ABSTRACT
A significant factor affecting neurotoxicity is the various ways a neu rotoxicant can enter, distribute within tissues, and leave the body. A neuro toxic chemical may enter the gastrointestinal tract through diet or drinking water; it may enter the upper airway and lungs in the form of gas, aerosol, particle, dust, or fume; or it may enter the body through the skin. Neurotox icity occurs after neurotoxicants enter circulation and gain access to various tissues of the body. Metabolic biotransformation may produce more active or less active metabolites. These processes generally lead to more polar metabolites that eventually enhance the excretion of neurotoxic chemicals (Abou-Donia and Nomeir, 1986). The term metabolism encompasses all of these processes: absorption, tissue distribution, storage, biotransformation, and elimination. The rate of these processes that pertain to toxicity are defined as toxicokinetics (Abou-Donia, 1983).
