A neurotoxin is any toxin that effects the structure or function of nerves or neurotransmitters. Most heavy metals and biological toxins fall into this category. In addition, some chemicals that are essential for the proper functioning of the nervous system, such as glutamate, become toxic at higher concentrations. Alcohol is the neurotoxin with the greatest health effect, as it has both temporary and permanent effects depending on the dosage.

The effects of neurotoxicity have been known since ancient times. The effect of lead toxicity was particularly notable to those who were involved in lead smelting or who used lead plumbing.

One of the functions of the blood-brain barrier is to filter out possible neurotoxins to prevent damage to the brain, which is made up almost entirely of nerve cells.

A neurotoxin can act in about a dozen different ways, such as inhibiting the passage of sodium through the membranes of nerve cells or inhibiting neurotransmitter receptors.

Neurotoxin at Wikipedia