Effects of short duration exposures to acetone and methyl ethyl ketone

Workers are commonly exposed to mixtures or combinations of chemical agents, and these mixtures often consist of solvents. One group of solvents that has been extensively studied for its neurotoxic properties has been the ketones. However, previous research has focused on neuropathies produced by extended exposures and not on the simple pharmacokinetics or the reversible central nervous system (CNS) effects from short-duration exposures. In this research, 137 volunteers were recruited and tested for neurobehavioral performance changes and biochemical indicators during and after a short-duration (4-h) exposure to either acetone at 250 ppm, methyl ethyl ketone (MEK) at 200 ppm, acetone at 125 ppm with MEK at 100 ppm, or a chemical-placebo. Ethanol (95%, 0.84 ml/kg) was used as a positive control. Testing took place in an environmental chamber with four test stations. The computer-controlled test regimen took 10 h, and several measures were collected: (1) biochemical measurements of venous blood and alveolar breath; (2) psychomotor tests of choice reaction time, visual vigilance, dual task (auditory tone discrimination and tracking), and memory scanning; (3) one sensorimotor (postural sway) test; and (4) one psychological (Profile of Mood States [POMS]) test. Blood and breath concentrations during and after exposure did not demonstrate any interaction between the two solvents, nor were statistically significant sex differences present during uptake or elimination. The 250-ppm acetone exposure produced small but statistically significant differences from controls in two measures of the auditory tone discrimination task, and on the anger-hostility scale (males only) of the POMS test. The other chemical exposure conditions, MEK at 200 ppm and combination MEK with acetone, produced no consistent statistically significant results, which suggests there was no potentiation of the acetone effects with the co-exposure to MEK or vice versa under these test conditions. Ethanol at 0.07-0.08% blood alcohol concentration (BAC) caused significant decrements on both the auditory tone and tracking tests in the dual task.