Advantages of using TEM when analysing asbestos in ambient air

Asbestos is an industrial term to describe some fibrous silicate minerals, which belong to the amphiboles or serpentines group. Six minerals are defined as asbestos including: chrysotile (white asbestos), amosite (grunerite, brown asbestos), crocidolite (riebeckite, blue asbestos), anthophyllite, tremolite and actonolite, but only in their fibrous form. In 1973, the IARC (International Agency for Research on Cancer) classified the asbestos minerals as carcinogenic substances (IARC,1973). The Swiss threshold limit (VME) is 0.01 fibre/ml (SUVA, 2007). Asbestos in Switzerland has been prohibited since 1990, but this doesn't mean we are over asbestos. Up to 20'000 tonnes/year of asbestos was imported between the end of WWII and 1990. Today, all this asbestos is still present in buildings renovated or built during that period of time. During restorations, asbestos fibres can be emitted into the air. The quantification of the emission has to be evaluated accurately. To define the exact risk on workers or on the population is quite hard, as many factors must be considered. The methods to detect asbestos in the air or in materials are still being discussed today. Even though the EPA 600 method (EPA, 1993) has proved itself for the analysis of bulk materials, the method for air analysis is more problematic. In Switzerland, the recommended method is VDI 3492 using a scanning electron microscopy (SEM), but we have encountered many identifications problems with this method. For instance, overloaded filters or long-term exposed filters cannot be analysed. This is why the Institute for Work and Health (IST) has adapted the ISO10312 method: ambient air - determination of asbestos fibres - direct-transfer transmission electron microscopy (TEM) method (ISO, 1995). Quality controls have already be done at a French institute (INRS), which validate our practical experiences. The direct-transfer from MEC's filters on TEM's supports (grids) is a delicate part of the preparation for analysis and requires a lot of trials in the laboratory. IST managed to do proper grid preparations after about two years of development. In addition to the preparation of samples, the micro-analysis (EDX), the micro-diffraction and the morphologic analysis (figure 1.a-c) are also to be mastered. Theses are the three elements, which prove the different features of asbestos identification. The SEM isn't able to associate those three analyses. The TEM is also able to make the difference between artificial and natural fibres that have very similar chemical compositions as well as differentiate types of asbestos. Finally the experiments concluded by IST show that TEM is the best method to quantify and identify asbestos in the air.

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Pollution of air, water and soil by industrial chemicals presents a potential health risk to humans. Such chemicals can enter the human body by three routes, namely by inhalation, dermal absorption, and ingestion and in special cases by injection (needle sticks, bites, cuts, etc.). In the workplace, pulmonary and dermal absorption are the main routes of entry, but poor personal hygiene and work habits can result in ingestion that contributes to the dose. Air monitoring provides reliable information on inhalation exposure, and patches can be used to estimate dermal exposure. Local adverse effects, such as skin and eye irritation, or nose and lung irritation, are closely related to the external exposure. Systemic adverse effects, on the other hand, are related to the absorbed amount (dose), or to the level of the pollutant or its metabolite in the target organ. Human biological monitoring is becoming a powerful tool for scientists and policy makers to assess and manage the risk of exposure to chemicals both in the general population and at the workpalce. This chapter will focus on the occupational environment keeping in mind that biological monitoring in humans is a very actual issue in public health politics, in environmental medicine, and in science in general.

Reversible and irreversible pollutant-induced bacterial cellular stress effects measured by ethidium bromide uptake and efflux.

Chemical pollution is known to affect microbial community composition but it is poorly understood how toxic compounds influence physiology of single cells that may lay at the basis of loss of reproductive fitness. Here we analyze physiological disturbances of a variety of chemical pollutants at single cell level using the bacterium Pseudomonas fluorescens in an oligotrophic growth assay. As a proxy for physiological disturbance we measured changes in geometric mean ethidium bromide (EB) fluorescence intensities in subpopulations of live and dividing cells exposed or not exposed to different dosages of tetradecane, 4-chlorophenol, 2-chlorobiphenyl, naphthalene, benzene, mercury chloride, or water-dissolved oil fractions. Because ethidium bromide efflux is an energy-dependent process any disturbance in cellular energy generation is visible as an increased cytoplasmic fluorescence. Interestingly, all pollutants even at the lowest dosage of 1 nmol/mL culture produced significantly increased ethidium bromide fluorescence compared to nonexposed controls. Ethidium bromide fluorescence intensities increased upon pollutant exposure dosage up to a saturation level, and were weakly (r(2) = 0.3905) inversely correlated to the proportion of live cells at that time point in culture. Temporal increase in EB fluorescence of growing cells is indicative for toxic but reversible effects. Cells displaying high continued EB fluorescence levels experience constant and permanent damage, and no longer contribute to population growth. The procedure developed here using bacterial ethidium bromide efflux pump activity may be a useful complement to screen sublethal toxicity effects of chemicals.

Anthropogenic radionuclides in atmospheric air over Switzerland during the last few decades.

The atmospheric nuclear testing in the 1950s and early 1960s and the burn-up of the SNAP-9A satellite led to large injections of radionuclides into the stratosphere. It is generally accepted that current levels of plutonium and caesium radionuclides in the stratosphere are negligible. Here we show that those radionuclides are present in the stratosphere at higher levels than in the troposphere. The lower content in the troposphere reveals that dry and wet deposition efficiently removes radionuclides within a period of a few weeks to months. Since the stratosphere is thermally stratified and separated from the troposphere by the tropopause, radioactive aerosols remain longer. We estimate a mean residence time for plutonium and caesium radionuclides in the stratosphere of 2.5-5 years. Our results also reveal that strong volcanic eruptions like Eyjafjallajökull in 2010 have an important role in redistributing anthropogenic radionuclides from the stratosphere to the troposphere.

Influence de la topographie et des accumulations d'air froid sur les températures moyennes mensuelles et annuelles en Suisse

Les températures moyennes mensuelles et annuelles mesurées à 177 endroits de la Suisse ont été ramenées à une même altitude à l'aide d'une formule empirique afin de détecter les influences de la topographie locale sur ce paramètre. Ces calculs ont montré que des accumulations d'air froid influencent fortement les températures moyennes en saison froide au fond de certaines vallées alpines larges et dépressions du Jura sur une épaisseur d'environ 100 mètres. Le déficit thermique dans ces vallées peut atteindre 2 à 3°C à l'échelle annuelle et 5 à 7°C en hiver comparativement aux versants et sommets environnants. Ces accumulations d'air froid n'influencent que peu les températures moyennes dans les vallées étroites et bien ventilées.

Extraction and concentration of vapors from fire debris for forensic purposes: evaluation of the use of Radiello Passive Air Sampler

The Radiello Passive Air Sampler is one of the latest innovations developed for the sampling of pollutants in the air by passive headspace. It has been reported that its properties allow an enhanced sensitivity, reproducibility and adsorption capacity. It therefore appears to be of interest in the extraction of potential residues of ignitable liquids present in fire debris when arson is suspected. A theoretical approach and several laboratory tests have made it possible to precisely characterize in a forensic perspective the potential of the device in extracting and concentrating the vapors of ignitable liquids found in fire debris. Despite some advantages, the Radiello device appears to be less efficient than traditional axial symmetry samplers.

First day of an oil spill on the open sea: early mass transfers of hydrocarbons to air and water.

During the first hours after release of petroleum at sea, crude oil hydrocarbons partition rapidly into air and water. However, limited information is available about very early evaporation and dissolution processes. We report on the composition of the oil slick during the first day after a permitted, unrestrained 4.3 m(3) oil release conducted on the North Sea. Rapid mass transfers of volatile and soluble hydrocarbons were observed, with >50% of ≤C17 hydrocarbons disappearing within 25 h from this oil slick of <10 km(2) area and <10 μm thickness. For oil sheen, >50% losses of ≤C16 hydrocarbons were observed after 1 h. We developed a mass transfer model to describe the evolution of oil slick chemical composition and water column hydrocarbon concentrations. The model was parametrized based on environmental conditions and hydrocarbon partitioning properties estimated from comprehensive two-dimensional gas chromatography (GC×GC) retention data. The model correctly predicted the observed fractionation of petroleum hydrocarbons in the oil slick resulting from evaporation and dissolution. This is the first report on the broad-spectrum compositional changes in oil during the first day of a spill at the sea surface. Expected outcomes under other environmental conditions are discussed, as well as comparisons to other models.

aIr-1, a newly found locus on mouse chromosome 16 encoding a trans-acting activator factor for MHC class II gene expression.

RJ 2.2.5 is a human B cell line that has lost the capacity to express MHC class II genes. The human class II-positive phenotype is restored in somatic cell hybrids between RJ 2.2.5 and mouse spleen cells. By karyotype and molecular studies of an informative family of hybrids we have now shown that the reexpression of human class II gene products, as well as the maintenance of the mouse class II-positive phenotype, correlates with the presence of mouse chromosome 16. Thus, the existence on this mouse chromosome of a newly found locus, designated by us aIr-1, that determines a trans-acting activator function for class II gene expression, is established. Possible implications of this finding are discussed.