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PubMed1992

[Activity of selected enzymes of peripheral blood erythrocytes and serum haptoglobin levels in workers occupationally exposed to styrene and formaldehyde].

In 48 and 30 workers exposed to styrene and formaldehyde respectively activities of erythrocyte acetylcholinesterase lactate dehydrogenase and glucose-6-phosphate dehydrogenase, were determined. Hematocrit, haemoglobin concentration, red blood cell count and serum haptoglobin levels were also determined. Significant decrease in erythrocyte acetylcholinesterase activity in workers exposed to styrene for 61-180 months was stated. Moreover, increased erythrocyte lactate dehydrogenase activity and decreased serum haptoglobin level was found in workers exposed to formaldehyde for 3-24 months. There were no differences in basic hematological parameters and erythrocyte glucose-6-phosphate dehydrogenase activity in both groups studied as compared to the control group.

Acetylcholinesterase↗
PubMed1991

Styrene revisited--exposure assessment and risk estimation in reinforced plastics industry.

A survey performed in 32 workshops in reinforced plastics industry showed the mean TWA 8 h concentration of styrene in personal air to be 43 ppm (range 5-182 ppm) among laminators and 11 ppm (range 1-133 ppm) among other workers. The biological measurement of urinary mandelic acid + phenylglyoxylic acid showed mean values of 2.4 mmol/l among laminators without respirators and 1.3 mmol/l when respirators were used. No effects of work related exposure were detected in the cytogenetic parameters, chromosome aberrations, sister chromatid exchanges or micronuclei analyzed in peripheral blood lymphocytes. Grading of the exposure on the basis of lamination method, years of exposure, daily laminating time, air styrene concentration and urinary mandelic acid among laminators, neither revealed any dose dependency.

Air Pollutants, Occupational↗
PubMed1990

[Experimental studies of the combined effect of styrene and general vibration].

People working in modern carpet industry are exposed to a complex of factors of different origin, the most important among which are general vibration and styrene vapors. It has been found out in animal experiments simulating working conditions, that the central nervous system is the most sensitive both under an isolated and joint exposure to the factors. The joint exposure of animals to styrene and vibration may be evaluated as having different targets depending on the parameters under study.

Animals↗
PubMed1989

[Urinary enzymes: early biochemical indicators in the biological monitoring study of subjects exposed to styrene].

This paper studies the urinary enzymes N-acetyl-beta-glucosaminidase (NAG) and alanine aminopeptidase (AAP) in workers exposed to styrene. It is possible to consider these enzymes as early biochemical indicators of renal damage, owing to their ability to show alterations in the renal tubule when the creatinine clearance is still in the normal range. This preliminary study shows an increase in the two enzymes in workers exposed to styrene.

Acetylglucosaminidase↗
PubMed1989

[Health status of workers exposed to styrene used in the manufacture of glass laminates].

A group of 37 workers exposed to styrene used in the plastic mass manufacture was investigated. No damage of the hepatic parenchyma, hematopoiesis or other internal affection was proved; irritative styrene effects were, however, observed, skin was attacked and higher genetic risk was evidenced. From the viewpoint of neurotoxicology, pseudoneurasthenic syndromes, predominantly inhibitory, could be seen, which was proved also by electroencephalography; higher incidence of lesion findings was also found in the risk group. Slight neuropathies of distal type, sensitive-motor, not dependent on the length of exposure were found by electromyography. Abnormalities in electrophysiological examinations appear earlier. The results obtained are significant for further preventive follow-up of persons under exposure.

Adult↗
PubMed1987

Binding to and internalization by cultured cells of neocarzinostatin and enhancement of its actions by conjugation with lipophilic styrene-maleic acid copolymer.

The binding of a copoly(styrene-maleic acid)-conjugated neocarzinostatin (NCS) designated as smancs (Mr 16,000), and parental NCS (Mr 12,000) to cultured cells was investigated. These drugs were labeled with fluorescein isothiocyanate which retained biological activity and were used for binding studies. The binding of these drugs to HeLa cells was dependent on time and temperature, with 2 times more drug being bound at 37 degrees C than at 0 degree C. In the presence of a 100-fold molar excess of unlabeled NCS, the binding of smancs or NCS to HeLa cells was inhibited similarly. Therefore, it was suggested that smancs binds to NCS-binding sites (receptor) of the cell surface. However, the amount of cell-bound smancs was increased about 20-fold compared with that of NCS. Scatchard plot analyses of the binding of these drugs to HeLa and WISH cells indicated that this increase was due to alterations in affinity resulting from polymer conjugation of the drug to receptor rather than to an increase in the number of drug-binding sites at the cell surface. Furthermore, when the cytotoxicity of these drugs to HeLa cells was compared, smancs needed only 5 min to achieve 50% inhibition of the control. In contrast, the same dose level of NCS required more than 90 min to achieve the same toxic effect. More rapid internalization of smancs than NCS was also elucidated under fluorescence microscopy at 37 degrees C. There was no intracellular incorporation of these drugs below 20 degrees C. These results indicated that an increased lipophilicity of smancs appears to be responsible for its increased cell surface affinity, internalization rate, and toxic effect. Concordant to this interpretation was that among various copoly(styrene-maleic acid) esters, a more hydrophobic derivative showed more internalization (butyl greater than ethyl greater than carboxylate). These results suggest the possibility of utilizing protein tailoring to augment the subcellular activity of functional proteins.

Antibiotics, Antineoplastic↗
PubMed1988

Single-strand breaks in DNA of peripheral lymphocytes of styrene-exposed workers.

Single-strand breaks (SSB) were determined by means of the DNA unwinding technique in peripheral lymphocytes of styrene-exposed workers and referents. A slight increase in SSB was observed among exposed subjects in comparison with a control group of office workers. A correlation was found between SSB, the excretion of mandelic acid and the concentration of styrene glycol in blood. The present work suggests that the DNA unwinding technique can be used for screening workers exposed to genotoxic compounds.

DNA Damage↗
PubMedDate not supplied

New FDA migration cell used to study migration of styrene from polystyrene into various solvents.

A new cell was evaluated for studying the migration of components of plastic food packaging materials into various food simulating solvents. Data obtained using this cell to study the migration of styrene from polystyrene at 40 and 70 degrees C are presented. Food simulating solvents tested were: water; 3% acetic acid; 8, 20, 50, and 100% ethanol; corn oil; HB-307; heptane; hexadecane; and decanol. An iterative Basic computer program is described that fits the migration vs time data obtained to mathematical models, based on Ficks' law, yielding migrant/polymer diffusion coefficients (Dp). Dp values determined for styrene migration from polystyrene at 40 and 70 degrees C were 3 X 10(-13) and 4 X 10(-12) sq. cm/s, respectively.

Chemical Phenomena↗
PubMed1984

Urinary excretion of mandelic and phenylglyoxylic acids after human exposure to styrene vapour.

The kinetics of the urinary excretion of mandelic and phenylglyoxylic acids were studied in volunteers exposed to the known concentrations of styrene vapour. The level and the time of exposure were suitably changed to simulate situations in the industrial environment. The aim was to find out the reasons for the contradictory reports in the literature and to verify parameters characterizing the course of excretion of both metabolites. It was found that the course of mandelic acid excretion might be influenced by the length of styrene exposure. If exposure was longer than 4 hours the maximum of excretion was at the end of the exposure time; after short-term exposures (4 h or less) it was somewhat delayed. Maximum excretion of phenylglyoxylic acid was delayed both after short-term and 8-hour exposures. Excretion of the metabolites was diphasic (biexponential). The effective half-lives were found to be independent of the level of exposure. The apparent half-lives (determined in the post-exposure time of 0-16 hours) tended to become prolonged at daily repeated exposures. The ratio of mandelic to phenylglyoxylic acid changed considerably with the level of exposure. In biological monitoring it is advisable to determine both metabolites.

Female↗
PubMed1993

Cytogenetic studies of rodents exposed to styrene by inhalation.

Female B6C3F1 mice and Fischer 344 rats were exposed to styrene at nominal concentrations of 125, 250 and 500 ppm by inhalation for 6 h per day for 14 consecutive days. One day after the final exposure, murine peripheral blood lymphocytes, spleen and lungs were removed, and the cells were cultured for analysis of chromosomal aberrations, micronucleus induction (using the cytochalasin B-block method) and sister chromatid exchange. Peripheral blood smears were scored for micronucleus induction in normochromatic erythrocytes. For the rats, peripheral blood lymphocytes were cultured for analyses of sister chromatid exchange, chromosomal aberrations and micronuclei in cytochalasin B-induced binucleated cells and were also examined in the single-cell gel assay for analysis of DNA strand breakage under alkaline conditions. Bone-marrow smears were made from femurs of rats for analysis of micronucleus induction in normochromatic erythrocytes. Small but statistically significant concentration-related increases in the frequency of sister chromatid exchange were seen in both mice and rats in all cell types examined. No statistically significant concentration-related increase in chromosomal aberration or micronucleus induction frequencies were observed in either species, and there was no significant increase in DNA strand breakage in peripheral blood lymphocytes from exposed rats. These results indicate that styrene is a weak inducer of sister chromatid exchange in vivo when administration to rodents by inhalation.

Administration, Inhalation↗
PubMed1993

The roles of His-64, Tyr-103, Tyr-146, and Tyr-151 in the epoxidation of styrene and beta-methylstyrene by recombinant sperm whale myoglobin.

Previous studies demonstrated that at least two mechanisms are involved in the epoxidation of styrene and stilbene by myoglobin and H2O2 (Ortiz de Montellano, P. R., and Catalano, C. E. (1985) J. Biol. Chem. 260, 9265-9271). One mechanism, reaction of the olefin with the ferryl oxygen, preserves the olefin stereochemistry and incorporates an oxygen from H2O2 into the epoxide. The second mechanism, proposed to be a protein-mediated co-oxidation process, results in loss of stereochemistry and incorporation of an atom of molecular oxygen. To examine the role of individual residues in olefin epoxidation, we have examined the catalytic activities of the possible Tyr-->Phe mutants, the His-64-->Val mutant, and a protein combining all the tyrosine and histidine mutations. The latter protein is less stable than the other mutants and is the only one for which a protein radical is not detected in the reaction with H2O2. The Km and Vmax for styrene epoxidation range, respectively, from 0.3-8 mM and 12-35 pmol/min/nmol of protein. Incubation with H(2)18O2 results in 20-30% incorporation of labeled oxygen into the epoxide with all the mutants except Y103F/Y151F, Y146F/Y151F, H64V, and H64V/Y103F/Y146F/Y151F, for which 52, 58, 89, and 96% of the epoxide oxygen, respectively, is labeled. Oxidation of cis-beta-methylstyrene by wild-type myoglobin yielded a 54:46 ratio of cis- and trans-beta-methylstyrene oxides. The cis-isomer accounts for 47-100% of the epoxide produced by the mutant hemoproteins, with the two H64V mutants yielding almost exclusively the cis-epoxide. The oxygen in the cis-epoxide derives primarily or exclusively from H2O2 and that in the trans-epoxide from an alternative source. These results indicate that tyrosine residues may participate in, but are not essential for, protein-mediated epoxidation. In contrast, His-64 appears to be essential for co-oxidative epoxidation because in its absence olefin epoxidation is mediated almost exclusively by ferryl oxygen transfer.

Amino Acid Sequence↗
PubMed2004

Mortality patterns among workers exposed to styrene in the reinforced plastic boatbuilding industry: an update.

BACKGROUND: Mortality was updated through 1998 for 5,204 workers exposed to styrene between 1959 and 1978 at two reinforced plastic boatbuilding plants. The a priori hypothesis: leukemia and lymphoma excesses would be found. METHODS: Standardized mortality ratios (SMR) and 95% confidence intervals (CI) used Washington State and U.S. rates. RESULTS: Overall, 860 deaths occurred (SMR 1.09, CI 1.02-1.17), with excess mortality for esophageal cancer (n = 12, SMR 2.30, CI 1.19-4.02), prostate cancer (n = 24, SMR 1.71, CI 1.09-2.54), and accidents (n = 99, SMR 1.26, CI 1.02-1.53). Among 2,062 highly exposed workers, urinary tract cancer (n = 6, SMR 3.44, CI 1.26-7.50) and respiratory disease (n = 12, SMR 2.54, CI 1.31-4.44) rates were elevated. Urinary tract cancer SMR increased with duration of employment. CONCLUSIONS: We found no excess leukemia or lymphoma mortality. Unanticipated excess urinary tract cancer and respiratory disease mortality, possibly associated with styrene exposure, are difficult to interpret and could be chance findings.

Adult↗
PubMed1994

Impairment of color vision among workers exposed to low concentrations of styrene.

A field study was conducted among 21 male workers exposed to styrene of concentration below 30 ppm in a fiber-reinforced plastic boat manufacturing plant. Twenty-one male workers with similar age groupings, years of education, and social and occupational state served as referents. The mean end-of-shift urinary mandelic acid (MA) and phenylglycoxylic acid (PGA) for the exposed workers were 84 mg/g creatinine and 66 mg/g creatinine, respectively. The Lanthony D-15 Hue Desaturated Panel was used to evaluate color discrimination of the exposed and referent groups. The results of the test were expressed as total color difference score (TCDS). The exposed workers' mean TCDS (a higher score denotes poorer color discrimination ability) was significantly (p < 0.0006) higher than the referents'. Neurobehavioral tests were also conducted, using the World Health Organization's Neurobehavioral Core Test Battery (NCTB). All the results of the NCTB were poorer for the exposed than for the referents. However, significant differences were observed only for Digit Span, Digit Symbol, and Benton Visual Retention tests. These results suggest that low exposure to styrene could affect some psychometric performance and may impair color vision.

Adult↗
PubMed2003

Novel visible-light-induced photocurable tissue adhesive composed of multiply styrene-derivatized gelatin and poly(ethylene glycol) diacrylate.

A novel photocurable tissue adhesive glue, which is composed of styrene-derivatized (styrenated) gelatin, poly(ethylene glycol) diacrylate (PEGDA), and carboxylated camphorquinone in phosphate-buffered saline (PBS), was prepared. The prototype formulation suitable for arterial repair was determined based on the gel yield, degree of swelling, tissue adhesive strength, and breaking (or burst) strength in vitro. The formulated photocurable tissue adhesive glue with an appropriate viscosity was converted to a water-swollen gel within 1 min of visible light irradiation. The tissue adhesive glue, which was coated on a rat abdominal aorta incised with a pair of scissors, was immediately converted to a swollen gel upon subsequent irradiation with visible light, and concomitantly hemostasis was completed. Histological examination showed that the produced gel was tightly adhered to the artery shortly after photoirradiation. The gel gradually degraded with time and was completely absorbed within 4 weeks after treatment. These results indicate that the photocurable glue developed here may serve as a tissue adhesive glue applicable to vascular surgery.

Animals↗
PubMed1992

Monitoring of workers exposed to a mixture of toluene, styrene and methanol vapours by means of diffusive air sampling, blood analysis and urinalysis.

Exposure of 34 male workers to combined toluene, styrene and methanol was monitored by personal diffusive sampling of solvent vapours in breathing zone air, analysis of shift-end blood for the 3 solvents and analysis of shift-end urine for hippuric, mandelic and phenylglyoxylic acids and methanol. The exposure of most of the workers was below current occupational exposure limits. Regression analysis showed that a linear correlation exists for each of the 3 solvents between any pairs of the concentrations in air, blood and urine. Namely, toluene, styrene and methanol concentrations in blood obtained at the end of a shift are linearly related to the time-weighted average intensity of exposure to corresponding solvents, and also hippuric, mandelic and phenylglyoxylic acids as well as methanol in shift-end urine. The concentrations of hippuric, mandelic and phenylglyoxylic acids as well as methanol in urine correlated with the respiratory exposure intensity. Comparison of the present results with the exposure--excretion relationship after occupational exposure to the individual solvent showed that no modification in metabolism is induced by the combined exposure when exposure is low, as in the present case.

Air Pollutants, Occupational↗
PubMed1990

Haemopoietic stem cells in mice chronically exposed to styrene vapour.

Female C57BL/6X DBA/2 hybrid mice were exposed to two concentrations of styrene in inhalation chambers for 6 h/day, 5 days per week. The concentrations were 220 ppm for a period of up to 8 weeks and 440 ppm for 2 days, followed by 330 ppm for up to 8 weeks due to early deaths after 440 ppm. Parallel groups were also treated with 5% ethanol in the drinking water during the days of styrene exposure. In the peripheral blood only a lymphocytopenia was found. The numbers of pluripotent haemopoietic stem cells, CFU-S, were unaffected, as were granuloid committed stem cells, CFU-C. Early and late erythroid stem cell numbers, BFU-E and CFU-E, showed high variability. At 220 ppm about half of the animals had CFU-E numbers below 80% of controls, at 440/330 ppm about two-thirds of the animals had BFU-E and CFU-E numbers below this level. An additional effect of ethanol was not found.

Air↗
PubMed1991

Effects of cysteine derivatives of styrene on the transport of p-aminohippurate ion in renal plasma membrane vesicles.

The effects of cysteine conjugates of styrene, e.g. S-1/2-(phenyl-hydroxyethyl) cysteine (PEC) and its N-acetyl derivative (NAPEC) on the transport of p-amino-hippurate (PAH) ion in plasma membranes were studied in vitro using isolated rat renal brush-border membrane (BBM) and basolateral membrane (BLM) vesicles. The uptake of PAH was significantly inhibited by both PEC and NAPEC in both the membrane vesicles, as verified by decrease of the membrane/medium concentration ratio of PAH as the concentration of either PEC or NAPEC in the medium increased. These results show that both PEC and NAPEC are capable of interfering with the accumulation of PAH (a model organic anion for renal tubular transport system) by both energy-independent and energy-dependent carrier-mediated transport processes. The inhibition of PAH uptake in BBM vesicles due to 10 mM PEC or NAPEC was found to be nearly competitive, almost similar to probenecid, whereas in BLM vesicles such inhibition was found to be partially noncompetitive, as verified by the double reciprocal plots. Both PEC and NAPEC showed dose-dependent inhibition of the specific activity of the marker enzyme in each membrane, e.g. gamma-glutamyl transferase in BBM and Na(+)-K(+)-ATPase in BLM vesicles. However, no such inhibition was noticed with probenecid. The in vitro pretreatment with probenecid prevented the inhibition of gamma-glutamyl transferase activity in BBM due to PEC or NAPEC, but such was not the case for the Na(+)-K(+)-ATPase activity in BLM. In conclusion, the data suggest that the transport of cysteine or N-acetylcysteine conjugates of styrene by renal proximal tubular cells across both the membrane vesicles accompanied by the inhibition of the membrane-specific enzymes may lead to cellular dysfunction and consequently to the initial development of their nephrotoxicity.

Animals↗
PubMed2002

Simultaneous determination of styrene, toluene, and xylene metabolites in urine by gas chromatography/mass spectrometry.

Exposure to styrene, toluene, and xylene (STX) frequently occurs in various industrial settings leading to several adverse health effects. Therefore, the biological monitoring by determination of urinary mandelic acid (MA) and phenylglyoxylic acid (PGA), hippuric acid (HA), and 2-, 3-, and 4-methylhippuric acids (2-, 3-, and 4-MHAs), the metabolites of STX, is required or at least recommended in case of workers exposed by these agents. Considering the fact that co-exposure to STX frequently occurs, methods that have been described for the separate analysis of these compounds in urine samples cannot be used effectively for monitoring. Therefore, a reliable gas chromatographic/mass spectrometric (GC/MS) method was developed for the simultaneous identification and quantification of these metabolites. Following solid phase extraction of the urine samples, the extracts were silylated and analyzed by GC/MS using a HP-5MS capillary column. The method was evaluated for linearity, limits of detection and quantification, and specificity, as well as for precision, extraction efficiency, and stability at three different concentrations prepared in urine. The assay was linear up to 0.16 mg/ml for MA, and 0.32 mg/ml for PGA, HA, and 2-, 3- and 4-MHAs. The limits of detection and quantification of STX metabolites varied between 0.001 and 0.02 mg/ml, and from 0.01 to 0.04 mg/ml, respectively. The within-day and between-day precision, determined at low, medium, and high concentrations, ranged from 2 to 12% and 2 to 19%, respectively. The extraction efficiency was 70-80%. No degradation of the metabolites occurred in the urine samples under the possible working conditions. The method was applied for the analysis of the urine samples from exposed workers. The cost- and time-effectiveness, the technical advantages and validity parameters of this GC/MS analysis make it suitable for biological monitoring of mixed exposure to styrene, toluene and xylene.

Environmental Monitoring↗