FURTHER EVALUATION OF THE KINETICS OF WHITE SPIRIT IN HUMAN VOLUNTEERS

This paper gives supplementary information on the kinetics of aliphatic white spirit in humans. Eight volunteers were exposed to 600 mg/m3 (100 p.pm) white spirit during 3 hrs. Calculated pulmonary uptake (dose) was 392 .+-. 38 mg, residence time 47.5 hrs, volume of distribution 749.1, and total body clearance 263 ml/min. Then 7 volunteers were exposed to 600 mg/m3 white spirit 6 hrs daily in 5 consecutive days. Calculated pulmonary uptake was 3464 .+-. 329 mg. A mathematical model is presented which uses the blood concentrations to calculate the tissue concentrations during repeated doses administered over an extended period. By means of this model and the measured concentrations in blood and fat, the partition coefficient fat: blood for white spirit was calculated to 47. Estimated redistribution phase of white spirit in adipose tissue was approximately 20 hrs for the first 5 exposures, and half-life in adipose tissue after redistribution 46-48 hrs. During exposure to 600 mg/m3 white spirit for 6 hrs daily, 5 days a week, calculated maximum steady state concentrations were 55 mg/kg fat and 5 mg/kg brain, minimum steady state concentrations 35 mg/kg fat and 0.6 mg/kg brain. These values for half-life and steady-state concentrations are considered more correct than our previously reported values, which did not take into account the existence of a redistribution phase.