Retention of styrene following controlled exposure to constant and fluctuating air concentrations.

An experiment was designed to determine whether the respiratory retention of styrene vapor, as estimated from measurements of end-exhaled air, was the same during periods of both constant and fluctuating exposure. Six human subjects were exposed to styrene inside a experimental chamber. A computer-controlled system was used to generate time-varying air concentrations of styrene over 4-5h in both multistep sequences of constant exposure (four subjects exposed to 15-99 ppm of styrene in 100-min steps) and fluctuating patterns representative of occupational exposures (two subjects exposed to mean concentrations of styrene of 50 ppm). In the latter case, lognormally distributed exposures, which fit one of two first-order autoregressive models, were generated at intervals of 2.5 min. It was found that the concentration of styrene in end-exhaled air was reduced by about half if the subject inhaled one to three breaths of clean air prior to sampling. This suggests that significant amounts of styrene were desorbed from the lining of the lungs during the initial exhalation. The retention of styrene vapor during constant exposures was 0.935 and was independent of the level. During each of the two sets of fluctuating exposure the retention of styrene was also constant and was independent of both the variance and autocorrelation coefficient. However, the retention of styrene during the fluctuating exposure (estimates ranged from 0.957 to 0.973) was significantly higher than that observed during the constant exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

A field method for measuring solvent vapors in exhaled air--application to styrene exposure.

A method is described for measuring solvent vapors in mixed-exhaled air. The subject exhales through a carbon-containing tube connected to a Wright respirometer. Adsorbed vapors are subsequently eluted by carbon disulfide and analyzed by gas chromatography. Twenty-minute exposures to styrene and the corresponding concentrations of styrene in the breath and venous blood were repeatedly measured for two subjects. Regression analyses indicated that the breath measurements were highly correlated with both the exposures and the blood concentrations of styrene. In another study, styrene was measured simultaneously in the mixed-exhaled air by this technique and in the end-exhaled air by a portable gas chromatograph. The mixed-exhaled air obtained with this method contained about half alveolar air. Analysis of the components of the variance obtained from all the data indicated that the error in measurement by this method was about one-fourth of the total variance.