Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Styrenes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed1999

Electrochemical generation of ferrylmyoglobin during oxidation of styrene with films of DNA and a poly (ester sulfonic acid) ionomer.

The chemistry of electrochemically-driven myoglobin-catalyzed oxidation of styrene was investigated in films of DNA or Eastman AQ ionomer on optically transparent electrodes. Conversion of styrene to styrene oxide proceeded via a ferrylmyoglobin radical intermediate. Ferrylmyoglobins were clearly detected by spectroelectrochemistry in films of 1-4 mm thick. The ferrylmyoglobin radical is produced by reaction of metmyoglobin (Mb) in the films with hydrogen peroxide formed by electrochemical catalytic reduction of oxygen catalyzed by Mb. Thus, electrochemically-driven styrene oxidation with these films proceeds by a 'doubly catalytic' electrode-driven reduction-oxidation pathway. Ferrylmyoglobin formation during electrolysis of Mb-DNA films in aerobic solutions was much faster, and styrene oxidation occurred with less Mb decomposition compared to the Mb-AQ films. The better performance of Mb-DNA films is correlated with a larger fraction of electroactive Mb and better stability than for the Mb-AQ films.

Animals↗
PubMed2003

Sperm-FISH analysis and human monitoring: a study on workers occupationally exposed to styrene.

Occupational exposure to styrene, a chemical extensively used worldwide, is under investigation for possible detrimental effects on human health, including male reproductive capacity. Aneuploidy in germ cells is the main cause of infertility, abortions and congenital diseases. Fluorescence in situ hybridisation (FISH), is the most efficient cytogenetic molecular technique to date to analyse numerical alterations of chromosomes in spermatozoa. We investigated the frequencies of aneuploidy and diploidy in individuals occupationally exposed to styrene and in healthy unexposed controls. We performed multicolour FISH, using DNA probes specific for the centromeric regions of sex chromosomes and chromosome 2, in decondensed sperm nuclei of samples with normal semen parameters for a total of 18 styrene-exposed subjects and 13 unexposed controls of the same age range. Exposed individuals had worked for at least 2 years during the last 5 years, and continuously for 6 months, in factories producing reinforced plastics. The incidence of aneuploidy and diploidy for the tested chromosomes did not show a statistically significant difference between workers and controls. The exposure to styrene was associated with increased frequencies of nullisomy for sex chromosomes in the group of non-smokers, although only a limited number of subjects belonged to this sub-group. Considering the whole study population, age was associated with an increased frequency of XX disomy, whereas smoking was associated with meiosis II non-disjunction of sex chromosomes. Overall, confounding factors appeared to exert a more important effect than exposure to styrene on numerical chromosome alterations in sperm nuclei of subjects selected for normal semen parameters.

Adult↗
PubMed2003

Kinetics and thermodynamics of H. transfer from (eta5-C5R5)Cr(CO)3H (R = Ph, Me, H) to methyl methacrylate and styrene.

The rates of H/D exchange have been measured between (a) the activated olefins methyl methacrylate-d(5) and styrene-d(8), and (b) the Cr hydrides (eta(5)-C(5)Ph(5))Cr(CO)(3)H (2a), (eta(5)-C(5)Me(5))Cr(CO)(3)H (2b), and (eta(5)-C(5)H(5))Cr(CO)(3)H (2c). With a large excess of the deuterated olefin the first exchange goes to completion before subsequent exchanges begin, at a rate first order in olefin and in hydride. (Hydrogenation is insignificant except with styrene and CpCr(CO)(3)H; in most cases, the radicals arising from the first H. transfer are too hindered to abstract another H. .) Statistical corrections give the rate constants k(reinit) for H. transfer to the olefin from the hydride. With MMA, k(reinit) decreases substantially as the steric bulk of the hydride increases; with styrene, the steric bulk of the hydride has little effect. At longer times, the reaction of MMA or styrene with 2a gives the corresponding metalloradical 1a as termination depletes the concentration of the methyl isobutyryl radical 3 or the alpha-methylbenzyl radical 4; computer simulation of [1a] as f(t) gives an estimate of k(tr), the rate constant for H. transfer from 3 or 4 back to Cr. These rate constants imply a DeltaG (50 degrees C) of +11 kcal/mol for H. transfer from 2a to MMA, and a DeltaG (50 degrees C) of +10 kcal/mol for H. transfer from 2a to styrene. The CH(3)CN pK(a) of 2a, 11.7, implies a BDE for its Cr-H bond of 59.6 kcal/mol, and DFT calculations give 58.2 kcal/mol for the Cr-H bond in 2c. In combination the kinetic DeltaG values, the experimental BDE for 2a, and the calculated DeltaS values for H. transfer imply a C-H BDE of 45.6 kcal/mol for the methyl isobutyryl radical 3 (close to the DFT-calculated 49.5 kcal/mol), and a C-H BDE of 47.9 kcal/mol for the alpha-methylbenzyl radical 4 (close to the DFT-calculated 49.9 kcal/mol). A solvent cage model suggests 46.1 kcal/mol as the C-H BDE for the chain-carrying radical in MMA polymerization.

Chromium↗
PubMed2001

An application of the challenge assay in boat builders exposed to low levels of styrene--a feasibility study of a possible biomarker for acquired susceptibility.

Sensitivity to carcinogens and susceptibility for malignant diseases may be related to genetic predisposition, e.g. polymorphisms in toxicant-metabolizing enzymes or DNA repair deficiencies. The latter may also be acquired by exposure to substances that interfere with DNA repair processes. Application of the challenge assay to an exposed population may allow scientists to study the interference of DNA repair as an acquired susceptibility phenomenon. The assay was therefore used in a feasibility study to evaluate its application. A group of 14 workers exposed to low levels of styrene (mean < 100 mg/m3 styrene in air; 35 micrograms/l styrene in blood) and a reference of seven controls were investigated for structural chromosomal aberrations using FISH. The rate of exchange-type aberrations per 100 metaphases was 0.14 (95% CI, 0.05-0.31) in controls and 0.22 (95% CI, 0.13-0.36) in exposed workers. The difference is not statistically significant. Interaction with DNA repair was measured in the 14 workers and 2 historical controls using the challenge assay. Exchange-type aberrations per 100 metaphases after X-ray challenge of 1.66 Gy were 13.26 (10.53-16.50) and 16.19 (15.00-17.40) for the controls and exposed, respectively. The difference is statistically significant (p < 0.038). Among the exposed group, the challenge response was also significantly correlated with the cumulative lifetime exposure to styrene (R2 = 0.3996; p < 0.015) but not with the current exposure as measured in blood (R2 = 0.0226; p = 0.700). The challenge responses in the short-term and long-term exposed subgroups were 15.55 (14.23-16.96) and 17.90 (15.64-20.39), respectively, based on sample sizes of 5 and 9, respectively. The difference was not significant. Hence, data from our study are consistent with the hypothesis that long-term exposure to styrene can interfere with DNA repair activities. The lack of statistically significant differences in some of the data may be due to the small sample size and a possible confounding by age in our investigation. Additional data from our ongoing study should clarify this uncertainty.

Adult↗
PubMed2005

Migration of styrene monomer, dimers and trimers from polystyrene to food simulants.

Migration experiments with polystyrene were performed in two-sided contact with n-heptane and distilled water as the food simulants at temperatures of 10, 24 and 40, and 40, 60 and 90 degrees C, respectively. The surface/volume ratios in the migration cell were set at 8.04 and 10.05 dm2 l(-1) for n-heptane and distilled water, respectively. Styrene monomer, styrene dimers and styrene trimers migrating to the food simulants were determined by GC-FID analysis. Heptane fully extracted the styrene monomer and the oligomers from the polystyrene sheet, whereas in the distilled water only the migrated styrene trimers could be detected. To determine the apparent diffusion coefficient, the migration process was analysed based on Fick's law. The higher the molecular weight of the oligomers, the more significant the reduction in the diffusion coefficient. Higher molecular weight oligomers also had lower activation energy of diffusion when the temperature dependence of diffusivity was analysed by the Arrhenius equation. The diffusion coefficient of the trimers was much higher for heptane contact than for water. The activation energy of the diffusion of trimers for water contact was higher than that for heptane.

Chromatography, Gas↗
PubMed2006

Styrene metabolism, genotoxicity, and potential carcinogenicity.

This report reviews styrene biotransformation, including minor metabolic routes, and relates metabolism to the genotoxic effects and possible styrene-related carcinogenicity. Styrene is shown to require metabolic activation in order to become notably genotoxic and styrene 7,8-oxide is shown to contribute quantitatively by far the most (in humans more than 95%) to the genotoxicity of styrene, while minor ring oxidation products are also shown to contribute to local toxicities, especially in the respiratory system. Individual susceptibility depending on metabolism polymorphisms and individual DNA repair capacity as well as the dependence of the nonlinearity of the dose-response relationships in the species in question and the consequences for risk evaluation are analyzd.

Animals↗
PubMed1999

Occupational exposure to styrene in Norway, 1972-1996.

Occupational exposure to styrene has been of special concern in Norway since the beginning of the 1970s, especially the exposure in the reinforced plastic industry. Campaigns have been carried out by the Norwegian Directorate of Labour Inspection and various measures have been set forth to reduce the workers' exposure to styrene. Alongside the campaigns, extensive monitoring programs were carried out. The measurement results are compiled in the database EXPO at the National Institute of Occupational Health (Norway). This article presents a statistical analysis of the measurement data to assess the occupational exposure to styrene in Norway since the 1970s. Results from 7,011 measurements carried out in 234 enterprises covering the period 1972-1996 are included in the database. The analyses show occupational exposure to styrene of 33.0 ppm (median) (mean: 49.4 ppm) for this period. The analyses show a decrease from a median of 62 ppm in the 1970s to 7.1 ppm in the 1990s. The analyses do not disclose any crucial impact from any single preventive measure implemented by the authorities to reduce exposure level. The reduction in the level is probably due to a contribution from different measures. The decline in the styrene exposure coincides with a similar reduction in other countries, and it may be that international concern and technical improvements in the manufacturing process have been an important factor in the exposure level reduction in the Norwegian plastic reinforced industry as well.

Air Pollutants↗
PubMed1979

Effect of styrene and fiber glass on small airways of mice.

Three groups of 20 mice each were exposed to respirable glass fibers, to 300 ppm styrene vapor, and to glass fibers plus 300 ppm styrene. The glass fiber concentration was congruent to 1070/cm3; fiber diameters were under 3 micron and fiber lenths under 10 microns. The 5 h/d, 5 d/wk inhalation experiment lasted 6 wk. Glass fibers did not cause any lung damage when inhaled separately but combined styrene and glass fibers induced a change in the cellularity of the bronchiolar lining, where aprocrine-type cells became predominant. The same type of bronchiolar epithelial change was found in 10% of the styrene-exposed mice, while most of the styrene-exposed animals (90%) presented thickened bronchiolar walls becasue of stratification of the bronchiolar epithelium.

Aerosols↗
PubMedDate not supplied

Styrene emissions from the spray-up and vacuum injection processes--a quantitative comparison.

Styrene emissions were studied during manufacturing of two identical glass-fiber reinforced plastic boats by two different manufacturing methods. The manufacturing methods were spray-up, which is an open method, and vacuum injection, which is a closed method. Changing the manufacturing process from an open method to a closed method decreased the styrene evaporation dramatically in this particular case. By using vacuum injection, the styrene emission during the laminate application was reduced by 98% compared with the styrene emission during laminate application by spray-up. Gel coat application by spraying will remain a major source for styrene emissions. The greatest environmental benefit is achieved with closed manufacturing methods when products without gel coat are made. The whole manufacturing process can then be performed in a closed system virtually free from emissions.

Air Movements↗
PubMed2006

Encapsulation of chondrocytes in photopolymerizable styrenated gelatin for cartilage tissue engineering.

We have developed a photopolymerizable styrenated gelatin that can cross-link through polymerization induced by irradiation with visible light. The purpose of this study was to investigate the feasibility of using photopolymerizable styrenated gelatin as a cell carrier in chondrocyte transplantation. As visible light activates camphorquinone added as a photoinitiator, free radicals induce the polymerization of the gelatin macromer; the styrenated gelatin then becomes cross-linked. Rabbit articular chondrocytes were cultured in styrenated gelatin hydrogels and also in collagen gels as a control. After being cultured in the gels, the cells were collected from both gels and counted. Reverse transcriptase-polymerase chain reaction, histological examination, and quantification of the synthesized glycosaminoglycan were performed. On average, 26% of the embedded cells were collected from the gelatin hydrogel immediately after the crosslinking reaction. The surviving chondrocytes expressed the mRNA of type II collagen and aggrecan core protein and produced a cartilaginous matrix throughout the gelatin after 3 weeks. A slightly insufficient accumulation of the matrix was found in the internal region of the gelatin hydrogels, suggesting that less permeability for nutrients due to the high concentration and closely packed structure resulted in less cell viability. Although some limitations became evident, these results indicate that it may be possible to use photopolymerizable styrenated gelatin as a cell carrier in chondrocyte transplantation.

Animals↗
PubMed2004

Dermal exposure to styrene in the fibreglass reinforced plastics industry.

OBJECTIVES: The aim of this study was to assess the potential dermal exposure to styrene in the fibreglass reinforced plastics industry. METHODS: Assessment was performed during spraying and rolling using a patch sampling technique. The patch was made of charcoal sandwiched between two layers of cotton fabric. Samplers were fastened at 12 different spots on a sampling overall, each spot representing a body area. One patch was fastened at the front of a cap. A patch fastened to a string worn around the neck assessed the exposure at chest level inside the clothing. Patches were fastened to cotton gloves at sites representing the dorsal side and the palm of the hand to evaluate exposure on these areas. Following sampling the patches were solvent desorbed and styrene was analysed by gas chromatography flame ionization detection. RESULTS: The potential body exposure for the participating individuals was between 544 and 17 100 mg/h with a geometric mean (GM) of 3780 mg/h. The legs, arms and outer chest in general had the highest exposures. The left and right hands had mean (GM) exposures of 344 and 433 mg/h, respectively. Styrene was determined for the patch at the inside of the clothing, indicating contamination of the dermal layer. CONCLUSIONS: The charcoal patch can be used to evaluate potential exposure to styrene. The results indicate that the dermal layer of the worker is exposed to styrene. Precautions should be performed to reduce dermal exposure.

Aerosols↗
PubMed2006

Effect of styrene on postural stability among reinforced plastic boat plant workers in Finland.

OBJECTIVE: Many drugs are vestibulotoxic and may impair balance. Styrene is both ototoxic and neurotoxic, but its effect on balance has been little studied. We evaluate the effect of low concentrations of styrene on balance among Finnish fiberglass-reinforced plastic boat manufacturers. METHODS: From 252 male employees, we measured postural stability and urine mandelic and phenylglycolic acid concentrations. Individual exposure to styrene in breathing zone was measured for 148 workers. For analysis, 88 matched pairs were selected. RESULTS: The postural stability of laminators was aggravated compared with nonlaminators. This impairment was observed in young workers, and it worsened with age. CONCLUSIONS: This study documents styrene as an additional risk factor in impaired postural stability, with the negative effects of the styrene exposure starting already in younger workers.

Adolescent↗
PubMed2002

Biochemistry, genetics and physiology of microbial styrene degradation.

The last few decades have seen a steady increase in the global production and utilisation of the alkenylbenzene, styrene. The compound is of major importance in the petrochemical and polymer-processing industries, which can contribute to the pollution of natural resources via the release of styrene-contaminated effluents and off-gases. This is a cause for some concern as human over-exposure to styrene, and/or its early catabolic intermediates, can have a range of destructive health effects. These features have prompted researchers to investigate routes of styrene degradation in microorganisms, given the potential application of these organisms in bioremediation/biodegradation strategies. This review aims to examine the recent advances which have been made in elucidating the underlying biochemistry, genetics and physiology of microbial styrene catabolism, identifying areas of interest for the future and highlighting the potential industrial importance of individual catabolic pathway enzymes.

Aerobiosis↗
PubMed1980

Behavioural and glial cell effects of inhalation exposure to styrene vapour with special reference to interactions of simultaneous peroral ethanol intake.

Male Wistar rats were exposed to 300 p.p.m. of styrene vapour with simultaneous ethanol ingestion for 4 to 17 weeks. The effects on behaviour were analyzed after 4, 9 and 13 weeks of the experiment. The most manifest behavioural effects were found in rats exposed to the combination, and the changes included increased preening time at the 4th week and increased ambulation and rearing at the end of the exposure. The ethanol ingestion affected also the accumulation of the solvent burden by delaying the peak solvent concentration in the perirenal fat to the 8th week of exposure. The fat solvent concentration did not differ from each other in the two groups at the end of the experiment, and they were similar as compared the concentration found in phenobarbital-pretreated rats exposed for reference. The styrene exposure had almost no effects on cerebral glial cells whereas ethanol induced unexpectedly increased protein destruction in them throughout the experiment. Co-exposure to ethanol and styrene decreased the magnitude of protein destruction in the glial cells. Withdrawal of the rats after an 8-week exposure showed that the styrene effects were largely abolished in two weeks of exposure-free period as analyzed by the determination of brain RNA and acid proteinase activity. Brain RNA was lower than control after two weeks of ethanol deprivation. The present data indicate that marked metabolic interactions between ethanol and styrene take place in agreement with experience on other similar solvent combinations.

Adipose Tissue↗
PubMed1994

Metabolism of styrene by Rhodococcus rhodochrous NCIMB 13259.

Rhodococcus rhodochrous NCIMB 13259 grows on styrene, toluene, ethylbenzene, and benzene as sole carbon sources. Simultaneous induction tests with cells grown on styrene or toluene showed high rates of oxygen consumption with toluene cis-glycol and 3-methylcatechol, suggesting the involvement of a cis-glycol pathway. 3-Vinylcatechol accumulated when intact cells were incubated with styrene in the presence of 3-fluorocatechol to inhibit catechol dioxygenase activity. Experiments with 18O2 showed that 3-vinylcatechol was produced following a dioxygenase ring attack. Extracts contained a NAD-dependent cis-glycol dehydrogenase, which converted styrene cis-glycol to 3-vinylcatechol. Both catechol 1,2- and 2,3-dioxygenase activities were present, and these were separated from each other and from the activities of cis-glycol dehydrogenase and 2-hydroxymuconic acid semialdehyde hydrolase by ion-exchange chromatography of extracts. 2-Vinylmuconate accumulated in the growth medium when cells were grown on styrene, apparently as a dead-end product, and extracts contained no detectable muconate cycloisomerase activity. 3-Vinylcatechol was cleaved by catechol 2,3-dioxygenase to give a yellow compound, tentatively identified as 2-hydroxy-6-oxoocta-2,4,7-trienoic acid, and the action of 2-hydroxymuconic acid semialdehyde hydrolase on this produced acrylic acid. A compound with the spectral characteristics of 2-hydroxypenta-2,4-dienoate was produced by the action of 2-hydroxymuconic acid semialdehyde hydrolase on the 2,3-cleavage product of 3-methylcatechol. Extracts were able to transform 2-hydroxypenta-2,4-dienoate and 4-hydroxy-2-oxopentanoate into acetaldehyde and pyruvate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylates↗
PubMed1993

Exposure dependent increase in DNA single strand breaks in leucocytes from workers exposed to low concentrations of styrene.

Single strand breaks in DNA were monitored in leucocytes from 17 men occupationally exposed to styrene. Personal air monitoring was carried out during one workday with two diffusion samplers and a portable photoionisation detector placed in the breathing zone. Exposure to styrene was also monitored by analysing styrene in blood and urine and mandelic acid in urine. Single strand breaks were measured in leucocytes by the alkaline elution technique. The biological samples were collected before a shift, at the end of a shift, and the next morning, before the next shift. An exposure dependent increase in single strand breaks was seen at the end of a shift but not before a shift or the next morning. Linear regression analysis indicated that the amount of DNA damage was roughly doubled after eight hours of exposure to 18 ppm styrene or at a urine concentration of 240 mg mandelic acid/g creatinine compared with the damage in non-exposed men. This study indicates that monitoring of single strand breaks with the alkaline elution technique may be a sensitive marker of genotoxic effects. To our knowledge, this is the first time that such a marker has been shown to correlate with exposure to less than 20 ppm styrene.

Adult↗
PubMed2003

Exposure assessment of monoterpenes and styrene: a comparison of air sampling and biomonitoring.

BACKGROUND: Within- and between-worker variance components have seldom been reported for both environmental and biological data collected from the same persons. AIMS: To estimate these variance components and their ratio for air contaminants and urinary metabolites in two different work environments and to predict the attenuation of exposure-response relationships based on these measures. METHODS: Parallel measurements of air and urine were performed among workers exposed to monoterpenes in sawmills (urinary metabolite: verbenol) and styrene in reinforced plastics factories (urinary metabolite: mandelic acid). RESULTS: Among the sawmill workers, variance components of the air and urinary verbenol results were similar; for the reinforced plastics workers the estimated between-worker variance component was greater for styrene in air than mandelic acid in urine. This suggests that attenuation bias would be about equal if air or biological monitoring were employed for monoterpene exposures, but would be greater if urinary mandelic acid were used instead of airborne styrene in an investigation of styrene exposure. CONCLUSIONS: Personal air samplers provide data with similar or superior quality to urinary metabolites as measures of exposure to these monoterpenes in sawmills and styrene in reinforced plastics factories.

Air Pollutants, Occupational↗
PubMed2000

[Effects of low concentration of styrene monomer vapor on pregnancy].

To investigate the effects of exposure to styrene vapor on pregnancy, mice proved to be pregnant were exposed to 0, 2, 20 and 100 ppm styrene continuously for 24 hours during the period from day 0 to day 15 of gestation. A special small exposure chamber which can accurately maintain a constant low concentration of styrene vapor was made and used in the experiment. 1) In the 100 ppm group, hyperkinesis was presented in the chamber during the exposure period and inhibition of body weight gain was found (p < 0.01). No deaths occurred in any of the groups. 2) At necropsy of dams, no significant difference was found between the styrene exposed groups and the control group in any of the fertility indices, number of implantations, number of live fetuses, percentage of resorptions, or in the percentage of dead fetuses. The 100 ppm group showed lower fetal and placental weights (p < 0.01). 3) Gross necropsy of dams in the 100 ppm group showed significantly decreased adipose tissue. The liver, kidney and spleen weights were also low (p < 0.01). 4) When exposed to 100 ppm, which corresponds to 5 times the permissible concentration, i.e., 20 ppm, for 24 hours, non-pregnant dams showed no abnormality, while pregnant dams showed inhibition of body weight gain and significantly lower fetal and placental weights and maternal organ weights. Therefore, careful consideration should be given to exposure of women of childbearing age to styrene.

Animals↗