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PubMed1989

[Chromosome aberrations in peripheral blood lymphocytes in workers occupationally exposed to styrene].

We performed the investigation of the number of chromosomal aberrations in the peripheral blood lymphocytes of 13 women--workers occupationally exposed to styrene. Our set consisted exclusively of women in the age span from 23 to 54 years. Nine of the workers were smokers, 4 of them did not smoke. The control group was represented by 6 women working in the offices of the same factory. The clinical investigation of both the groups of women was performed at the Clinic of occupational diseases. The common physical check-up was combined with the hematological and biochemical tests including the assessment of the mandelinic acid level in the urine. Also the styrene concentration in the working place was measured by the help of the Regional hygiene center. The average working day's concentration of styrene was found to be 225 +/- 89 mg.m-3 ranging from 83 to 366 mg.m-3. From hte total number of 1220 cytogenetically investigated cells in the group of higher risk in 31 of them (2.54% AB.C.) the chromosomal aberration were found. In 27 cases (2.21%) the structural aberrations were involved; mostly the chromatid breaks and four times the chromosomal breaks were present. Four cells were laden by the numeric aberrations (type of 4n). Moreover, there was also checked the number of gaps (total of 9 gaps; 6 of chromatid, 3 chromosomal ones) and the number of satellite association of chromosomes (total of 87). The number of chromosomal aberrations in the exposed group is statistically significantly higher when compared with the control group (1.17% of AB.C.). Due to the restricted volume of the set our results cannot be taken as a confirmation of the relevant factory to be a working place with the higher exposition to genotoxic agents. Nevertheless, concerning the upper limit of spontaneous aberrations in the unladen population reaching maximally 2% we must consider our results to witness the increased occupational hazard.

Adult↗
PubMed1985

Cytogenetic analysis of peripheral blood lymphocytes of workers occupationally exposed to styrene.

The genetic risk run by workers occupationally exposed to styrene vapors was assessed in two different plants A and B, using the cytogenetic analysis of peripheral blood lymphocytes. In plant A engaged in the manufacture of polystyrene vessels the mean styrene exposure level was found to range between 70 and 150 mg . m-3, in plant B manufacturing sports boats, plastic slides for children and plastic guard-stones it reached the level of about 200 mg . m-3. The rate of aberrant cells (AB.C.) found in plant A workers (N = 36) at the time of first sampling was 1.38% and the value of break/cell (B/C) ratio was 0.015; at the second sampling the rate of AB.C. was 1.41% and the B/C ratio was 0.014. The group of matched controls (N = 19) was found to have 1.26% of AB.C. and 0.014 breaks per cell. Plant B workers (N = 22) exhibited at the first sampling 1.72% of AB.C. and their value of B/C ratio was 0.018, the group of matched controls (N = 22) had 1.36% of AB.C and the B/C ratio 0.015; the respective values at the time of second sampling were 2.81% for AB.C. rate and 0.029 for B/C ratio in the exposed and 1.89% for AB.C. rate and 0.021 for B/C ratio in the control group. It is concluded that styrene exposure levels below 100 mg . m-3 do not pose any serious genetic risk for the exposed population groups. The variations found in the degree of chromosome injury by smoking habits, drug intake pattern, or sex were not statistically significant.

Adult↗
PubMed1993

Neurotoxicity in workers exposed to styrene.

Quantitative electroencephalography (EEG) for 99 workers exposed to styrene in the reinforced-plastics industry was analysed and compared with exposure parameters. The work places and factories from which the subjects were selected had been evaluated previously, and exposure levels were known relatively accurately. That information and data on individual exposures were combined to create an exposure index, which reliably reflected long-term exposure to styrene in various occupational settings. All of the subjects underwent careful medical and neurophysiological examinations. Quantitative EEG was recorded on 19 channels and analysed for absolute and relative power, asymmetry, coherence, frequency distribution, and statistical normative data base comparisons (neurometrics). When the workers were divided into three groups on the basis of exposure, workers with the highest exposure had significantly more EEGs classified as abnormal and had higher absolute EEG power in alpha band in the fronto-temporal regions of the brain. The findings indicate that abnormalities can occur in cerebral function even after relatively low mean exposures. We conclude that the efforts to lower regulatory hygienic levels of styrene are justified.

Adult↗
PubMed1997

[The effect of antioxidant therapy on indicators of activity of free radicals in workers exposed to risks of styrene].

To 30 workers exposed to the risk of styrene for a period of 30 days a mixture of antioxidants was administered: vitamin C 200 mg, vitamin E 300 mg, selenium 20 mg, troxerutin 600 mg and beta-carotene 6 mg. Before the onset of supplementation and immediately afterwards laboratory indicators of antioxidant protection and lipid peroxidation were investigated. Before treatment workers exposed to the risk of styrene had a significantly higher malondialdehyde concentration (p < 0.01) and antioxidant capacity (p < 0.01) as compared with the control group. Due to the established positive correlation between these parameters (r = 0.42, p < 0.05) the findings can be evaluated as the result of increased exposure to free radicals. After supplementation a marked decline of the malondialdehyde concentration occurred p < 0.001) and a further rise of the antioxidant capacity (p < 0.001). The selenium concentration increased also markedly, the rise being more marked in subjects who had originally a lower concentration. There was a significant rise of uric acid which has an antioxidant effect (p < 0.01). The antioxidant enzymes superoxide dismutase and gluathione peroxidase did not change significantly. The results indicate the favourable effect of antioxidant treatment in subjects exposed to the risk of styrene.

Adult↗
PubMed2003

Optimization of electrochemical and peroxide-driven oxidation of styrene with ultrathin polyion films containing cytochrome P450cam and myoglobin.

The catalytic and electrochemical properties of myoglobin and cytochrome P450(cam) in films constructed with alternate polyion layers were optimized with respect to film thickness, polyion type, and pH. Electrochemical and hydrogen peroxide driven epoxidation of styrene catalyzed by the proteins was used as the test reaction. Ionic synthetic organic polymers such as poly(styrene sulfonate), as opposed to SiO(2) nanoparticles or DNA, supported the best catalytic and electrochemical performance. Charge transport involving the iron heme proteins was achieved over 40-320 nm depending on the polyion material and is likely to involve electron hopping facilitated by extensive interlayer mixing. However, very thin films (ca. 12-25 nm) gave the largest turnover rates for the catalytic epoxidation of styrene, and thicker films were subject to reactant transport limitations. Classical bell-shaped activity/pH profiles and turnover rates similar to those obtained in solution suggest that films grown layer-by-layer are applicable to turnover rate studies of enzymes for organic oxidations. Major advantages include enhanced enzyme stability and the tiny amount of protein required.

Algorithms↗
PubMed1987

Hearing loss in rats caused by inhalation of mixed xylenes and styrene.

We have reported that inhalation exposure of rats to toluene causes permanent hearing loss, e.g. Pryor et al. Neurobehav. Toxicol. Teratol. 5, 53-62 (1983). Therefore, it was of considerable interest to examine the ototoxic potential of two structurally related solvents--mixed xylenes and styrene--compared with that of toluene. Male, weanling Fischer-344 rats were exposed to clean air or solvents in four identical 62.5 l Plexiglas chambers. Exposures to 800, 1000, and 1200 ppm were daily for 14 hours/day and lasted 6 weeks for mixed xylenes, 3 weeks for styrene. An additional experiment with xylenes examined the effect of exposure for only 4 (1700 ppm) or 8 (1450 ppm) hours or for 8 (1450 ppm) hours on three consecutive days to compare the results with those obtained with toluene under comparable exposure schedules. Both xylenes and styrene caused marked hearing loss as assessed by behavioral (conditioned avoidance) and electrophysiologic (brainstem auditory-evoked response) methods. Moreover, both solvents appeared to be more potent ototoxicants than toluene, as indicated by effective concentration, effective durations of exposure, and the range of frequencies affected.

Animals↗
PubMed1987

Evaluation of the nephrotoxic potential of styrene in man and in rat.

The urinary excretion of beta 2-microglobulin, retinol-binding protein and albumin was measured in 65 workers exposed to styrene at levels averaging 50 percent of the current threshold limit value (215 mg/m2) for 1-13 years (mean: 6 years). By comparison with a control group matched for age and socioeconomic status, no significant difference was observed in the urinary excretion of proteins. In rats, styrene was weakly nephrotoxic. No functional or morphological renal change could be disclosed in rats exposed to 565 mg of styrene/m3, 5 days/week for 13 weeks. The repeated i.p. injection of 1 g styrene/kg (1/5 of oral LD50) for 10 days induced only a slight tubular dysfunction as evidenced by a 5-fold increase in beta 2-microglobulinuria. Altogether, these epidemiological and experimental data suggest that the current threshold limit value for styrene (215 mg/m3) proposed by the American Conference of Governmental and Industrial Hygienists does not entail any risk of renal toxicity.

Adult↗
PubMed2004

Two-sample scale tests for comparison of metabolic rates for styrene in previously exposed and unexposed groups.

Statistical analysis procedure in two-sample treatment difference, as well as alternative hypothesis, may play a central role in statistical inference, especially in small sample size case. In this paper, simple non-parametric two-sample permutation tests for scale difference based on the Hodges-Lehmann estimator are reformulated, and are applied to a study examining whether previous styrene exposure increases (thus a one-sided alternative hypothesis rather than a two-sided one) the human liver's metabolic ability to convert styrene into styrene oxide, in which a three-compartment physiologically based pharmacokinetic (PBPK) model was used to compare the estimated metabolic constant kappaamong the previously exposed and unexposed groups. Contrary to the previous conclusion, the proposed tests for scale difference identified from a mixed-effects model showed a significant result.

Humans↗
PubMed1989

Effect of styrene administration on rat testis.

Styrene was administered through gavage to adult male rats for 60 days. At the lower dose of 200 mg/kg/day no overt signs of testicular toxicity were observed, while at the higher dose of 400 mg/kg/day activities of some marker enzymes for testicular function were found to be altered significantly, along with a decrease in spermatozoa number. Histopathological studies revealed marked degeneration of seminiferous tubules and lumen devoid of sperms, further confirming testicular toxicity of styrene. The present study suggests an overall sensitivity of the male reproductive system towards styrene exposure.

Animals↗
PubMed1982

Styrene exposure and biologic monitoring in FRP boat production plants.

A survey on styrene exposure was conducted in five small to medium-sized fiber-reinforced plastic (FRP) boat plants utilizing carbon felt dosimeters as personal and stationary samplers to measure 4h (TWA) exposure during workday afternoons. The heaviest exposure, up to 256 ppm by personal sampling and 174 ppm by stationary sampling, took place during the lamination on a mold to produce a boat shell, and the work inside narrow holds also resulted in exposures of a comparable degree. Styrene levels were much lower in other auxiliary works. The TWA of exposure in an entire boat production was estimated to be 40-50 ppm. Installation of several flexible hoses as an exhaust system was proved to be effective in decreasing the vapor concentration. Gas masks were also useful in reducing the exposure. Urine samples were collected from 96 male workers at the end of 8h work (4h in the morning and 4h in the afternoon) and also from 22 nonexposed male subjects, and analyzed for mandelic acid (MA), phenylglyoxylic acid (PhGA), and hippuric acid (HA). When the results of urinalyses were compared with 4-h styrene TWA as monitored by personal sampling, the best correlation was obtained with MA + PhGA/creatinine (the correlation coefficient, 0.88), followed by MA (0.84). For these two cases, regression lines and 95% confidence limits for the group means and for the individual values were calculated. The urinary level of MA, PhGA, and HA in the 22 nonexposed male subjects were also tabulated.

Air Pollutants↗
PubMed2001

Inter- and intra-individual sources of variation in levels of urinary styrene metabolites.

OBJECTIVE: Given the paucity of studies that have examined variability in biological measures of exposure to workplace contaminants, we quantified the intra- and inter-individual sources of variation in urinary levels of mandelic acid (MA) and phenylglyoxylic acid (PGA) among workers exposed to styrene. A secondary objective was to examine effects of job task and the timing of sampling during the workweek on the variation in workers' urinary styrene metabolite levels. METHODS: As part of routine biological monitoring, a total of 1,714 measurements of MA and PGA collected from 331 workers between 1985 and 1999 from eight reinforced-plastics plants were abstracted from laboratory reports. To evaluate sources of variation in levels of urinary styrene metabolites, we applied random-effects models. The influence of job task and day of sampling on metabolite levels was examined using mixed-effects models. RESULTS: PGA levels were characterized by less variation than levels of MA, as were metabolite levels expressed in terms of urinary creatinine concentration. The relative magnitude of the inter-individual to the intra-individual source of variation was generally higher for post-shift urine samples than for pre-shift urine samples. As expected, urinary metabolite levels were highest for laminators and for samples collected at the latter end of the workweek. Owing to the effects of variation from day-to-day, estimates of workers' exposures that rely on single measurements would generally perform poorly in a regression analysis designed to examine effects resulting from chronic exposure. However, the bias in an observed slope coefficient would be diminished if a second or third urine sample were collected. CONCLUSIONS: Quantification of the intra- and inter-individual sources of variation provides useful information that can be used to design optimal sampling strategies, which would allow for the collection of sufficient data to estimate workers' exposures reliably when evaluating health risks associated with occupational contaminants.

Glyoxylates↗
PubMed2002

Cytochrome P4502E1 phenotyping by the measurement of the chlorzoxazone metabolic ratio: assessment of its usefulness in workers exposed to styrene.

OBJECTIVES: To analyse the relationship between cytochrome P4502E1 (CYP2E1) activity as assessed by the chlorzoxazone metabolic ratio (CMR) and frequent CYP2E1 genotypes ( CYP2E1*5B, *6, *1B and *1D) and to assess the value of CMR in refining the biomonitoring of exposure to styrene. METHODS: Thirty-one workers from a fibreglass-reinforced plastics factory took part in the study. Ambient styrene concentration was determined during the whole workshift by passive sampling. Each worker received a 500-mg chlorzoxazone (CZX) tablet at the beginning of the workday, and blood was taken after 2 h for CMR and CYP2E1 genotypes determination. Urine was collected at the end of the shift for the determination of styrene-specific metabolites. RESULTS: While the only worker heterozygous for CYP2E1*1D allele presented the highest value of CMR, a trend to lower CMR value for individuals possessing at least one mutant CYP2E1*6 allele compared with homozygous wild type was observed. The integration of CMR value as an independent variable to explain inter-individual variability in urinary metabolite excretion was not conclusive. CONCLUSION: Although, in the present population of workers, the CMR test was able to detect a slight influence of some genotypes on the activity of the CYP2E1 enzyme, it must be recognised that this method is not appropriate for refining the biological monitoring of industrial compounds that are metabolised by CYP2E1.

Adult↗
PubMed2004

Determination of urinary styrene metabolites in the general Italian population by liquid chromatography-tandem mass spectrometry.

OBJECTIVE: To apply mass spectrometry-based techniques for the determination of background levels of metabolites of widespread organic solvents, such as styrene, in unexposed subjects from the general population. METHODS: The study population consisted of 129 healthy Italian subjects, not occupationally exposed to styrene (67 men; 37% smokers). Urinary levels of mandelic acid (MA) and phenylglyoxylic acid (PGA) were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: Using LC-MS/MS, we were able to detect the peaks of MA and PGA in 100% of samples. The distribution of styrene metabolites was log-normal, the geometric means of MA and PGA concentrations being 0.443 mg/g creatinine [geometric standard deviation (GSD) 2.34] and 0.107 mg/g creatinine (GSD 3.49), respectively. The reference intervals estimated for MA and PGA were 0.084-2.339 and 0.009-1.238 mg/g creatinine, respectively. CONCLUSION: The application of highly sensitive and selective mass spectrometry-based analytical techniques could be useful in the definition of reference values for metabolites of organic pollutants and for better assessment of low-level occupational exposure to organic solvents.

Adult↗
PubMed1999

Estimation of the percutaneous absorption of styrene in an industrial situation.

OBJECTIVE: This field study was designed to compare the level of styrene absorbed percutaneously with that absorbed by inhalation in a real situation in the fiberglass-reinforced polyester industry. METHODS: The study protocol consisted of comparisons of the patterns of urinary excretion of styrene metabolites by four groups of workers, all of whom performed the same task at the same time in the same workshop but wore the following different protective equipment: total protection with an insulating suit and mask, respiratory equipment only, percutaneous protection only, and no protection. RESULTS: The urinary excretion level of the group with total protection did not significantly differ from that of the group with respiratory protection only. CONCLUSIONS: Precutaneous absorption is not a particularly important pathway for styrene absorption during stratification work in the polyester industry. Completely insulating personal protective equipment provides no greater level of protection than does a respirator at positive pressure alone.

Analysis of Variance↗
PubMed1989

Singlet oxygen production from the peroxidase catalyzed formation of styrene glutathione adducts.

Recently, Stock et al. (J. Biol. Chem. 261, 15915-15922 [1986]) described a model enzyme system composed of horseradish peroxidase, hydrogen peroxide, phenol, glutathione and styrene. This system forms glutathione-styrene conjugates. Glutathione radicals and carbon-centered radicals are intermediates in this process. In the present study, this model enzyme system was also shown to generate singlet oxygen, probably via a Russell mechanism. No singlet oxygen was generated in the absence of styrene. Thus, contrary to prior suggestions, the reaction of glutathione radical with oxygen to produce a thiyl peroxyl radical is not a significant source of singlet oxygen.

Glutathione↗
PubMed1979

Effects of styrene oxide on chromosome aberrations, sister chromatid exchange and hepatic drug biotransformation in chinese hamsters in vivo.

In vivo inhalation exposure to styrene oxide (25, 50, 75 and 100 ppm) for 2, 4 or 20 days (25 ppm only) had no effects on chromosomal aberration rates or sister chromatid exchange (SCE) frequencies (BrdU/labelling performed in vitro) in the bone marrow cells of Chinese hamsters. The only positive response in aberration frequency was obtained when styrene oxide was injected in lethal concentration (500 mg/kg body weight, i.p.) into the animal. One animal out of six showed slightly elevated SCE values after this high dose. The response of the hepatic drug metabolizing enzymes to styrene oxide exposure was found to be rather weak, which may be due to rather high activity of epoxide hydratase in Chinese hamsters as compared to e.g. mouse.

Animals↗
PubMedDate not supplied

Styrene and vinyltoluene induce micronuclei in mouse bone marrow.

Male C57BL/6 mice were treated i.p. with a single dose of styrene (250, 500, 1000 or 1500 mg/kg b.wt; 4 animals/group), vinyltoluene (100, 200, 300 or 500 mg/kg b.wt; 4-5 animals/group) or olive oil (controls, 13 animals). A significant increase in micronucleated polychromatic erythrocytes was observed at 250 and 1000 mg/kg b.wt of styrene and at 200, 300 and 500 mg/kg b.wt of vinyltoluene. 1000 and 1500 mg/kg b.wt of styrene and 100, 200 and 300 mg/kg b.wt of vinyltoluene significantly decreased the ratio of polychromatic to normochromatic erythrocytes. There was no increase in normochromatic cells with micronuclei.

Animals↗
PubMedDate not supplied

Influence of occupational styrene exposure on memory and attention.

Short-term memory, perceptual speed, attention and psychomotor function were studied in 55 workers professionally exposed to styrene. The subjects were grouped according to their urinary styrene metabolites. Those with higher styrene exposure showed a significant impairment of short-term memory only.

Adult↗