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PubMed2002

Assessment of sperm DNA integrity in workers exposed to styrene.

BACKGROUND: Occupational exposure to toxic agents may cause infertility, congenital anomalies or death in offspring, but few studies have evaluated DNA integrity in germ cells of male workers. We investigated sperm DNA integrity in individuals occupationally exposed to styrene. METHODS AND RESULTS: Semen samples were obtained from 46 male workers exposed to styrene and 27 unexposed controls (age range 18-45 years). Exposed individuals had worked for at least 2 years in the last 5 years and continuously for 6 months in factories producing reinforced plastics. The Comet assay was performed to evaluate DNA integrity in sperm, as well as semen quality analysis to assess sperm concentration and morphology. There were no differences in the results of the standard semen analysis between exposed subjects and the reference group. However, we found a significant difference (P < 0.001) in sperm DNA damage by the Comet assay between exposed subjects and the reference group. CONCLUSIONS: The Comet assay proved to be sensitive in detecting an alteration in DNA integrity in germ cells of workers exposed to styrene. This finding contributes towards the understanding of the importance of male occupational exposure within the context of genetic risk assessment in humans.

Adult↗
PubMed2002

Audiometric findings in workers exposed to low levels of styrene and noise.

Audiometry and exposure measurements were conducted on workers from fiberglass and metal products manufacturing plants and a mail distribution terminal (N = 313). Workers exposed to noise and styrene had significantly worse pure-tone thresholds at 2, 3, 4, and 6 kHz when compared with noise-exposed or nonexposed workers. Age, noise exposure, and urinary mandelic acid (a biologic marker for styrene) were the variables that met the significance level criterion in the multiple logistic regression. The odds ratios for hearing loss were 1.19 for each increment of 1 year of age (95% confidence interval [CI], 1.11-1.28), 1.18 for every decibel >85 dB(A) of noise exposure (95% CI, 1.01-1.34), and 2.44 for each millimole of mandelic acid per gram of creatinine in urine (95% CI, 1.01-5.89). Our findings suggest that exposure to styrene even below recommended values had a toxic effect on the auditory system.

Adult↗
PubMed2005

Styrene and ischemic heart disease mortality among synthetic rubber industry workers.

OBJECTIVE: We examined the relation between styrene and ischemic heart disease (IHD) mortality among 16,579 men in the synthetic rubber industry. METHODS: Associations were measured using stratified and multivariable analysis. RESULTS: Compared with workers with no exposure to styrene, men in the highest quintile of average intensity of exposure (5.50+ parts per million [ppm]) and in the highest quintile of cumulative exposure (60.67+ ppm-years) had IHD rate ratios of 1.14 (95% confidence interval [CI]=0.96-1.35) and 1.07 (95% CI=0.90-1.27), respectively. Acute IHD was not associated with average intensity of exposure within the most recent 2 years or with other indices of exposure. Chronic IHD rates were elevated in subjects with the highest exposure; these associations were weak and imprecise, and evidence of a positive exposure-response relation was limited. CONCLUSION: This study does not indicate that exposure to styrene causes fatal IHD.

Adult↗
PubMed1996

Cloning and characterization of styrene catabolism genes from Pseudomonas fluorescens ST.

A gene bank from Pseudomonas fluorescens ST was constructed in the broad-host-range cosmid pLAFR3 and mobilized into Pseudomonas putida PaW340. Identification of recombinant cosmids containing the styrene catabolism genes was performed by screening transconjugants for growth on styrene and epoxystyrene. Transposon mutagenesis and subcloning of one of the selected genome fragments have led to the identification of three enzymatic activities: a monooxygenase activity encoded by a 3-kb PstI-EcoRI fragment and an epoxystyrene isomerase activity and an epoxystyrene reductase activity encoded by a 2.3-kb BamHI fragment. Escherichia coli clones containing the 3-kb PstI-EcoRI fragment were able to transform styrene into epoxystyrene, and those containing the 2.3-kb BamHI fragment converted epoxystyrene into phenylacetaldehyde or, only in the presence of glucose, into 2-phenylethanol. The three genes appear to be clustered and are probably encoded by the same DNA strand. In E. coli, expression of the epoxystyrene reductase gene was under the control of its own promoter, whereas the expression of the other two genes was dependent on the presence of an external vector promoter.

Acetaldehyde↗
PubMed2005

Dual role of response regulator StyR in styrene catabolism regulation.

In Pseudomonas fluorescens ST, the promoter of the styrene catabolic operon, PstyA, is induced by styrene and repressed by the addition of preferred carbon sources. PstyA is regulated by the StyS/StyR two-component system. The integration host factor (IHF) also plays a positive role in PstyA regulation. Three distinct StyR binding sites, which have different affinities for this response regulator, have been characterized on PstyA. The high-affinity StyR binding site (STY2) is necessary for promoter activity. The DNA region upstream of STY2 contains a lower-affinity StyR binding site, STY1, that partially overlaps the IHF binding site. Deletion of this region, designated URE (upstream regulatory element), has a dual effect on the PstyA promoter, decreasing the styrene-dependent activity and partially relieving the glucose repression. The lowest-affinity StyR binding site (STY3) is located downstream of the transcription start point. Deletion of the URE region and inactivation of the STY3 site completely abolished glucose-mediated repression of PstyA. In the proposed model StyR can act either as an activator or as a repressor, depending on which sites it occupies in the different growth conditions. We suggest that the cellular levels of phosphorylated StyR, as determined by StyS sensor kinase activity, and the interplay of this molecule with IHF modulate the activity of the promoter in different growth conditions.

Bacterial Proteins↗
PubMed2006

Coregulation by phenylacetyl-coenzyme A-responsive PaaX integrates control of the upper and lower pathways for catabolism of styrene by Pseudomonas sp. strain Y2.

The P(styA) promoter of Pseudomonas sp. strain Y2 controls expression of the styABCD genes, which are required for the conversion of styrene to phenylacetate, which is further catabolized by the products of two paa gene clusters. Two PaaX repressor proteins (PaaX1 and PaaX2) regulate transcription of the paa gene clusters of this strain. In silico analysis of the P(styA) promoter region revealed a sequence located just within styA that is similar to the reported PaaX binding sites of Escherichia coli and the proposed PaaX binding sites of the paa genes of Pseudomonas species. Here we show that protein extracts from some Pseudomonas strains that have paaX genes, but not from a paaX mutant strain, can bind and retard the migration of a P(styA) specific probe. Purified maltose-binding protein (MBP)-PaaX1 fusion protein specifically binds the P(styA) promoter proximal PaaX site, and this binding is eliminated by the addition of phenylacetyl-coenzyme A. The sequence protected by MBP-PaaX1 binding was defined by DNase I footprinting. Moreover, MBP-PaaX1 represses transcription from the P(styA) promoter in a phenylacetyl-coenzyme A-dependent manner in vitro. Finally, the inactivation of both paaX gene copies of Pseudomonas sp. strain Y2 leads to a higher level of transcription from the P(styA) promoter, while heterologous expression of the PaaX1 in E. coli greatly decreases transcription from the P(styA) promoter. These findings reveal a control mechanism that integrates regulation of styrene catabolism by coordinating the expression of the styrene upper catabolic operon to that of the paa-encoded central pathway and support a role for PaaX as a major regulatory protein in the phenylacetyl-coenzyme A catabolon through its response to the levels of this central metabolite.

Acetyl Coenzyme A↗
PubMed1982

TLC separation of hippuric, mandelic, and phenylglyoxylic acids from urine after mixed exposure to toluene and styrene.

A method using thin-layer chromatography is described to determine the concentration of hippuric acid, mandelic acid, and phenylglyoxylic acid present in the urine after occupational mixed exposure to toluene and styrene. These substances are known metabolites of toluene and styrene, and therefore the evaluation to mixed exposure to toluene and styrene may be carried out separating these metabolites beforehand. Procedures are proposed to separate the metabolites as follows: (1) separation of hippuric acid from mandelic acid, (2) separation of mandelic acid from phenylglyoxylic acid, and (3) separation of hippuric acid and mandelic acid from phenylglyoxylic acid. The developing reagent p-dimethylaminobenzaldehyde in acetic acid anhydride was used after separation on Kieselgel and Silicagel. The sensitivity of the method was 6 microgram of hippuric acid, 10 microgram of mandelic acid, and 7 microgram of phenylglyoxylic acid with an average recovery of 94%.

Chromatography, Thin Layer↗
PubMed1989

Neuropsychiatric effects of low exposure to styrene.

Workers exposed to styrene concentrations of about 50 mg/m3 at a plant manufacturing reinforced polyester boats were examined for neuropsychiatric symptoms both in close connection with exposure and also seven months after exposure had ceased. Physical workload is important for the uptake of styrene and was about 50 W at this plant. On the first occasion, after one week with no exposure, the workers reported a high frequency of neuropsychiatric symptoms such as fatigue, irritation, and forgetfulness whereas seven months later the frequency of these symptoms was low. These observations indicate that exposure to styrene at about 50 mg/m3 may induce reversible neuraesthenic symptoms. Even the relatively low Swedish standard (110 mg/m3 = 25 ppm) may, therefore, need revising.

Adult↗
PubMed1992

Subclinical impairment of colour vision among workers exposed to styrene.

The effects of exposure to styrene were studied among 60 men aged 20 to 56 (mean 29.5) employed in shipbuilding. Exposure was due to the handling of glass reinforced polyester materials. The study was cross sectional and the workers were compared with a control group matched for age, social and occupational state, and ethnic origin. During the study, the mean atmospheric exposure to styrene was 24.3 ppm. Mean urinary elimination was 230 mg/g creatinine for mandelic acid and 57.4 mg/g creatinine for phenylglyoxylic acid. The Farnsworth 100 hue test showed no significant differences between the exposed and control groups for error scores. A significant difference was found, however, for the number of subjects with errors axis in the red-green, or blue-yellow ranges, or both, which was larger among the exposed workers (32/60 v 20/60 for the controls (p < 0.05)). Psychometric tests were also conducted, using the World Health Organisation (WHO) neurobehavioural core test battery. Of the seven tests it included, anomalies were only found for the aiming test. These results suggest that exposure to moderate styrene concentrations of the order of 25 ppm can lead to impairment of colour vision.

Adult↗
PubMed1996

Exposure to styrene and mortality from nonmalignant respiratory diseases.

A cohort of 34,560 men and 6128 women employed in 660 European factories manufacturing reinforced plastic products, followed up originally to assess the risk of cancer, was used to assess the risk of non-malignant respiratory diseases associated with exposure to styrene. Mortality from pneumonia was associated with intensity of exposure to styrene, but this may have been due to chance. Mortality from bronchitis, emphysema, and asthma was not associated with styrene exposure.

Cohort Studies↗
PubMed1984

Chromosomal aberrations in lymphocytes of workers exposed to low levels of styrene.

Chromosomal aberrations were studied in lymphocytes of 15 workers exposed to styrene and 13 controls. The average styrene concentration in the work room air was 24 ppm, and the levels of urinary mandelic acid were below 2 mmol/l. No significant increase in the rates of gaps and breaks was found. However, the rate of micronuclei was significantly increased, which indicates that the mitotic spindle mechanism may be more sensitive to styrene and its metabolites than DNA.

Adult↗
PubMed2003

Effects of peak concentrations on the neurotoxicity of styrene in volunteers.

The manufacture of fibreglass reinforced plastic products may give rise to substantial peak exposures to styrene. Such exposure patterns need further consideration in terms of styrene neurotoxicity. The aim of this study was to evaluate the neurotoxic effects of short-term peak exposures in volunteers, at levels respecting the Quebec occupational exposure limits (8 hours time weighed average of 213 mg/m3 and 15 min average of 426 mg/ m3). The volunteers had not been previously exposed to styrene and they had no documented exposure to known neurotoxicants during the study. Twenty-four volunteers were exposed to five exposure scenarios during 6 hours: a, stable exposure to 106 mg/m3; b, variable exposure with a mean concentration of 106 mg/m3 with four 15 min peaks mounting up to 213 mg/m3; c, stable exposure to 213 mg/m3; d, variable exposure with a mean concentration of 213 mg/m3 and four peaks of 426 mg/m3 and e, two stable exposures to 5 mg/m3 (control). Before and after each exposure scenario, volunteers were submitted to a battery of sensory tests (visual and olfactory), neuropsychological tests (reaction time, attention, memory, psychomotor function), and self-evaluation questionnaires (mood and symptoms) in a test-retest design. The results show that the different exposure scenarios involving peak exposures did not influence either the performance to any test or subjective signs and symptoms. However, due caution must be exercised in extrapolation of the current results to occupational exposure since only acute exposures were tested and volunteers were at rest during exposure, which resulted in lower doses than those experienced by physically active workers.

Administration, Inhalation↗
PubMed2004

Evaluation of the efficiency of respiratory protective equipment based on the biological monitoring of styrene in fibreglass reinforced plastics industries.

The purpose of the present study was to determine the efficiency of respiratory protective equipment in a fibreglass reinforced plastic factory by comparing results of environmental and biological monitoring of exposure to styrene. Five factories including 39 workers were investigated. Three types of respiratory protective equipment were tested: one was a half-mask air-purifying respirator equipped with a cartridge for organic solvents, another was a disposable gauze respirator impregnated with charcoal filter, and the third was a dust-proof respirator. The frequency of cartridge exchange of a half-mask respirator was twice a day only at one factory, and that was less than once a month at other factories. The site concentrations exceeded 20 ppm at 10 of the 82 sampling points (12.2%), and 22 of the 39 workers' (56.4%) personal exposure exceeded 20 ppm which is the current occupational exposure limit recommended by the Japan Society for Occupational Health. The efficiency of disposable gauze respirators and dust-proof respirators was low or rather zero. The average efficiency of half-mask respirators in which cartridges were exchanged twice a day and once a month was 83.6% and 46.6%, respectively. There was a significant disparity in the efficiency of the respirator depending on the frequency of cartridge exchange (p<0.05). Overall this study showed that even though a half-mask respirator is used and its cartridge is exchanged every half a day, workers exposed to a styrene concentration at or over 122 ppm are expected to inhale more than 20 ppm of styrene.

Adult↗
PubMed1981

Effect of styrene on hepatic mixed function oxidases, glutathione content and glutathione-s-transferase activity in rats.

Effect of styrene administration (250, 450 and 900 mg/kg orally for 7 consecutive days) on hepatic mixed function oxidase (MFO) enzyme activities, glutathione content and glutathione-S-transferase activity were observed. Activity of aryl hydrocarbon hydroxylase and aniline hydroxylase was significantly enhanced at higher doses of styrene (450 and 900 mg/kg). A significant lowering of glutathione content accompanied with the inhibition of glutathione-S-transferase activity was also noticed at the highest dose of styrene (900 mg/kg).

Aniline Hydroxylase↗
PubMed1992

Mortality among workers engaged in the development or manufacture of styrene-based products--an update.

Mortality was updated another 11 years through 1986 for a previously studied cohort of 2904 male chemical workers who were potentially exposed to styrene and related materials for a year or more between 1937 and 1971. Substantial deficits in mortality from all causes and total cancer were observed in the cohort when it was compared with white males in the United States, and also other chemical workers who were unexposed to styrene-based products. Mortality from leukemia was slightly less than expected during the updated period, in contrast to an excess of lymphatic leukemia observed in the original period. Yet small elevations in risk of other types of lymphatic cancer, particularly multiple myeloma, persisted. The risk of these cancers did not increase with estimated intensity or duration of styrene exposure. The findings are discussed in context with those of studies of similarly exposed workers in related industries.

Cause of Death↗
PubMed1987

Mortality of workers exposed to styrene in the manufacture of glass-reinforced plastics.

Epidemiologic studies have suggested an increased risk of leukemia and lymphoma among workers exposed to styrene. In a further exploration of this possible hazard, an analysis was conducted of the mortality among 7,949 men and women employed during 1947-1984 in eight British companies manufacturing glass-reinforced plastics. The subjects were identified from company files and traced to the end of 1984 through National Health Service and National Insurance records. The overall mortality in the cohort was less than in the national population (693 deaths observed, 830.1 expected) as was mortality from cancer (181 deaths observed, 223.7 expected). In particular, there was a deficit of deaths from lymphoid and hemopoietic cancer (6 observed, 14.9 expected). The small excess of lung cancer (89 deaths observed, 80.1 expected) was not statistically significant and can probably be attributed to chance. Among 3,494 hand laminators (the job with the highest exposure to styrene) there was one death from lymphoma and none from leukemia. The findings do not exclude the possibility that styrene is a human carcinogen, but give no support to the hypothesis that it causes leukemia and lymphoma.

Female↗
PubMed1982

Obstetric histories of women occupationally exposed to styrene.

To evaluate the possible embryotoxic effects of styrene, 67 female lamination workers occupationally exposed to styrene and 67 age-matched female industrial workers with no obvious chemical exposure were interviewed. The women, all under 40 a of age, did not differ significantly with respect to number of births, pregnancies, or spontaneous and induced abortions prior to the exposure period. During the styrene exposure the number of births was significantly lower among the exposed group, a result partly explained by a higher number of induced abortions. No differences were found in this material with regard to the number of spontaneous abortions.

Abnormalities, Drug-Induced↗
PubMed1998

Experience with a vocabulary test for workers previously and still exposed to styrene.

OBJECTIVES: This study examined the possible influence of styrene exposure on the results of vocabulary tests because verbal ability is assumed to be relatively resistant to the toxic effects of organic solvents and short vocabulary tests are used as "hold tests" in many neurobehavioral epidemiologic studies, METHODS: To evaluate the chronic neurotoxic effects of styrene, a vocabulary test was administered to a group of still-exposed workers (N=27) and an earlier exposed group of workers (N=90). A self-administered questionnaire was filled out on life events, general health, educational level, and amount of education. The still-exposed group had a mean exposure duration of 4700 hours, and that for the formerly exposed group was 3610 hours. RESULTS: The vocabulary score of the still-exposed group was significantly lower [12.5 (SD 2.9, range 6-18)] than that of their former colleagues [14.3 (SD 3.4, range 8-22)], even though they originally belonged to the same group and had done the same tasks. The exposure duration explained a significant part of the vocabulary results, resulting in decreasing vocabulary scores even when the influence of years of education and age was taken into account. Even after correction for the possible influence of having been laid off or staying at work, there remained a negative influence on the vocabulary score for the duration of styrene exposure. CONCLUSIONS: The use of short vocabulary tests as hold tests in cross-sectional studies of solvent-exposed workers may be limited as they seem to lack the essential toxicity-independent property.

Air Pollutants, Occupational↗