Polyester Manufacturing Research Articles

ANALISIS RASIO TERHADAP LAPORAN KEUANGAN PADA PT. POLYCHEM INDONESIA TBK

This research focuses on the financial analysis of PT Polychem Indonesia Tbk, a company engaged in the manufacture of polyester and chemicals. In this analysis, various financial ratios are used, including liquidity, solvency, activity and profitability ratios. The results show that in 2022, the company's liquidity ratio is higher than the industry average, but in 2023, the company's quick and cash ratios are lower than the industry average. The company's solvency ratio also shows that the company still has a fairly high level of debt, which makes it difficult to Overall, the analysis results show that PT Polychem Indonesia Tbk still has several financial problems that need to be corrected to improve its performance.

Performance assessment of up-flow anaerobic multi-staged reactor followed by auto-aerated immobilized biomass unit for treating polyester wastewater, with biogas production

Polyester manufacturing industries produce highly polluted effluents, containing organics, nutrients, trace metals, and 1,4-dioxane, requiring a high degree of treatment before being discharged into the water bodies. This study focused on removing complex pollutants from a diluted polyester industrial effluent (DPIE) via a cost-efficient anaerobic/aerobic combined system, with biogas recovery. The integrated pilot-scale system was composed of an up-flow anaerobic multi-staged reactor (UASR; V = 41 L) followed by an auto-aerated immobilized biomass (AIB; Vsponge = 9.54 L) unit and operated at a total organic loading rate (OLR) of 0.75 ± 0.16 g COD/L/d and pH of 7.14 ± 0.14 at 25 °C. The UASR achieved removal efficiencies of 17.82 ± 3.14% and 15.90 ± 3.08% for chemical oxygen demand (COD, total and soluble) and 15.83 ± 4.68% for total Kjeldahl nitrogen (TKN), with bio-CH4 yield of 263.24 ± 31.98 mL/g COD. Adding the AIB unit improved the overall CODtotal, CODsoluble, and TKN to 93.94 ± 2.39%, 94.84 ± 2.23%, and 75.81 ± 3.66%, respectively. The NH4-N removal efficiency was 85.66 ± 2.90% due to the oxic/nitrification condition on the sponge’s outer surface. The entire system also achieved 73.26 ± 2.68%, 77.48 ± 5.74%, and 81.26 ± 6.17% removals for Fe (3.93 ± 0.95 ppm), Zn (5.92 ± 2.32 ppm), and 1,4 dioxane (2.50 ± 0.61 ppm). Moreover, the UASR-AIB maintained removal efficiencies of 76.53 ± 8.47% and 77.51 ± 7.38% for total suspended solids (TSS: 335.95 ± 42.84 mg/L) and volatile suspended solids (VSS: 263.50 ± 36.94 mg/L). Regarding the DPIE toxicity level, the EC50 value increased from 12.9 to 39.4% after UASR/AIB application. The UASR’s microbial community at the genus level demonstrated that the synergistic cooperation of solubilization, hydrolysis, acidogenesis, acetogenesis, and methanogenesis was responsible for the degradation of DPIE components.

Selective Electrified Propylene-to-Propylene Glycol Oxidation on Activated Rh-Doped Pd.

Renewable-energy-powered electrosynthesis has the potential to contribute to decarbonizing the production of propylene glycol, a chemical that is used currently in the manufacture of polyesters and antifreeze and has a high carbon intensity. Unfortunately, to date, the electrooxidation of propylene under ambient conditions has suffered from a wide product distribution, leading to a low faradic efficiency toward the desired propylene glycol. We undertook mechanistic investigations and found that the reconstruction of Pd to PdO occurs, followed by hydroxide formation under anodic bias. The formation of this metastable hydroxide layer arrests the progressive dissolution of Pd in a locally acidic environment, increases the activity, and steers the reaction pathway toward propylene glycol. Rh-doped Pd further improves propylene glycol selectivity. Density functional theory (DFT) suggests that the Rh dopant lowers the energy associated with the production of the final intermediate in propylene glycol formation and renders the desorption step spontaneous, a concept consistent with experimental studies. We report a 75% faradic efficiency toward propylene glycol maintained over 100 h of operation.

1,5-Pentanediol production from 3,4-dihydro-2H-pyran and acetic acid via successive reactions of esterification and hydrogenation

1,5-Pentanediol as an important chemical intermediate is commonly used for the manufacture of polyesters and polyurethanes. A novel process was developed for the production of bio-based 1,5-pentanediol (1,5-PDO) from 3,4-dihydro-2H-pyran (DHP) and acetic acid (AA) in this work. The esterification of DHP and AA achieved a 59.8% DHP conversion and 91.2% tetrahydropyran-2-yl acetate selectivity (THPOAc) at 373 ​K for 1 ​h and DHP/AA molar ratio of 1 without catalyst. Then the 1,5-PDO with selectivity of 54.5% was obtained from THPOAc via hydrogenation over Cu/Zn8/Al catalyst under the conditions of 453 ​K and 50 ​bar. The higher dispersion of Cu nanoparticles, the larger surface area of metallic Cu, the higher amount of Cu+ active sites and the lower acidity of Cu/Zn8/Al catalyst were beneficial for the hydrogenation of THPOAc to 1,5-PDO.

Multi-step biosynthesis of the biodegradable polyester monomer 2-pyrone-4,6-dicarboxylic acid from glucose

Background2-Pyrone-4,6-dicarboxylic acid (PDC), a chemically stable pseudoaromatic dicarboxylic acid, represents a promising building block for the manufacture of biodegradable polyesters. Microbial production of PDC has been extensively investigated, but low titers and yields have limited industrial applications.ResultsIn this study, a multi-step biosynthesis strategy for the microbial production of PDC was demonstrated using engineered Escherichia coli whole-cell biocatalysts. The PDC biosynthetic pathway was first divided into three synthetic modules, namely the 3-dehydroshikimic acid (DHS) module, the protocatechuic acid (PCA) module and the PDC module. Several effective enzymes, including 3-dehydroshikimate dehydratase for the PCA module as well as protocatechuate 4,5-dioxygenase and 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase for the PDC module were isolated and characterized. Then, the highly efficient whole-cell bioconversion systems for producing PCA and PDC were constructed and optimized, respectively. Finally, the efficient multi-step biosynthesis of PDC from glucose was achieved by smoothly integrating the above three biosynthetic modules, resulting in a final titer of 49.18 g/L with an overall 27.2% molar yield, which represented the highest titer for PDC production from glucose reported to date.ConclusionsThis study lays the foundation for the microbial production of PDC, including one-step de novo biosynthesis from glucose as well as the microbial transformation of monoaromatics.

Analysis of a Two-Phase MHD Free Convection Generalized Water–Ethylene Glycol (50 : 50) Dusty Brinkman-Type Nanofluid Pass through Microchannel

The water–ethylene glycol (50 : 50) nanofluid has applications in the manufacture of polyester as a raw agent, air conditioning systems, antifreeze formulation, dehydrating agents in the gas industry, a precursor in the plastic industry, and convective heat transfer. These developments in nanotechnology and nanoscience have caught the interest of several researchers. Because it keeps machines and engines cool by reducing friction between their different parts, grease is a vital part of many machinery and engines. Also, due to the extensive use of fractional derivatives, this work seeks to evaluate the combined impacts of free convection flow and heat transfer, magnetic field, and Brinkman-type water–ethylene glycol (50 : 50) dusty nanofluid among microchannel. The flow that the buoyant force provides helps to carry heat naturally via convection. While the left plate moves at a consistent velocity and the right plate stays stationary, the fluid is also evenly dispersed with all dust particles that have a spherical form. Partial differential equations (PDE) are used to present the mathematical modeling. The resultant PDEs are generalized by utilizing the Caputo–Fabrizio fractional derivative. The problem’s closed-form solution is produced by combining a Laplace transformation with a finite sine Fourier transformation. It has also been studied that temperature, Brinkman nanofluid, and dust particle velocity relate to a variety of other factors, such as the magnetic parameter, Grashof number, dusty fluid parameter, and volume friction parameter. The graphical outcomes for the dusty fluid, Brinkman nanofluid, and temperature profiles are plotted using Mathcad-15. The Brinkman nanofluid and dusty fluid behave similarly for a variety of embedded factors. It is found that compared to the traditional one, the fractional dusty nanofluid model displays more realistic characteristics. The addition of nanoparticles in water–ethylene glycol (50 : 50) dusty nanofluid enhances the rate of heat transfer up to 41.04478% by increasing their volume fractional.

An overview on synthesis, properties and applications of poly(butylene-adipate-co-terephthalate)–PBAT

A significantly growing interest is to design new biodegradable polymers in order to solve fossil resources and environmental pollution problems associated with conventional plastics. A kind of new biodegradable polymers, aliphatic–aromatic co-polyesters have been researched widely and developed rapidly in recent years, since that can combine excellent biodegradability provided from aliphatic polyesters and good properties from aromatic polyesters. Out of which, poly (butylene-adipate-co-terephthalate) (PBAT) shows the most importance. PBAT has been commercialized by polycondensation reaction of butanediol (BDO), adipic acid (AA) and terephthalic acid (PTA) using general polyester manufacturing technology. And it has been considered to have desirable properties and competitive costs to be applied in many fields. Therefore, this review aims to present an overview on the synthesis, properties and applications of PBAT.

Potential of esterase DmtH in transforming plastic additive dimethyl terephthalate to less toxic mono-methyl terephthalate

Dimethyl terephthalate (DMT) is a primary ingredient widely used in the manufacture of polyesters and industrial plastics; its environmental fate is of concern due to its global use. Microorganisms play key roles in the dissipation of DMT from the environment; however, the enzymes responsible for the initial transformation of DMT and the possible altered toxicity due to this biotransformation have not been extensively studied. To reduce DMT toxicity, we identified the esterase gene dmtH involved in the initial transformation of DMT from the AOPP herbicide-transforming strain Sphingobium sp. C3. DmtH shows 24–41% identity with α/β-hydrolases and belongs to subfamily V of bacterial esterases. The purified recombinant DmtH was capable of transforming DMT to mono-methyl terephthalate (MMT) and potentially transforming other p-phthalic acid esters, including diallyl terephthalate (DAT) and diethyl terephthalate (DET). Using C. elegans as an assay model, we observed the severe toxicity of DMT in inducing reactive oxygen species (ROS) production, decreasing locomotion behavior, reducing lifespan, altering molecular basis for oxidative stress, and inducing mitochondrial stress. In contrast, exposure to MMT did not cause obvious toxicity, induce oxidative stress, and activate mitochondrial stress in nematodes. Our study highlights the usefulness of Sphingobium sp. C3 and its esterase DmtH in transforming p-phthalic acid esters and reducing the toxicity of DMT to organisms.

Identification of Biogas Production by Bio Methane Potential (BMP) Test During the Anaerobic Digestion Process of Organic Wastewater from Polyester Manufacturing Processes

Organic wastewater generated from polyester manufacturing processes was selected from H company to investigate the feasibility of anaerobic digestion that produces gases including methane. Bio Methane Potential (BMP) tests were conducted to measure the gas production and methane concentration for 7 process wastewater and 2 kinds of sludges from the H company. Also, along with monitoring pH and alkalinity during the anaerobic digestion process, the concentrations of COD and 1,4-dioxane were measured with 4 different operating conditions for N Emulsion (NE) and Ethylene Glycol (EG) wastewater. The BMP tests showed that 65% of methane was produced from NE and EG wastewater. This suggests that the organic wastewater from H company can be effectively treated by an anaerobic digester by which more than 90% of COD was removed.

Trace elements in laundry dryer lint: A proxy for household contamination and discharges to waste water

Seventy samples of laundry dryer lint from 19 households have been analysed for trace elements (As, Br, Cu, Fe, Ni, Pb, Sb, Zn) by energy-dispersive portable X-ray fluorescence (XRF) spectrometry. Bromine, Fe and Zn were detected in more than sixty samples encompassing all households, with dry weight concentrations ranging from 5.5 to 213 μg g−1, 76 to 3580 μg g−1 and 24 to 3540 μg g−1, respectively. Lead and Sb were detected in twenty and eight samples from ten and seven households, respectively, with concentrations ranging from about 8 to 110 μg g−1 for Pb and 40 to 90 μg g−1 for Sb. In contrast, As was only detected in six samples from the same household with concentrations ranging from about 10 to 250 μg g−1. Analysis of 72 items of new or clean clothing and linen revealed the ubiquity of Sb in synthetic (largely polyester-based) articles and the presence of Br in a variety of natural and synthetic articles, suggesting that the dominant source of these elements in dryer lint is derived from clothing fibres themselves; specifically, Sb2O3 is employed as a catalyst in the manufacture of polyester and various brominated compounds appear to be used as disperse dyes. No detectable As or Pb in the clothing-linen samples indicates that their presence in dryer lint arises from contamination of laundry from extraneous sources (e.g. household dust and material accumulated from outdoor activities) and suggests that concentrations can be used as proxies for exposure or household contamination. Since dryer lint is representative of material shed during the washing of clothes and linen, its composition also serves as a proxy for contaminants entering the environment from this process. Of particular significance in this respect is the discharge of chemicals specific to textiles or associated with microfibers.

Electrochemical Conversion of Biologically Produced Muconic Acid: Key Considerations for Scale-Up and Corresponding Technoeconomic Analysis

Muconic acid, an unsaturated diacid that can be produced from cellulosic sugars and lignin monomers by fermentation, emerges as a promising intermediate for the sustainable manufacture of commodity polyamides and polyesters including Nylon-6,6 and polyethylene terephthalate (PET). Current conversion schemes consist in the biological production of cis,cis-muconic acid using metabolically engineered yeasts and bacteria, and the subsequent diversification to adipic acid, terephthalic acid, and their derivatives using chemical catalysts. In some instances, conventional precious metal catalysts can be advantageously replaced by base metal electrocatalysts. Here, we show the economic relevance of utilizing a hybrid biological–electrochemical conversion scheme to convert glucose to trans-3-hexenedioic acid (t3HDA), a monomer used for the synthesis of bioadvantaged Nylon-6,6. Potential roadblocks to biological and electrochemical integration in a single reactor, including electrocatalyst deactivation due to bioge...

Electrochemical Conversion of Cis,Trans-muconic Acid to Trans,Trans-muconic Acid and Trans-3-Hexenedioic Acid for Bio-Based Polymer Production

The production of biorenewable chemicals has significantly evolved over the past years and numerous processes either have reached commercial stage or are close to commercialization.1 Recently, the biological synthesis of diacids has been receiving greater attention for the manufacture of green polyesters and polyamides.2 Muconic acid, an unsaturated C6 diacid, is quickly evolving as a high interest intermediate for the production of a wide variety of renewable chemicals from biomass (Fig. 1). The increased interest is due to the increasing market size of adipic acid and the need for greener synthesis. Electrocatalytic hydrogenation (ECH) represents a promising approach to combine the fermentative synthesis of muconic acid with its chemical catalytic diversification to produce these value-added chemicals. ECH typically proceed by applying a -0.3 to -1.8 V potential vs. Ag/AgCl on a transition metal electrode. In contrast to high pressure hydrogenations using noble metals, the electrocatalytic hydrogenation of muconic acid is facilitated through the reduction of protons on the surface of base metal catalysts, yielding interesting selectivities and conversion rates. We demonstrate that the use of Earth-abundant catalysts such as Pb also mitigate the necessity to separate amino acids from the fermentation broth that have been shown to readily poison archetypical hydrogenation catalysts such as Ni, Pd, and Pt3. Herein we screen a wide variety of early, late, and post transition metal catalysts in an attempt to identify key parameters that govern ECH selectivity and faradaic efficiency. In particular, we differentiate the selected transition metals based on the free energy of hydrogen absorption ΔGH on ECH performance (Fig. 2). Our studies detail the synthesis of trans,trans-muconic acid and trans-3-hexenedoic acid, two bio-based intermediates for the production of polyamides and polyesters, using low hydrogen overpotential metal catalysts. In contrast, high hydrogen overpotential metals produced trans-3-hexenedioic acid with high yield and faradaic efficiency. Conversion and selectivities after 1 h reaction durations for two particular electrocatalysts are displayed in table 1. In all cases, the need to identify binding strengths of the organic reactant will necessitate further correlations that determine hydrogenation product selectivity.

Influence of genetic polymorphisms of styrene-metabolizing enzymes on the levels of urinary biomarkers of styrene exposure

Styrene exposure is still present in different occupational settings including manufacture of synthetic rubber, resins, polyesters and plastic. The aim of this work was to investigate the effects of polymorphic genes CYP2E1, EPHX1, GSTT1, and GSTM1 on the urinary concentrations of the styrene metabolites mandelic acid (MA), phenylglyoxylic acid (PGA) and on the concentration ratios between (MA+PGA) and urinary styrene (U-Sty) and airborne styrene (A-Sty), in 30 workers from two fiberglass-reinforced plastic manufacturing plants and 26 unexposed controls. Personal air sampling and biological monitoring results revealed that sometimes exposure levels exceeded both the threshold limit value (TLV) and the biological exposure index (BEI) suggested by the American Conference of Governmental Industrial Hygienists. A significantly reduced excretion of styrene metabolites (MA+PGA) in individuals carrying the CYP2E1*5B and CYP2E1*6 heterozygote alleles, with respect to the homozygote wild type, was observed only in the exposed group. A reduction was also detected, in the same group, in subjects carrying the slow allele EPHX1 (codon 113), through the lowering of (MA+PGA)/urinary styrene concentration ratio. In addition, the ratio between MA+PGA and the personal airborne styrene concentration appeared to be modulated by the predicted mEH activity, in the exposed group, as evidenced by univariate linear regression analysis. Our results confirm some previous hypotheses about the role of the polymorphism of genes coding for enzymes involved in the styrene detoxification pathway: this may significantly reduce the levels of excreted metabolites and therefore it must be taken into account in the interpretation of the biological monitoring results for occupational exposure.

Synthesis and Characterization of Novel Diol, Diacid and Di‐isocyanate from Oleic Acid

AbstractNovel linear diol 2, diacid 3, and diisocyanate 4 with functional groups located at each end of the chain have been produced from oleic acid via a diester precursor. All the compounds were fully characterized by IR, 1H NMR, 13C NMR and Mass Spectrometry. These unbranched terminally‐functionalized compounds are important monomers for the manufacture of biodegradable thermoplastic polyurethanes and polyesters. The general synthetic scheme should also prove useful for the syntheses of diols, diacids and diisocyanates from any unsaturated fatty acid.

Scientific Opinion on the safety assessment of the substance, 2,2,4,4‐tetramethylcyclobutane‐1, 3‐diol (TMCD), CAS No 3010‐96‐6, for use in food contact materials

This scientific opinion of EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety re-evaluation of 2,2,4,4-tetramethylcyclobutane with the CAS No 3010-96-6, the Ref. No 25187 and the FCM substance No 881 for use as monomer in the manufacture of polyesters. Final articles are intended to be used in contact with non-fatty foods for long time storage at room temperature or below and hot fill. This application represents an extension for single use excluding fatty foods. Migration of the substance, reaction products related to the manufacturing process and oligomers from two typical polyester samples into 3 % acetic acid and 10 % ethanol was considered. Migration of the substance was found to be up to 2 µg/kg in food simulants. Migration of the reaction products was in the range from 1 to 40 µg/kg. Migration of each oligomer containing the substance moiety is estimated to be approximately 10 µg/kg food. The substance was previously evaluated and considered non-genotoxic. No genotoxicity is anticipated for the reaction products and oligomeric species. Therefore the CEF Panel concluded that for single uses, the substance 2,2,4,4-tetramethylcyclobutane-1, 3-diol is not of safety concern for the consumer if the substance is used as co-monomer in the production of polyesters at use levels up to 35 mol % of the diol component, in contact with all food types other than spirits and highly fatty foods simulated by D2, for long time storage at room temperature or below and hot fill.

Technology change priorities influencing competition quality promotion: Case study of Iran Keaton Polyester Manufacturing Company

Article history: Received March 22, 2012 Accepted 20 June 2012 Available online June 21 2012 In the changing world with various customers’ demands the businesses tend to improve their advantages to beat their rivals by means of better quality, lower prices and so. For Iranian polyester market quality is of crucial importance and is achieved through changing and updating technologies. According to highly regarded model of CAPTECH, which is recommended by UNIDO, technology parameters are defined in each phase and not generally as a whole. In the end the biggest gaps are defined. The main goal is to prioritize the main parameters affecting Iranian polyester company's quality. In order to fulfill our goal, 20 high and medium managers were questioned for this paper. The questions were gathered according to UNIDO samples. After a qualitative and quantitative test we concluded that the biggest gap is for supply chain(56.91) and the lowest gap is for combination phase(43.97). © 2012 Growing Science Ltd. All rights reserved.

DNA Damage and Susceptibility Assessment in Industrial Workers Exposed to Styrene

Styrene is a widely used chemical in the manufacture of synthetic rubber, resins, polyesters, and plastics. The highest levels of human exposure to styrene occur during the production of reinforced plastic products. The objective of this study was to examine occupational exposure to styrene in a multistage approach, in order to integrate the following endpoints: styrene in workplace air, mandelic and phenylglyoxylic acids (MA + PGA) in urine, sister chromatid exchanges (SCE), micronuclei (MN), DNA damage (comet assay), and genetic polymorphisms of metabolizing enzymes (CYP2E1, EPHX1, GSTM1, GSTT1, and GSTP1). Seventy-five workers from a fiberglass-reinforced plastics factory and 77 unexposed controls took part in the study. The mean air concentration of styrene in the breathing zone of workers (30.4 ppm) and the mean concentration of urinary metabolites (MA + PGA = 443 ± 44 mg/g creatinine) exceeded the threshold limit value (TLV) and the biological exposure index (BEI). Significantly higher SCE frequency rate and DNA damage were observed in exposed workers, but MN frequency was not markedly modified by exposure. With respect to the effect of genetic polymorphisms on different exposure and effect biomarkers studied, an increase in SCE levels with elevated microsomal epoxide hydrolase activity was noted in exposed workers, suggesting a possible exposure–genotype interaction.

Green Polymer Precursors from Biomass-Based Levulinic Acid

Levulinic acid (LA) has been identified as a suitable chemical feedstock that can be isolated from biomass. Its conversion into γ-valerolactone (GVL) via hydrogenation and ringclosure to the lactone has been studied as a versatile route to the manufacture of biodegradable polyesters. For hydrogenation of LA using Ru/C catalyst (the first method), conversion of LA at 100% was observed after 50min at 90¡C in water, with a GVL selectivity of 73%. The product selectivity may be steered by the temperature. At low temperatures 4-HVA is formed selectively, whereas higher temperatures favour the formation of GVL. Meanwhile in the second method, hydrogenation of LA using biphasic water soluble Ru-TPPTS catalysis made in situ in dichloromethane/water biphasic mixtures showed essentially quantitative GVL yields (82%) at 45bar, 90 ¡C and 60min reaction time (1% mol catalyst). As product of the LA hydrogenation, GVL has a very low reactivity for ring-opening due to a very low ring strain. Several studies therefore focused on GVL ring opening into polymerizable compounds but the results so far are unsatisfactory. In this work a novel route has been also investigated using amines for the ring-opening. Because of the basic properties, adding of amine compounds, such as ammonia, aminoethanol, ethylenediamine and piperazine has successfully converted the lactone into compounds containing two functional group viz. alcohol and amide, in essentially quantitative yields. Product design through varying the structure of the amine compound, such as backbone structure and presence of functional groups, appears to be a promising polymer engineering pathway. As such, the novel pathway delivered co-monomers for use in polymer synthesis, to manufacture possible green polymers.

The removal of 1,4-dioxane from polyester manufacturing process wastewater using an up-flow Biological Aerated Filter (UBAF) packed with tire chips

1,4-Dioxane is one of the by-products from the polyester manufacturing process, which has been carelessly discharged into water bodies and is a weak human carcinogen. In this study, a laboratory-scale, up-flow biological aerated filter (UBAF), packed with tire chips, was investigated for the treatment of 1,4-dioxane. The UBAF was fed with effluent, containing an average of 31 mg/L of 1,4-dioxane, discharged from an anaerobic treatment unit at H Co. in the Gumi Industrial Complex, South Korea. In the batch, a maximum of 99.5 % 1,4-dioxane was removed from an influent containing 25.6 mg/L. In the continuous mode, the optimal empty bed contact time (EBCT) and air to liquid flow rate (A:L) were 8.5 hours and 30:1, respectively. It was also found that the removal efficiency of 1,4-dioxane increased with increasing loading rate within the range 0.04 to 0.31 kg 1,4-dioxane/m3·day. However, as the COD:1,4-dioxane ratio was increased within the range 3 to 46 (mg/L COD)/(mg/L 1,4-dioxane), the removal efficiency unexpectedly decreased.

Styrene exposure and risk of cancer

Styrene is widely used in the manufacture of synthetic rubber, resins, polyesters and plastics. Styrene and the primary metabolite styrene-7,8-oxide are genotoxic and carcinogenic. Long-term chemical carcinogenesis bioassays showed that styrene caused lung cancers in several strains of mice and mammary cancers in rats and styrene-7,8-oxide caused tumours of the forestomach in rats and mice and of the liver in mice. Subsequent epidemiologic studies found styrene workers had increased mortality or incidences of lymphohematopoietic cancers (leukaemia or lymphoma or all), with suggestive evidence for pancreatic and esophageal tumours. No adequate human studies are available for styrene-7,8-oxide although this is the primary and active epoxide metabolite of styrene. Both are genotoxic and form DNA adducts in humans.