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

Abstract

Styrene-7,8-oxide (SO) is generated at low concentrations from the oxidation of styrene during the processing of reinforced plastics. Since exposure to SO has important health implications, we developed air sampling and analytical methods to measure low levels of airborne SO in the presence of styrene and its other oxidation products, namely phenylacetaldehyde (PAA) and acetophenone (AP). Both active and passive air monitors were used. The active sampling method, which employed adsorption on Tenax, was suitable for measuring SO, PAA and AP but had limited capacity for styrene due to breakthrough. The passive monitor employed a carbon adsorbent and was suitable for measurement of styrene and SO but not PAA and AP due to poor recovery. After sampling, the analytes were extracted from the adsorbents with ethyl acetate and measured by gas chromatography with flame ionization detection or mass spectrometry. By maintaining the injection port at 70 degrees C, the thermal rearrangement of SO to PAA was minimized. Recovery of styrene and SO from the passive monitor depended upon loading and was corrected by linearization of the Freundlich isotherm. The limits of detection for SO, PAA, and AP were 0.2 ppb using the active monitor, and for SO was 1 ppb using the passive 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 over a range of exposures from 5-150 ppb. The corresponding precision for styrene 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 facilities manufacturing fiberglass-reinforced plastics (FRP) showed that levels 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 at levels of approximately equals 1 ppb in one facility manufacturing styrene butadiene rubber, suggesting that SO is generally present during the polymerization of styrene. Personal passive monitoring in the 12 FRP facilities (n = 657) 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 1,635:1 among the 12 FRP facilities.

An integrated approach to biomonitoring exposure to styrene and styrene-(7,8)-oxide using a repeated measurements sampling design

“…As expected this subject was also the one with the highest level of urinary biomarkers (see Figure 2). StyOX exposure in these workers was about three orders of magnitude lower than that of Sty, and in good agreement with previously published data (Pfäffli & Säämänen 1993, Nylander-French et al 1999, Tornero-Velez et al 2000. Moreover, we report for the first time that exposure to StyOX was measured during the production of varnishes that employed styrene as an ingredient.…”

“…Occupational exposures to styrene are accompanied by co-exposures to low levels of styrene-(7,8)-oxide (StyOX), which is produced from oxidation of Sty during the production of plastics, possibly via catalysis by hydroperoxides used as initiators of the polymerization process , Nylander-French et al 1999, Tornero-Velez et al 2000. StyOX is an animal carcinogen that is classified as a probable human carcinogen (group 2A) (IARC 1994b).…”

Rapid assessment of DNA damage induced by polystyrene nanosphere suspension using a photoelectrochemical DNA sensor

“…A lot of free radicals are produced during a short period of time to initiate the formation of polymers. Under such strong oxidizing conditions, styrene, the starting material for the polystyrene nanosphere, might be oxidized to styrene-7,8-oxide (SO), phenylacetaldehyde and acetophenone [32]. As indicated in Figure 5, the supernatant of 1.0 mg/mL PSNS suspension depicted a strong UV-visible absorption peak at 210 nm, a pattern similar to the characteristic peak of pure SO.…”

Predictors of occupational exposure to styrene and styrene-7,8-oxide in the reinforced plastics industry

“…2 Although rarely mentioned, direct exposures to SO can also occur at low (mg/m 3 ) levels in styrene-using industries where SO is released into air as a byproduct of styrene oxidation. [6][7][8][9][10][11] The biological importance of SO is generally considered within the context of styrene metabolism due to the vastly greater abundance of styrene in air. However, this assumption has been questioned because, whereas metabolically derived SO is efficiently detoxified by epoxide hydrolases in the liver, inhaled SO is rapidly absorbed and distributed to the tissues where it can exert genotoxic effects.…”

“…However, this assumption has been questioned because, whereas metabolically derived SO is efficiently detoxified by epoxide hydrolases in the liver, inhaled SO is rapidly absorbed and distributed to the tissues where it can exert genotoxic effects. 6 8 12 Different factors have been linked to increased levels of styrene exposure in the FRP industry. In a review of industrial hygiene surveys, Lemasters et al 13 observed significant differences in airborne styrene levels due to the type of product (highest in the boat and truck manufacturing groups) and the type of process (open moulds higher than press moulds).…”