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PubMed2002

Lead within ecosystems on metalliferous mine tailings in Wales and Ireland.

A comparative study of the concentrations of lead in ecosystems developed on metalliferous mine tailings was undertaken. Mine soils, vegetation, ground-dwelling invertebrates and Apodemus sylvaticus from nine abandoned mines in Wales and a modern Irish mine site were sampled in order to evaluate and compare exposure risks to wildlife. The mine sites had a wide range of relatively high concentrations of total lead in their tailings (from 1058 to 46,630 mg kg(-1)) but the extractable lead fractions were extremely variable and not clearly related or proportional to the total values. The high soil concentrations were reflected in vegetation collected from most of the sites with the exception of the modern mine, but there was no statistical relationship, on a site basis, between available soil lead and that in plant leaf samples. The highest plant concentrations were found in litter, which in all but one of the Welsh sites exceeded the threshold guideline value of 150 mg kg(-1). Food-chain transfer was shown by high concentrations of lead in invertebrates and A. sylvaticus from the abandoned Welsh mines. A highly significant relationship existed between lead in grass and the grasshopper, Chorthippus brunneus. Adverse effects on soil invertebrates, essential to the decomposition processes and cycling of essential nutrients, were identified as probably the major obstacle to natural ecosystem development on the abandoned Welsh sites. Toxicological risk of lead to the small mammals from the Welsh sites, but not the modern Irish tailings, is indicated given the high lead concentrations in dietary items and the resultant residues in kidney with some evidence of renal oedema in animals from two sites. The absence of a significant relationship between the estimated dietary lead concentration. calculated on a site basis, and the total body concentration in A. sylvaticus, was attributed, in part, to the large size of the home range and the partial feeding of individual animals off the contaminated mine site.

Animals↗
PubMed2001

Modelling the closure-related geochemical evolution of groundwater at a former uranium mine.

A newly developed reactive transport model was used to evaluate the potential effects of mine closure on the geochemical evolution in the aquifer downgradient from a mine site. The simulations were conducted for the Königstein uranium mine located in Saxony, Germany. During decades of operation, uranium at the former mine site had been extracted by in situ acid leaching of the ore underground, while the mine was maintained in a dewatered condition. One option for decommissioning is to allow the groundwater level to rise to its natural level, flooding the mine workings. As a result, pore water containing high concentrations of dissolved metals, radionuclides, and sulfate may be released. Additional contamination may arise due to the dissolution of minerals contained in the aquifer downgradient of the mine. On the other hand, dissolved metals may be attenuated by reactions within the aquifer. The geochemical processes and interactions involved are highly non-linear and their impact on the quality of the groundwater and surface water downstream of the mine is not always intuitive. The multicomponent reactive transport model MIN3P, which can describe mineral dissolution-precipitation reactions, aqueous complexation, and oxidation-reduction reactions, is shown to be a powerful tool for investigating these processes. The predictive capabilities of the model are, however, limited by the availability of key geochemical parameters such as the presence and quantities of primary and secondary mineral phases. Under these conditions, the model can provide valuable insight by means of sensitivity analyses.

Forecasting↗
PubMedDate not supplied

Spatial distributions of arsenic exposure and mining communities from NHEXAS Arizona. National Human Exposure Assessment Survey.

Within the context of the National Human Exposure Assessment Survey (NHEXAS), metals were evaluated in the air, soil, dust, water, food, beverages, and urine of a single respondent. Potential doses were calculated for five metals including arsenic. In this paper, we seek to validate the potential dose calculations through spatial analysis of the data. Others report elevated arsenic concentrations in biological and environmental samples from residents of mining towns, particularly Ajo, Arizona. These reports led us to expect potential arsenic doses above the 90th percentile of the NHEXAS exposure distribution to be from residents of mining communities. Arsenic dose was calculated using media concentrations, time activity patterns, and published exposure factors. Of the 179 homes evaluated, 54 were in mining communities; 11 of these were considered separately for reasons of population bias. Of the 17 homes with the greatest potential arsenic doses, almost half (47%) were in mining communities. We evaluated the potential doses by media from nonmining and mining areas using the nonparametric Mann-Whitney U test. Statistically significant (p = 0.05) differences were found between mining (n = 43) and nonmining sites (n = 122) for total exposure and for each of the following media: house dust, yard soil, outdoor air, beverage consumed, and water consumed. No differences were found in either food or indoor air of mining and nonmining areas. We eliminated outliers and repeated the test for all media; significance increased. Dietary, organic arsenic from fish consumption contributed to elevated arsenic exposure among people from nonmining communities and acted as an initial confounder. When controlling for fish consumption, we were able to validate our potential dose model using arsenic, particularly in Ajo. Further, we identified three mining communities lacking elevated arsenic exposure. Additional work is needed speciating the arsenic and evaluating health risks. The utilization of Geographic Information System facilitated spatial this project and paves the way for more sophisticated future spatial analyses.

Adult↗
PubMed1995

Variability of particle size-specific fractions of personal coal mine dust exposures.

This study estimated the ratio of the tracheo-bronchial dust fraction to the fraction collected by a respirable dust sampler for a variety of job classifications found in conventional, continuous, and longwall coal mining sections. The ratios could then be applied in epidemiologic studies to existing respirable dust measurements to estimate thoracic mass concentrations for evaluation of the relative importance of the respirable and thoracic dust fractions to obstructive lung disease. Data collected include particle size distributions from four U.S. underground coal mines using eight-stage personal cascade impactors. A total of 180 samples were examined by mine, occupation and occupations grouped by proximity to the mine face, and by mining technology. Several fractions--that collected by the 10-mm nylon cyclone, the American Conference of Governmental Industrial Hygienists respirable and thoracic particulate mass fractions, and the estimated alveolar and tracheo-bronchial deposition fractions--were estimated. These were not significantly different when grouped by occupation, by proximity of work to the mine face, or by the type of mining technology in use. Distributions from one mine varied from the others, perhaps because it used diesel equipment in the haulage ways, which contributed to the fine aerosol fractions. Results suggest that although the tracheo-bronchial dust fraction may contribute to the development of obstructive lung disease, occupation-specific tracheo-bronchial dust fractions are not likely to produce stronger exposure-response estimates than the historically collected respirable dust concentrations.

Bronchi↗
PubMed2005

High exposure to respirable dust and quartz in a labour-intensive coal mine in Tanzania.

Labour-intensive mines are numerous in several developing countries, but dust exposure in such mines has not been adequately characterized. The aim of this study was to identify and quantify the determinants of respirable dust and quartz exposure among underground coal mine workers in Tanzania. Personal respirable dust samples (n = 134) were collected from 90 underground workers in June-August 2003 and July-August 2004. The development team had higher exposure to respirable dust and quartz (geometric means 1.80 and 0.073 mg m(-3), respectively) than the mining team (0.47 and 0.013 mg m(-3)), the underground transport team (0.14 and 0.006 mg m(-3)) and the underground maintenance team (0.58 and 0.016 mg m(-3)). The percentages of samples above the threshold limit values (TLVs) of 0.9 mg m(-3) for respirable bituminous coal dust and 0.05 mg m(-3) for respirable quartz, respectively, were higher in the development team (55 and 47%) than in the mining team (20 and 9%). No sample for the underground transport team exceeded the TLV. Drilling in the development was the work task associated with the highest exposure to respirable dust and quartz (17.37 and 0.611 mg m(-3), respectively). Exposure models were constructed using multiple regression model analysis, with log-transformed data on either respirable dust or quartz as the dependent variable and tasks performed as the independent variables. The models for the development section showed that blasting and pneumatic drilling times were major determinants of respirable dust and quartz, explaining 45.2 and 40.7% of the variance, respectively. In the mining team, only blasting significantly determined respirable dust. Immediate actions for improvements are suggested to include implementing effective dust control together with improved training and education programmes for the workers. Dust and quartz in this underground mine should be controlled by giving priority to workers performing drilling and blasting in the development sections of the mine.

Coal Mining↗
PubMed1991

Practical difficulties in determining 222Rn flux density in underground uranium mines.

Radon-222 flux density, J, has been determined in a number of locations in an underground U mine. Measurements were conducted using the Two-Point Measurement (2PM) method, consisting of measuring the 222Rn concentration at two different points a distance apart within a given section of the mine. Several mine models were used for determining J by the above method. The 2PM method is sensitive to sources and sinks of 222Rn other than mine walls, as well as mining operations and mining activities of a diverse nature, and to local variations in airflow conditions. Because of this, J obtained by the 2PM method represents an "apparent" flux density. Significant differences were found in the flux density calculated according to different mine models. In addition, J measurements using the flux "can" method were also carried out in mine walls and compared with the values obtained by the 2PM method. Wide discrepancies between the two methods were found. The practical and theoretical difficulties in determining J are discussed.

Air Pollutants, Radioactive↗
PubMedDate not supplied

Ground water flow parameterization of an Appalachian coal mine complex.

We examined a large (240 km2) northern Appalachian bituminous coal basin (Irwin Syncline, Westmoreland County, Pennsylvania) comprising 27 mine complexes with nine major (> 2.5 x 10(3) L/min) discharges. The synclinal basin was divided into seven subbasins based on equilibrium hydraulic relationships established during the past 25 years. Recharge rates, mine pool velocity, and residence times respond to hydraulic changes in the overburden induced by mine subsidence. The estimated maximum depth for subsidence fractures is 60 m (30 times mined thickness) with recharge rates decreasing significantly in subbasins with thicker overburden (> 75 m). Calculated subbasin recharge rates range from 2 to 6 x 10(-4) L/min/m2 and are significantly lower than the previously used rate for the basin. Residence time of ground water in the Irwin subbasins calculated using average linear velocity ranged from one to five years and were more consistent with field observations than estimates obtained using discharge and basin volume area. A positive correlation (r2 = 0.80) exists between net alkalinity of the mine water-impacted discharges and residence time in the mine pools. Our results for the Irwin coal basin suggest that use of a subbasin approach incorporating overburden depth, mining methodology, and the extent of postmining inundation will lead to improved determination of ground water flow parameters in mined watersheds in northern Appalachia and elsewhere.

Appalachian Region↗
PubMed1998

Effects of oral exposure to mining waste on in vivo dopamine release from rat striatum.

Several single components of mining waste (arsenic, manganese, lead, cadmium) to which humans are exposed at the mining area of Villa de la Paz, Mexico, are known to provoke alterations of striatal dopaminergic parameters. In this study we used an animal model to examine neurochemical changes resulting from exposure to a metal mixture. We used microdialysis to compare in vivo dopamine release from adult rats subchronically exposed to a mining waste by oral route with those from a control group and from a sodium arsenite group (25 mg/kg/day). We found that arsenic and manganese do accumulate in rat brain after 2 weeks of oral exposure. The mining waste group showed significantly decreased basal levels of dihydroxyphenylacetic acid (DOPAC; 66.7 +/- 7.53 pg/ microl) when compared to a control group (113.7 +/- 14.3 pg/ microl). Although basal dopamine release rates were comparable among groups, when the system was challenged with a long-standing depolarization through high-potassium perfusion, animals exposed to mining waste were not able to sustain an increased dopamine release in response to depolarization (mining waste group 5.5 +/- 0.5 pg/ microl versus control group 21.7 +/- 5.8 pg/ microl). Also, DOPAC and homovanillic acid levels were significantly lower in exposed animals than in controls during stimulation with high potassium. The arsenite group showed a similar tendency to that from the mining waste group. In vivo microdialysis provides relevant data about the effects of a chemical mixture. Our results indicate that this mining waste may represent a health risk for the exposed population.

Administration, Oral↗
PubMed1979

Acid mine drainage and subsidence: effects of increased coal utilization.

The increases above 1975 levels for acid mine drainage and subsidence for the years 1985 and 2000 based on projections of current mining trends and the National Energy Plan are presented. No increases are projected for acid mine drainage from surface mines or waste since enforcement under present laws should control this problem. The increase in acid mine drainage from underground mines is projected to be 16 percent by 1985 and 10 percent by 2000. The smaller increase in 2000 over 1985 reflects the impact of the PL 95-87 abandoned mine program. Mine subsidence is projected to increase by 34 and 115 percent respectively for 1985 and 2000. This estimate assumes that subsidence will parallel the rate of underground coal production and that no new subsidence control measures are adopted to mitigate subsidence occurrence.

Acids↗
PubMedDate not supplied

[Report on health status of residents in areas with industrial, mining or military sites in Sardinia, Italy].

The work described in the present report has been requested by the Secretary of Hygiene, Health and Social Welfare of the Sardinia Region (Italy). It has been carried out by the Regional Epidemiological Observatory within the domain of ESA (Epidemiology Development and Environment) and with the support of the European Union. Eighteen areas (for a total of 73 municipalities) were identified a priori as "potentially polluted", accounting for a population of 917,977 in 2001 census (56% of the total population of Sardinia). The areas have been named after the most important town, as listed below (in brackets rounded 2001 population), major activities in industrial areas are briefly described. INDUSTRIAL AREAS: Portoscuso (59,000). Processing of aluminium and other metals. Foundry. Power plants. Dismissed mines (mainly coal mining, lead, zinc). Plants for storing and treating special wastes. Italian Law 349/1986 classified this area as "at high risk of environmental crisis" and classified some plants as being "at high technological risk" (Norma Seveso Decree 334/1999). The area is part of the Sulcis National Restoration site. San Gavino (24,000). Industrial and commercial activities. Lead and zinc foundry. Dairy factories. Food industry. Sarroch (52,000). Petrochemical and refinery industry. Power plants. Mining. Incinerator. Plants for storing and treating special wastes. Gas and mineral oil deposits. Ottana (15,000). Chemical industry. Production of plastics and synthetic fibres. Denim production. Porto Torres (168,000). Chemical industry: production of basic chemicals (benzene, toluene, ethylene, propylene and others), polyethylene, elastomers and vinyl chloride. Textile industry. First and second category landfills. Some plants have been classified "at high technological risk" (Norma Seveso Decree 334/1999). The area is a National Restoration site. The town of Sassari is included. Tortolì (23,000). Construction of steel structures for offshore facilities of the oil and gas industry. Paper industry. Tempio Pausania (21,000). Cork production. Stone quarries. Macomer (17,000). Textile industry (velvet). First and second category landfills. Incinerator. MINING AREAS: Arbus (30,000). Extraction of zinc, lead and silver. Iglesias (39,000). Extraction of zinc, lead and silver. MILITARY SITES: Teulada (16,000). La Maddalena (11,000). Naval army shipyards. Salto di Quirra (31,000). Mining area. URBAN AREAS: Cagliari (299,000). Petrochemical plants, port, airport. Nuoro (37,000). Olbia (47,000). Port and airport. Oristano (31,000). Sassari (121,000). RESULTS: THE COMPARISON SARDINIA-ITALY: In 1997-2001, the age-standardized mortality rate (x1,000 person-years) among males was higher than in Italy (84.4 vs 80.8) while the reverse occurred in females (50.9 vs 52.0). Ill defined causes of death were 1.4% in males and 2.5% in females (vs corresponding estimates of 1.1% and 1.4% in Italy). Compared to Italian national data, regional age-standardized estimates were higher in Sardinia for infectious diseases (23% in males and 12% in females), respiratory diseases (22% and 14%: pneumoconiosis was more than 6 times more frequent in Sardinia than in Italy), diseases of the digestive system (26% and 9%: for liver cirrhosis, the excess was 33% in males and 9% in females; corresponding figures for liver cancer were 13% and 16%), breast cancer in females (5%). On the other hand, regional mortality rates were lower than the national rates for cardiovascular diseases (-1.3% and -7.4% in males and females respectively), all cancers considered as a whole (-9% and -7%) and lung cancer (-5% and -32%). Regional and national death rates for non Hodgkin lymphoma in both sexes and for leukaemia in females were almost identical, whereas the latter rate in males was slightly higher in Sardinia than in Italy (9.4 vs 8.4 x100,000 person-years). Particularly in men, the differences in mortality rates from all causes and from cardiovascular, respiratory diseases and lung cancer among the four traditional Provinces (Cagliari, Nuoro, Oristano and Sassari) were greater than the difference between Sardinia and Italy. Remarkably enough, also death rates from lymphohaemopoietic tumours were more heterogeneous within Sardinia. RESULTS IN THE INVESTIGATED AREAS: Rates of hospital discharges in Sardinia showed a high variability, which is partly attributable to differences in the availability of both hospital beds and alternative forms of care. This heterogeneity must be taken into account in the interpretation of rates of hospital discharge. These were relatively high in some areas (Cagliari, Iglesias, Portoscuso, Tortolì) and low in others (Olbia, Porto Torres, Sassari). All the reported observed/expected ratios were based on material deprivation adjusted figures. All the estimated statistics were reported with 90% Confidence Interval. INDUSTRIAL AREAS: In 1997-2001, deaths from respiratory diseases were significantly in excess in males in Portoscuso (obs/exp 205/124.77) and in San Gavino (69/46.77). Deaths from pneumoconiosis were recorded sporadically, with the exception of Portoscuso, where the excess was impressive (obs/exp 112/30.46). SMRs for lung cancer in males ranged between 0.62 in Ottana and 1.22 in San Gavino, with statistically significant departure from expected values in Portoscuso and Sarroch (both with SMR significantly in excess in males: 1.24). In Porto Torres mortality from all causes was in significant excess in both sexes (SMRs 1.04 in males and 1.09 in females), for respiratory diseases (1.08 and 1.28), for diseases of the digestive system (1.13 and 1.21), for all cancers (1.04 and 1.09). Liver cancer deaths were also in excess in both sexes (SMRs 1.18 and 1.21). The latter finding is confirmed by incidence rates from the local cancer registry. Among industrial areas, Porto Torres was also the one with a stronger evidence of an excess of deaths from lymphohaemopoietic cancer in males (obs/exp 99/83.60) and females (73/68.20). MINING AREAS: These areas are characterized by statistically significant excesses of mortality in males, largely caused by non neoplastic respiratory conditions (obs/exp 119/86.41 in Iglesias and 156/62.55 in Arbus). In recent years, deaths from pneumoconiosis averaged 20 per year in Arbus and 10 per year in Iglesias. Lung cancer in males was also significantly in excess in both areas (obs/exp 72/56.38 in Arbus and 108/72.14 in Iglesias). There is a time trend (1981-2001) towards a decrease of mortality from respiratory conditions, which nevertheless remains largely in excess over the regional average also in the most recent period. MILITARY AREAS: Statistically significant excesses of deaths and hospital discharges for non Hodgkin lymphoma were detected in La Maddalena (mortality, 1981-2001, in males 17 observed cases vs 6.13 expected, in females 8/5.64). In Salto di Quirra in 1997-2001 deaths from myeloma (in males 5/2.3) and leukaemias were increased in both sexes (total obs/exp 20/13.3, statistically non significant). URBAN AREAS: Urban areas in Sardinia are relatively well developed with high values of socioeconomic indicators. The health profile in Cagliari and Sassari is typical of towns of the Western world. In Cagliari there is a higher mortality for colorectal, breast, cervical and lung cancer. CONCLUSIONS: Environmental (non occupational) pollution might explain some of the observed excesses of disease in the investigated industrial areas of Sardinia, particularly in women, less likely to be exposed to hazards in the work environment, whereas in the mining areas studied the disease pattern suggests a major role of occupational exposures. On the other hand, the causal links between disease occurrence and exposures in the screened military areas remain uncertain. The disease patterns in the cities of Sardinia are likely to be associated with lifestyle and urban pollution. Historically, southern Italian Regions have been characterized by an advantage over the rest of the country in terms of health, but during the last decade such advantage tended to vanish. Sardinia confirms this secular trend. However in the most recent years studied, overall age-standardized mortality rate in Sardinian females still remains lower than Italian average, but this is not the case for males any more. Differences in the health profile between residents in different areas of Sardinia have been found to be far greater than the difference between Sardinia as a whole and Italy. A major contribution to intraregional differences is given by the 18 investigated areas where excesses were registered for: respiratory diseases (including cancer) in the industrial areas of Portoscuso, Sarroch and Porto Torres, and in the mining areas; diseases of the digestive tract, liver cancer and lymphohaemopoietic cancer in the area of Porto Torres; cancer of the lymphohaemopoietic system in some military areas; cancers of the colon and rectum, lung, breast and uterus in some of the major cities of the Region.

Catchment Area, Health↗
PubMed1996

Copper, Zinc, and Cadmium Concentrations in Peromyscus maniculatus Sampled Near an Abandoned Copper Mine

Concentrations of zinc, copper, and cadmium were determined in soil and liver, kidney, bone and stomach contents of deer mice (Peromyscus maniculatus) from two sites near an abandoned mine and one control site, on Vancouver Island, British Columbia, Canada. Soil concentrations of copper were significantly elevated at the mine and off site vs the reference site. In contrast, there was no difference in soil cadmium and zinc concentrations between the mine and reference site. Concentrations of copper, cadmium and zinc in livers of mice from the mine site were significantly elevated relative to the reference and off site locations. Cadmium kidney concentrations tended to be greater in mice from the mine versus the off site and reference site. No differences in bone cadmium, copper and zinc and, kidney copper and zinc concentrations were noted among mice from the three locations. Diet of mice from mine and off sites contained significantly greater copper concentrations than the reference population; no differences in cadmium or zinc diet concentrations in mice from the three sites were noted. Comparison of ratios of metal concentrations in diet:soil and concentrations in liver:soil suggest that for zinc and copper, soil and diet are of equal importance as a source of metal contamination to these mice. In contrast, cadmium diet:soil and cadmium liver:soil ratios were much greater than one indicative of bioconcentration of cadmium from soil to diet and from soil to liver. For assessing routes of metal exposure, in this case for deer mice inhabiting an abandoned mine site, for copper and zinc, soil will most likely be indicative of exposure conditions. In contrast, concentrations of cadmium in diet will be more representative of amounts that the animal is potentially ingesting. Of further importance is that relative to reference sites, mice inhabiting an abandoned copper mine site have significantly elevated tissue levels of copper. This is turn will provide a route of metal exposure to carnivorous birds such as owls and hawks. The toxicological significance of this exposure to birds of prey has yet to be assessed adequately.

Journal Article↗
PubMed2006

Predictive data mining in clinical medicine: current issues and guidelines.

BACKGROUND: The widespread availability of new computational methods and tools for data analysis and predictive modeling requires medical informatics researchers and practitioners to systematically select the most appropriate strategy to cope with clinical prediction problems. In particular, the collection of methods known as 'data mining' offers methodological and technical solutions to deal with the analysis of medical data and construction of prediction models. A large variety of these methods requires general and simple guidelines that may help practitioners in the appropriate selection of data mining tools, construction and validation of predictive models, along with the dissemination of predictive models within clinical environments. PURPOSE: The goal of this review is to discuss the extent and role of the research area of predictive data mining and to propose a framework to cope with the problems of constructing, assessing and exploiting data mining models in clinical medicine. METHODS: We review the recent relevant work published in the area of predictive data mining in clinical medicine, highlighting critical issues and summarizing the approaches in a set of learned lessons. RESULTS: The paper provides a comprehensive review of the state of the art of predictive data mining in clinical medicine and gives guidelines to carry out data mining studies in this field. CONCLUSIONS: Predictive data mining is becoming an essential instrument for researchers and clinical practitioners in medicine. Understanding the main issues underlying these methods and the application of agreed and standardized procedures is mandatory for their deployment and the dissemination of results. Thanks to the integration of molecular and clinical data taking place within genomic medicine, the area has recently not only gained a fresh impulse but also a new set of complex problems it needs to address.

Clinical Medicine↗
PubMed1998

The relationship between hetero-oligomer formation and function of the topological specificity domain of the Escherichia coli MinE protein.

MinE is an oligomeric protein that, in conjunction with other Min proteins, is required for the proper placement of the cell division site of Escherichia coli. We have examined the self-association properties of MinE by analytical ultracentrifugation and by studies of hetero-oligomer formation in non-denaturing polyacrylamide gels. The self-association properties of purified MinE predict that cytoplasmic MinE is likely to exist as a mixture of monomers and dimers. Consistent with this prediction, the C-terminal MinE22-88 fragment forms hetero-oligomers with MinE+ when the proteins are co-expressed. In contrast, the MinE36-88 fragment does not form MinE+/MinE36-88 hetero-oligomers, although MinE36-88 affects the topological specificity of septum placement as shown by its ability to induce minicell formation when co-expressed with MinE+ in wild-type cells. Therefore, hetero-oligomer formation is not necessary for the induction of minicelling by expression of MinE36-88 in wild-type cells. The interference with normal septal placement is ascribed to competition between MinE36-88 and the corresponding domain in the complete MinE protein for a component required for the topological specificity of septal placement.

Antibodies↗
PubMed1995

Deletion analysis of gene minE which encodes the topological specificity factor of cell division in Escherichia coli.

Division inhibition caused by the minCD gene products of Escherichia coli is suppressed specifically at mid-cell by MinE protein expressed at physiological levels. Excess MinE allows division to take place also at the poles, leading to a minicell-forming (Min-) phenotype. In order to investigate the basis of this topological specificity, we have analysed the ability of truncated derivatives of MinE to suppress either minCD-dependent division inhibition in a chromosomal delta(minB) background, or the division inhibition exerted by MinCD at the cell poles in a minB+ strain. Our results indicate that these two effects are not mediated by identical interactions of MinE protein. In addition, gel filtration and the yeast two-hybrid system indicated that MinE interacts with itself by means of its central segment. Taken together, our results favour a model in which wild-type MinE dimer molecules direct the division inhibitor molecules to the cell poles, thus preventing polar divisions and allowing non-polar sites to divide. This model explains how excess MinE, or an excess of certain MinE derivatives which prevent the accumulation of the division inhibitor at the poles, can confer a Min- phenotype in a minB+ strain.

Amino Acid Sequence↗
PubMed2003

Mapping the MinE site involved in interaction with the MinD division site selection protein of Escherichia coli.

Interactions between the MinD and MinE proteins are required for proper placement of the Escherichia coli division septum. The site within MinE that is required for interaction with MinD was mapped by studying the effects of site-directed minE mutations on MinD-MinE interactions in yeast two-hybrid and three-hybrid experiments. This confirmed that the MinE N-terminal domain is responsible for the interaction of MinE with MinD. Mutations that interfered with the interaction defined an extended surface on one face of the alpha-helical region of the MinE N-terminal domain, consistent with the idea that the MinE-MinD interaction involves formation of a coiled-coil structure by interaction with a complementary helical surface within MinD.

Adenosine Triphosphatases↗
PubMedDate not supplied

Environmental health consequences of land mines.

This article reviews the literature on the environmental effects of anti-personnel land mines globally. Land mines represent an immediate environmental health problem. Between 60 and 70 million land mines are currently in place in over 70 countries. Designed to kill or main humans, including civilians, they injure an estimated 1, 200 persons and kill another 800 every week. Land-mine injuries tend to be serious; an estimated 300,000 persons worldwide have been disabled by them. The problem, politically very controversial, can be resolved only by preventing the further placement of mines, by demining of areas already mined, and by coping with the personal and environmental devastation that they have already caused. Environmental health personnel should be involved in promoting awareness of the problem, in improving services for land-mine victims, and in promoting political efforts to ban further use of land mines.

Blast Injuries↗
PubMed2002

Environmental management of small-scale and artisanal mining: the Portovelo-Zaruma goldmining area, southern Ecuador.

This paper considers technical measures and policy initiatives needed to improve environmental management in the Portovelo-Zaruma mining district of southern Ecuador. In this area, gold is mined by a large number of small-scale and artisanal operators, and discharges of cyanide and metal-laden tailings have had a severe impact on the shared Ecuadorian-Peruvian Puyango river system. It is shown to be technically possible to confine mining waste and tailings at a reasonable cost. However, the complex topography of the mining district forces tailings management to be communal, where all operators are connected to one central tailings impoundment. This, in turn, implies two things: (i) that a large number of operators must agree to pool resources to bring such a facility into reality; and (ii) that miners must move away from rudimentary operations that survive on a day-to-day basis, towards bigger, mechanized and longer-term sustainable operations that are based on proven ore reserves. It is deemed unlikely that existing environmental regulations and the provision of technical solutions will be sufficient to resolve the environmental problems. Important impediments relate to the limited financial resources available to each individual miner and the problems of pooling these resources, and to the fact that the main impacts of pollution are suffered downstream of the mining district and, hence, do not affect the miners themselves. Three policy measures are therefore suggested. First, the enforcement of existing regulations must be improved, and this may be achieved by the strengthening of the central authority charged with supervision and control of mining activities. Second, local government involvement and local public participation in environmental management needs to be promoted. Third, a clear policy should be defined which promotes the reorganisation of small operations into larger units that are strong enough to sustain rational exploration and environmental obligations. The case study suggests that mining policy in lesser-developed countries should develop to enable small-scale and artisanal miners to form entities that are of a sufficiently large scale to allow adequate and cost-effective environmental protection.

Cost-Benefit Analysis↗
PubMed2003

Effects of mining activities on heavy metal concentrations in water, sediment, and macroinvertebrates in different reaches of the Pilcomayo River, South America.

From 1997 until 1999 the extent and the ecological effects of zinc, copper, lead, and cadmium pollution were studied in different reaches of the South American Pilcomayo River. A comparison of metal concentrations in water, sediment, and chironomid larvae, as well as the diversity of macroinvertebrate species, was made between sites near the origin of the Pilcomayo River, with hardly any mining activities, sites in the Potosí region, with intensive mining, and sites located 500 km or further downstream of Potosí, in the Chaco plain. Samples were also collected in an unpolluted river (Cachi Mayu River) and in the Tarapaya River, which is strongly contaminated by mine tailings (1000 tons a day). The upper parts of the Pilcomayo River are strongly affected by the release of mine tailings from the Potosí mines where mean concentrations of lead, cadmium, copper, and zinc in water, filtered water, sediment, and chironomid larvae were up to a thousand times higher than the local background levels. The diversity of the benthic macroinvertebrate community was strongly reduced in the contaminated parts; 97% of the benthic macroinvertebrates consisted of chironomid larvae. The degree of contamination in the lower reaches of the river, however, was fairly low because of sedimentation processes and the strong dilution of mine tailings with enormous amounts of clean sediment from erosion processes. Analysis of sediment cores from the Ibibobo floodplain, however, reveal an increase of the heavy metal concentrations in the lower reaches since the introduction of the contaminating flotation process in the mine industry in 1985.

Animals↗