Neurotoxicity Assessment of Chemicals on Exposed Workers — A Review of Neurobehavioral and Neurophysilogical Tests

Abstract

With the wide utilization of neurotoxic substances, more and more people are exposed to them occupationally or environmentally. Neurotoxicity has been defined as any adverse effect on the structure or function of the central and /or peripheral nervous system by biological, chemical and physical agent. Neurotoxic effect may be permanent or reversible, caused by neuropharmacological or neurodegenerative properties of a neurotoxicant. The nervous system is very sensitive and fragile to chemicals. The early adverse effects should be detected as early as possible because they are reversible, functional and chemical, not structural. A multidisciplinary approach is necessary to assess neurotoxicity because of the complexity and diverse functions of the nervous system. Many of the relevant effects can be measured directly by neurochemical, neurophysiological, and neuropathological techniques, whereas, others must be inferred from observed behavior and psychic performance. Neurotoxicity in humans is most commonly measured by relatively noninvasive neurophysiological and neurobehavioral methods that assess cognitive, affective, sensory, and motor function. The biomarker assay can be complement. In general, due to the speciality and difficult accessibility, the biomarkers that manifest the neurotoxicity of chemicals in nervous system are difficult to obtain, but a number of biochemical and molecular parameters similar to those involved as toxicity targets in the nervous system are also present in more easily accessible tissues, such as cerebrospinal fluid (CSF), blood, plasma and peripheral blood cells. These tissues can be surrogate indicators. With the multidisciplinary approach, the neurotoxicity of chemicals can be assessed or screened sensitively and practically.