Neurobehavioral test performance in the third National Health and Nutrition Examination Survey.

The third National Health and Nutrition Examination Survey (NHANES III) contained three computerized neurobehavioral tests from the Neurobehavioral Evaluation System (NES): simple reaction time, symbol-digit substitution and serial digit learning. The neurobehavioral data that were collected came from a nationally representative sample of adults 20-59 years old. Performance on the tests was related to sex, age, education level, family income and race-ethnicity. Performance decreased as age increased, and increased as education level and family income increased. Differences in performance between sexes, levels of education and racial-ethnic groups tended to decrease as family income increased. The relationship between age and performance on the symbol-digit substitution test varied by education level and by racial-ethnic group. The relationship between age and performance on the serial digit learning test varied by racial-ethnic group. Questionnaire variables that were related to performance on one or more of the tests included the reported amount of last night's sleep, energy level, computer or video game familiarity, alcoholic beverages within the last 3 h and effort. Persons who took the tests in English or Spanish performed differently on the symbol-digit substitution and serial digit learning tests. Performance on all the tests decreased as test room temperature increased.

Work-site clinical and neurobehavioral assessment of solvent-exposed microelectronics workers.

Twenty-five workers, five currently and 20 formerly involved in the manufacture of hybrid microcircuits, underwent clinical evaluations at the request of a management-union committee concerned about chronic solvent exposures in a research and development laboratory. A battery of neurobehavioral tests was administered to compare the solvent-exposed group with 32 age-, gender-, ethnicity-, and education-matched controls. The tests included: MMPI-I, hand grip strength, tactile sensitivity, dexterity, color discrimination, visual acuity and contrast sensitivity, and tests selected from the computerized Neurobehavioral Evaluation System (NES2). Clinical narratives and retrospective exposure assessments in the study group suggested chronic low-level exposure to solvents, with intermittent acute excursions. Work-related diagnoses included upper respiratory mucosal irritation and sinusitis (44%), lower respiratory reactive airway disease (12%), and dermatitis (5%). Three workers (12%) had findings consistent with a solvent-induced encephalopathy. Significant differences (after Bonferroni correction) were found between the two groups on 5 of 11 NES subtests: symptom scale, mood scale, finger tapping, simple reaction time, and symbol-digit substitution. Differences also reached significance for overall vibration sensitivity thresholds, visual contrast sensitivity, and grip strength. The MMPI average clinical scale elevation was significantly higher in the exposed group than controls. These results support an association between chronic low-dose solvent exposure and measurable neurobehavioral changes.

Exposure of humans to a volatile organic mixture. I. Behavioral assessment.

Exposure to a low-level mixture of volatile organic compounds, typical of those found in new buildings, has been reported to impair neurobehavioral function in persons who have experienced sick building syndrome (SBS). Sixty-six healthy young males who had no history of chemical sensitivity were exposed for 2.75 h to a complex mixture of volatile organic compounds at 0 and 25 mg/m3. Even though subjects reported more fatigue and more mental confusion following exposure to volatile organic compounds than to clean air, performance on 13 neurobehavioral tests was not affected. Practice or learning effects were observed if administration of many behavioral tests were repeated. Further studies are needed to clarify the relationship of exposure to volatile organic chemicals, neurobehavioral performance, and subject characteristics, e.g., age, gender, and chemical sensitivity.