Toxicokinetics of inhaled 2-butoxyethanol (ethylene glycol monobutyl ether) in man

Seven male volunteers were exposed to 2-butoxyethanol at the Swedish occupational exposure limit (20 ppm or 0.85 mmol/m3) during light physical exercise (50 W) on a bicycle ergometer. The exposure took place in an exposure chamber and lasted 2 h. Expired air was collected at regular time intervals for estimation of the respiratory uptake of the solvent. Arterialized capillary blood and urine were sampled during and after the exposure period and analyzed for 2-butoxyethanol and its metabolite butoxyacetic acid. A new sensitive method for analyzing 2-butoxyethanol in biological specimens is described. 2-Butoxyethanol was derivatized with pentafluorobenzoyl chloride and analyzed by gas chromatography with electron capture detection. The respiratory uptake of 2-butoxyethanol averaged 10.1 mumol/min or 57% of the inspired amount. The concentration in blood reached a plateau level of 7.4 mumol/l. The apparent values of elimination half-time, mean residence time, total blood clearance, and steady-state volume of distribution were 40 min, 42 min, 1.2 1/min and 54 l, respectively. The amount of 2-butoxyethanol excreted in urine was less than 0.03% of the total uptake, while that of butoxyacetic acid ranged from 17 to 55%.