Uptake, distribution and elimination of styrene in man. Concentration in subcutaneous adipose tissue.

Abstract

Seven male subjects were exposed to 210 mg/m3 of styrene in inspired air during 30 min at rest and three 30 min periods of work on a bicycle ergometer at intensities of work capacity at a heart beat of 50, 100 and 150 beats/min. The uptake in the organism was measured by the Douglas bag technique. The mean uptake was 490 mg, corresponding to 63% of the amount inspired. During the last 30 min period, the uptake in the orgamism was 5-6 .times. higher than during the 1st period at rest. The elimination of styrene by the airways during 19 h after the exposure was estimated to be about 3% of the amount retained in the body during exposure. Needle biopsy of s.c. adipose tissue was performed on all the subjects before exposure and 0.5, 2, 4 and 20-24 h after the exposure. Four men were subjected to biopsies during the 1-2 wk following exposure. The concentration of styrene in adipose tissue was determined by gas chromatography after evaporation into N at a high temperature. About 24 h after the exposure the mean concentration of styrene in adipose tissue was on about the same level as 2-4 h after exposure, i.e., about 3.5 mg/kg. Retention of styrene in adipose tissue was noticed as late as 13 days after the short exposure at a concentration in inspired air corresponding to the Swedish threshold limit value. The estimated half-life of the concentration of styrene in adipose tissue was 2-4 days. In spite of the rapid metabolism of styrene, industrial exposure is accompanied by the risk of accumulation in adipose tissue because of the slow elimination rate.