石棉表面改性对石棉诱导人胚肺细胞产生羟基自由基的影响

为了研究用柠檬酸铝、混合稀土或亚硒酸钠预处理温石棉对石棉诱导人胚肺(HEL)细胞产生羟基自由基(·OH)的影响,笔者用不同浓度的柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡温石棉1小时后,再将其与人胚肺细胞共同孵育,利用电子自旋捕获法测定反应体系中羟基自由基信号。结果显示,石棉可诱导人胚肺细胞产生羟基自由基,并且所产生的自由基信号(峰高)随石棉浓度升高而增强,呈一定的剂量依赖性。经3种化合物预处理的温石棉组人胚肺细胞所产生的自由基信号(峰高)均明显低于未处理温石棉组。上述结果表明,温石棉可诱导人胚肺细胞产生羟基自由基,但用3种化合物预处理温石棉,均可抑制温石棉诱导人胚肺细胞产生羟基自由基。     

几种化合物对温石棉诱导入胚肺细胞蛋白激酶C活性的影响

为了探讨几种化合物对温石棉诱导人胚肺（HEL）细胞蛋白激酶C（PKC）活性的影响，该研究用不同浓度的柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡温石棉1小时后，再将其与HEL细胞共同孵育24小时，测定了HEL细胞胞浆和胞膜中PKC的活性。其结果显示：随着石棉剂量的增加，HEL细胞胞浆和胞膜中的PKC活性逐渐升高，均呈明显的剂量依赖性；经3种化合物预处理的石棉，其所诱导的HEL细胞胞浆和胞膜中的PKC活性均明显低于未处理温石棉组。笔者提示：温石棉可能通过改变细胞内PKC的活性进一步促进肿瘤的发生；用3种化合物预处理温石棉，均可抑制温石棉对HEL细胞PKC活性的诱导作用。     

Cytotoxicity of single-walled carbon nanotubes,multi-walled carbon nanotubes,and chrysotile to human lung epithelial cells

Carbon nanotubes (CNTs) have found numerous applications in various industries. Recently, adverse effects of these materials on human and animal cells in vitro have been reported. In the present study, the cytotoxicity of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and chrysotile asbestos in human lung epithelial cells has been studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The cells were exposed for 6 h and 24 h to between 0.97 and 1500 μg mL^?1 of CNTs and chrysotile fibers prepared in two culture media containing 5% serum and 0.5% dimethylsulfoxide. Dose–response curves were obtained to determine the nonobservable adverse effect concentration and the half-maximum inhibitory concentration (IC₅₀). The way of dispersion affects the cytotoxicity of CNTs. For MWCNT, the toxicological indexes were lower than for SWCNT. Chrysotile fibers were even less cytotoxic than CNTs. Therefore, workplace control measures are recommended as priority for occupational and environmental conditions.     

ASSESSING POTENTIAL SOURCES OF ASBESTOS FIBERS IN WATER SUPPLIES OF S. E. QUEBEC1

ABSTRACT: A comparative study of the concentration of asbestos fibers in drinking water supplies of southeastern Quebec was undertaken to assess the relative contributions of fibers by asbestos-bearing railway ballast and naturally occurring asbestos deposits. Water samples were taken from areas where one or the other potential sources or neither potential source was present. In addition, rainwater samples were taken to assess the importance of atmospheric contributions. The sampling design accounted for potential variations in fiber counts due to the season, location and analytical procedures. Fiber concentrations were estimated from counts made on a JEOL 100CX scanning transmission electron microscope and statistically compared among areas. These levels were then compared with levels found in other areas of Canada and the United States. The results indicate that the rail ballast could be contributing statistically (albeit marginally) significant quantities of fibers to water supplies during the summer but not in the spring. Estimated concentrations in water supplies ranged between 1.7 × 10⁶fibers/liter and 147.8 × 10⁶fibers/liter. Fiber levels in samples taken during the spring were significantly higher and more variable than those taken during the summer. The presence of fibers in rainwater samples at concentrations of 1.9 × 10⁶fibers/liter, 18.3 × 10⁶fibers/liter and 23.7 × 10⁶fibers/liter suggests that atmospheric transport may play an important role in contributing fibers to regional systems. Fiber levels found in these systems are not unique when compared to levels observed elsewhere in North America.     

三种化合物浸泡处理对石棉晶格结构和表面电荷的影响

为了研究经柠檬酸铝、混合稀土或亚硒酸钠浸泡处理温石棉对温石棉晶格结构和表面电荷的影响,用不同浓度的柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡温石棉1小时后,通过透射电镜测定其衍射环直径的大小,分析石棉晶格结构的改变,并利用石棉纤维吸附亚甲蓝能力的测定方法,分析温石棉表面电荷。结果显示,用三种化合物处理石棉后,其衍射环直径均增大,而且用三种化合物处理后的石棉对亚甲蓝的吸附能力均明显降低,并且随着化合物剂量的增加其降低愈明显。上述结果表明,用三种化合物处理石棉,均可改变石棉的晶格结构,且可能减少其表面电荷。     

温石棉致豚鼠肺泡巨噬细胞酸性磷酸酶释放的干预效应研究

为了探讨几种化合物对温石棉致肺泡巨噬细胞（AM）酸性磷酸酶（ACP）释放的干预效应。本研究用不同浓度的柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡温石棉1小时后，再将其与豚鼠肺泡巨噬细胞共同孵育，测定了细胞培养液中酸性磷酸酶的活性。结果显示，随着石棉剂量的增加和作用时间的延长，细胞培养液中酸性磷酸酶的活性逐渐升高，呈明显的剂量依赖性和时间，效应关系。经3种化合物预处理的石棉组，细胞培养液中酸性磷酸酶的活性均明显低于未处理温石棉组。提示，用3种化合物预处理温石棉，均可减轻温石棉对豚鼠肺泡巨噬细胞的毒性作用。     

石棉表面改性对石棉所致人胚肺细胞内游离钙离子浓度改变的抑制作用

为了探讨研究温石棉及用柠檬酸铝、混合稀土或亚硒酸钠预处理的温石棉对人胚肺（HEL）细胞内游离钙离子（[Ca^2＋]i）浓度的影响。用Flou3／AM标记体外培养的HEL细胞内Ca^2＋后，将不同浓度的温石棉及用柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡过的温石棉与HEL细胞作用1h，荧光分光光度计测定细胞内[Ca^2＋]i。结果显示，20、40、80μg／ml温石棉单独作用于HEL细胞1h，可使HEL细胞内[Ca^2＋]i浓度分别升高3．0％、53．1％和116．7％，且具有明显的剂量-效应关系（r=0．976，P=0．024）。经三种化合物预处理的温石棉组HEL细胞内[Ca^2＋]i浓度均明显低于未处理温石棉组。得出结论，温石棉可致人胚肺细胞内游离钙离子浓度升高，但用三种化合物预处理温石棉，均可抑制温石棉所致人胚肺细胞内游离钙离子浓度的升高。     

A state of the science review of the potential health hazards associated with asbestos in shielded metal arc welding rods in the United States

Due to its unique chemical properties, chrysotile asbestos was historically incorporated into a wide variety of products, including the outer covering, or “flux” of certain classifications of general arc mild steel welding electrodes. The purpose of this analysis is to review the historical engineering, toxicology, regulatory, and epidemiology information relevant to asbestos in mild steel welding rods in order to assess whether mild steel welders are at increased risk of developing asbestos-related diseases as a result of welding rod use. We divided our analysis into four distinct time periods, based on what we perceived to be seminal events in welding technology or in the evolution of knowledge regarding asbestos and asbestos-related diseases. These time periods are as follows: late 1800s to 1929, 1930–1955, 1956–1970, and 1971–2006. We found that studies that attempted to measure airborne asbestos directly in welding rod fumes found no measurable fibers; this is likely due to the fact that the fibers degrade at high temperatures present in the welding arc. In addition, “worst-case” use simulation studies, specifically intended to generate airborne flux particles, reported that airborne asbestos concentrations were either undetectable or very low. The airborne concentrations generated were always below the current OSHA permissible exposure limit (0.1 f/cc TWA), and the lifetime doses associated with “worst-case” use were found to be far below the plausible thresholds for mesothelioma and lung cancer. The epidemiology of mild steel welders is difficult to interpret due to confounding exposures such as (1) possible exposure to nickel and hexavalent chromium in stainless steel welding fumes (lung cancer), (2) smoking (lung cancer), and (3) bystander exposure to amphibole asbestos (lung cancer and mesothelioma). None of the published welder studies controlled for all three factors, yet when any single source of bias was controlled for, the majority of the studies reported no significant risk in either asbestos-related disease. Furthermore, none of the investigators in any of the welder studies suggested that asbestos in welding rods might be a risk factor for lung cancer or mesothelioma, and there is not a single case report in the medical literature that attempts to link welding rod use to an asbestos-related disease. We conclude that the weight of evidence indicates that welders were not historically at risk of developing asbestos-related diseases as a result of welding rod use.     

我国与主要国家温石棉安全使用政策和法规对比研究

我国作为温石棉的生产和使用大国,在温石棉及其制品的危害及防控方面开展了较为系统的研究,但对于其他主要国家在温石棉安全使用政策和法规方面的研究则相对较少。本文简要介绍温石棉安全使用的理论基础,对美国、加拿大等主要国家在温石棉安全生产和使用方面的主要政策和法规进行研究,并对我国温石棉产业政策以及相关法规进行梳理,通过对比发现,我国与美国、加拿大等国家在温石棉及其制品的安全使用法规、标准建设等方面存在一定差距。最后,基于相关对比分析结果,对我国温石棉产业职业病防治、环境保护以及温石棉制品等方面的法规标准的建设提出建议。     

几种化合物对温石棉诱导人胚肺细胞蛋白激酶C活性的影响

为了探讨几种化合物对温石棉诱导人胚肺(HEL)细胞蛋白激酶C(PKC)活性的影响,该研究用不同浓度的柠檬酸铝、混合稀土或亚硒酸钠溶液浸泡温石棉1小时后,再将其与HEL细胞共同孵育24小时,测定了HEL细胞胞浆和胞膜中PKC的活性。其结果显示:随着石棉剂量的增加,HEL细胞胞浆和胞膜中的PKC活性逐渐升高,均呈明显的剂量依赖性;经3种化合物预处理的石棉,其所诱导的HEL细胞胞浆和胞膜中的PKC活性均明显低于未处理温石棉组。笔者提示:温石棉可能通过改变细胞内PKC的活性进一步促进肿瘤的发生;用3种化合物预处理温石棉,均可抑制温石棉对HEL细胞PKC活性的诱导作用。