Exposure to styrene in a polymerization plant. Uptake in the organism and concentration in subcutaneous adipose tissue.

Abstract

Three male employees exposed to styrene in the processing of polyester tanks were studied during a work week. From Tuesday-Friday the concentration of styrene in ambient air was measured continuously in the breathing zone. The uptake in the organism was estimated as the product of the time-weighted average of the concentration in inspiratory air, the time-weighted average of 8 h pulmonary ventilation and the percentage pulmonary uptake. Pulmonary ventilation was measured with the Wright respirometer. Percentage pulmonary uptake was estimated by an anthropometric method. The concentration of styrene in s.c. adipose tissue was determined by gas chromatography after needle biopsy before and after the workshift on Monday, Wednesday and Friday. The time-weighted average of the concentration of styrene in inspiratory air during the work week was 32-85 mg/m3, i.e., below 1/2 of the Swedish threshold limit value (210 mg/m3). The mean daily uptake in the organism was 193-558 mg. On Monday morning the concentration of styrene in adipose tissue was 2.8-8.1 mg/kg and on Friday afternoon 4.7-11.6 mg/kg. The concentrations were higher in the 2 subjects with a higher exposure of longer duration, as compared to the concentrations in the recently employed subject, who was exposed to lower concentrations in inspiratory air. Both of the 2 former subjects had a considerable estimated amount of body fat (27 and 41 kg). The calculated half-life of the concentration of styrene in adipose tissue after the end of exposure was 5.2 and 2.8 days for these 2 subjects. An elimination time of about 5 wk is needed by the subject with the slowest elimination before the limit of detection (0.1 mg/kg) is reached.