UC Davis

Neurotoxicity refers to the direct or indirect effect of chemicals that disrupt the nervous system of humans or animals. Numerous chemicals can produce neurotoxic diseases in humans, and many more are used as experimental tools to probe molecular and cellular mechanisms of physiology and pathophysiology in the nervous system of animal tissues in vivo and in vitro, and in human neural progenitor cell lines. Some chemicals act directly on neural cells, others interfere with metabolic processes on which the nervous system is especially dependent. Emerging evidence suggests that toxic effects on physiological systems outside the brain, in particular the endocrine system, immune system and gut microbiome, may also adversely impact the nervous system. Some neurotoxic chemicals disrupt neural function, others alter normal developmental trajectories of the brain or cause damage to the adult nervous system. Perturbations may appear and disappear rapidly, evolve slowly over days or weeks and regress over months or years, or cause permanent deficits. Neurotoxicity is usually self-limiting after exposure ceases and rarely progressive in the absence of continued exposure, although there may be a significant delay between exposure and manifestation of neurotoxic effects.