Neurotoxicology or Neurotoxicity is adverse change in a structure, function of the nervous system. The chemical or physical agent voluntarily and involuntarily exposed to a range of chemicals that affect the nervous system. Many billions of dollars spend every year voluntarily for purchasing chemicals such as caffeine, alcohol, and nicotine to influence the nervous system. Many of us are familiar with the undesirable effects of too much caffeine or alcohol, which form neurotoxicity.