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Objectives: A historical cohort study was carried out to investigate mortality from nonmalignant diseases of the genitourinary system among workers in the reinforced plastics industry, where high workroom concentrations of styrene are encountered., Methods: The external comparisons in this report were based on an average of 12.6 years of retrospective follow-up of 35 443 workers who were first employed in the reinforced plastics industry during 1945-1991 and were known to have been exposed to styrene in their work. For the internal comparisons, 2641 subjects with incomplete occupational histories were excluded, leaving 32 802 subjects. Previous individual exposure histories to styrene were reconstructed through job histories and environmental and biological monitoring data., Results: Mortality from nonmalignant diseases of the genitourinary system (N = 20) was associated with average exposure to styrene (P for trend 0.05). Weaker increasing trends in risk were seen for time since first exposure and cumulative exposure, while no increase was identified for duration of exposure. There was a significant increasing trend in mortality from nephritis and nephrosis (N = 5), associated with an increasing average level of exposure to styrene (P for trend 0.03). No clear trend was observed for time since first exposure, duration of exposure, or cumulative exposure., Conclusions: In this large cohort study of workers exposed to styrene, mortality from nonmalignant diseases of the genitourinary system increased as the average intensity of exposure increased. This finding indicates that other data should be scrutinized.

Objectives: The partitioning of lipophilic toxicants into blood and into adipose tissue plays an important role in the physiological distribution and toxicology of these substances. The partition coefficients between blood and air and adipose tissue and air were determined for widely used aromatic solvents in an in vitro test system using human tissue samples., Methods: Samples of whole venous blood (N = 35) were drawn from 10 subjects. In addition, samples of perirenal and epididymal adipose tissue were obtained from F344 rats, along with subcutaneous, omental, or inguinal adipose tissue from 43 patients who had undergone surgery. Portions of each tissue were injected into vials for equilibration with atmospheres containing deuterated and nondeuterated organic solvents. Gas chromatographic headspace analysis was then used to determine the partition coefficients between blood and air and adipose tissue and air., Results: The mean partition coefficients between human blood and air or adipose tissue and air were 334 (SE 11) (adipose tissue) for benzene; 1764 (SE 49) (adipose tissue) for ethylbenzene; 3184 (SE 84) (adipose tissue) for styrene; 18.3 (SE 0.24) (blood) and 962 (SE 32) (adipose tissue) for toluene; 35.2 (SE 0.45) (blood) and 2460 (SE 63) (adipose tissue) for O-xylene; 31.9 (SE 0.45) (blood) and 1919 (SE 53) (adipose tissue) for m-xylene; and 39.0 (SE 0.70) (blood) and 2019 (SE 102) for p-xylene. Regression analyses revealed coefficients of determination of 0.88 (human) and 0.98 (rat) between blood and air and log tissue and air. A value of 0.98 was found for partition coefficients between rat and human adipose tissue., Conclusions: The partition coefficients between blood and air and adipose tissue and air were strongly correlated. The partitioning of aromatic solvents into rat adipose tissue is predictive of partitioning into human adipose tissue.

The urinary excretion of styrene represents a promising indicator of exposure to this solvent. Nevertheless extensive research under field conditions is scant. In this investigation 214 styrene-exposed workers from 10 fiberglass-reinforced plastics factories were studied. Environmental monitoring was performed by personal passive sampling. Blood styrene and the urinary excretion of styrene and its main metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA), were measured. The correlation coefficient between the time-weighted average of environmental styrene and the mean urinary excretion of styrene was 0.88 (0.91 after logarithmic transformation), compared with the 0.82 and 0.78 of the end-of-shift MA and PGA values, respectively. A high correlation (0.86) was also found between styrene in the blood and urine. The results, obtained under field conditions with a large group of exposed workers, confirm the usefulness of the urinary excretion of styrene as an exposure index for the biological monitoring of 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.

BASF has been producing styrene and polystyrene since 1931. An investigation of morbidity was undertaken for 84 workers employed in the styrene plant and exposed for 1--36 years and 93 workers employed in the polystyrene plant and exposed for 1--38 years. In all groups the concentration of styrene in the atmosphere was measured at various points of the workplace. All workers underwent a thorough physical examination and also extensive laboratory tests, including the determination of urinary mandelic acid. The absenteeism and accident rates were also taken into consideration in both plants. Blood samples were also taken and mandelic acid tests made on a small group of 16 persons employed in polyester processing plants not attached to the BASF.

The vapors of styrene (vinylbenzene) were trapped on charcoal in a glass tube. Air from the worker's breathing zone was sucked through the tube by a battery-operated, modified, MSA personal sampling pump. The sampler and pumping system were worn by the worker. The styrene were eluted with dimethyl formamide and estimated by gas chromatography. The range and sensitivity of the method when sampling with a flow rate of 0.2 1/min during 1 h were 5 to 1,500 ppm, and during 4 h they were 2 to 400 ppm. The recovery (accuracy) was over 90%. The precision for the method, in terms of relative standard deviation, was 8.4%.

Polystyrene without additional compounds was treated in a laboratory oven at elevated temperatures (200 degrees, 350 degrees, 500 degrees C) under slight air flow (0.7 l/min). The thermal degradation products appearing in different phases (gases, vapors, aerosols) were collected and analyzed by methods of chromatography. Thermogravimetric analysis showed the thermal degradation of the polymer to begin at 270 degrees C in air and stop at 425 degrees C. The main groups of vaporized compounds generated were monoalkyl-substituted aromatic hydrocarbons and their oxidized products, of which styrene monomer and benzaldehyde were the most abundant. Only trace amounts of carbon monoxide and aliphatic compounds (hydrocarbons, aldehydes, and acids) were produced. The aerosol produced, the amount of which increased as the temperature rose, contained mainly fragments of the polymer chain (e.g., dimers and trimers of styrene). The traces of styrene, cumene, and ethylbenzene that appeared at 200 degrees could represent residual compounds in the initial polymer and indicate the beginning of the thermal degradation. If proportional concentrations are kept as a criterion, the important products, from the point of view of industrial hygiene, were styrene, benzaldehyde, styrene oxide, acetophenone, and l-phenylethanol. The large amount of aerosol that appeared may also be of practical importance.

Styrene and styrene oxide concentrations were measured during the lamination process in the reinforced plastics industry. The mean concentration of styrene in the personal samples was 130 ppm, the highest value measured being 350 ppm. The average concentration for styrene oxide alone was 0.1 ppm, whereas the corresponding measurement for styrene oxide and its decomposition products combined was 0.7 ppm. In comparison then, the concentrations of styrene oxide and its derivatives were much lower (about 0.5% of the total) than those of styrene.

Obtaining reliable results of exposure to styrene in field studies requires an appropriate methodology not only for analytical methods but also for the main strategy of conducting the surveys. This paper briefly describes how and why analytical methods for styrene in air, for its main metabolites in urine (mandelic and phenylglyoxylic acids) and for critical biological function tests were either chosen from the literature or adapted or developed to fit our criteria of convenience and reliability. In a second step of the preparation of field studies, experimental exposures to styrene were carried out on volunteers so that the best indicators of exposure could be determined and data could be obtained on the elimination kinetics of the urinary metabolites and the quantitative relationships between exposure and the urinary concentrations of mandelic and phenylglyoxylic acids. Finally field investigations, including air and biological monitoring, complete industrial hygiene surveys and medical examinations, have been organized and are being carried out in the Swiss polyester industry. Preliminary results concerning biological monitoring are given.