Standardization of a questionnaire for neurotoxic symptoms.

A new version of the "Psychological-Neurological Questionnaire," designed for screening purposes, was investigated concerning its sensitivity to detect early signs of occupational exposure to potential neurotoxicants. A study population of 361 subjects was stratified into four age groups (<34, 35-44, 45-54, and >54 years) and three exposure groups (no, low, and high). According to dose and exposure history, workers exposed to dioxins and furans in combustion products, to volatile organic compounds, and to chromates were classified as low exposure. Workers exposed to alkyl lead, single solvents, and solvent mixtures were classified as high exposure. Only the group with the oldest age and highest exposure could be separated clearly from other groups, indicating an interaction effect between exposure and age. The low-exposure group could not be separated from the nonexposed controls. The most effective discriminators were neurologic symptoms. Psycho- and neurovegetative lability and irritative disturbances contributed less to the differentiation. Gastrointestinal and sleep disorders, as well as alcohol intolerance, showed no differentiation quality. The observed type of interaction effect fits models of delayed neurotoxicity.