BACKGROUND: Indoor air quality (IAQ) is an important determinant of human health. In Japan, IAQ guidelines have been established for 13 chemicals since 1997. Regarding ethylbenzene (EB), a previous guideline value of 3800 µg/m³ was established in 2000. However, the Ministry of Health, Labour, and Welfare decided to revise the value because of the publication of new hazard information after the establishment of the previous guideline value and the establishment of their respective IAQ guidelines by foreign organizations based on the new hazard information. This study conducted a detailed hazard assessment on EB and derived hazard assessment values to provide a toxicologically valid basis for revising the IAQ guideline value. METHODS: As it was defined that the IAQ guidelines would not exert adverse health effects on humans even if they inhaled the chemicals from indoor air over a lifetime, we investigated the general toxicity, developmental and reproductive toxicity, genotoxicity, and carcinogenicity of EB based on reliable hazard information cited in published assessment documents by domestic, foreign, or international risk assessment organizations. All the collected hazard information was examined, and we originally judged the no-observed adverse effect level and the lowest observed adverse effect level of each toxicity study. We then selected the most appropriate key study, an endpoint, and a point of departure and derived the hazard assessment values for each toxicity category. Finally, we selected a representative hazard assessment value for EB from the minimum hazard assessment value among general toxicity, developmental and reproductive toxicity, and carcinogenicity. RESULTS: Among the three toxicity categories, the minimum hazard assessment value was obtained from general toxicity, which was 0.0858 ppm (370 µg/m³) based on the loss of the outer hair cells in the organ of Corti in the cochlea observed in a 13-week repeated-dose inhalation toxicity study using rats. CONCLUSIONS It would be appropriate to adopt 0.0858 ppm (370 µg/m³) as a representative hazard assessment value to provide a basis for revising the IAQ guideline value for EB.
Japan ; Air Pollution, Indoor/adverse effects* ; Risk Assessment ; Humans ; Benzene Derivatives/toxicity* ; Guidelines as Topic ; Animals ; Air Pollutants/toxicity*

Objective: To investigate the protective effect of diallyl sulfide (DAS) , against benzene-induced genetic damage in rat. Methods: In September 2018, Sixty adult male adaptive feeding 5 days, were randomly divided into six groups according to their weight. Control groups, DAS control groups, benzene model groups, benzene+low DAS groups, benzene+middle DAS groups, benzene+High DAS group, 10 in each group. Rats in the DAS and DAS control group were orally given DAS at 40, 80, 160, 160 mg/kg, blank control and benzene model groups were given corn oil in the same volume. 2 h later, the rats in the benzene model and DAS treatment groups were given gavage administration of benzene (1.3 g/kg) mixed with corn oil (50%, V/V) , blank and DAS control groups were given corn oil in the same volume. Once a day, for 4 weeks. Samples were collected for subsequent testing. Results: Compared with the blank control group, In benzene treated rat, peripheral WBC count was reduced 65.06% (P=0.003) , lymphocyte ratiowas reduced (P=0.000) , micronucleus rate was increased (P=0.000) , Mean fluorescent intensity and relative fluorescence intensity of γH2AX in BMCs were increased 32.69%、32.64% (P=0.001、0.008) , Mean fluorescent intensity and relative fluorescence intensity of γH2AX in PBLs were increased 397.70%、396.26% (P=0.000、P=0.003) respectively. Compared with the benzene model group, the WBC count increased respectively (P=0.000、0.003、0.006) and the micronucleus rate decreased (P=0.000、0.000、0.000) in the DAS groups, Mean fluorescent intensity and relative fluorescence intensity ofγH2AX in BMCs were significantly reduced in the high DAS groups (P=0.000、0.000) , Mean fluorescent intensity and relative fluorescence intensity ofγH2AX in PBLs were significantly reduced in the low, middle, high DAS groups (P=0.000、0.000) . Conclusion: DAS can effectively suppress benzene induced genotoxic damage in rats.
4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid/analogs & derivatives* ; Allyl Compounds/pharmacology* ; Animals ; Benzene/toxicity* ; Corn Oil ; DNA Damage ; Male ; Rats ; Sulfides/pharmacology*

OBJECTIVETo investigate the effect of ethylbenzene on the expression of heme oxygenase-1 (HO-1) intrarenal tissues.

METHODSForty male Sprague-Dawley rats were randomly and equally allocated to control group, low-dose exposure group, moderate-dose exposure group, and high-dose exposure group to inhale different doses of ethylbenzene (0, 433.5 mg/m(3) (100 ppm), 4335.0 mg/m(3) (1000 ppm), and 6500.0 mg/m(3) (1500 ppm)) for 6 h per day, 5 days per week, for 13 weeks. After the rat model of subchronic ethylbenzene exposure was established, the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) in renal tissues were measured, and the mRNA and protein expression levels of HO-1 in renal tissues were measured by real-time PCR and Western blot.

RESULTSCompared with the control group, all exposure groups showed significantly decreased activities of GSH-Px and CAT in renal tissues and the moderate- and high-dose exposure groups showed significantly decreased activity of SOD in renal tissues (P < 0.05). All exposure groups showed significantly higher expression of HO-1 than the control group (P < 0.05). The high-dose exposure group showed significantly higher expression of HO-1 than the low- and moderate-dose exposure group (P < 0.05), and the moderate- and high-dose exposure group had significantly higher expression of HO-1 than the control group and low-dose exposure group (P < 0.05).

CONCLUSIONA certain dose of ethylbenzene can induce elevated expression of HO-1 and decreased antioxidant levels in rat renal tissues, thus leading to oxidative stress damage.

Animals ; Benzene Derivatives ; administration & dosage ; toxicity ; Catalase ; metabolism ; Glutathione Peroxidase ; metabolism ; Heme Oxygenase (Decyclizing) ; metabolism ; Inhalation Exposure ; Kidney ; enzymology ; Male ; Rats ; Rats, Sprague-Dawley ; Superoxide Dismutase ; metabolism

OBJECTIVETo study the oxidative damage and apoptosis of renal tubular epithelial cells (NRK-52e cell line) induced by ethylbenzene.

METHODSNRK-52e cells were exposed to 30, 60, 90, 120 μmol/L ethylbenzene for 24 hours. Cell viability were measured using MTT, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), the contents of malondialdehyde (MDA) and glutathione (GSH) were detected respectively. PI fluorescent staining assay was applied to detect percentage of apoptosis in ethylbenzene-treated groups.

RESULTSCompared with control group, cell outline became clear, cell diopter increased, cell became smaller and shrinkage, some cells broke in 60 μmol/L ethylbenzene-treated group. Plenty of cells died, suspension cells increased significantly in 90 μmol/L ethylbenzene-treated group. Compared with control group, cell viability the activities of SOD and CAT and the content of GSH were significantly decreased in 60 and 90 μmol/L ethylbenzene-treated groups (P<0.05). The MDA content were remarkably elevated in 90 μmol/L ethylbenzene-treated groups (P<0.05).

CONCLUSIONEthylbenzene can induce oxidative stress and apoptosis in NRK-52e cells (P<0.05).

Animals ; Apoptosis ; drug effects ; Benzene Derivatives ; toxicity ; Cell Line ; Epithelial Cells ; drug effects ; metabolism ; Kidney Tubules ; cytology ; Oxidation-Reduction ; Oxidative Stress ; drug effects ; Rats ; Reactive Oxygen Species ; metabolism

OBJECTIVETo investigate the influence of ethylbenzene on oxidative damage, ultrastructure and the expressions of apoptosis-related genes in the rat brain tissues.

METHODSFour groups of 10 males of Sprague-Dawley rats were allocated randomly, and inhaled daily with different doses of ethylbenzene: 0, 433.5 mg/m³, 4335.0 mg/m³, and 6500.0 mg/m³ 6 h daily, 5 days per week for 13 weeks. The contents of glutathione (GSH) and malondialdehyde (MDA) and activity of acetylcholinesterase (AChE) were assayed, respectively. The ultrastructure of brain tissues was observed via electron microscope. The gene expression levels of Bax, Bcl-2, cytochrome C, caspase-9 and caspase-3 in brain tissues were measured by real-time polymerase chain reaction (PCR), respectively.

RESULTSThe contents of MDA [(2.03 ± 0.56), (4.17 ± 1.31) nmol/mg pro] in the brain tissues of 4335.0 mg/m³ and 6500.0 mg/m³ ethylbenzene-treated groups were significantly higher than that [(1.08 ± 0.26) nmol/mg pro] in the control group (P < 0.05), while AChE activities [(0.321 ± 0.066), (0.276 ± 0.031), (0.202 ± 0.041) U/mg] and GSH contents [(35.19 ± 15.08), (33.42 ± 15.32), (27.99 ± 7.53) mg/g pro] in all ethylbenzene-treated groups were remarkably depressed (P < 0.05, P < 0.05, respectively). After 6500.0 mg/m³ ethylbenzene inhalation, the nucleolus exhibit demilune with decreased mitochondria. Electrondense of myelin occurred in the injured nerve, ascribing to lipid peroxidationed membrane. The gene expression level of Bax in brain tissue of 4335.0 mg/m³ and 6500.0 mg/m³ ethylbenzene-treated group was significantly higher than that in the control group (P < 0.05). Compared with the control group, the gene expression levels of cytochrome C, caspase-9 and caspase-3 in all ethylbenzene-treated groups were enhanced (P < 0.05, P < 0.05, respectively), while bcl-2 gene expression levels in all ethylbenzene-treated groups were decreased (P < 0.05).

CONCLUSIONEthylbenzene can induce oxidative damage and apoptosis in brain tissues. The apoptotic mechanism might be involved with up-regulation of Bax, cytochrome C, caspase-9 and caspase-3, as well as restraint of Bcl-2.

Animals ; Apoptosis ; Benzene Derivatives ; toxicity ; Brain ; drug effects ; metabolism ; ultrastructure ; Caspase 3 ; metabolism ; Caspase 9 ; metabolism ; Cytochromes c ; metabolism ; DNA Damage ; Female ; Gene Expression ; Male ; Oxidative Stress ; drug effects ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo investigate the influence of ethylbenzene on the levels of mandelic acid (MA) and phenylglyoxylic acid (PGA) in urine, the ultrastructure and the expressions of mitochondrial apoptotic-related genes in the rat nephridial tissues.

METHODSFour groups of 10 males of Sprague-Dawley rats were allocated randomly into four groups: control (C) group, low (L) group, moderate (M) group and high (H) group, and inhaled daily with different doses of ethylbenzene: 0, 433.5 mg/m(3), 4335 mg/m(3), and 6500 mg/m(3) 6 h per day, 5 days per week for 13 weeks. The mandelic acid and phenylglyoxylic acid in the urine was assayed by high performance liquid chromatography. The ultrastructure of nephridial tissue was observed via electron microscope. The protein expression levels of Bax, Bcl-2, cytochrome C, Caspase-9 and Caspase-3 in nephridial tissues were measured by Western blot, respectively.

RESULTSThe levels of MA [(0.303 +/- 0.148) mg/L, (0.404 +/- 0.154) mg/L] and PGA [(0.168 +/- 0.104) mg/L, (0.174 +/- 0.092) mg/L] in the urine of M and H groups were significantly higher than that in the control and L group [(0.084 +/- 0.070) mg/L, (0.041 +/- 0.029) mg/L] (P < 0.05, respectively). It has been shown a dose-effect relationship between the contents of MA, PGA and MA + PGA and inhaled ethylbenzene, respectively. The mitochondria of rat nephridial tissue of H group became a compact and vacuolar structure with disorder and loss of cristae. The expression levels of Bax in mitochondria of nephridial tissues of M and H groups were significantly lower than that in the control group (P < 0.05). Caspase-3 expression level in H group was remarkably higher than that in the control group (P < 0.05). Compared with the control group, the expression levels of cytochrome C and Caspase-9 were enhanced, while the expression levels of Bcl-2 were restrained in all ethylbenzene-treated groups (P < 0.05, P < 0.05, respectively). The expression levels of Caspase-3 in M and H groups were significantly higher than that in the control group and L group (P < 0.05).

CONCLUSIONEthylbenzene can induce apoptosis in the cells of nephridial tissues. The apoptotic mechanism might be involved with up-regulation of Bax, cytochrome C, Caspase-9 and Caspase-3, as well as restraint of Bcl-2. The level of MA and PGA in the rat urine could be a parameter of biological dose in vivo after ethylbenzene inhalation.

Animals ; Apoptosis ; Benzene Derivatives ; toxicity ; Caspase 3 ; metabolism ; Caspase 9 ; metabolism ; Disease Models, Animal ; Glyoxylates ; urine ; Kidney ; drug effects ; metabolism ; ultrastructure ; Male ; Mandelic Acids ; urine ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Rats, Sprague-Dawley ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo investigate the chemical constituents of Desmodium blandum and their cytotoxic activity against the growth of several tumor cells.

METHODVarious chromatographic techniques including silica gel, Sephadex LH-20 column chromatography were employed for the isolation and purification of the constituents. The structures of compounds were elucidated by spectral analyses (IR, UV, NMR, MS). Their cytotoxic activity was then studied.

RESULTEight compounds were isolated from the stems of D. blandum and identified as N, N-dimethyltryptamine (1), 5-methoxy-N, N-dimethyltryptamine (2), citrusinol (3), yukovanol (4), (Z)-1-(4-hydroxy-2, 3-dimethoxyphenyl)-3-(4-hydroxyphenyl) propene (5), (Z)-1-(3-hydroxy-2, 4-dimethoxy-phenyl)-3-(4-hydroxy-3-methoxy-phenyl) propene (6), methylprotocatechuate (7), katuranin (8).

CONCLUSIONAmong these compounds, compound 6 was isolated from D. blandum for the first time. In the MTT test, compounds 2 and 6 exhibit cytotoxic activities against the KB cell, and compounds 3 and 6 exhibit the same activities against the HepG2 cell.

Alkenes ; chemistry ; pharmacology ; Benzene Derivatives ; chemistry ; pharmacology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Drugs, Chinese Herbal ; chemistry ; toxicity ; Fabaceae ; chemistry ; Humans ; Magnetic Resonance Spectroscopy ; Molecular Structure ; N,N-Dimethyltryptamine ; chemistry ; Plant Leaves ; chemistry ; Spectrometry, Mass, Electrospray Ionization ; Spectrophotometry, Infrared

OBJECTIVETo observe the urinary S-phenylmercapturic acid (S-PMA) variation in the benzene dynamic exposed rat models and benzene exposed workers, and study the feasibility of use of urinary S-PMA as the biomarker in benzene exposed.

METHODSIn an animal model study, forty-eight adult Wistar rats were randomly divided into 4 groups: the control group, low-dose group, middle-dose group and high-dose group. The exposed groups were dynamically exposed for 28 days (4 periods) by benzene and the concentration was monitored. The urine was immediately collected after every exposure period and detected by the liquid chromatographic/mass spectrometry methods. In a cohort study, eighty benzene exposed workers in a ship-yard in Guangzhou were selected as the exposed subjects while forty healthy officers in the same shipyard who were not occupationally exposed to benzene were treated as the control. The urine was collected after work shift. The urinary S-PMA and the benzene in the workplace was treated as the rat model.

RESULTSIn the animal model study, the urinary S-PMA increased along with the environment benzene in every period and had significantly difference in the different exposed groups (P < 0.01 or P < 0.05), but did not change along with the exposed time course (P > 0.05). In the cohort study, the urinary S-PMA in the high-dose group [(27.2 +/- 7.9)microg/L] was significantly higher than the low-dose group [(13.6 +/- 3.4)microg/L] (P < 0.01). Otherwise, the background of urinary S-PMA was lower than 5microg/L in both workers and rat models.

CONCLUSIONThe urinary S-PMA can be proposed as a sensitive biomarker of occupational benzene exposure.

Acetylcysteine ; analogs & derivatives ; urine ; Adult ; Animals ; Benzene ; administration & dosage ; toxicity ; Environmental Exposure ; adverse effects ; Female ; Humans ; Male ; Middle Aged ; Rats ; Rats, Wistar ; Young Adult

Adult ; Benzene ; toxicity ; Chromatography, High Pressure Liquid ; Humans ; Occupational Exposure ; Reference Values ; Sorbic Acid ; analogs & derivatives ; analysis

OBJECTIVETo establish an oxidative stress model induced by cumene hydroperoxide (cHP) in testis and epididymis of rats in vivo, and to understand the peroxidative damage of oxidative stress in testis, epididymal sperm and its propensity to induce nuclear DNA damage during spermatogenesis and sperm maturation in vivo.

METHODSAn organic hydroperoxide, cHP, 70% aqueous, diluted by 0.9% NaCl, was employed as model prooxidant. Ninety-day-old male Wistar rats were divided into a control and three cHP groups, and were administered intraperitoneally 0, 1/10, 1/6 and 1/4 LD50 cHP per day respectively at a dose of 2 ml/kg, for 7 consecutive days and were observed for any toxic symptoms and mortality. Twenty-four hours after the last dose, rats were sacrificed and induction of oxidative stress was ascertained by monitoring the degree of lipid peroxidation expressed as nano molar of malondialdehyde (MDA) in testicular homogenate and epididymal sperm. Nuclear DNA damage in testes and epididymal sperms was determined by comet assay. Motility of caudal sperms was counted and the morphology of testes and epididymis was observed under light microscope.

RESULTSRats of cHP administered groups were less vigorous than those of the control, but there were not death of rats during treatment. 1/10 LD50 per day for 7 consecutive days resulted in only a marginal increase in testicular MDA levels. However, 1/6 and 1/ 4 LD50 per day for 7 days of cHP administered to adult rats induced marked oxidative stress in testis and epididymal sperms as evidenced by a marked increase in MDA or nuclear DNA damage in testis and caput sperms, as well as significant decreases both in the body weight-and motility of caudal sperms. While the nuclear DNA damage caput sperms of 1/6 and 1/4 LD50 cHP administered rats increased significantly, nuclear DNA damage in caudal sperms showed no treatment related alterations.

CONCLUSIONOxidative stress in testis and epididymal sperms can be safely induced by applying multiple doses of cHP (1/6 and 1/4 LD50 per day for seven consecutive days). DNA damage caused by cHP induced oxidative stress may occurred mainly in testes.

Animals ; Benzene Derivatives ; toxicity ; DNA Damage ; Epididymis ; drug effects ; pathology ; Lipid Peroxidation ; drug effects ; Male ; Rats ; Rats, Wistar ; Sperm Count ; Spermatozoa ; drug effects ; pathology ; Testis ; drug effects ; pathology