Spatial distribution,contamination levels,sources, and potential health risk assessment of trace elements in street dusts of Urumqi city,NW China

Abstract

A total of 83 dust samples were collected from the streets of Urumqi city in NW China and analyzed for the concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn elements. The spatial distribution, contamination levels, main sources, and potential health risks of these trace elements were determined based on geostatistical analysis, geo-accumulation index, multivariate analysis, and the health risk assessment model introduced by the USEPA, respectively. The obtained results indicate that the average concentrations of Cd, Cr, Cu, Hg, Ni, Pb, and Zn exceed the corresponding background values determined in Xinjiang soils by factors of 2.0, 1.35, 1.38, 8.24, 1.28, 2.09, and 3.26, respectively. The spatial distribution patterns of the nine trace elements in street dust were found to be substantially heterogeneous, and the contamination level decreased in the following order: Hg?>?Zn?>?Pb?>?Cd?>?Cr?>?Cu?>?As?>?Ni?>?Mn. Based on the identified concentrations, the collected dust samples were found to be moderately polluted by Hg, and not polluted by As, Cr, Cu, Mn, and Ni. The remaining elements, Cd, Pb, and Zn lie on the borderline between non-pollution and moderate pollution levels. Furthermore, it was shown that Mn and Zn in street dusts originate from both, natural and anthropogenic sources, while As, Cd, Cr, Cu, Hg, Ni, and Pb are mainly produced by anthropogenic sources. Overall, the carcinogenic and non-carcinogenic health risks of the analyzed elements, instigated primarily by oral ingestion of street dusts, were found to be within the acceptable range for both, children and adults. As and Cr are the main non-carcinogenic elements, whereas Cr is the major carcinogenic element among the investigated dust-bound metals in the study area.     

Assessing the Bioavailability and Risk from Metal-Contaminated Soils and Dusts

Exposure to contaminated soil and dust is an important pathway in human health risk assessment. Physical and chemical characteristics and biological factors determine the bioaccessibility/bioavailability of soil and dust contaminants. Within a single sample, contamination may arise from multiple sources of toxic elements that may exist as different species that impact bioavailability. In turn, the bioaccessibility/bioavailability of soil and dust contaminants directly impacts human health risk. Research efforts focusing on development and application of in vitro and in vivo methods to measure the bioaccessibility/bioavailability of metal-contaminated soils have advanced in recent years. The objective of this workshop was to focus on developments in assessing the bioaccessibility/bioavailability of arsenic-contaminated soils, metals’ contamination in urban Canadian residences and potential children's exposures to toxic elements in house dust, an urban community-based study (i.e., West Oakland Residential Lead Assessment), bioavailability studies of soil cadmium, chromium, nickel, and mercury and human exposures to contaminated Brownfield soils. These presentations covered issues related to human health and bioavailability along with the most recent studies on community participation in assessing metals’ contamination, studies of exposures to residential contamination, and in vitro and in vivo methods development for assessing the bioaccessibility/bioavailability of metals in soils and dusts.     

Shotgun Pyrosequencing Metagenomic Analyses of Dusts from Swine Confinement and Grain Facilities

Inhalation of agricultural dusts causes inflammatory reactions and symptoms such as headache, fever, and malaise, which can progress to chronic airway inflammation and associated diseases, e.g. asthma, chronic bronchitis, chronic obstructive pulmonary disease, and hypersensitivity pneumonitis. Although in many agricultural environments feed particles are the major constituent of these dusts, the inflammatory responses that they provoke are likely attributable to particle-associated bacteria, archaebacteria, fungi, and viruses. In this study, we performed shotgun pyrosequencing metagenomic analyses of DNA from dusts from swine confinement facilities or grain elevators, with comparisons to dusts from pet-free households. DNA sequence alignment showed that 19% or 62% of shotgun pyrosequencing metagenomic DNA sequence reads from swine facility or household dusts, respectively, were of swine or human origin, respectively. In contrast only 2% of such reads from grain elevator dust were of mammalian origin. These metagenomic shotgun reads of mammalian origin were excluded from our analyses of agricultural dust microbiota. The ten most prevalent bacterial taxa identified in swine facility compared to grain elevator or household dust were comprised of 75%, 16%, and 42% gram-positive organisms, respectively. Four of the top five swine facility dust genera were assignable (Clostridium, Lactobacillus, Ruminococcus, and Eubacterium, ranging from 4% to 19% relative abundance). The relative abundances of these four genera were lower in dust from grain elevators or pet-free households. These analyses also highlighted the predominance in swine facility dust of Firmicutes (70%) at the phylum level, Clostridia (44%) at the Class level, and Clostridiales at the Order level (41%). In summary, shotgun pyrosequencing metagenomic analyses of agricultural dusts show that they differ qualitatively and quantitatively at the level of microbial taxa present, and that the bioinformatic analyses used for such studies must be carefully designed to avoid the potential contribution of non-microbial DNA, e.g. from resident mammals.     

A high docosahexaenoic acid diet alters lung inflammation and recovery following repetitive exposure to aqueous organic dust extracts

Agricultural workers, especially those who work in swine confinement facilities, are at increased risk for developing pulmonary diseases including asthma, chronic obstructive pulmonary disease, and chronic bronchitis due to exposures to fumes, vapors, and organic dust. Repetitive exposure to agricultural dust leads to unresolved inflammation, a common underlying mechanism that worsens lung disease. Besides occupational exposure to dusts, diet also significantly contributes to inflammation and disease progression. Since DHA (docosahexaenoic acid), a polyunsaturated omega-3 fatty acid and its bioactive metabolites have key roles in inflammation resolution, we rationalized that individuals chronically exposed to organic dusts can benefit from dietary modifications. Here, we evaluated the role of DHA in modifying airway inflammation in a murine model of repetitive exposure to an aqueous extract of agricultural dust (three-week exposure to swine confinement dust extract, HDE) and after a one-week resolution/recovery period. We found that mice fed a high DHA diet had significantly increased bronchoalveolar lavage fluid (BALF) levels of DHA-derived resolvins and lower TNFα along with altered plasma levels of endocannabinoids and related lipid mediators. Following the one-week recovery we identified significantly reduced BALF cellularity and cytokine/chemokine release along with increased BALF amphiregulin and resolvins in DHA diet-fed versus control diet-fed mice challenged with HDE. We further report observations on the effects of repetitive HDE exposure on lung Ym1+ and Arg-1+ macrophages. Overall, our findings support a protective role for DHA and identify DHA-derived resolvins and endocannabinoids among the potential mediators of DHA in altering airway inflammation in chronic agricultural dust exposure.     

Sustainable management of grassland ecosystems for controlling Asian dusts and desertification in Asian continent and a suggestion of Eco-Village study in China

Asian dusts, yellow sand, or dust and sand storms (DSS) in Asian continent are the end products of desertification, which became a regional environmental problem being aggravated by time. It is closely related to an issue of sustainability in the region. As the desertification is caused not only by natural factors, such as the climate change, strong wind, and low precipitation, but also by rapidly increasing human activities, such as overgrazing, misuse of water resources, and irrational land use, it is urgent to make efforts to combat desertification in Asian continent including China. In this regard, it is necessary to consider socio-economic aspects as well as ecological aspects and, consequently, the project for the construction of a Demonstration Model Village for eco-environmental rehabilitation should be paid to a special attention. The authors deal with this regional issue in consideration of three Es, which are represented by ecology, economy, and environment in providing the perspectives in sound approach to the issue. As an approach to the issue of Asian dusts and desertification in Asian continent, this Eco-Village study provides one way forward.     

城市地表灰尘中重金属的来源、暴露特征及其环境效应

地表灰尘是城市环境重金属的“源”、“汇”载体,与环境质量和人类健康有着密切关系.分析了城市地表灰尘重金属污染研究的意义,综述了国内外城市地表灰尘重金属地球化学行为研究进展,包括地表灰尘重金属来源、暴露特征及其影响因素分析、环境效应等方面.提出应加强时间序列及小尺度微观研究;地理因素对地表灰尘中重金属暴露特征、环境效应的影响机理研究.     

THE USE OF TETRA- AND PENTA-CHLORONITRO-BENZENES IN THE CONTROL OF BOTRYTIS DISEASE AND RHIZOCTONIA ATTACK OF LETTUCE

Botrytis disease in the 'spring' lettuce crop was controlled by six talc dusts containing s, 10 or 20 % of tetra- or penta-chloronitrobenzene. All the dusts increased equally the final stand in the frames, but the number of seedlings with stem lesions decreased with increasing concentrations of both compounds. At similar concentrations the tetra- was more effective than the penta-compound. The percentage survival in the field was increased by the dust treatments. The 20% dust of the penta- was only as effective as the 5% dust of the tetra-compound.
The dusts affected the leaves, stunted the seedlings and delayed hearting. At similar concentrations the tetra- was more harmful than the penta-compound. The 5 % dust of the tetra- was less damaging than the 20% dust of the penta-compound.
The spread of Rhizoctonia solani was reduced by incorporating the dusts with soil. Again, the 5% tetra- dust was as effective as the penta- dust at 20%. At 12·5 g. of dust per 20 kg. of soil, none of the dusts retarded the rate of emergence of lettuce seedlings but the highest concentration of the tetra- series reduced the number emerging.
Foliage applications of two dusts, 5% tetra- and 20% penta- dusts, controlled the spread of R. solani.     

Should bioactive trace elements not recognized as essential,but with beneficial health effects,have intake recommendations

Today, most nutritionists do not consider a trace element essential unless it has a defined biochemical function in higher animals or humans. As a result, even though it has been found that trace elements such as boron and silicon have beneficial bioactivity in higher animals and humans, they generally receive limited attention or mention when dietary guidelines or intake recommendations are formulated. Recently, the possibility of providing dietary intake recommendations such as an adequate intake (AI) for some bioactive food components (e.g., flavonoids) has been discussed. Boron, chromium, nickel, and silicon are bioactive food components that provide beneficial health effects by plausible mechanisms of action in nutritional and supra nutritional amounts, and thus should be included in the discussions. Although the science base may not be considered adequate for establishing AIs, a significant number of findings suggest that statements about these trace elements should be included when dietary intake guidance is formulated. An appropriate recommendation may be that diets should include foods that would provide trace elements not currently recognized as essential in amounts shown to reduce the risk of chronic disease and/or promote health and well-being.     

Marking Triatoma brasiliensis,Triatoma pseudomaculata and Rhodnius nasutus Nymphs with Trace Elements: Element Persistence and Effects of Marking on Insect Mortality

BackgroundField ecologists often rely on mark-release-recapture (MRR) experiments to estimate population dynamics parameters for a given species. In the case of a medically important taxon, i.e., a disease vector, inferences on species survival and dispersal rates are particularly important as they have the potential to provide insights into disease transmission dynamics in endemic areas. Medical entomologists have traditionally used fluorescent dusts to externally mark the cuticle of insects. However, dust marking is usually restricted to the adult life stage because immature insects lose the mark when they molt.Conclusions/SignificancePrevious evidence shows that there is little or no genetic differentiation between populations at the microgeographic level, which often precludes indirect estimations of dispersal capability based on genetic markers. In such situations, MRR studies are more suitable as they measure insect movement directly from one site to another, instead of effective migration (i.e. gene flow). The determination of a reliable and persistent marking method is the first step towards the development of meaningful ecological estimates through the application of MRR methodology. Here, we have identified trace elements that can be used for mark and recapture studies of three triatomine species in Brazil.     

Trace elements as paradigms of developmental neurotoxicants: Lead,methylmercury and arsenic

Trace elements have contributed unique insights into developmental neurotoxicity and serve as paradigms for such adverse effects. Many trace elements are retained in the body for long periods and can be easily measured to assess exposure by inexpensive analytical methods that became available several decades ago so that past and cumulated exposures could be easily characterized through analysis of biological samples, e.g. blood and urine. The first compelling evidence resulted from unfortunate poisoning events that allowed scrutiny of long-term outcomes of acute exposures that occurred during early development. Pursuant to this documentation, prospective studies of children's cohorts that applied sensitive neurobehavioral methods supported the notion that the brain is uniquely vulnerable to toxic damage during early development. Lead, methylmercury, and arsenic thereby serve as paradigm neurotoxicants that provide a reference for other substances that may have similar adverse effects. Less evidence is available on manganese, fluoride, and cadmium, but experience from the former trace elements suggest that, with time, adverse effects are likely to be documented at exposures previously thought to be low and safe.     

Radon sources and impacts: a review of mining and non-mining issues

Radon is a ubiquitous natural carcinogen derived from the three primordial radionuclides of the uranium series (²³⁸U and ²³⁵U) and thorium series (²³²Th). In general, it is present at very low concentrations in the outdoor or indoor environment, but a number of scenarios can give rise to significant radiological exposures. Historically, these scenarios were not recognised, and took many centuries to understand the links between the complex behaviour of radon and progeny decay and health risks such as lung cancer. However, in concert with the rapid evolution in the related sciences of nuclear physics and radiological health in the first half of the twentieth century, a more comprehensive understanding of the links between radon, its progeny and health impacts such as lung cancer has evolved. It is clear from uranium miner studies that acute occupational exposures lead to significant increases in cancer risk, but chronic or sub-chronic exposures, such as indoor residential settings, while suggestive of health risks, still entails various uncertainties. At present, prominent groups such as the BEIR or UNSCEAR committees argue that the ‘linear no threshold’ (LNT) model is the most appropriate model for radiation exposure management, based on their detailed review and analysis of uranium miner, residential, cellular or molecular studies. The LNT model implies that any additional or excess exposure to radon and progeny increases overall risks such as lung cancer. A variety of engineering approaches are available to address radon exposure problems. Where high radon scenarios are encountered, such as uranium mining, the most cost effective approach is well-engineered ventilation systems. For residential radon problems, various options can be assessed, including building design and passive or active ventilation systems. This paper presents a very broad but thorough review of radon sources, its behaviour (especially the importance of its radioactive decay progeny), common mining and non-mining scenarios which can give rise to significant radon and progeny exposures, followed by a review of associated health impacts, culminating in typical engineering approaches to reduce exposures and rehabilitate wastes.     

Inert dust insecticides: Part I. Mechanism of action

The mode of action of inert dust insecticides on the grain weevil ( Calandra granaria L.) has been investigated by determination of mortality-time curves and by a detailed study of the influence of dusts on the water relations of the insects. It has been found that dusts do not depend for their action on any chemical reactivity, some highly inert substances such as diamond and carborundum being very effective. A physical process is therefore indicated.
Dusts do not penetrate into the respiratory system, and although large amounts are ingested these seem to have little harmful effect.
It has been demonstrated that effective dusts increase the rate of evaporation of water from insects to the air, and that the relative killing powers of different dusts run parallel with their capacities for promoting evaporation. The results are in harmony with the view (proposed by earlier workers) that inert dusts kill insects by inducing death by desiccation.     

Compounds of Mo, V and W in biochemistry and their biomedical activity.

Molybdenum, vanadium and tungsten compounds are widely applied as analytical reagents for determination of numerous pharmacologically active substances and different biochemical parameters. Recent data from the available literature pointed to a very potent biomedical activity of compounds containing these trace elements. The present paper represents a survey on the structure and chemical properties of these compounds, as well as on their biological activity, mostly based on their interaction with cations of biomolecules, such as phospholipids and proteins. Besides, their potent inhibitory effects on cellular targets, bacterial and viral DNA and RNA polymerases will be discussed, as well. Numerous authors clearly demonstrated the antiviral (especially anti-HIV), anticoagulant and antineoplastic properties of the compounds containing the above trace elements. It has been also shown that these compounds act on some cellular enzymatic systems leading to the normalisation of blood pressure, blood glucose and serum lipid levels. Also, compounds of these trace elements represent potent antiobesity agents and express hepatoprotective and antioxidative stress activity.     

山楂叶中微量元素的含量测定

本文采用高频等离子体发射光谱法(ICP-AES)测定了山楂叶中的17种微量元素,其中有8种是必需的微量元素,K、Ca、P、Mg 含量较高,Zn、Cu含量比值为2.7。这些微量元素的存在对维持人体健康极为重要.     

Role of diet modification in cancer prevention

Carcinogenesis encompasses a prolonged accumulation of injuries at several different biological levels and include both genetic and biochemical changes in the cells. At each of these levels, there are several possibilities of intervention in order to prevent, slow down or even halt the gradual march of healthy cells towards malignancy. Diet modification is one such possibility. A number of natural foodstuffs, especially fruits and vegetables contain substantial quantities of molecules that have chemopreventive potential against cancer development. Such compounds include vitamins, trace elements and a variety of other molecules with antioxidant properties. Carotenoids, flavanoid polyphenols, isoflavones, catechins, and several other components that found in cruciferous vegetables are molecules that are known to protect against the deleterious effect of reactive oxygen species. A number of epidemiological and experimental studies have shown that vitamin C and E, Beta-carotene and the essential trace element selenium can reduce the risk of cancer. Consistent observations during the last few decades that cancer risk is reduced by a diet rich in vegetables, fruits, legumes, grains and green tea have encouraged research to identify several plant components especially phytochemicals that protect against DNA damage. Many of these substances block specific carcinogen pathways. Dietary supplements are part of an overall health program, along with a high intake of fruits and vegetables that help to combat damage to cells, which in turn may initiate cancer development. This paper will review current knowledge concerning diet modification and cancer prevention with special reference to minerals and trace elements.     

Application of PCR-SSCP for molecular epidemiological studies on the exposure of farm children to bacteria in environmental dust

The environmental exposure of farm children to microorganisms in dust has become a focus of interest, since microbial exposure on farms has been related to a reduced prevalence of asthma and atopic diseases in children. Previous studies almost exclusively focused on the determination of microbial counts using conventional culturing or the determination of microbial compounds i.e. endotoxins. In this study PCR-SSCP (single-strand conformation polymorphism) was modified for characterising bacterial communities in environmental dusts and their sensitivity and reproducibility was validated. A fivefold repeated PCR-SSCP analyses of a well homogenised mattress dust, cow-shed dust, swine-shed dust, chicken-shed dust and a horse-shed dust sample, respectively, showed similarities, based on Pearson correlations, ranging from 89.7% to 95.2%. The reproducibility of day to day variations (five days) and gel to gel variations (five gels) was also around 90%. The detection limit of Escherichia coli was 7 x 10(1) cfu g(-1) whereas Listeria monocytogenes and Bacillus licheniformis containing 30% spores showed visible bands at 7 x1 0(2) cfu g(-1). Application of this method to dust samples of 37 sheds and 63 children's mattresses showed that distinct farm environment dusts reflected different SSCP profiles. However, digital analysis of the gels showed that some bands in the profiles of shed- and mattress dusts were found at the same position in the gels. By excision, cloning, sequencing and phylogenetic analyses, these bands were identified as Corynebacterium tuberculostearicum, Corynebacterium mucifaciens, Staphylococcus epidermidis, Acinetobacter lwoffii, Brevibacterium iodinum, Brevibacterium linens and Arthrobacter spp, respectively. These results may reflect transfer of microorganisms from animal sheds to mattresses. In conclusion this study demonstrates that PCR-SSCP is a promising method with sensitive detection limits and moderate sample variances to be applied for epidemiological studies characterizing the exposure of farmers using environmental dust.     

Morphological studies of the rat liver after experimental administration of carbon ashes and coal dust

The experiments were carried out in Wistar rats which were given intratracheally samples of carbon ashes or soil dust in the form of the respirable fraction. The morphologic changes and the glycogen content in the experimental animals' livers were evaluated. The content of the trace elements was determined in the applied carbon ashes and soil dust by means of the X-rays diffraction method. The results of the studies show that the morphologic changes in liver depend on the kind of dust and are related to the content of the trace elements and the free silicon dioxide in the carbon ashes and the soil dust.     

Radioepidemiology in the aftermath of the nuclear program of the former Soviet Union: Unique lessons to be learnt

  The military and civilian nuclear activities in the former Soviet Union led to unique exposures and resulted in high cumulative doses in several populations. In comparison to the atomic bomb survivors, at present the most important cohort in radiation epidemiology, collective and individual doses received by early workers in the plutonium production facilities at Mayak (Chelyabinsk), Techa River residents downstream of Mayak, populations downwind of the Semipalatinsk test site, and subpopulations of Chernobyl victims surpass the Hiroshima/Nagasaki experience in most cases. Even more importantly, the dose rates cover the full range of exposures relevant for radiation protection, i.e., acute to year-long chronic exposures from environmental contamination and bone seeking radionuclides. Parallel to the humanitarian need to mitigate health effects from these exposures, the unique opportunities for research on radiation risks related to low dose rate and chronic radiation have to be explored. Increased efforts by the global radiation research community are needed to address the many questions which cannot be answered by the acutely irradiated survivors of Hiroshima/Nagasaki. Specific attention needs to be drawn to the validation of available exposure and health records and to dose reconstruction which must include dietary sources of exposure. Preliminary intercomparison and validation exercises indicate potentially large sources of error, e.g., due to uncertainties in the reconstruction of early exposures and effects and due to continuing incorporation. Received: 29 February 1996 / Accepted in revised form: 6 March 1996     

酵母生物多样性开发及工业应用

酵母是一类包括酿酒酵母和非常规酵母在内的多种单细胞真菌的总称,其中酿酒酵母是应用较多的重要工业微生物,广泛应用于生物医药、食品、轻工和生物燃料生产等不同生物制造领域。近年来,研究者从不同生态环境中分离了大量的酵母菌株,鉴定了多个新种,也发现了抗逆性不同以及具有多种活性产物合成能力的菌株,证明天然酵母资源具有丰富的生物多样性和功能多样性。利用基因组挖掘以及转录组、蛋白组等多组学分析研究,可进一步开发利用酵母遗传多样性,获得酶和调节蛋白的基因以及启动子等遗传元件改造酵母菌株。除了利用酵母的天然遗传多样性,还可通过诱变、驯化、代谢工程改造及合成生物学等技术产生具有多种非天然多样性的菌株。此外,对天然遗传元件也可以进行突变和定向进化,所产生的新遗传元件可用于有效提升菌株的性能。开发利用酵母的生物多样性,对构建高效酵母细胞工厂,生产生物酶、疫苗以及多种活性天然产物等产品具有重要意义。文中对酵母生物多样性的研究现状进行综述,并对未来高效开发利用酵母菌株资源和遗传资源的研究进行了展望。文中所总结的研究方法和思路也可为研究其他工业微生物的多样性及进行高效菌株的选育提供参考。