Concentration Of Styrene In Air Research Articles

Occupational exposure to BTEX and styrene in West Asian countries: a brief review of current state and limits.

The aim of introducing occupational exposure limits (OELs) is to use them as a risk management tool in order to protect workers’ health and well-being against harmful agents at the workplace. In this review we identify OELs for benzene, toluene, ethylbenzene, xylene (BTEX), and styrene concentrations in air and assess occupational exposure to these compounds through a systematic literature search of publications published in West Asian countries from 1980 to 2021. OELs for BTEX and styrene have been set in Iran and Turkey to levels similar to those in European countries and the US. The search yielded 49 full-text articles that cover studies of exposure assessment in six countries, but most (n=40) regard Iran. Average occupational exposure to benzene of workers in oil-related industries is higher than recommended OEL, while average occupational exposure to other compounds is lower than local OELs (where they exist). Currently, information about levels of occupational exposure to BTEX and styrene is insufficient in West Asian countries, which should be remedied through OEL regulation and application. Furthermore, coherent research is also needed to determine actual levels of occupational exposure, dose-responses, and the economic and technical capacity of local industries to address current issues.

Significant association between decreased ALDH2 activity and increased sensitivity to genotoxic effects in workers occupationally exposed to styrene.

ALDH2 is involved in the metabolism of styrene, a widely used industrial material, but no data are available regarding the influence of this enzyme on the metabolic fate as well as toxic effects of this chemical. In this study, we recruited 329 workers occupationally exposed to styrene and 152 unexposed controls. DNA strand breaks, DNA-base oxidation in leukocytes and urinary 8-hydroxydeoxyguanosine (8-OH-dG) were assayed as biomarkers to measure genotoxic effects. Meanwhile, we examined the genetic polymorphisms, including ALDH2, EXPH1, GSTM1, GSTT1 and CYP2E1, and also analyzed the levels of styrene exposure through detecting urinary styrene metabolites and styrene concentration in air. In terms of DNA damage, the three genotoxic biomarkers were significantly increased in exposed workers as compared with controls. And the styrene-exposed workers with inactive ALDH2 *2 allele were subjected to genotoxicity in a higher degree than those with ALDH2 *1/*1 genotype. Also, lower levels of urinary styrene metabolites (MA + PGA) were observed in styrene-exposed workers carrying ALDH2 *2 allele, suggesting slower metabolism of styrene. The polymorphisms of other enzymes showed less effect. These results suggested that styrene metabolism and styrene-induced genotoxicity could be particularly modified by ALDH2 polymorphisms. The important role of ALDH2 indicated that the accumulation of styrene glycoaldehyde, a possible genotoxic intermediate of styrene, could account for the genotoxicity observed, and should be taken as an increased risk of cancer.

A Field Study to Determine the Effectiveness of Several Respiratory Protection Masks on the Styrene Exposure during Lamination Activities

The purpose of this study is to examine the effectiveness of several types of personal respiratory protection equipment at styrene exposed laminators under real work place conditions. 99 male styrene exposed workers were examined. During their lamination activities the average styrene concentrations in air ranged between 30 to 60 ppm (maximum: 205 ppm). The laminators were followed during an usual workweek from Monday to Thursday. The external styrene exposure was measured by means of passive active carbon badges. The excretion of mandelic acid (MA) and phenyl glyoxylic acid (PGA) in end-of-shift urine samples was used to quantify the internal styrene load. During the work shift some laminators did not use respiratory protection masks. The majority used either a half face mask with active carbon filter or an air purifying respirator. The respiratory masks were worn during an average between 31% and 72% of the work time. The styrene concentrations of the ambient air were -depending on the activity- in the range of 30 to 60 ppm. The end-of-shift concentrations of MA and PGA in urine samples varied considerably, their means range from 153 to 606 mg/g creatinine. The comparison shows that workers with air purifying respirators experience the lowest internal styrene body burden in spite of high external exposures. Their effectiveness during usual working condition was around 83% whereas the use of half face masks with active carbon filters reduce styrene exposure only of 26% as an average. The use of styrene-containing resins in boatbuilding can be associated with increased external styrene exposure of the laminators. During the use of different types of respiratory protection masks it is shown that only the application of air purifying respirators leads to a significant reduction of the internal styrene body burden of 83% when worn during 72% of the total work time. In this way it is possible to comply with or to stay clearly below the biological limit value of 600 mg MA + PGA/g creatinine (BAT-value).

Low human exposure to styrene in relation to chromosome breaks, gaps and sister chromatid exchanges.

Hansteen, I.-L., Jelmert, o., Torgrimsen, T. and Forsund, B. 1584. Low human exposure to styrene in relation to chromosome breaks, gaps and sister chromatid exchanges. —Hereditas 100: 87–91. Lund, Sweden. ISSN 0018–0661. Received May 30, 1983 Measurements of styrene concentration in air and determination of urine metabolites were performed each day for one week prior to taking blood samples for cytogenetic investigation, in order to compare these findings with the cytogenetic results. The results showed levels of styrene exposure well below the recommended level of 50 ppm for all the 18 workers tested. No increase in number of chromosome breaks and SCE's was found in the workers for this low level of styrene exposure compared to a control group. A significant increase in gaps was found in the workers, however, and the possibility of using gaps as an indication of low level exposure is discussed. When the material was grouped according to smoking habits, a significant increase in chromosome breaks was found in the smokers, but no increase in SCE was found, indicating that the SCE method must be applied with caution and on a large number of individuals when used for monitoring purposes.

Neurobehavioural changes and persistence of complaints in workers exposed to styrene in a polyester boat building plant: influence of exposure characteristics and microsomal epoxide hydrolase phenotype

OBJECTIVESTo investigate neurobehavioural effects and the persistence of complaints in workers exposed to styrene relative to exposure characteristics and the enzyme microsomal epoxide hydrolase (mEH) activity.METHODSA cross sectional study was...

An evaluation of styrene genotoxicity using several biomarkers in a 3-year follow-up study of hand-lamination workers

A study employing several biomarkers of styrene exposure and genotoxicity was carried out in a group of lamination (reinforced plastic) workers and controls, who had been repeatedly sampled during a 3-year period. Special attention will be paid to the last sampling (S.VI), reported here for the first time. Styrene concentration in the breathing zone, monitored by personal dosimeters, and urinary mandelic acid (MA) were measured as indicators of external exposure. Blood samples were assayed for styrene-specific O 6-guanine adducts in DNA, N-terminal valine adducts of styrene in haemoglobin, DNA single-strand breaks (SSB), determined by use of the single cell gel electrophoresis (Comet) assay), and hypoxanthine guanine phosphoribosyl transferase (HPRT) mutant frequencies (MF) in T-lymphocytes. O 6-styrene guanine adduct levels were significantly higher in the exposed group (5.9±4.9 adducts/10 8 dNp) as compared to laboratory controls (0.7±0.8 adducts/10 8 dNp; P=0.001). DNA adduct levels significantly correlated with haemoglobin adducts, SSB parameters and years of employment. Styrene-induced N-terminal valine adducts were detected in the lamination workers (1.7±1.1 pmol/g globin), but not in the control group (detection limit 0.1 pmol/g globin). N-terminal valine adducts correlated strongly with external exposure indicators, DNA adducts and HPRT MF. No significant correlation was found with SSB parameters. A statistically significant difference in HPRT MF was observed between the laminators (22.3±10.6/10 6) and laboratory controls (14.2±6.5/10 6, P=0.039). HPRT MF in the laminators significantly correlated with styrene concentration in air, MA and haemoglobin adducts, as well as with years of employment and age of the employees. No significant difference ( P=0.450) in MF between the laminators and the factory controls was observed. Surprisingly, we detected differences in MF between sexes. When data from all measurements were combined, women showed higher MF (geometric mean 15.4 vs. 11.2 in men, P=0.020). The styrene-exposed group exhibited significantly higher SSB parameters (tail moment (TM), tail length (TL) and the percentage of DNA in the tail (TP)) than the control group ( P<0.001). SSB parameters correlated with indicators of external exposure and with O 6-styrene guanine adducts. No significant correlation was found between SSB parameters and haemoglobin adducts or HPRT MF. The data encompassing biomarkers from repeated measurements of the same population over a 3-year period are discussed with respect to the mechanisms of genotoxic effects of styrene and the interrelationship of individual biomarkers.

Increase in neuropsychiatric symptoms after occupational exposure to low levels of styrene.

The results of this study suggest that exposure to styrene below the current Swedish permissible exposure limit of 20 ppm induces neurotoxic effects expressed as an increased number of neuropsychiatric symptoms. Twenty men exposed to styrene at a plastics factory participated. The reference group included 20 non-exposed men matched for age, working schedule, and physical work load. Exposure to styrene during one workday was assessed by personal air monitoring and biological monitoring. To evaluate the physical work load the pulse(heart) rate was measured. One week before the study each man completed a neuropsychiatric symptom questionnaire containing 16 items. Also 17 questions regarding acute symptoms of local irritation and symptoms of the central nervous system were presented after the psychometric tests were performed. The tests were simple reaction time, colour word vigilance, and symbol digit. A follow up with regard to the symptoms among the exposed men was done after their summer vacation, about two to five weeks after their last exposure. The mean eight hour time weighted average (TWA) concentration of styrene in air, measured by passive dosimetry was 8.6 ppm (range 0.04-50.4 ppm). The exposed men had significantly more symptoms than the referents although there were no significant differences for the psychometric tests. At the follow up the exposed men reported fewer symptoms. This study indicates that symptoms are earlier indicators of adverse effects than complex tests and underlines the importance of regular follow up of people exposed to styrene (and probably organic solvents in general).

Occupational exposures to styrene in denmark 1955‐88

An assessment of the occupational exposure to styrene and associated chemicals in Denmark was carried out by retrieving all measurements from the archives of the Danish National Institute of Occupational Health. A total of 2,528 air samples containing styrene had been collected from 256 workplaces during the years 1955-88 and analyzed by the chemical laboratory at the Institute. The mean for all samples was 265 mg/m3. The concentration decreased from 714 mg/m3 in the early period (1955-70) to 172 mg/m3 in the late period (1981-88). Spraying and unspecified lay-up and production of boats, carriages, and stationary containers were associated with the highest concentration. A total of 34 chemicals were measured. The most frequent co-contaminant to styrene was acetone, which was measured in 2,263 samples with a mean concentration of 131 mg/m3. Dichloromethane was measured in 208 samples with a mean concentration of 51 mg/m3, xylene in 148 samples with a mean concentration of 49 mg/m3, and toluene in 116 samples with a mean concentration of 113 mg/m3. The study was undertaken to analyze historical styrene concentrations in air to aid in the selection of industrial cohorts to be included in epidemiologic studies.

Possible metabolic interaction of styrene with organic solvents.

Excretion of metabolites of styrene (dose: 2.2 mmol/kg i.p.) in 24-h urine was suppressed when rats were coinjected intraperitoneally with either toluene or trichloroethylene (dose: 2.2--11.0 mmol/kg) in addition to styrene, while a coinjection of n-hexane, ethyl acetate, methylchloroform, or acetone at an equimolar dose was ineffective in all cases. Suppressive effects of toluene and trichloroethylene were further confirmed by 6-h vapor exposure to (a) 0 to 1,300 ppm of toluene in addition to 150--170 ppm of styrene and (b) 0 to 4,000 ppm of trichloroethylene together with 100 or 150 ppm of styrene. The relationship between the amounts of three metabolites (i.e., phenylglyoxylic, mandelic and hippuric acids) in urine and styrene concentration in air was also determined.

Charcoal sampling method for determining the concentration of styrene in air.

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

LATE RESULTS OF INJECTION TREATMENT OF VARICOSE VEINS

<h3>OBJECTIVES</h3> To investigate neurobehavioural effects and the persistence of complaints in workers exposed to styrene relative to exposure characteristics and the enzyme microsomal epoxide hydrolase (mEH) activity. <h3>METHODS</h3> A cross sectional study was performed in a retrospective cohort of workers of a polyester boat building plant 3 years after the main activity shut down in 1989. Workers still currently exposed to a much lower concentration of styrene in air than before (n=27) and formerly exposed workers (n=90) were compared with matched control workers (n=64). Currently and formerly exposed workers laminated 4700 and 3610 hours on average at mean exposure to styrene concentrations of 148 and 157 mg/m³ respectively. A structured neurological anamnesis into former and present complaints, the NSC-60 questionnaire, and computer assisted neurobehavioural tests (NES) were administered. The mEH phenotype activity was measured in lymphocytes with a novel gas chromatography-mass spectroscopy (GC-MS) method. <h3>RESULTS</h3> For the period before 1989, currently and formerly exposed workers reported more complaints than control workers which related well with the mean exposure to airborn styrene concentration (p=0.03). Most complaints disappeared after the end of exposure, although the chest, equilibrium, and somatic category scores of NSC-60 and the number of workers reporting diminished sense of smell remained increased in formerly exposed workers (p⩽0.05). Symbol-digit substitution and digit span forwards test results were worse in currently and formerly exposed workers (p⩽0.01). In the combined group of currently and formerly exposed workers, the symbol-digit substitution and colour-word vigilance results related well to duration of exposure (p&lt;0.01 and p=0.03) and mEH phenotype activity (p=0.01 and p=0.05), whereas the digit span forwards results only showed associations of borderline significance (duration of exposure (p=0.08) and mEH phenotype activity (p=0.08)). <h3>CONCLUSION</h3> Most subjective symptoms were reversible but some persisted after the end of exposure to styrene, whereas dysfunction of visuomotor performance and perceptual speed seemed to persist. Duration of exposure at lamination tasks and the interaction, duration of exposure×concentration of exposure, were found to be the best predictors of worsening visuomotor and perceptual speed performances. Activity of the mEH phenotype may play a modulating part in styrene neurotoxicity. The results suggested that less than 10 years of exposure to atmospheric styrene at an average concentration of 155 mg/m³ may result in persistent neurotoxic effects.