BEHAVIORAL-TOXICOLOGY, RISK ASSESSMENT, AND CHLORINATED HYDROCARBONS

Behavioral end points are being used with greater frequency in neuroto xicology to detect and characterize the adverse effects of chemicals o n the nervous system. Behavioral measures are particularly important f or neurotoxicity risk assessment since many known neurotoxicants do no t result in neuropathology. The chlorinated hydrocarbon class consists of a wide variety of chemicals including polychlorinated biphenyls, c lioquinol, trichloroethylene, hexachlorophene, organochlorine insectic ides (DDT, dicofol, chlordecone, dieldrin, and lindane), and phenoxyhe rbicides. Each of these chemicals has effects on motor, sensory, or co gnitive function that are detectable using functional measures such as behavior. Furthermore, there is evidence that ii exposure occurs duri ng critical periods of development, many of the chlorinated hydrocarbo ns are developmental neurotoxicants. Developmental neurotoxicity is fr equently expressed as alterations in motor function or cognitive abili ties or changes in the ontogeny of sensorimotor reflexes. Neurotoxicit y risk assessment should include assessments of the full range of poss ible neurotoxicological effects, including both structural and functio nal indicators of neurotoxicity.