that combines elements of toxicology, neuroscience, pharmacology, and behavioral science. By studying the effects of chemicals on the nervous system, neurotoxicology aims to identify potential risks, improve our understanding of neurotoxic mechanisms, and contribute to the development of safer chemicals, drugs, and environmental practices.