Neurobehavioral effects of acute styrene exposure in fiberglass boatbuilders.

A field investigation of the effects of acute exposure to styrene among fiberglass boatbuilders was performed. Personal samples of styrene in breathing zone air and postshift urinary mandelic acid were collected for 105 workers exposed and not exposed to styrene in 6 fiberglass boatbuilding companies in New England. Three tests from the computerized Neurobehavioral Evaluation System (NES) were performed by the subjects in the morning before exposure to styrene, near midday, and at the end of the work day. Duration of exposure averaged 2.9 years (SD = 4.6), 8-hour TWA styrene exposure averaged 29.9 ppm (SD = 36.2), and urinary mandelic acid averaged 347 mg/g creatinine (SD = 465). Regression analyses indicated a statistically significant relationship between postshift performance on the Symbol-Digit test and both acute styrene exposure and mandelic acid. Other analyses comparing workers exposed to less than 50 ppm and greater than 50 ppm styrene also showed a significant effect on Symbol-Digit performance. All three NES tests showed test-retest correlation coefficients above .80, and ease of use for collection of neurobehavioral data under field conditions was demonstrated.

Experimental nitrous oxide exposure as a model system for evaluating neurobehavioral tests.

A recent study reported that a minimally suprathreshold dose of 20% nitrous oxide significantly affected performance on 3 of 9 computer-administered neurobehavioral tests. Performance decrements were observed in that study on 3 tests of psychomotor speed while other neurobehavioral functions such as visuospatial ability, verbal learning and mood were not significantly affected. The current study was undertaken to assess the reproducibility of these earlier results. Its experimental design was expanded to include an additional dose of the anesthetic and a more complex reaction time task implemented by the authors since the earlier study. Fifteen males aged 24-34 years were tested with the Neurobehavioral Evaluation System (NES) test battery on 4 separate occasions. An initial training session was followed by randomly presented control, 20%, and 40% drug sessions. Drug-induced decrements in performance were observed in the current study at the 20% dose for 2 of the 3 tests of psychomotor speed which had shown effects in the earlier study, and average decrement in performance on the third approached statistical significance in the current study (P = 0.055). Performance on a complex reaction time task was significantly affected at the low dose. The higher dose of nitrous oxide impaired performance on 8 of the 9 tests administered, and impairment on the ninth test was nearly significant (P = 0.055). Overall, these data are consistent with those in the previous study and with other reports that higher doses of nitrous oxide produce impairments in more cognitive CNS functions. Owing to its relative safety at low dosages, ease of administration, and ready acceptance by experimental subjects, nitrous oxide appears to be a useful model for evaluating the validity of neurobehavioral tests.