Toxicity of some phenolic derivatives--in vitro studies.

Cytotoxicity of 5 phenol derivatives (phenol, catechol, resorcinol, hydroquinone and phloroglucinol) was tested using a mouse 3T3 fibroblast cell line. Its relationships with structural and physicochemical properties were investigated. Linear regression analysis and Pearson's correlation coefficient were used to characterise the relationship between cytotoxicity (expressed by IC(50) values) and physicochemical parameters of compounds or their toxicity in vivo expressed by LD(50) values. The studies showed that physicochemical properties of compounds seemed to have less influence on their cytotoxic potency than structural properties. Cytotoxicity of the compounds probably depends on the number of -OH groups and their location in the aromatic ring more than on physicochemical properties of compounds. The best correlation was obtained for IC(50) values and LD(50) values determined following rabbit skin administration and experimental skin irritation score.     

The Cytotoxicity of Some Organic Solvents on Isolated Hepatocytes in Monolayer Culture

The cytotoxic effects of volatile and water-insoluble organic solvents (ethylbenzene, tetrachloroethylene, n-hexane) were tested on isolated hepatocytes in monolayer culture by using the 3-(4,5 dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction assay. All of the tested compounds inhibited metabolic activity of hepatocytes and this effect depended on the concentration of solvents in the incubatory medium. The presence of fetal calf serum in the medium did not change the cytotoxicity of xenobiotics. IC₅₀ values calculated on the basis of the MTT assay indicated that ethylbenzene was more cytotoxic than tetrachloroethylene and n-hexane. Using hepatocyte monolayer culture and the MTT assay to assess cytotoxicity of organic solvents causes many technical problems. It seems that it cannot be used as a rapid, cheap, and credible method.     

不同粒径的大气细颗粒物对A549细胞的毒性研究

研究了不同粒径的大气细颗粒物对人肺癌上皮细胞A549的生物学效应,探讨了大气中细颗粒物粒径与细胞毒性的关系。采集杭州市大气中不同粒径的细颗粒物,制备成不同粒径的颗粒物总悬浮液,将A549细胞暴露于该制备液24 h后,测定细胞活力(MTT法)和培养液上清液中的LDH含量;并选择最佳浓度为后续暴露剂量,测定ROS生成量,评价不同粒径大气细颗粒物对细胞损伤效应。此外,还采用RTPCR测定凋亡基因P50、BAX、BCL-2表达情况。不同粒径的细颗粒物均显著抑制A549细胞活力,LDH显著增多,并存在剂量-效应关系;最佳染毒质量浓度为10μg/m L;ROS的生成量和各个凋亡基因的mRNA表达量均高于对照组。大气中不同粒径的细颗粒物均能对A549细胞产生毒性,并且随粒径增加,颗粒物对细胞的毒性呈降低趋势。     

Permeability of Medical Gloves to Mono- and Dimethacrylate Monomers in Dental Restorative Materials

Dental personnel manually handle methacrylate-based restorative materials, which can cause skin irritation and allergies. The protection given by different types of medical gloves is not well known. Breakthrough time (BTT, min) was used as a measure of protection according to a European standard, using 2 test mixtures consisting of respectively 3 and 5 monomers. Fourteen gloves representing natural rubber latex, synthetic rubber, and synthetic polymeric material were tested. The BTT ranged from some minutes to more than 2 hrs for the 4 monomers with a molecular mass less than 300. The longest protection was recorded for Nitra Touch (nitrile rubber), Tactylon (synthetic rubber), and Metin (PVC).     

Improved VOC bioremediation using a fluidized bed peat bioreactor

A gas–solid fluidized bed bioreactor was successfully used to treat air contaminated with a volatile organic compound (VOC). A bioreactor containing both a fluidized and packed bed of moist peat granules removed ethanol, a representative VOC, from an air stream. The fluidized bed operation mode of the bioreactor outperformed the packed bed mode. The maximum elimination capacity (EC) of ethanol in the fluidized mode was 1520 g m⁻³ h⁻¹, with removal efficiencies ranging between 45 and 100%, at loadings up to 3400 g m⁻³ h⁻¹. Maximum EC was 530 g m⁻³ h⁻¹ in the packed bed mode. Removal efficiency in the fluidized bioreactor was best at the lowest velocity, where the bubbling bed fluidization regime predominated. As gas velocity increased, the size and amount of large bubbles (slugs) increased and removal efficiency decreased while elimination capacity increased.     

Protection from steam at high pressures: development of a test device and protocol.

Extensive use of pressurized steam in the oil and gas sectors has led to incidents where workers were seriously injured. In this study a test device and procedure to measure heat transfer through fabrics during steam exposure were developed and evaluated. Several factors were considered while designing the test device to simulate work site conditions. Fabrics were exposed to steam at 2 distances (50 and 100 mm) and 2 pressures (207 and 69 kPa). Theoretical considerations included heat and mass transfer, and fabric structure and performance properties. The test device and procedure differentiated well among both fabrics and exposure conditions. For all fabrics, maximum heat transfer was observed at highest steam pressure and shortest distance. Laminated and coated fabrics performed better than a fabric without such treatments.     

Safety Level of Acrobatic Work: A Probabilistic Study

Acrobatic work constitutes an activity during which individuals intervene on buildings, cliffs, towers, and so forth, through the use of mountaineering or speleological techniques. The most dangerous situations occur particularly when ascending a rope with ascenders or roping with a descender. Any free fall or false manoeuvre will result in a strong shock on the belaying system that may cause its rupture. The fatal accident rate (FAR) of a given occupation is defined as the average number of fatal accidents per 10⁸ hrs of exposure to a given hazard. In this study it is assumed that the FAR is proportional to the average number of fall-initiating events, η, per worker and per hour of exposure to the fall hazard. η is estimated to be between 10^-3 and 3 × 10^-3. The maximum values of the rupture probability of the securing systems are calculated for the FAR of acrobatic work to be smaller than the FAR of the three most dangerous activity groups of the construction industry in France. These values allow the varying ranges of the parameters that influence this rupture probability to be determined.     

一体式膜生物反应器污水处理工艺研究

在一体式膜生物反应器研制开发实验及反应器各参数运行协调理论分析的基础上,提出了一体式膜生物反应器工艺各参数间的设计原则、方法、步骤及设计实例,对该工艺的运行能耗作了评价.     

Heart Rate Variability in Exposure to High Altitude Hypoxia of Short Duration

Abstract

The objective of the study is to attempt an evaluation of heart rate (HR) and heart rate variability (HRV) regulatory mechanisms in the presence of autonomous nervous system (ANS) components in transient exposure to high altitude hypoxia.

During 24 hrs including a stay in hypobaria, the participants had their HR continuously recorded using the Holter method. The following parameters were calculated at rest and during the stay in a thermobarochamber: spectral power in low frequency bands (LF) 0.04-0.15 Hz and high frequency bands (HF) 0.15-0.5 Hz, and the sympathetic-parasympathetic balance index LF/HF.

Under hypobaric conditions, a decrease in mean spectral power of R-R intervals was noted within both frequency ranges, compared with the study performed in normobaria. The observed differences were larger at daytime.     

Self-assessment of hearing status and risk of noise-induced hearing loss in workers in a rolling stock plant

Noise measurements and questionnaire inquiries were carried out for 124 workers of a rolling stock plant to develop a hearing conservation program. On the basis of that data, the risk of noise-induced hearing loss (NIHL) was evaluated. Additionally, the workers' hearing ability was assessed with the (modified) Amsterdam inventory for auditory disability and handicap, (m)AIADH. The workers had been exposed to noise at A-weighted daily noise exposure levels of 74-110 dB for 1-40 years. Almost one third of the workers complained of hearing impairment and the (m)AIADH results showed some hearing difficulties in over half of them. The estimated risk of hearing loss over 25 dB in the frequency range of 3-6 kHz was 41-50% when the standard method of predicting NIHL specified in Standard No. ISO 1999:1990 was used. This risk increased to 50-67% when noise impulsiveness, coexposure to organic solvents, elevated blood pressure and smoking were included in calculations.     

不同煤矿噪声暴露时间对视觉认知影响研究

噪声是煤矿井下主要危害,对人体视觉系统的影响不容忽视。为了提高暴露在噪声环境中工人的视觉认知能力,进而减少人因事故的发生,针对视觉认知随噪声暴露时间的变化进行研究,利用Eye Link II眼动仪采集被试者的平均注视时间、平均眼跳幅度和眼跳次数3个眼动指标来衡量视觉认知能力随着综采工作面噪声暴露时间的变化。结果表明:1)噪声能够使视觉注意力下降,对视觉认知效率的影响不显著,对视觉辨识能力的影响较复杂;2)噪声在0~10 min和40~55 min时间段对视觉注意力影响较严重,在0~15 min和50~80 min时间段对视觉辨识能力影响较严重;3)被试者随时间变化出现视觉性疲劳后,噪声可轻微提高视觉认知效率和视觉辨识能力。     

Computer professionals and Carpal Tunnel Syndrome (CTS).

Carpal Tunnel Syndrome (CTS) is an important problem among computer professionals. Hence the prevalence of CTS among computer professionals and risk factors were studied. 648 subjects were selected from 4,276 computer professionals from 21 companies by with simple random sampling method. CTS was diagnosed based on clinical features. The prevalence of CTS was found to be 13.1% (95% CI 10.5-15.7%). Subjects with over 8 years of computer work, over 12 hrs of work per day and system administrators were at a higher risk for CTS (OR 3.3, 4.9 and 2.5 respectively). Flexed or extended hand position had higher risk for CTS. Higher risk for CTS was found with higher exposure to computer work. Ergonomic considerations are important in facilitating proper positioning of hand while working with a computer. Further studies on CTS risk factors among computer professionals are essential for planning prevention.     

Health effects associated with long-term occupational exposure of employees of a chlor-alkali plant to mercury

This study aimed to evaluate possible health effects associated with long-term occupational exposure to low levels of mercury vapors. Forty-six subjects exposed to mercury and 65 healthy unexposed employees were studied. The subjects were administered a questionnaire on experienced symptoms and underwent clinical examinations as well as routine biochemical tests. Atmospheric and urinary concentrations of mercury were measured, too. Environmental concentrations of mercury were estimated to be 3.97 ± 6.28 μg/m(3) and urinary concentrations of mercury in exposed and referent groups were 34.30 ± 26.77 and 10.15 ± 3.82 μg/dm(3), respectively. Additionally, symptoms such as somatic fatigue, anorexia, loss of memory, erethism, blurred vision and teeth problems were significantly more common among exposed individuals. These observations indicate that occupational exposure to mercury vapors, even at low levels, is likely to be associated with neurological and psychological symptoms.     

Computer Professionals and Carpal Tunnel Syndrome (CTS)

Carpal Tunnel Syndrome (CTS) is an important problem among computer professionals. Hence the prevalence of CTS among computer professionals and risk factors were studied. 648 subjects were selected from 4,276 computer professionals from 21 companies with a simple random sampling method. CTS was diagnosed based on clinical features.

The prevalence of CTS was found to be 13.1% (95% CI 10.5–15.7%). Subjects with over 8 years of computer work, over 12 hrs of work per day and system administrators were at a higher risk for CTS (OR 3.3, 4.9 and 2.5 respectively). Flexed or extended hand position had higher risk for CTS.

Higher risk for CTS was found with higher exposure to computer work. Ergonomic considerations are important in facilitating proper positioning of hand while working with a computer. Further studies on CTS risk factors among computer professionals are essential for planning prevention.     

间歇曝气对膜生物反应器影响的试验研究

膜生物反应器是生物处理和膜分离相结合的一种高效的废水处理方法.通过研究,膜生物反应器具有较好的硝化能力.主要通过间歇曝气的运行方式来考察MBR对有机物和氨氮的去除效果.试验结果表明:合理的间歇时间能提高反应器对有机物和氨氮的去除效果.     

Research on simultaneous impact of hand-arm and whole-body vibration

This article presents the results of laboratory tests on the combined effect of whole-body vibration (WBV) and hand-arm vibration (HAV). The reactions of subjects exposed to various combinations of vibration were recorded. The vibrotactile perception threshold (VPT) test identified changes caused by exposure to vibration. Ten male subjects met the criteria of the study. There were 4 series of tests: a reference test and tests after exposure to HAV, WBV, and after simultaneous exposure to HAV and WBV. An analysis of the results (6000 ascending and descending VPTs) showed that the changes in VPTs were greatest after simultaneous exposure to both kinds of vibration. The increase in VPT, for all stimulus frequencies, was then higher than after exposure to HAV or WBV only.     

An Ergonomics Study of a Semiconductors Factory in an IDC for Improvement in Occupational Health and Safety

The study aimed to conduct an ergonomic intervention on a conventional line (CL) in a semiconductor factory in Malaysia, an industrially developing country (IDC), to improve workers’ occupational health and safety (OHS). Low-cost and simple (LCS) ergonomics methods were used (suitable for IDCs), e.g., subjective assessment, direct observation, use of archival data and assessment of noise. It was found that workers were facing noise irritation, neck and back pains and headache in the various processes in the CL. LCS ergonomic interventions to rectify the problems included installing noise insulating covers, providing earplugs, installing elevated platforms, slanting visual display terminals and installing extra exhaust fans. The interventions cost less than 3 000 USD but they significantly improved workers’ OHS, which directly correlated with an improvement in working conditions and job satisfaction. The findings are useful in solving OHS problems in electronics industries in IDCs as they share similar manufacturing processes, problems and limitations.     

ZnO nanoparticles induced cytotoxicity on human pulmonary adenocarcinoma cell line LTEP-a-2

Novel nanoparticles (NPs) such as zinc oxide (ZnO) NPs are widely produced and applied in our daily lives at a rapid pace. Thus, the toxicity of ZnO NPs should be monitored as an important standard for environmental risk assessment. Here we assessed the in vitro cytotoxicity of ZnO NPs on human pulmonary adenocarcinoma cells LTEP-a-2 by tetrazolium salt colorimetric assay of cell proliferation in the presence or absence of ZnO NPs. ZnO NPs-induced morphological changes in LTEP-a-2 cells were examined by light and scanning electron microscopy. The mechanism by which ZnO NPs impose the cytotoxic effect was investigated by a combination of active oxygen test, lactose dehydrogenase-release assay, and apoptosis detection. Results showed that ZnO NPs significantly inhibited the proliferation and induced evident morphological changes (cell shrinkage and chromosome condensation) in LTEP-a-2 cells. Additionally, ZnO NPs increased the level of intracellular reactive oxygen species and induced the formation of apoptotic vesicles as well as the lysis of cell nuclei. Zn²⁺ ions released from ZnO NPs into aqueous solution are important components that exert cytotoxic effects on LTEP-a-2 cells. This study provides new insights to the cytotoxicity of ZnO NPs against human health.     

Mass transfer and bioremediation of aromatics from NAPL in a baffled roller bioreactor

A non-aqueous phase liquid (NAPL) containing dissolved naphthalene or phenol was used to simulate water insoluble contaminants which are produced during the processing of oil sands. Mass transfer and biodegradation of organic contaminants in the aqueous phase were studied in a baffled roller bioreactor. Mass transfer of both naphthalene and phenol from NAPL into the aqueous phase was completed in less than 60 min, by which time naphthalene reached its saturation concentration in the aqueous phase and phenol was completely transferred into the aqueous phase. Pseudomonas putida (ATCC 17484) was subsequently used in biodegradation experiments in the baffled bioreactor containing the model NAPL contaminant. The optimum loading of NAPL for biodegradation of naphthalene at 500 mg/L was found to be 40%. High biodegradation rates (136.4 mg/L h for naphthalene and 13.2 mg/L h for phenol based on the working volume of the bioreactor) were achieved. In the case of simultaneous biodegradation of naphthalene and phenol, the highest total biodegradation rate of 102.6 mg/L h was achieved.