Occupational Hearing Loss among Chinese Municipal Solid Waste Landfill Workers: A Cross-Sectional Study

Background

Occupational hearing loss is an increasingly prevalent occupational condition worldwide, and has been reported to occur in a wide range of workplaces; however, its prevalence among workers from municipal solid waste landfills (MSWLs) remains less clear. This study aimed to investigate the occupational hearing loss among Chinese MSWL workers.

Methods

A cross-sectional study of 247 workers from 4 Chinese MSWLs was conducted. Noise and total volatile organic compounds (TVOCs) levels at worksites were determined. We conducted hearing examinations to determine hearing thresholds. A worker was identified as having hearing loss if the mean threshold at 2000, 3000 and 4000 Hz in either ear was equal to or greater than 25 dB. Prevalence of occupational hearing loss was then evaluated. Using unconditional Logistic regression models, we estimated the odds ratios (ORs) of MSWL work associated with hearing loss.

Results

According to the job title for each worker, the study subjects were divided into 3 groups, including group 1 of 63 workers without MSWL occupational hazards exposure (control group), group 2 of 84 workers with a few or short-period MSWL occupational hazards exposure, and group 3 of 100 workers with continuous MSWL occupational hazards exposure. Both noise and TVOCs levels were significantly higher at worksites for group 3. Significantly poorer hearing thresholds at frequencies of 2000, 3000 and 4000 Hz were found in group 3, compared with that in group 1 and group 2. The overall prevalence rate of hearing loss was 23. 5%, with the highest in group 3 (36.0%). The OR of MSWL work associated with hearing loss was 3.39 (95% confidence interval [CI]: 1.28-8.96).

Conclusion

The results of this study suggest significantly higher prevalence of hearing loss among MSWL workers. Further studies are needed to explore possible exposure-response relationship between MSWL occupational hazards exposure and hearing loss.     

Development of Diagnostic Methods for Detecting Ganoderma-infected Oil Palms

Two diagnostic methods have been applied for detecting the plant pathogenic fungus Ganoderma , a basidiomycete, causing the basal stem rot (BSR) diseaseof oil palms. One approach was the use of polyclonal antibodies (PAbs) raised against mycelial proteins of a single Ganoderma isolate and a mixture of nine different Ganoderma isolates. Both PAbs could detect Ganoderma in diseased oil palm root tissue by applying an indirect enzyme-linked immunosorbent assay. Low cross-reactions were observed with the five mainly occurring saprophytic fungi which could be isolated from diseased oil palms and were used as negative controls. The other approach was based on the polymerase chain reaction (PCR) in order to increase the sensitivity of the Ganoderma detection. The primers were generated from the internal transcribed spacer region 1 of rDNA of Ganoderma boninense and produced an PCR product of 167 bp in size. Fungal isolates and oil palm root samples were processed for PCR by three different DNA extraction methods. The most suitable extraction procedure was a simple alkaline extraction method. For a practical approach, a semiquantification was performed by assessing the PCR sensitivity limits of pure culture Ganoderma and naturally infected root samples.     

转基因水稻检测方法的研究进展

近年来,转基因作物在全球得到了迅猛发展,1988年第一批水稻转基因植株问世以来,各国科学家在水稻转基因研究领域取得了一系列成果,而对转基因水稻及其产品的检测,也成为世界各国公众关心的热点,从PCR法、基因芯片法等讨论转基因水稻的检测方法的研究进展,让读者对转基因水稻检测方法有初步的认识和了解,对开展转基因水稻检测的研究工作有一定的参考价值。     

Methods for Sampling of Airborne Viruses

Summary: To better understand the underlying mechanisms of aerovirology, accurate sampling of airborne viruses is fundamental. The sampling instruments commonly used in aerobiology have also been used to recover viruses suspended in the air. We reviewed over 100 papers to evaluate the methods currently used for viral aerosol sampling. Differentiating infections caused by direct contact from those caused by airborne dissemination can be a very demanding task given the wide variety of sources of viral aerosols. While epidemiological data can help to determine the source of the contamination, direct data obtained from air samples can provide very useful information for risk assessment purposes. Many types of samplers have been used over the years, including liquid impingers, solid impactors, filters, electrostatic precipitators, and many others. The efficiencies of these samplers depend on a variety of environmental and methodological factors that can affect the integrity of the virus structure. The aerodynamic size distribution of the aerosol also has a direct effect on sampler efficiency. Viral aerosols can be studied under controlled laboratory conditions, using biological or nonbiological tracers and surrogate viruses, which are also discussed in this review. Lastly, general recommendations are made regarding future studies on the sampling of airborne viruses.     

Composition of Microbial Fouling on the Surface of Plastics and Steel Exposed in a Pond at a Solid Waste Landfill

Microbiology - The work was aimed at investigation of the composition of microbial communities formed on the surface of samples of polyethylene terephthalate (PET), polystyrene (PS) and steel (ST)...     

Methods for Detecting Food-borne Enteroviruses

A method previously reported for detecting virus in a model system composed of cottage cheese contaminated with coxsackievirus type A9 has been adapted to detecting selected strains of enteroviruses in a variety of foods. Bentonite is omitted and serum is added for extracting virus from low-protein foods. Samples of foods, usually 25 g, must contain at least 3 to 4 plaque-forming units for a 50% probability of detecting virus. Sensitivity in detecting echovirus type 6 was lower than that for the other viruses used. After extraction from potato salad, poliovirus type 2 was completely reactivated if it had been neutralized with coproantibody, but it was only partially reactivated if neutralized with hyperimmune rabbit serum.     

Studies on the Survival and Fate of Enteroviruses in an Experimental Model of a Municipal Solid Waste Landfill and Leachate

In laboratory scale municipal solid waste lysimeters containing simulated refuse, and seeded with either laboratory or field strains of poliovirus type 1 and echovirus type 7, viruses were not detected in the lysimeter leachate produced over a 4-month period. In addition, viruses were detected in the lysimeter refuse contents after termination of lysimeter operation. These results appeared to be due to virus retention in the lysimeter caused by virus adsorption and virus inactivation. Evidence for virus inactivation was provided by the results of experiments on virus inactivation in composite leachate samples. Evidence for virus adsorption was supported by the rapid adsorption of viruses to various municipal solid waste components in the presence of a salt similar in composition to the major inorganic salts of leachates.     

口蹄疫等5种动物病毒基因芯片检测技术的研究

用分子克隆方法获得口蹄疫病毒、水泡性口炎病毒、蓝舌病病毒、鹿流行性出血热病毒和赤羽病病毒各一段高度保守的基因片段,用芯片点样仪点样到包被过的玻璃片上,制备成检测芯片。提取样品中的RNA,进行反转录和荧光标记后滴加到芯片上进行特异性杂交,对杂交结果进行扫描检测,可同时诊断上述5种动物传染病,此方法不但快速、准确、敏感,而且可同时进行多种病毒的检测,达到大批动物高通量检疫的目的。     

微卫星DNA检测方法的研究

在检测牙鲆的微卫星变异时,对聚丙烯酰胺凝胶的种类、浓度及其银染方法进行了优化.实验总结了一套适用于微卫星检测的方法.该方法具有灵敏度高、凝胶透明度高、对环境污染小、条带清晰和染色时间短等特点,能显著提高检测分辨率,具有广泛的推广价值.     

A Comparison of Methods for Counting Viruses in Aquatic Systems

In this study, we compared different methods—including transmission electron microscopy—and various nucleic acid labeling methods in which we used the fluorochromes 4′,6′-diamidino-2-phenylindole (DAPI), 4-[3-methyl-2,3-dihydro-(benzo-1,3-oxazole)-2-methylmethyledene]-1-(3′-trimethyl ammoniumpropyl)-quinilinium diioide (YOPRO-1), and SYBR Green I, which can be detected by epifluorescence microscopy (EM), for counting viruses in samples obtained from freshwater ecosystems whose trophic status varied and from a culture of T7 phages. From a quantitative and qualitative viewpoint, our results showed that the greatest efficiency for all ecosystems was obtained when we used the EM counting protocol in which YOPRO-1 was the label, as this fluorochrome exhibited strong and very stable fluorescence. A modification of the original protocol in which YOPRO-1 was used is recommended, because this modification makes the protocol faster and allows it to be used for routine analysis of fixed samples. Because SYBR Green I fades very quickly, the use of this fluorochrome is not recommended for systems in which the viral content is very high (>10⁸ particles/ml), such as treated domestic sewage effluents. Experiments in which we used DNase and RNase revealed that the number of viruses determined by EM was slightly overestimated (by approximately 15%) because of interference caused by the presence of free nucleic acids.     

Compartments for the Management of Municipal Solid Waste

Despite technological developments and improved liner-material applications, heavy metals in landfill leachate still penetrate the soil profile, polluting the soil and ground-water. An alternative approach therefore must be explored to reduce heavy-metal migration in soil-bentonite landfill liners. By considering the interaction of different heavy metals and their synergetic and antagonistics behaviors, such an approach could be developed. Low mobility metals such as Cu²⁺, and Pb²⁺ inhibit the adsorption of Cd²⁺ which is a moderate-mobility metal and Cu²⁺ sorption is decreased by the presence of Zn²⁺ and Cd²⁺. Therefore, Zn²⁺, a low-mobility metal, cannot be grouped with Cu²⁺. This way, four compatible metal groups have been identified: (1) low mobility: Pb²⁺, Cu²⁺, and Ag, (2) low mobility: Zn²⁺ and Cr³⁺; (3) moderate mobility: As²⁺, Fe²⁺, and Ni²⁺; (4) high mobility: Cd²⁺ and Hg²⁺. Cd²⁺ with a moderate mobility pattern is synergetic to Fe²⁺ and is more mobile with Ni²⁺. Therefore, Cd²⁺ is separated from the moderate-mobility group and is consigned with Hg, a high-mobility metal. The liner materials suitable for Hg²⁺ are assumed to be suitable for Cd²⁺ as well. Based on this concept, and to reduce heavy metal mobility, wastes should be segregated on compatibility basis according to their heavy metal contents before being disposed in different individual compartments. For wastes containing several incompatible heavy metals, sorting should be based on the heavy-metal with the highest concentration. Another solution is the manufacturing of products using compatible heavy metal combinations and then labeling them accordingly. Such waste segregation and landfill compartmentalization lowers risks of groundwater contamination and liner cost.     

细胞程序性死亡的判定方法

胞程序性死亡有别于一般意义上的死亡──坏死,所以对其判定显得格外重要．国内外目前常从细胞形态、细胞膜完整性、DNA及某些重要生化指标等方面进行判定．     

五种主要上呼吸道病毒多重RT-PCR 检测方法的建立

目的:建立甲型、乙型流感病毒、呼吸道合胞病毒A型、B型(RSV-A、RSV-B)和腺病毒(ADV)五种主要上呼吸道病毒的多重RT-PCR检测方法。方法:利用Primer premier5.0分别针对甲型流感病毒的M基因、乙型流感病毒的PB1基因、RSV-A和RSV-B的F基因及ADV的hexon基因设计五对特异性引物,对Mg2+、dNTP、引物浓度及退火温度等进行优化,建立同时检测甲型、乙型流感病毒、RSV-A、RSV-B和ADV的多重RT-PCR方法,并验证该检测方法的灵敏性。结果:所建立的五种病毒的多重RT-PCR方法可以同时或者分别扩增甲型、乙型流感病毒、RSV-A、RSV-B及ADV的141bp、635bp、525bp、377b和283bp基因片段,敏感度分别达到770PFU/ml、800PFU/ml、680PFU/ml、970PFU/ml和850PFU/ml,且五种病毒间无交叉反应。结论:所建立的多重RT-PCR方法可以迅速准确地检测甲型、乙型流感病毒、RSV-A、RSV-B和ADV,为五种病毒的检测提供了一种方便易行的方法。     

水体中病毒浓缩方法及其条件优化

本研究探讨了在自来水和污水两种不同的水体环境中, 三氯化铝沉淀法和正电荷滤膜法浓缩回收病毒的效率, 并比较应用不同的浓缩条件、洗脱物质时的病毒回收率, 从而建立有效的环境样本中病毒的浓缩方法。结果表明, 三氯化铝沉淀法在两种水体中的回收率均较高, 最高回收率分别达到96.0%和92.0%, 但正电荷滤膜法在两种水体中的回收率差别较大。在自来水中, 正电荷滤膜法的最高回收率为93.9%, 在污水中的最高回收率仅为69.9%, 这说明正电荷滤膜法适用于病毒含量较高且悬浮物等杂质较少的样本。在应用于自来水样时, 两种方法均可起到有效的病毒浓缩作用, 但在悬浮物等杂质较多的污水中, 三氯化铝法具有较好的回收效率。     

Metachromatic Agar-Diffusion Methods for Detecting Staphylococcal Nuclease Activity

Based on the metachromatic property of Toluidine Blue O, three, convenient agar-diffusion methods have been developed that enable detection of the nuclease of Staphylococcus aureus at concentrations as low as 0.005 mug/ml in agar and broth cultures. The interactions of agar and deoxyribonucleic acid with Toluidine Blue O are discussed.     

Life Cycle Management of Municipal Solid Waste

Life-cycle assessment concepts and methods are currently being applied to evaluate integrated municipal solid waste management strategies throughout the world. The Research Triangle Institute and the U.S. Environmental Protection Agency are working to develop a computer-based decision support tool to evaluate integrated municipal solid waste management strategies in the United States. The waste management unit processes included in this tool are waste collection, transfer stations, recovery, compost, combustion, and landfill. Additional unit processes included are electrical energy production, transportation, and remanufacturing. The process models include methodologies for environmental and cost analysis. The environmental methodology calculates life cycle inventory type data for the different unit processes. The cost methodology calculates annualized construction and equipment capital costs and operating costs per ton processed at the facility. The resulting environmental and cost parameters are allocated to individual components of the waste stream by process specific allocation methodologies. All of this information is implemented into the decision support tool to provide a life-cycle management evaluation of integrated municipal solid waste management strategies.     

特定序列DNA检测的几种新方法

特定序列DNA的检测方法通常使用PCR、DNA杂交、连接酶反应等专法。近年来根据不同的啄理又发展出一些新方法,其中比较重要的是基于非酶连接反应、分子信号灯、纳米微粒、以及酶抑制剂-DNA-酶(IDE)的方法。     

蛋白质O-GlcNAc修饰的检测技术

O-连接的N-乙酰葡糖胺（O-GlcNAc）修饰是位于细胞浆和细胞核蛋白质的丝氨酸或苏氨酸上的一种翻译后修饰,在高等真核生物细胞中广泛存在.越来越多的研究表明,O-GlcNAc修饰在代谢调控、压力应激、细胞周期、凋亡、糖尿病、心血管疾病和癌症等多种生理和病理过程中发挥重要作用,因此, O-GlcNAc修饰已受到众多生命科学领域研究人员的关注.然而,由于O-GlcNAc修饰与传统的N聚糖和O聚糖修饰有所不同,常规糖基化修饰的检测方法并不适用于O-GlcNAc.本文对O-GlcNAc修饰的检测及其修饰位点的确定方法进行了综述,并分析了各种方法的优缺点.     

Feature Selection Methods for Identifying Genetic Determinants of Host Species in RNA Viruses

Despite environmental, social and ecological dependencies, emergence of zoonotic viruses in human populations is clearly also affected by genetic factors which determine cross-species transmission potential. RNA viruses pose an interesting case study given their mutation rates are orders of magnitude higher than any other pathogen – as reflected by the recent emergence of SARS and Influenza for example. Here, we show how feature selection techniques can be used to reliably classify viral sequences by host species, and to identify the crucial minority of host-specific sites in pathogen genomic data. The variability in alleles at those sites can be translated into prediction probabilities that a particular pathogen isolate is adapted to a given host. We illustrate the power of these methods by: 1) identifying the sites explaining SARS coronavirus differences between human, bat and palm civet samples; 2) showing how cross species jumps of rabies virus among bat populations can be readily identified; and 3) de novo identification of likely functional influenza host discriminant markers.     

An Integrated Approach Combining Chemical Analysis and an In Vivo Bioassay to Assess the Estrogenic Potency of a Municipal Solid Waste Landfill Leachate in Qingdao

Various adverse effects related to landfill leachate have made leachates an important issue in past decades, and it has been demonstrated that landfill leachate is an important source of environmental estrogens. In this study, we employed chemical analysis of some already evaluated estrogenic substances, in combination with a bioassay using several specific biomarkers (e.g., plasma vitellogenin and sex steroids, enzyme activity of gonad gamma-glutamyl transpeptidase, and gonadosomatic index) to evaluate the estrogenic activities in outlets from different stages of the leachate treatment process. The results indicated that 5 environmental estrogens (4-t-octylphenol, bisphenol A, di-ethyl phthalate, di-n-butyl phthalate, and diethylhexyl phthalate) were detected by a gas chromatography-mass spectrometry, and the concentrations in leachate samples were 6153 ng/L, 3642 ng/L, 2139 ng/L, 5900 ng/L, and 9422 ng/L, respectively. Leachate (1∶200 diluted) induced the synthesis of plasma vitellogenin and led to decreased enzyme activity of gonad gamma-glutamyl transpeptidase and gonadosomatic index in male goldfish (Carassius auratus) after a 28-day exposure, while increased circulating 17β-estradiol level was also observed in males exposed to treated effluent. Although the target EEs were partially removed with removal rates varying from 87.2% to 99.77% by the “membrane bioreactor+reverse osmosis+aeration zeolite biofilter” treatment process, the treated effluent is still estrogenic to fish. The method combined chemical techniques with the responses of test organisms allowing us to identify the group of estrogen-like chemicals so that we were able to evaluate the overall estrogenic effects of a complex mixture, avoiding false negative assessments.