A benzenesulfonic acid-modified organic polymer monolithic column with reversed-phase/hydrophilic bifunctional selectivity for capillary electrochromatography / 药物分析学报

Here,a styrene-based polymer monolithic column poly(VBS-co-TAT-co-AHM)with reversed-phase/hydrophilic interaction liquid chromatography(RPLC/HILIC)bifunctional separation mode was success-fully prepared for capillary electrochromatography by the in situ polymerization of sodium p-styrene sulfonate(VBS)with cross-linkers 3-(acryloyloxy)-2-hydroxypropyl methacrylate(AHM)and 1,3,5-triacryloylhexahydro-1,3,5-triazine(TAT).The preparation conditions of the monolith were optimized.The morphology and formation of the poly(VBS-co-TAT-co-AHM)monolith were confirmed by scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FT-IR).The separation perfor-mances of the monolith were evaluated systematically.It should be noted that the incorporation of VBS functional monomer can provide π-π interactions,hydrophilic interactions,and ion-exchange in-teractions.Hence,the prepared poly(VBS-co-TAT-co-AHM)monolith can achieve efficient separation of thiourea compounds,benzene series,phenol compounds,aniline compounds and sulfonamides in RPLC or HILIC separation mode.The largest theoretical plate number for N,N'-dimethylthiourea reached 1.7×105 plates/m.In addition,the poly(VBS-co-TAT-co-AHM)monolithic column showed excellent reproducibility and stability.This novel monolithic column has great application value and potential in capillary electrochromatography(CEC).

Screening potential P-glycoprotein inhibitors by combination of a detergent-free membrane protein extraction with surface plasmon resonance biosensor

P-glycoprotein (P-gp) highly expressed in cancer cells can lead to multidrug resistance (MDR) and the combination of anti-cancer drugs with P-gp inhibitor has been a promising strategy to reverse MDR in cancer treatment. In this study, we established a label-free and detergent-free system combining surface plasmon resonance (SPR) biosensor with styrene maleic acid (SMA) polymer membrane proteins (MPs) stabilization technology to screen potential P-gp inhibitors. First, P-gp was extracted from MCF-7/ADR cells using SMA polymer to form SMA liposomes (SMALPs). Following that, SMALPs were immobilized on an SPR biosensor chip to establish a P-gp inhibitor screening system, and the affinity between P-gp and small molecule ligand was determined. The methodological investigation proved that the screening system had good specificity and stability. Nine P-gp ligands were screened out from 50 natural products, and their affinity constants with P-gp were also determined. The in vitro cell verification experiments demonstrated that tetrandrine, fangchinoline, praeruptorin B, neobaicalein, and icariin could significantly increase the sensitivity of MCF-7/ADR cells to Adriamycin (Adr). Moreover, tetrandrine, praeruptorin B, and neobaicalein could reverse MDR in MCF-7/ADR cells by inhibiting the function of P-gp. This is the first time that SMALPs-based stabilization strategy was applied to SPR analysis system. SMA polymer can retain P-gp in the environment of natural lipid bilayer and thus maintain the correct conformation and physiological functions of P-gp. The developed system can quickly and accurately screen small molecule ligands of complex MPs and obtain affinity between complex MPs and small molecule ligands without protein purification.

Evaluation of the Suitability of Establishing Biological Exposure Indices of Styrene

BACKGROUND: This study was designed to provide logical backgrounds for the revision of biological exposure indices (BEIs) for styrene exposure in Korea. In order to investigate the correlation between airborne styrene and biological exposure indices, we measured urinary mandelic acid (MA) and phenylglyoxylic acid (PGA) in workers exposed to styrene occupationally, as well as airborne styrene at workplaces. METHODS: Surveys were conducted for 56 subjects. The concentrations of airborne styrene and urinary metabolites of styrene were measured in 36 workers who were occupationally exposed to styrene, and in 20 controls. Air samples were collected using personal air samplers and analyzed by gas chromatography. Urine samples were collected at the end of the shift and analyzed by high performance liquid chromatography. RESULTS: The geometric mean concentration of airborne styrene was 9.6 ppm. The concentrations of urinary MA, PGA, and MA+PGA in the exposure group were 267.7, 143.3, and 416.8 mg/g creatinine, respectively. The correlation coefficients for correlation between airborne styrene and MA, PGA, and MA+PGA were 0.714, 0.604, and 0.769, respectively. The sum of urinary MA and PGA corresponding to an exposure of 20 ppm styrene was 603 mg/g creatinine. CONCLUSION: The correlation of the sum of urinary MA and PGA with airborne styrene was better than the correlation of each individual urinary determinant. It is considered appropriate to amend the concentration of urinary MA+PGA to 600 mg/g creatinine as a BEI, which corresponds to an airborne styrene concentration of 20 ppm in Korea.

Synthesis of curcuminoid-imprinted polymers applied to the solid-phase extraction of curcuminoids from turmeric samples / 药物分析学报

A molecular imprinting polymer technique was successfully applied to precipitation polymerization by using styrene as a functional monomer, curcuminoids as templates, acetonitrile as a porogenic solvent, benzoyl peroxide as the initiator, and ethylene glycol dimethacrylate as the crosslinker. The effects of interaction on the adsorption capacity of the molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) were investigated. A comparison of the adsorption capacity for MIP and NIP indicated that the NIP had the lowest adsorption capacity. The curcuminoid-imprinted polymer (Cur-MIP) was syn-thesized from 0.0237 mmol of styrene, 47.0 g of acetonitrile, 1.0238 mmol of ethylene glycol dimetha-crylate, 0.0325 mmol of curcuminoids, and 0.2480 mmol of benzoyl peroxide. A high-performance liquid chromatography method with fluorescence detection was developed and validated for various chro-matographic conditions for the determination of the curcuminoids in turmeric samples. The sample solution was separated using the Cur-MIP via solid-phase extraction and analyzed on a Brownlee ana-lytical C18 column (150 mm × 6 mm, 5μm) using an isocratic elution consisting of acetonitrile and 0.1%trichloroacetic acid (40:60, v/v). The flow rate was maintained at 1.5 mL/min. The fluorescence detector was set to monitor atλex = 426 nm andλem = 539 nm. The quantification limit values were found to be 16.66, 66.66, and 33.33μg/L for curcumin, demethoxycurcumin, and bisdemethoxycurcumin, respec-tively. Thus, we concluded that the Cur-MIP and high-performance liquid chromatographic-fluorescence method could be applied to selective extraction and could be used as a rapid tool for the determination of curcuminoids in medicinal herbal extracts.

Study on the Migration of Residual Styrene to Moxifloxacin Hydrochloride and Sodium Chloride Injection from Five-layer Co-extrusion Bags / 中国药师

Objective:To establish a monitoring method for the detection of styrene monomer migration to moxifloxacin hydrochlo-ride and sodium chloride injection. Methods:A GC-MS method with a DB-5MS (30 m×0.25 mm,0.25 μm) column was used to determine styrene by the manner of large volume headspace purge-trap. Results:The linearity of styrene was good within the range of 0.009 1-0.364 μg·ml-1(r=0.999 9),and the average recovery of styrene in moxifloxacin hydrochloride and sodium chloride injec-tion was 99.4%(RSD=1.1%,n=9). After the detection of several batches of samples,the amount of styrene migration was all be-low the detection limit.Conclusion:The method can be used to measure the migration of styrene remained in five-layer co-extrusion in-fusion bags to moxifloxacin hydrochloride and sodium chloride injection.

Determination of phenylglyoxylic acid and mandelic acid in urine by high performance liquid chromatography method / 中华劳动卫生职业病杂志

Objective@#To revise the standard method for the determination of phenylglyoxylic acid(PGA)and mandelic acid(MA) in urine by ultra-performance liquid chromatography.@*Methods@#The original standard method was evaluated by experiment, and the chromatographic column, the detection limit,quantitation limit and stabilityof the method were studied.@*Results@#The samples were separated by BEH Phenyl(50mm×2.1mm×1.7μm)column and the internal standard working curve method was used. The regression equations were y=3.660 7x+0.066 3 and y=5.161 2x-0.007 3 for MA and PGA respectively. Linear correlation coefficients were 0.999 3 and 0.999 1. Linearity ranges were 0.10-1.00 mg/ml,0.04-0.40 mg/ml. The recoveries of PGA and MA were 91.6%-97.1% and 84.3%-99.0%,the precision were 0.9%-4.6% and 0.5%-1.9%. The detection limit and quantitation limit of the method were 1.1 mg/L and 3.7 mg/L for PGA, 5.4 mg/L and 17.9 mg/L for MA.@*Conclusion@#The method uses the phenyh modified chromatographic column, determines the detection limit. The method can improve quantitation limit, the detection accuracy and meet the detection of occupational population samples.

Occupational Styrene Exposure on Auditory Function Among Adults: A Systematic Review of Selected Workers

A review study was conducted to examine the adverse effects of styrene, styrene mixtures, or styrene and/or styrene mixtures and noise on the auditory system in humans employed in occupational settings. The search included peer-reviewed articles published in English language involving human volunteers spanning a 25-year period (1990–2015). Studies included peer review journals, case–control studies, and case reports. Animal studies were excluded. An initial search identified 40 studies. After screening for inclusion, 13 studies were retrieved for full journal detail examination and review. As a whole, the results range from no to mild associations between styrene exposure and auditory dysfunction, noting relatively small sample sizes. However, four studies investigating styrene with other organic solvent mixtures and noise suggested combined exposures to both styrene organic solvent mixtures may be more ototoxic than exposure to noise alone. There is little literature examining the effect of styrene on auditory functioning in humans. Nonetheless, findings suggest public health professionals and policy makers should be made aware of the future research needs pertaining to hearing impairment and ototoxicity from styrene. It is recommended that chronic styrene-exposed individuals be routinely evaluated with a comprehensive audiological test battery to detect early signs of auditory dysfunction.

A new styrene dimer derivative from Litsea greenmaniana / 中国中药杂志

A new styrene dimer derivative has been isolated from the branch of Litsea greenmaniana by column chromatography over silica gel and Sephadex LH-20, as well as semi-preparative HPLC. Its structure was identified by spectroscopic data analysis (MS, UV, IR, 1D and 2D NMR) as (E)-2,4-bis(p-hydroxyphenyl)-2-butenol, named as listeanol. At a concentration of 1×10-5 mol•L⁻¹, compound 1 was inactive in the assays, including cytotoxicity against human tumor cell lines (HCT-8, Bel-7402, BGC-823, A549 and A2780), antioxidant activity in Fe²⁺-cystine-induced rat liver microsomal lipid peroxidation, neuroprotective activity against serum deprivation or glutamate induced neurotoxicity in cultures of PC12 cells, and the inhibitory activity against protein tyrosine phosphatase 1B (PTP1B).

RISUG: An intravasal injectable male contraceptive.

Over the last two decades RISUG has been drawing attention in the field of male contraception. It promises to sterile men for a period of up to 10-15 years. According to recent studies in animal models, it proves to be completely reversible. Practically, there are no better options available that can assure complete sterility and precise reversibility. Regardless of so much of information available, RISUG is still holding up for many reasons, firstly, the available information engender bewilderment such as what is this copolymer, how does it work and is reversal really possible? Secondly, advancement of this outstanding invention is drastically slow and thirdly, effects of long-term contraception with RISUG and reports on evaluation of anomalies (if any) in F1, F2 progenies, are lacking. In this review the lacunae as well as advances in the development of RISUG in the light of published work and available resources are pointed out. Formulation of the RISUG, its mode of action and clinical trials have been addressed with particular emphasis.

Biofiltration of a styrene/acetone vapor mixture in two reactor types under conditions of styrene overloading

This aim of study was to compare the performance of a biofilter (BF) and trickle bed reactor (TBR) under increased styrene loading with a constant acetone load, 2 gc/m3/h. At styrene loading rates up to 30 gc/m3/h, the BF showed higher styrene removal than TBR. However, the BF efficiency started to drop beyond this threshold loading and could never reach steady state, whereas the TBR continued to yield a 50% styrene removal. The acetone removal remained constant (93-98%) in both the reactors at any styrene loading. Once the overloading was lifted, the BF recovered within 26 min, whereas the TBR efficiency bounced back only to 95%, gradually returning to complete removal only in 10 h.

Research on Pretreatment Method of Styrene Type Macroporous Resin and Its Application on Separation and Purification of Traditional Chinese Medicine / 世界科学技术-中医药现代化

This article was aimed to study pretreatment method of styrene type macroporous resin and its application in the industrial production. The organic residues and heavy metals of styrene type macroporous resin were detected respectively by gas chromatography and atomic absorption spectrophotometry before and after pretreatment to optimize the pretreatment process. The results showed that contents of organic residues and heavy metals of styrene type macroporous resin with the preferred method of pretreatment are in line with relevant regulations. It was concluded that this pretreatment method was simple and feasible, which is suitable to be applied in the industrial production.

Development of hot melt pressure sensitive adhesive for transdermal use and in vitro evaluation / 中国药学杂志

OBJECTIVE: To develop hot melt pressure sensitive adhesive (HMPSA) for transdermal use, and to investigate the in vitro drug release and permeation property of HMPSA based patches. METHODS: HMPSA was prepared using styrene-isoprene-styrene triblock copolymer (SIS), C5 petroleum resin hydrogenate, lanoline, liquid paraffin, dibutyl phthalate, 2, 6-ditertbutyl-cresol as material under orthogonal design. The formulation of HMPSA was screened using stickiness, melt temperature and vapor permeation rate as index. The in vitro drug release behavior and transdermal property of the optimized HMPSA were evaluated using a-asarone as model drug. RESULTS: The optimized formulation of HMPSA (HMPSA-OP) was followed as: SIS: C5 petroleum resin hydrogenate: lanoline: liquid paraffin: dibutylphthalate: 2, 6-ditertbutyl-cresol=100:140:20:40:20:2. HMPSA-OP had shown more rapid drug release than ordinary HMPSA. And the in vitro transdermal flux of HMPSA-OP was (4.75±0.84) μg · cm-2 · h-1, higher than that of ordinary HMPSA and acrylate PSA. CONCLUSION: The HMPSA-OP shows good property and was suitable to prepare transdermal patch.

Preparation of testosterone hot melt pressure sensitive adhesive transdermal patch / 中国药学杂志

OBJECTIVE: To prepare testosterone hot melt pressure sensitive adhesive (HMPSA) transdermal patch and investigate its percutaneous permeability in vitro. METHODS: The matrix of thermoplastic elastomer styrene-isoprene-styrene(SIS) hot melt pressure sensitive adhesive was used for testosterone transdermal patch. The percutaneous permeability through excised nude mice skin or porcine skin in vitro was conducted by Franz diffusion cells. Cumulative permeation quantity (Q) and steady state permeation rate (Jss) were evaluated to optimize drug loading capacity and enhancer. The optimal transdermal patches were compared with reference patches with regard to percutaneous behaviors using excised nude mice skin and porcine skin. RESULTS: The optimal formulation contained 2% testosterone, 6% transdermal enhancer isopropyl myristate(IPM). Its permeation behavior in vitro followed zero-order kinetics. The permeation behavior of the optimal patches was better than the reference patches for excised nude mice skin and porcine skin. CONCLUSION: SIS HMPSA has a broad application potential for transdermal drug delivery system.

Effect of a chloride channel inhibitor on proliferation and apoptosis of human trabecular meshwork cell / 中华实验眼科杂志

Background5-Nitro-2-(3-styrene-acrylic amine) benzoic acid ( NPPB),a chloride channel inhibitor,has a promoting effect on cell apoptosis in myocardial ischemia and reperfusion of domestic rabbit.The CIC chloride channel has been found in the ocular trabecular cells.However,the effect of NPPB on the shape and function of trabecular cells is unclear. Objective This study was performed to investigate the effect of NPPB on the proliferation,cell cycle progression and apoptosis of human trabecular meshwork cells.MethodsThe immortalized human trabcular cell strain was cultured,and logarithmic-phase cells were incubated in 96-well plates at a density of 1 ×106/ml.Different concentrations of NPPB (10,50,100 μ mol/L) were added to the medium,and the MTT assay was used to assess the growth and proliferation of the cells.Flow cytometry was used to evaluate the cell cycle.Then,100 mg/L 5-FU or 100 mg/L 5-FU + 100 μmol/L NPPB was used to induce cell apoptosis,which was assessed by Annexin V-PI.The membrane potential of mitochondria was examined using rhodamine 123 (△ψm).Results After 48 hours of treatment with NPPB,the abosorbency (A value) of the cells was gradually lowered with the increasing dose of NPPB,with significant differences among the 4 groups (F =7.230,P =0.006).Compared with the 10 μmol/L NPPB group,the A values were significantly declined in the 50 and 100 μmol/L NPPB groups (t =1.610,P =0.025 ;t =12.270,P =0.001 ).Forty-eight hours after exposure to NPPB,the percentage of cells in G0/G1 phase was increased and that in the S phase was decreased.The percentages of cells in different phases of cell cycle were significantly different in comparison with their control groups (without NPPB)( P＜0.05 ).Twenty-four and 48 hours after the treatment with 100 mg/L 5-FU,the apoptosis rates of the cells were raised in the 100 mg/L 5-FU group and 100 mg/L 5-FU + 100 μmol/L NPPB group compared to the without NPPB group (t24h =2.130,P =0.023;t48h =4.810,P=0.011 ) ;while that in the 100 mg/L 5-FU+100 μmol/L NPPB group was higher than the 100 mg/L 5-FU group ( t24 h =1.980,P =0.037 ; t48 h =1.290,P =0.028 ),and the mitochondrial membrane potential was lowered ( t24h =1.580,P =0.029 ; F48 h =6.200,P =0.015 ).Conclusions NPPB suppresses the proliferation of human trabecular cells and promotes the cells to enter S phase via the G1/S check point.In addition,ClC might be involved in an anti-apoptosis mechanism through the internal mitochondrial pathway.

Modelling the steady state and dynamic conditions of a biotrickling filter treating styrene and acetone in air

The aim of this work was the study a trickling biofilter, where water was circulated throughout the bed. In the first steady state experiment, the packing materials used were 25mm Pall rings. The airflow rate was increased gradually and the concentration of styrene in the air stream was held constant. In the second experiment, 15mm Pall rings were used. In this case, the feed contained both styrene and a small amount of acetone. The concentration of acetone and the air flow rate were kept constant, but the styrene inlet concentration was increased. The concentrations were measured at the input, and also at an intermediate and the outlet position in the biotrickling filter to determine the concentration profile along the reactor. Using the values of coefficient of determination (R²) and the coefficient of variation of the fitted constant as criteria, a zero order model with diffusional limitation was chosen as the best representation of the data. Then a further, third, set of experiments were done at unsteady state, using step changes of the inlet concentration levels of both styrene and acetone at a steady air flow-rate . Inlet and outlet concentrations were measured as a function of time and the results were adequately described using a simple first order model.

Styrene biofiltration in a trickle-bed reactor

The biological treatment of styrene waste gas in a trickle-bed filter (TBF) was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm) filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC).The main aim of our study was to observe the effect of empty-bed residence time (EBRT) on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3). EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC) of 11.3 gC.m-3.h-1 was reached at an organic loading (OL) rate of 18.6 gC.m-3.h-1.

Exposición a estireno en cabinas prefabricadas: Estudio comparativo 2003-2005 / Styrene exposure in pre-built cabins: Comparative study 2003-2005

Los objetos fabricados con las resinasreforzadas pueden liberar al medio ambiente, vapor de estireno, lo que conlleva a tener una exposición al disolvente. En Uruguay, para el desarrollo de diferentes tareas administrativas, de vigilancia, de comercio, etc. se utilizan unas cabinas que son fabricadas con resinas de poliester no saturadas. En un trabajo anterior se comprobó que existía exposición a estireno en este tipo de cabinas. El objetivo de este trabajo fue estudiar los riesgos higiénicos a los que está expuesto el personal de empresa que desarrolla sus tareas administrativas en cabinas de fibra de vidrio reforzadas de resina. Se realizaron muestreos ambientales en cabinas ubicadas en diferentes zonas del Montevideo durante el año 2004 y 2005. Los valores de referencia que se utilizaron fueron los de la American Conference of Governmental Industrial Hygienists (ACGIH) de 2006.El trabajo realizado demuestra que no existe exposición del personal a vapores de estireno en sus lugares de trabajo con el consiguiente riesgo descrito para estos productos. Considerando los resultados del año 2003, se concluye que los valores obtenidos ese año fueron puntuales del tipo de cabinas.

The objects made with reinforced resins can release styrene steam to the indoor environment, which involves worker´s exposure to this toxic solvent. In Uruguay, some administrative, commerce, and more tasks are carried out in those fiber glass cabins which are manufactured with those resins. In a previous study we had high values of styrene in air and his metabolites in urine for people working in this buildings. The aim of this study is the evaluation of the hygienic risks to exposed workers from different companies who perform their administrative tasks in reinforced fiber glass cabins. Environmental samplings were made. The reference values used were those of the American Conference of Industrial Governmental Hygienists of 2005 (ACGIH). The results obtained demonstrates that there was no exposure to styrene released from the cabin. The study in 2003 was a particular cabins problem.

Badge-type Passive Personal Sampler Used in Determination of Styrene in Air / 环境与健康杂志

Objective To make a passive personal sampler for the determination of the styrene in the air. Methods To make a passive personal sampler for the determination of the styrene in the air. Results Under the condition of wind velocity of 100-600 cm/s, relative humidity of 40%-80% and temperature of 10-40 ℃, the sampling flux of the passive sampler was 61.8 ml/min, the capacity was 5.95 mg, the shortest sampling time was 30 min, the self life was at least 30 days, the storage stability was at least 14 days, the RSDs were 8.07%-9.37%. Conclusion This new kind of passive personal sampler can be used as a new device for the determination of the styrene in the air.

Relationship between Phenylglyoxylic Acid in Urine and Postural Body Sway in Styrene Exposed Workers / 대한산업의학회지

OBJECTIVE: Until now,no effective screening tools have been available for evaluating the neurotoxicity of organic solvents and metals. The aim of this study was to evaluate the usefulness of posturography as a screening tool for the chronic neurotoxicity of organic solvents. METHOD: 36 workers in 4 septic tank manufacturers,who were exposed to styrene over a period of 1 year (exposed group),and 15 hospital volunteer manual workers were examined by posturography.The subjects' physical,medical,and occupational characteristics were obtained by means of a physical examination and a questionnaire. We excluded from both groups those persons who had psychiatric problems, diabetes, neurologic symptoms, gait disturbance,or a history of stroke.The sway area of the exposed group was compared to that of the non-exposed group using bivariate and multiple regression analysis. We controlled a number of variables including age, alcohol consumption,smoking, weight, height, and body mass index. RESULT: The sway area of the exposed group was found to be higher than that of the non-exposed group after taking into consideration the effects of other characteristics by means of multiple regression analysis. CONCLUSION: We concluded the posturography would be an effective tool for the screening of chronic neurotoxicity in workers exposed to styrene.

The primary death pathway of outer hair cells of rat cochlea following styrene exposure / 解放军医学杂志

Objective To compare the prevalence of apoptosis and necrosis, and investigate the primary death pathway of outer hair cells of rat cochlea following styrene exposure. Methods Fourteen adult Long Evans rats were used in the present study. The animals were randomly assigned into test group (n=8) and control group (n=6). Animals in test group were exposed to styrene by gavage at 400 mg/kg (2g styrene was mixed with 1ml olive oil). Treatment was performed once a day, 5 days per week for 3 weeks. Animals in control group were fed by gavage the same volume of olive oil on an identical time schedule used for the test group. The auditory brainstem response (ABR) thresholds of both ears elicited with clicks were measured before and at the end of the 3-week styrene or olive oil treatment. After hearing was re-assessed, animals were sacrificed and cochleae were quickly removed from the skull. Following fixation, whole specimens comprising the basilar membrane with Corti's organ were separated from the modiolus. Apoptotic, necrotic and missing outer hair cells (OHCs) were distinguished by combined assays of nuclear staining with propidium iodide (PI), TUNEL assay and filamentous actin(F-actin)staining with FITC-phalloidin. Each Corti's organ was thoroughly examined by fluorescence microscopy. The numbers of damaged OHCs (apoptotic, necrotic and missing OHCs) were documented. Results Neither threshold shift of ABR nor sign of hair cell (HC) damage was found in the cochlea of control animals. The animals of test group showed both physiological and pathological changes in the cochleae following the 3-week styrene treatment. ABR testing revealed an average of 15 dB of threshold shifts. F-actin staining exhibited the maximal level of OHCs damage in the middle portion of Corti's organ. The major damage occurred in the third row of OHCs, followed by the second and first rows of OHCs. Three types of morphological changes in damaged OHC nuclei were revealed by PI labeling: nuclear condensation, nuclear swelling and nuclear missing. Strong TUNEL green fluorescence appeared in the OHCs with condensed nuclei. Quantitative analysis showed that the average number of apoptotic OHCs was approximately three times greater than the number of necrotic OHCs (P=0.01). Conclusion It is indicated that apoptosis is the primary death pathway of OHCs leading to generation of the cochlear lesion following styrene exposure.