Exposure to chemicals that can cause effects on the nervous system is common, and neurotoxic disorders are one of NIOSH's 10 leading diseases and injuries. Many epidemiologic studies of workers have demonstrated neurobehavioral effects of chemical exposures. However, screening of individuals for early signs of neurotoxicity from workplace exposures is currently rarely performed. Screening of individuals is rare due to the cost of full-scale clinical neuropsychological testing, the limited availability of qualified personnel, and the absence of efficient screening tools. The main goal of this effort is to produce a new computer-based neurobehavioral testing system to screen workers for early signs of occupational neurotoxicity. The results of this screening test would provide information to help decide whether individual workers exposed to potential neurotoxicants should be referred for more expensive full-scale clinical neuropsychological assessment. This tool is intended for widespread use in clinics and factories. A two-phase effort is envisioned. The present proposal concerns the first phase, development of the new computer-based testing instrument. The aims of the present project are to create a set of computer-based neurobehavioral tests specifically for screening of individuals exposed to potentially neurotoxic agents, to pilot test the instrument for feasibility of use among 50 outpatients at an occupational medicine clinic, to develop extensive training materials to instruct potential users of the computer-based testing system, and to evaluate those training materials on students in an occupational and environmental health training program. The project will employ new hardware and software technology to accomplish these aims. A pen-based notebook computer with a speech production device will be an improvement over existing computer-based batteries by allowing both auditory presentation of the tests and recording of responses in a manner equivalent to paper-and-pencil neuropsychological tests. The set of tests will include tests of a range of behavioral functions: orientation, verbal learning, spatial memory, visual and cognitive tracking. Multi- media capabilities of the hardware/software development environment will be utilized to develop the training materials. Successful completion of the proposed project work will lead to the second phase of the overall research program, which will be proposed separately. The second phase will include: (l) assembling a network of clinics to use the neurobehavioral screening system, (2) performing a normative data project within the clinic network, and (3) performing a validation study within the clinic network. The system could be adapted to allow its effective use in other countries and in populations potentially most susceptible to effects of neurotoxic exposure such as the elderly and children.