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11.
用非洲爪蟾胚胎致畸实验和黑斑蛙胚胎发育毒性实验,比较研究了PFOS及其4种替代品对两栖动物胚胎的发育毒性。结果发现,用调聚法合成的织物三防整理剂和50%的全氟丁基有机铵盐阳离子表面活性剂同PFOS一样对非洲爪蟾胚胎有明显毒性,且织物三防整理剂和表面活性剂的毒性强于PFOS;电解氟化法合成的C4织物及C6织物三防整理剂(以下简称C4及C6织物三防整理剂)对非洲爪蟾胚胎没有明显毒性。与非洲爪蟾不同,PFOS和4种替代品对黑斑蛙胚胎没有明显毒性。结果显示,从生物安全性的角度分析,C4和C6织物三防整理剂可作为PFOS的替代品使用,而织物三防整理剂和表面活性剂的毒性比PFOS大,作为PFOS替代品使用需要慎重考虑。  相似文献   
12.
The paper by Dr. William Hallenbeck of the University of Illinois on pp. 23–32 of this issue ofEnvironmental Management contains an estimate of the risk of respiratory cancer resulting from exposure to asbestos fibers emitted from asbestos-containing hairdryers. The study, which is described as a worst case analysis, concludes that the use of these hairdryers would result in a maximum of 0.15 deaths from respiratory cancer per year in the United States, based on a median case estimate of asbestos fiber emission from hair-dryers. This estimate of risk was developed using data from one epidemiologic study.In this critique, we suggest that the use of other epidemiologic studies and the inclusion of other minor, reasonable changes to the basic assumptions made by Hallenbeck could significantly change the estimate in the direction of greater risk. Indeed, the use of other epidemiologic studies in the risk estimate results in an increase in the predicted risk of up to 3 orders of magnitude. Inclusion of changes both in the epidemiologic study used and in certain model assumptions results in an increased risk prediction of over 4 orders of magnitude in the extreme.Since there is no definitive basis on which to include or exclude certain assumptions or relevant studies, the risk estimate at best must be represented as a range of values. Such a range demonstrates the inherent uncertainties associated with estimating the risk to humans from known carcinogens. The size of the range developed in this analysis may actually be underestimated since no attempt has been made to evaluate the uncertainty associated with the choice of the dose-response model.The material found within this paper contains the views of the authors who are employees of the Consumer Product Safety Commission and does not necessarily reflect official opinions or policies of the U.S. Consumer Product Safety Commission.This paper was prepared in the course of the official duties of the authors as employees of the U.S. Consumer Product Safety Commission. It is in the public domain and may be freely copied and reproduced.  相似文献   
13.
我国石棉替代品生产、使用、危害及防护措施状况   总被引:2,自引:2,他引:2  
虽然石棉的用途广泛、价格低廉 ,但因其危害严重 ,存在着致癌问题 ,部分发达国家对石棉的使用进行了严格限制 ;为了降低石棉对人体健康的伤害 ,国际上大力提倡使用石棉替代品。针对我国石棉替代品使用的现状 ,重点对目前使用最多的石棉替代品 :玻璃棉、岩棉等的生产、使用、危害及其防护措施状况进行了概要的回顾和简单分析。  相似文献   
14.
Nanotechnology has the potential for the development of new materials and processes that can substitute for toxic materials now used in industry. Excitement over this possibility is tempered, however, by the potential adverse environmental health and safety aspects of the new nanomaterials. Although a few examples from the literature are encouraging, e.g., wire and cable insulation, great care must be taken to perform complete alternatives assessment evaluations of any new nanotechnology-enabled product before its adoption.  相似文献   
15.
Background, aim, and scope  The adverse environmental impacts of chlorinated hydrocarbons on the Earth’s ozone layer have focused attention on the effort to replace these compounds by nonchlorinated substitutes with environmental acceptability. Hydrofluoroethers (HFEs) and fluorinated alcohols are currently being introduced in many applications for this purpose. Nevertheless, the presence of a great number of C–F bonds drives to atmospheric long-lived compounds with infrared absorption features. Thus, it is necessary to improve our knowledge about lifetimes and global warming potentials (GWP) for these compounds in order to get a complete evaluation of their environmental impact. Tropospheric degradation is expected to be initiated mainly by OH reactions in the gas phase. Nevertheless, Cl atoms reaction may also be important since rate constants are generally larger than those of OH. In the present work, we report the results obtained in the study of the reactions of Cl radicals with HFE-7000 (CF3CF2CF2OCH3) (1) and its isomer CF3CF2CF2CH2OH (2). Materials and methods  Kinetic rate coefficients with Cl atoms have been measured using the discharge flow tube–mass spectrometric technique at 1 Torr of total pressure. The reactions of these chlorofluorocarbons (CFCs) substitutes have been studied under pseudo-first-order kinetic conditions in excess of the fluorinated compounds over Cl atoms. The temperature ranges were 266–333 and 298–353 K for reactions of HFE-7000 and CF3CF2CF2CH2OH, respectively. Results  The measured room temperature rate constants were k(Cl+CF3CF2CF2OCH3) = (1.24 ± 0.28) × 10−13 cm3 molecule−1 s−1and k(Cl+CF3CF2CF2CH2OH) = (8.35 ± 1.63) × 10−13 cm3 molecule−1 s−1 (errors are 2σ + 10% to cover systematic errors). The Arrhenius expression for reaction 1 was k 1(266–333 K) = (6.1 ± 3.8) × 10−13exp[−(445 ± 186)/T] cm3 molecule−1 s−1 and k 2(298–353 K) = (1.9 ± 0.7) × 10−12exp[−(244 ± 125)/T] cm3 molecule−1 s−1 (errors are 2σ). The reactions are reported to proceed through the abstraction of an H atom to form HCl and the corresponding halo-alkyl radical. At 298 K and 1 Torr, yields on HCl of 0.95 ± 0.38 and 0.97 ± 0.16 (errors are 2σ) were obtained for CF3CF2CF2OCH3 and CF3CF2CF2CH2OH, respectively. Discussion  The obtained kinetic rate constants are related to the previous data in the literature, showing a good agreement taking into account the error limits. Comparing the obtained results at room temperature, k 1 and k 2, HFE-7000 is significantly less reactive than its isomer C3F7CH2OH. A similar behavior has been reported for the reactions of other fluorinated alcohols and their isomeric fluorinated ethers with Cl atoms. Literature data, together with the results reported in this work, show that, for both fluorinated ethers and alcohols, the kinetic rate constant may be considered as not dependent on the number of –CF2– in the perfluorinated chain. This result may be useful since it is possible to obtain the required physicochemical properties for a given application by changing the number of –CF2– without changes in the atmospheric reactivity. Furthermore, lifetimes estimations for these CFCs substitutes are calculated and discussed. The average estimated Cl lifetimes are 256 and 38 years for HFE-7000 and C3H7CH2OH, respectively. Conclusions  The studied CFCs’ substitutes are relatively short-lived and OH reaction constitutes their main reactive sink. The average contribution of Cl reactions to global lifetime is about 2% in both cases. Nevertheless, under local conditions as in the marine boundary layer, τ Cl values as low as 2.5 and 0.4 years for HFE-7000 and C3H7CH2OH, respectively, are expected, showing that the contribution of Cl to the atmospheric degradation of these CFCs substitutes under such conditions may constitute a relevant sink. In the case of CF3CF2CF2OCH3, significant activation energy has been measured, thus the use of kinetic rate coefficient only at room temperature would result in underestimations of lifetimes and GWPs. Recommendations and perspectives  The results obtained in this work may be helpful within the database used in the modeling studies of coastal areas. The knowledge of the atmospheric behavior and the structure–reactivity relationship discussed in this work may also contribute to the development of new environmentally acceptable chemicals. New volatile materials susceptible of emission to the troposphere should be subject to the study of their reactions with OH and Cl in the range of temperature of the troposphere. The knowledge of the temperature dependence of the kinetic rate constants, as it is now reported for the case of reactions 1 and 2, will allow more accurate lifetimes and related magnitudes like GWPs. Nevertheless, a better knowledge of the vertical Cl tropospheric distribution is still required.  相似文献   
16.
一次性塑料是指生产生活中使用一次或几乎不重复利用的塑料,约占塑料总消费量的50%,是塑料制品的重要构成部分.近年来,随着电子商务的兴起,一次性塑料的生产和消费量迅速增长.随着人们对塑料以及由此引起的微塑料污染危害的认识不断提高,国际社会对削减一次性塑料污染的呼声日益高涨,迫切需要开发可持续、环境友好的替代品以减少一次性塑料的消费量.从全球范围来看,一次性塑料制品替代主要包括非塑料材料替代和可生物降解塑料材料替代两大类.建议我国尽快完善相关立法和标准,鼓励一次性塑料制品替代并加强替代产品的质量监管;为一次性塑料制品替代提供差别化的产业政策,提高环境友好替代产品的市场竞争力,同时还应将一次性塑料制品的环境治理成本纳入其价格成本;鼓励科技创新,研发更具市场竞争力的替代材料和产品;最后,还要唤起社会公众的共同参与,主动选择替代产品并减少一次性塑料制品的使用,才能从源头上解决塑料垃圾的污染问题.   相似文献   
17.
全氟辛烷羧酸(perfluorooctanoic acid,PFOA)和全氟辛烷磺酸(perfluorooctyl sulfonate,PFOS)等长链全氟化合物(perfluorinated compounds,PFCs)具有持久性、生物累积性和毒性,近年来发现一些短链PFCs具有相对较短的半衰期,可以成为PFOA和PFOS的替代品,这些物质包括C4和C6结构的PFCs,如全氟丁烷羧酸(perfluorobutanoic acid,PFBA)、全氟己烷羧酸(perfluorohexanoic acid,PFHx A)、全氟丁烷磺酸(perfluorobutyl sulfonate,PFBS)和全氟己烷磺酸(perfluorohexyl sulfonate,PFHx S)。为解析我国城市污水厂短链PFCs污染水平和地域分布特征,本研究调查了我国不同地区17座城市污水处理厂的进水、二沉出水和污泥中4种短链PFCs的分布和浓度水平。结果表明4种短链PFCs、PFOA和PFOS在17座污水厂进水中检出率均为100%(6种目标物单体浓度范围:0.19~274.72 ng·L-1);污泥中PFOS和PFOA检出率为100%(PFOS:2.08~72.31 ng·g-1,PFOA:1.03~24.81 ng·g-1),PFBA、PFHx A检出率为100%(0.60~3.33 ng·g-1),PFBS和PFHx S的检出率分别为42.11%和63.16%。在污水厂进水中,将PFOA和PFOS与其同类的短链PFCs浓度进行比较,发现短链PFCs分别相对于PFOA和PFOS的比例最高可达93.47%和94.57%。4种短链PFCs、PFOA和PFOS的地域分布差异明显,总浓度呈现出华东、华南地区高于西北、东北、华北地区的趋势,其中华东地区调查的污水处理厂浓度最高。污水厂4种短链替代物主要通过污水排放,不同污水厂的日排放总量(污泥和出水)为0.25~273.07 g·d-1,万吨水排放量范围为0.04~1.37 g。研究将为我国全氟化合物替代物污染和控制提供数据基础和科学依据。  相似文献   
18.
Transformational leadership is associated with a range of positive outcomes. Yet, according to substitutes for leadership theory, there may be circumstances under which it is difficult, if not impossible, for leaders to inspire and challenge their employees. Therefore, we hypothesize that transformational leadership behaviors as well as employee self‐leadership strategies contribute to employee work engagement and job performance. Furthermore, we hypothesize that transformational leadership behaviors are more effective when employees have a high need for leadership, whereas self‐leadership strategies are more effective when employees have a low need for leadership. A sample of 57 unique leader–employee dyads filled out a quantitative diary survey at the end of each week, for a period of five weeks. The results of multilevel structural equation modeling showed that employees were more engaged in their work and received higher performance ratings from their leader when leaders used more transformational leadership behaviors, and when employees used more self‐leadership strategies. Furthermore, we showed that transformational leadership behaviors were more effective when employees had a high (vs. low) need for leadership and that the opposite was true for employee self‐leadership. These findings contribute to our understanding of the role of employees in the transformational leadership process. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
19.
保护生物多样性生物多样性是人类社会赖以生存和发展的物质基础,保护生物多样性,保证生物资源的持续利用是一项全球性任务,也是全球环境保护行动计划的重要组成部分。按照生物多样性国际公约的定义,生物多样性“是指所有来源和形形色色的生物体,这些来源包括陆地、海...  相似文献   
20.
介绍了年产万吨的国内第一条煤矸石岩棉生产线的工艺流程及其生产性试验,产品的主要技术性能达到了国空标准GB11835-89中的优等品种质量规定,并探讨了煤矸石熔制岩棉的机理,为煤矸石的深度开发利用提供了新途径。  相似文献   
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