The effect of the solvent white spirit on psychological functions, such as perceptual speed, reaction time, short-term memory, numerical ability, and manual dexterity, was studied in two separate series of experiments employing 14 and 8 healthy male students, respectively. Each subject was tested repeatedly in each series in exposure to 625, 1,250, 1,875 and 2,500 mg/m:~of white spirit in inspiratory air and under control conditions with exposure to pure air. In another experimental series each subject was tested during exposure to 4,000 mg/m 8 of white spirit and under control conditions. Alveolar air samples were taken every fifth minute. No effect on examined functions was observed in the first experimental series, However, a prolonged reaction time and a probable impaired short-term memory was observed in subjects exposed to 4,000 mg/m:), At this concentration of white spirit in inspiratory air an alveolar air concentration was obtained which corresponded to values obtained in exposure to 2,500 mg/m a during light exercise. Key w01'ds: experiment

Exposure to xylene and ethylbenzene: III. Effects on central nervous functions. Scand. j. work environ. & health 4 (1978) 204-211. The effect of exposure to the solvent xylene on performance of tests of numerical ability, reaction time (simple and choice), short-term memory, and critical flicker fusion was studied in i\iwo separate laboratory series. In the first series fifteen healthy male subjects were studied individually on three separate occasions with exposure to 435 and 1,300 mg/m 3 xylene in inspired air and under control conditions. In a second series eight of the subjects were exposed to 1,300 mg/m 3 xylene in inspired air. This exposure period began with 30 min of work on a bicycle ergometer (100 W) and continued during the behavioral tests. The procedure was the same under control conditions. Each exposure period lasted 70 min. At certain times during exposure, samples of the subjects alveolar air were collected. Exposure to xylene did not cause any noticeable change in performance during the first laboratory series, when the subjects' total uptake of xylene was estimated to be on an average 180 and 540 mg, respectively. In the sec'ond 8eries the physical work induced an increase in the total uptake up to an average of 1,200 mg. In this series clear evidence of performance decrement was observed in three of the performance tests.

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Twelve subjects were exposed to 300 or 600 mg/m 3 of butyl alcohol in inspired air during rest and during exercise on a bi'Cycle ergometer. Exposure lasted 2 h. The results were puzzling in view of the high blood/air partition coefficient for butyl alcohol. The arterial blood coneentration was low. The concentration in the last part of the e~pired air, i.e., the "alveol>ar" concentration, was low. The quotient of "alveolar" concentration X lOO/inspired concentration was low in rel,ation to the low percentage uptake. However the high solubility of butyl aleohol in wa1er may explain the resuLts. ButY'1 aIlcohol was probably partially taken up in the water of the dead &pace mucous membranes during inspiration. It was then partiaHy released from the membranes. Therefore the concentration of butyl aloohol in the last part of ,expiration was probably not ,the same as the concentration in the alveolar air.