Direct on-filter assay of subtilisin-type proteolytic enzymes for rapid analysis of analyte captured from the workplace atmosphere

A simple assay for some proteolytic enzymes has been developed which can be performed directly on the surface of a cellulose nitrate filter used to capture the analyte during workplace monitoring for health and safety purposes. Following air sampling the analysis is performed on the filter which is retained within the air sampler. This involves two steps: first, a 15 min incubation in which the captured enzyme is dissolved and then digests an alkaline-phosphatase-labelled antibody immobilised as a small dot on the surface of the filter; and second, is a 10 min incubation with substrate solution, which follows an in situ wash under a vacuum. During the incubation colour develops on the spot at the location of the immobilised enzyme antibody conjugate. The intensity of the spot can be assessed visually within the sampler to ascertain the presence or absence of captured enzyme, or alternatively quantitative results can be obtained using an optical scanner. The limit of detection is 5 ng per filter for subtilisin (20 ng for visual discrimination between this standard and the zero). The assay is stable to the effects of ambient air sampling at 31 min(-1) for 18 h.     

A novel approach to rapid detection of acute water toxicity and its policy implications for grassroots sustainable environmental monitoring

Unknown chemicals, emerging contaminants, and the resulting reactions among them make early detection and warning of acute water toxicity extremely challenging. The conventional approach using small fish for toxicity monitoring normally requires a designated species of fish and over a week's time to complete, including dilution of the wastewater, a pre-test, and a full test. It often increases chances for error and delays emergency management. This paper reports a novel approach, based on grassroots knowledge and field and lab experience in Jilin, China. This approach uses a combination of different species of aquarium fish to achieve fast and reliable monitoring. It tests the original source water directly without going through the dilution procedure, while paying attention to the time factor. The approach does not require a pre-test and may shorten the time needed for detecting acute toxicity to a few minutes, using a new classification of aquatic toxicity levels. It is inexpensive to use and may be easily adopted by grassroots organizations. The approach is "greener" and more financially and socially sustainable than traditional approaches. The wide use of the approach has the potential to encourage policy innovations for making toxicity monitoring grassroots based and more effective in reducing acute contamination emergencies.     

The development of cryoprobe nuclear magnetic resonance spectroscopy for the rapid detection of organic contaminants in potable water

The detection of trace levels of a range of organic contaminants (including pesticides, toxins and an explosive) in potable water, using cryoprobe NMR spectroscopy with limited sample preparation and rapid acquisition times, is described. Emphasis is placed on the applicability of NMR spectroscopy for use in emergency scenarios as the unbiased nature of the technique facilitates the detection and characterization of unknown compounds at levels as low as 50 microg L(-1).     

快速测试管法现场测定水中总余氯

余氯在水中极不稳定 ,需现场测定。通过研制一种测试管 ,从而能快速、简便地测水中的总余氯。常规法测定时间需要 3～ 5小时 ,而该测试管法仅需 1 0分钟。分析成本也大为降低     

Sampling and analysis considerations for the determination of hexavalent chromium in workplace air

Airborne hexavalent chromium (Cr[VI]) is a known human respiratory carcinogen and allergen. Workers in a variety of industries may be exposed to airborne hexavalent chromium, with exposures frequently occurring via inhalation and/or dermal contact. Analytical methods for the measurement of Cr(VI) compounds in workplace samples, rather than for the determination of total elemental chromium in workplace air, are often desired because exposure limit values for Cr(VI) compounds are much lower than for total Cr. For years, sampling and analytical test methods for airborne Cr(VI) have been investigated so as to provide means for occupational exposure assessment to this highly toxic species. Inter-conversion of trivalent chromium (Cr[III]) and Cr(VI) can sometimes occur during sampling and sample preparation, and efforts to minimize unwanted redox reactions involving these chromium valences have been sought. Because of differences in toxicity, there is also interest in the ability to differentiate between water-soluble and insoluble forms of Cr(VI), and procedures that provide solubility information concerning Cr(VI) compounds have been developed. This paper reviews the state of the art concerning the measurement of airborne Cr(VI) compounds in workplace aerosols and related samples.     

A rapid and sensitive analytical method for the quantification of residues of endosulfan in blood

A new sensitive analytical procedure has been developed for the determination of residues of endosulfan in human blood samples. The method involves the extraction of residues of endosulfan from blood samples by the addition of 60% sulfuric acid at 10 degrees C, liquid/liquid partitioning by using hexane and acetone mixture (9:1) and quantification by using GC-ECD. Residues of endosulfan in blood samples were quantified as the sum of alpha-endosulfan, beta-endosulfan, endosulfan sulfate and endosulfandiol. The influence of temperature during the extraction has been studied. Recovery experiments were conducted over the concentration range 1.0-50 ng ml(-1) and the relative standard deviation calculated. The method was found to be sufficiently sensitive to quantify the residue of total endosulfan up to the 1.0 ng ml(-1) level. The recovery was 92% with a calculated relative standard deviation of 1.96%. Conversion of endosulfan to endosulfandiol is found to be less than 0.5% under the defined conditions. The method was applied to the analysis of residue contents of endosulfan and its metabolites in blood samples collected from the exposed population. The data obtained has been confirmed by GC-MS-EI in selective ion monitoring (SIM) mode.     

Application of PCR and probe hybridization techniques in detection of airborne fungal spores in environmental samples

Specific PCR amplification and probe hybridization techniques were applied to examine the compositions of airborne fungi in samples from three different environments. The results from microscopic and CFU counting were compared to those of the molecular-based detections. The detection sensitivity for PCR amplifications was 9 to 73 spores and 1.3 to 19.3 CFUs per PCR reaction. The hybridization detection limit was 2 to 4 spores and 0.2 to 1.2 CFU. The hybridization method was more sensitive than PCR amplification and showed less variation among samples. Using specific PCR primers and probes we identified the presence of several fungal groups and species in the air samples. Specific detections through probe hybridization to PCR products amplified with universal or group-specific fungal primers have promising applications in the examination of air samples for environmental monitoring.     

Use of the instream flow incremental methodology: A tool for negotiation

The resolution of conflicts arising from differing values and water uses requires technical information and negotiating skills. This article outlines the Instream Flow Incremental Methodology (IFIM), developed by the US Fish and Wildlife Service, and demonstrates that its use to quantify flows necessary to protect desired instream values aids negotiation by illustrating areas of agreement and possible compromises between conflicting water interests. Pursuant to a Section 404 permit application to the US Army Corps of Engineers made by City Utilities of Springfield, Missouri, in 1978, IFIM provided the means by which City Utilities, concerned with a secure water supply for a growing population, and those advocating instream values were satisfied that their requirements were met. In tracing the 15-month process, the authors conclude that the application of IFIM, as well as the cooperative stance adopted by the parties involved, were the key ingredients of the successful permit application.     

A review of workplace aerosol sampling procedures and their relevance to the assessment of beryllium exposures

Standardized conventions governing the fractions of airborne particles that can penetrate the human head airways, the thoracic airways and the alveolar spaces have been internationally (although not universally) adopted. Several agencies involved in setting limit values for occupational exposure concentrations have taken these conventions into account when considering the appropriate standard for specific chemicals, in order to ensure the standards are biologically relevant. A convention is selected based on the characteristic health effects, and forms the basis of measurement against the limiting concentration value. In order to assess exposure for comparison to this metric or any other purposes, it is necessary to choose a sampler whose performance matches the convention, and protocols have been developed and used to test sampler performance. Several aerosol sampling devices are available, nominally at least, for each of the conventions. Some considerations important to the sampling of airborne particles containing beryllium with regard to the sampling conventions, the test protocols and sampler performance are discussed.     

Sensitive immunoassay detection of multiple environmental chemicals on protein microarrays using DNA/dye conjugate as a fluorescent label

Indirect competitive immunoassays were developed on protein microarrays for the sensitive and simultaneous detection of multiple environmental chemicals in one sample. In this assay, a DNA/SYTOX Orange conjugate was employed as an antibody label to increase the fluorescence signal and sensitivity of the immunoassays. Epoxy-modified glass slides were selected as the substrate for the production of 4 × 4 coating antigen microarrays. With this signal-enhancing system, competition curves for 17β-estradiol (E2), benzo[a]pyrene (BaP) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) were obtained individually on the protein microarray. The IC(50) and calculated limit of detection (LOD) are 0.32 μg L(-1) and 0.022 μg L(-1) for E2, 37.2 μg L(-1) and 24.5 μg L(-1) for BaP, and 31.6 μg L(-1) and 2.8 μg L(-1) for BDE-47, respectively. LOD of E2 is 14-fold lower than the value reported in a previous study using Cy3 labeled antibody (Du et al., Clin. Chem, 2005, 51, 368-375). The results of the microarray immunoassay were within 15% of chromatographic analysis for all three pollutants in spiked river water samples, thus verifying the immunoassay. Simultaneous detection of E2, BaP and BDE-47 in one sample was demonstrated. There was no cross-reaction in the immunoassay between these three environmental chemicals. These results suggest that microarray-based immunoassays with DNA/dye conjugate labels are useful tools for the rapid, sensitive, and high throughput screening of multiple environmental contaminants.     

Assessing workplace chemical exposures: the role of exposure monitoring

Occupational exposure is the condition of being subjected through employment to a chemical, physical, or biological agent, or to a specific process, practice, behavior, or organization of work. Exposure to a chemical agent is typically the contact of that agent with the outer boundary of a subject, such as the respiratory system, skin, or digestive system. In occupational hygiene we are most concerned with exposure through the respiratory system, although, increasingly we are concerned with the results of dermal exposures, including those exposures to the skin that can be transferred to the mouth and digestive system. This presentation will detail methods available for assessing personal exposures to chemicals through monitoring. The results from monitoring can then be compared to established guidelines and regulations, although this is not the only rationale for making measurements. These monitoring methods are currently used around the world to establish the benchmark hazard from which risk to the worker can be predicted. The presentation will describe the general techniques for assessing exposures to the respiratory system from chemical gases and vapors, chemical dusts, and exposures to the skin from bulk chemicals or chemical contamination of surfaces. For respiratory exposures, direct-reading instruments are available for spot measurements, and for monitoring short-term fluctuations in concentration. However, most standards and regulations are based on time-integrated (time-weighted average) exposures, requiring longer-term integrative methods. Therefore, the specific focus of this review will be the methods available for full work-shift sampling. For gases and vapors this will include taking whole-air samples in canisters or polymer bags, or concentration of chemicals by absorption in liquids or adsorption on solid sorbents, with subsequent chemical analysis. Chemical concentration can take place by pumping air through the sorbing media, or by allowing molecules to diffuse to the sorbent surface. Transfer of the collected chemicals to the analytical instrumentation can be accomplished using solvent displacement and injection, or through the application of heat to bring the collected molecules back into the vapor phase. For particles, the particle size is important as this determines the site of deposition in the lungs, and so time-integrated sampling on filters using various types of size-selective samplers is preferred. Finally, some techniques that have been used to assess the potential for chemical contamination of the skin are presented. Biomonitoring is another tool that can be used to assess exposure, and the results are more relevant to dosimetric considerations than exposure. Biomonitoring is a complex subject worthy of a separate review, and will be considered only briefly here.     

Evaluation of simple microbiol tests for detection of fecal coliforms directly at 44.5 degrees C

Simple microbial test comprising H₂S paper strip test,presence-absence (PA) test, and fluorogenic brila broth (BB)test performed directly at 44.5 °C were evaluated andcompared with the standard most probable number (MPN) method fordetection of fecal coliforms in 173 drinking water sources. BBand PA test were comparable with standard MPN method, whereas,poor compliance was noted for H₂S test. PA test whencompared with standard MPN test only 15%; disagreement wasdetected, whereas, highest disagreement of 40%; was observed incase of H₂S test. BB test was found to be highly sensitiveas only 7.8% disagreement with that of standard MPN test wasfound. Three hundred cultures obtained from positive tests wereidentified in order to evaluate the specificities of test usedin detection of fecal indicator Escherichia coli. BB testwas also found highly specific in detection of indicatororganism as compared to PA and H₂S test. Among theorganisms isolated from BB test 84.4%; of them were identifiedas E. coli as compared to 43.4 and 33.3 in PA and H₂Stest, respectively. The low incidence of recovery of E.coli (18.1%) for the standard MPN method places doubt on thevalidity of its application in tropical areas. The result ofthis investigation suggest that BB performed directly at 44.5 °C could be suitable cost effective test to assess themicrobiological quality of drinking water in India and other tropical countries.     

Performance of methods for measurement of exposure to inorganic acids in workplace air

BGIA has organised round robins for the analysis of samples of inorganic acids in workplace air for a number of years. Test samples of the volatile acids HCl and HNO(3) are collected from a standard atmosphere and samples of the non-volatile acids H(3)PO(4) and H(2)SO(4) are prepared by spiking filters with acid solution. The last two round robins have also covered the sampling of volatile acids, with up to 15 "active" participants able to visit the test facility in Dresden and take samples themselves. For other "passive" participants, BGIA takes samples from the same atmosphere. The acid concentrations generated lie between 0,1 and 1 times the German limit values for HCl and HNO(3). The results for the last round robin showed no significant difference between the performance of the "active" and "passive" participants. The participant means were in good agreement with the theoretical concentrations and the quality control measurements. For "active" participants RSDs were between 7% and 14% and for all participants between 8% and 16%. The round robin for the non-volatile acids showed similar results. The participant means were again in excellent agreement with the quality control measurements and RSDs were between 12% and 15%. The BGIA round robins have demonstrated the proficiency of laboratories measuring exposure to inorganic acids in air. However, concerns remain about the performance of published methods. It has shown that the sampling efficiency of sorbent tubes falls off with increasing particle size and hence silica gel tube methods may give low results for acid mists. Another issue with silica gel tubes is that a substantial proportion of the sample can be collected on the glass wool plugs that retain the sorbent. This can be up to 50% for HCl and 100% for HNO(3). Hence, low results may be obtained if the glass wool plugs are discarded. Similarly, methods for volatile inorganic acids that use a pre-filter to remove particulates usually overlook the fact that the acids can react with co-particulate matter on the pre-filter. Low recoveries in the range 30%-50% have been found when sampling HCl through filters loaded with potential interferents. Finally, particulate salts interfere with filter sampling methods for non-volatile inorganic acids. A two-part International Standard is in preparation for inorganic acids by ion chromatography and the issues discussed above are being taken into consideration during its development.     

Evaluation of diffusive samplers and photoionisation detectors for measuring very short peak exposures in the workplace

The extent to which very short peak widths, peak frequency, sampling time and post-sampling/pre-capping time impact upon occupational exposure measurements of toluene has been investigated using diffusive tubes. Additionally, the effect of the width of the peak on the estimation of peak maximum concentration and time-weighted average (TWA) concentration from real-time instruments (photoionisation detectors-PIDs) was also studied, and their responses modelled. No clear differences were perceived between diffusive and pumped tube results. Mean biases of -5 to +6% were recorded but no trend could be distinguished with respect to any of the variables examined; the main source of uncertainty was attributed to analytical uncertainty. The diffusive tubes can therefore be used to measure short term transient toluene concentrations (e.g. 5 s duration) over short (15 min) exposure periods. The two slower responding PIDs (t50 = 4 s) underestimated the maximum concentration of short term peaks having durations less than 10 s. The other three PIDs (t50 < or = 2 s) only significantly underestimated the maximum concentration of short term peaks having durations of 2 s and below. Pulse duration appeared to affect the PID's estimation of peak height more than peak area (TWA concentration).     

Evaluation of a standardized method for determining soluble silver in workplace air samples

Several occupational exposure limits and guidelines exist for silver, but the values for each depend on the chemical form of the silver compound in question. In the past, it generally was not possible, without prior knowledge of the work process, to distinguish soluble silver from insoluble silver compounds collected in workplace air samples. Therefore, analytical results were historically reported as total silver. In this study, work was conducted to evaluate a method to differentiate between the quantities of water-soluble silver compounds and total silver collected on filters. The investigation entailed an evaluation of an International Organization for Standardization method to determine soluble silver in airborne particulate matter. The study design incorporated laboratory experiments to evaluate analytical figures of merit, such as selection of appropriate filter media and extraction solution, analytical recovery, and sample stability during storage. Polytetrafluoroethylene (PTFE) filters (2 microm, 37 mm) in opaque cassettes were either spiked with known amounts of silver nitrate or contained a known mass of solid silver nitrate. Results showed that over 90% of the silver was recovered from PTFE filters. Also, field studies were conducted in which workplace air samples were collected in two silver refineries. Some of these samples were analyzed only for soluble silver while others were sequentially extracted and analyzed, first, for soluble silver, then for total silver. The mass fractions of soluble silver, as compared to total silver, were approximately 2% or less. This investigation served to validate an international standard procedure for the determination of soluble silver in workplace air samples.     

The first monoclonal antibody-based,matrix-resistant immunoassay for the carbamate herbicide asulam,in water

To date, no ligand binding assay has been described for the carbamate herbicide asulam, although a variety of physical methods, dependent on pre-concentration of water samples, have been documented for its assessment. However, asulam is increasingly used in sensitive agricultural areas, and statutory regulations concerning its monitoring will undoubtedly become more stringent. Antibodies are optimal partners in ligand binding assays, but it is commonly understood by immunological researchers that where no antibody reactive with a particular antigen has yet been described, the immunogenicity of the antigen may be particularly restricted. By the expedient of employing a specialised approach to final immunisation with an asulam-protein conjugate, prior to the immortalisation of a specific anti-asulam antibody-producing cell, we have succeeded in generating a monoclonal antibody reactive specifically with asulam that can be configured in a convenient immunoassay. This antibody may be used flexibly in a number of ways: small sample volumes of 10 microl can be assessed to sensitivities of 4.35 x 10(-7) M (10 microg L(-1)) while avoiding discrepancies contributed by the assay matrix; this antibody-based assay can also be formatted to deliver sensitivities at levels stipulated by regulatory authorities (e.g., 4.35 x 10(-9) M or 0.1 microg L(-1)) directly from a water sample, without prior pre-concentration.     

A method of rapid identification of the most important ecological problems in polluted areas

A comprehensive method is presented for the evaluation of the living elements of the environment by way of an example of an area situated within the emission range of a non ferrous metal works. The exposure of particular components of the environment is shown using the method of indices, taking into consideration the action of pollutants on the most essential and sensitive receptors. Methods of exposure reduction are also suggested. The proposed method may be helpful in land-use planning in polluted environments and can also be applied to determine the sequence of activities aimed at diminishing the effects of pollution.     

Assessment of diesel particulate matter exposure in the workplace: freight terminals

A large study has been undertaken to assess the exposure to diesel exhaust within diesel trucking terminals. A critical component of this assessment is an analysis of the variation in carbonaceous particulate matter (PM) across trucking terminal locations; consistency in the primary sources can be effectively tracked by analyzing trends in elemental carbon (EC) and organic molecular marker concentrations. Ambient samples were collected at yard, dock and repair shop work stations in 7 terminals in the USA and 1 in Mexico. Concentrations of EC ranged from 0.2 to 12 microg m(-3) among the terminals, which corresponds to the range seen in the concentration of summed hopanes (0.5 to 20.5 ng m(-3)). However, when chemical mass balance (CMB) source apportionment results were presented as percent contribution to organic carbon (OC) concentrations, the contribution of mobile sources to OC are similar among the terminals in different cities. The average mobile source percent contribution to OC was 75.3 +/- 17.1% for truck repair shops, 65.4 +/- 20.4% for the docks and 38.4 +/- 9.5% for the terminal yard samples. A relatively consistent mobile source impact was present at all the terminals only when considering percentage of total OC concentrations, not in terms of absolute concentrations.     

Real-time PCR for detection of the Aspergillus genus

Aspergillus is a genus of mold that has strong indoor sources, including several species capable of acting as opportunistic pathogens. Previous studies suggest that Aspergillus could serve as an indicator for abnormal mold growth or moisture, making it an important genus for environmental monitoring. Here, a quantitative polymerase chain reaction (qPCR, or real-time PCR) assay is presented for Aspergillus. The assay shows good specificity for the genus, detecting all Aspergillus species tested, although a few non-Aspergillus species are also amplified. Sensitivity testing demonstrates that DNA representing one conidium can be detected. A validation study compared qPCR results against direct microscopy counts using A. fumigatus conidia aerosolized into a laboratory chamber. The assay was then used to quantify Aspergillus in indoor air samples, demonstrating its utility for environmental monitoring. Analysis of a small number of clinical sputum samples showed complete agreement with culturing results.     

A groundwater flow model for water resources management in the Ismarida plain,North Greece

This paper presents the development of a regional flow simulation model of the stream–aquifer system of Ismarida plain, northeastern Greece. It quantifies the water budget for this aquifer system and describes the components of groundwater and the characteristics of this system on the basis of results of a 3-year field study. The semiconfined aquifer system of Ismarida Lake plain consists of unconsolidated deltaic clastic sediments, is hydraulically connected with Vosvozis River, and covers an area of 46.75 km². The annual precipitation ranges in the study area from 270 to 876 mm. Eighty-seven irrigation wells are densely located and have been widely used for agricultural development. Groundwater flow in this aquifer was simulated with MODFLOW. Model calibration was done with observed water levels, and match was excellent. To evaluate the impacts of the current pumping schedule and propose solutions, four management scenarios were formulated and tested with the model. Based on model results, the simulated groundwater budget indicates that there must be approximately 33% decrease of withdrawals to stop the dramatic decline of groundwater levels. The application of these scenarios shows that aquifer discharge to the nearby river would be very low after a 20-year period.