Neuropsychological effects of chronic exposure to environmental dioxins and furans.

The environmental contamination by dioxins and furans (PCDD/PCDF) of a local area in southwest Germany due to pyrolytic processes led to a survey of health consequences in the exposed population. 2,3,7,8-TCDD (8000 ng/kg TE (ppt)) was found in the soil and up to 585000 ng/kg TE in attic dust in private homes. In a randomized study group of definitively exposed persons, a neuropsychological test battery was applied and its value as a diagnostic tool investigated. A total group of 19 persons participated in a standard neuropsychological examination including common procedures to evaluate mnestic and attentional performance and psychomotor speed (e.g., WAIS, WMS-R, TMT, and symptom and mood checklists). The range of PCDD/PCDF between 16 and 80 (mean 31) ppt did not vary substantially from blood fat values in a national sample. Results of neuropsychological testing showed only slight deviations from the expected range. Nevertheless, in a high-level exposure group, a reduction of verbal conceptualization, mnestic organization of verbal and visual stimuli, and psychomotor slowing was found. Among other correlations visual exploration speed (TMT) was most directly related to TE. Affective symptoms (such as irritability and emotional instability) were also related to exposure. Results indicate that standard neuropsychological testing can be recommended for the routine evaluation of chronic dioxin exposure.