Measurement of styrene-7,8-oxide and other oxidation products of styrene in air

Styrene-7,8-oxide (SO) is generated at low concentrations from the oxidatio n of styrene during the processing of reinforced plastics. Since exposure t o SO has important health implications, we developed air sampling and analy tical methods to measure low levels of airborne SO in the presence of styre ne and its other oxidation products, namely phenylacetaldehyde (PAA) and ac etophenone (AP). Both active and passive air monitors were used. The active sampling method, which employed adsorption on Tenax, was suitable for meas uring SO, PAA and AP but had limited capacity for styrene due to breakthrou gh. The passive monitor employed a carbon adsorbent and was suitable for me asurement of styrene and SO but not PAA and AP due to poor recovery. After sampling, the analytes were extracted from the adsorbents with ethyl acetat e and measured by gas chromatography with flame ionization detection or mas s spectrometry. By maintaining the injection port at 70 degrees C, the ther mal rearrangement of SO to PAA was minimized. Recovery of styrene and SO fr om the passive monitor depended upon loading and was corrected by lineariza tion of the Freundlich isotherm. The limits of detection for SO, PAA, and A P were 0.2 ppb using the active monitor, and for SO was 1 ppb using the pas sive monitor. The sampling precision for SO (RSD from personal measurements ) was 5.0% for the passive monitor and was 13.4% for the active monitor ove r a range of exposures from 5-150 ppb. The corresponding precision for styr ene was 5.3% for the passive monitor for levels ranging from 1.2 to 104 ppm . Measurements of 235 personal exposures with the active monitor in 12 faci lities manufacturing fiberglass-reinforced plastics (FRP) showed that level s of AP and PAA were below 7.8 ppb and 5 ppb, respectively. In contrast, SO averaged 30.4 ppb (SE = 2.4) in these FRP facilities, ranging from below 0 .2 ppb to 190 ppb. The active monitor was also used to detect airborne SO a t levels of approximate to 1 ppb in one facility manufacturing styrene buta diene rubber, suggesting that SO is generally present during the polymeriza tion of styrene. Personal passive monitoring in the 12 FRP facilities (n=65 7) revealed mean concentrations of styrene ranging between 1.8 and 55.4 ppm , and for SO between 1.7 and 62.6 ppb. The ratio of the mean styrene level to the mean SO level varied between 449:1 and 1635:1 among the 12 FRP facil ities.