Neurobehavioural effects of experimental isopropanol exposure

Objectives: The study investigated the acute effects of isopropanol exposur e at the maximum allowable concentration (MAC) level on the performance of neurobehavioural functions. Methods: In an exposure chamber 20 healthy subj ects aged between 21 and 30 years were exposed to isopropanol at a concentr ation of 400 ppm (Swiss MAC value) for 8 h. A control group of another 20 s ubjects of the same age range, gender and education as used in a previous s tudy with methylformate were subjected to the same test procedures without exposure. Mood was measured with the profile of mood states (POMS) in the m orning, at noon and in the evening. Neurobehavioural performance tests were administered using the Wiener Test System (Wiener reaction test, Stroop, n onverbal learning, Wiener determination test, "Konturtracking" test), and t he digit span test of the Neurobehavioural evaluation system (NES2). A test for postural sway was also conducted. During the POMS and the Wiener deter mination test the electromyography of the forehead and the left neck muscle as well as the pulse were registered. In the morning and evening spirometr y (FVC, FEV, MEF and PEF) and odour threshold were measured. Results: Only postural sway in bipedal standing at noon showed stronger deterioration in the exposed than in the control group when compared with the morning values . The evening values of monopedal standing were also more impaired in the e xposed than the control group. In the other tests, no solvent effect could be established. Conclusions: It can be assumed, that, similar to other alco hols, isopropanol affects postural balance. Our results point to such a dis turbance, but because it is the only study so far using the MAC value, any conclusions about safety risks would be premature.