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PubMed2005

Anaerobic microbial mobilization and biotransformation of arsenate adsorbed onto activated alumina.

Due to the enactment of a stricter drinking water standard for arsenic in the United States, larger quantities of arsenic will be treated resulting in larger volumes of treatment residuals. The current United States Environmental Protection Agency recommendation is to dispose spent adsorbent residuals from arsenic treatment into non-hazardous municipal solid waste (MSW) landfills. The potential of microorganisms to alter the speciation affecting the mobility of arsenic in the disposal environment is therefore a concern. The purpose of this paper was to evaluate the potential of an anaerobic microbial consortium to biologically mobilize arsenate (As(V)) adsorbed onto activated alumina (AA), a common adsorbent used for treating arsenic in drinking water. Three anaerobic columns (0.27 l) packed with 100 g dry weight of AA containing 0.657 mg adsorbed As(V) (expressed as arsenic) per gram dry weight were continuously flushed with synthetic landfill leachate for 257 days. The fully biologically active column was inoculated with methanogenic anaerobic sludge (10 g volatile suspended solids l(-1) column) and was operated with a mixture of volatile fatty acids (VFA) in the feed (2.5 g chemical oxygen demand l(-1) feed). At the end of the experiment, 37% of the arsenic was removed from the column, of which 48% was accounted for by arsenical species identified in the column effluent. The most important form of arsenic eluted was arsenite (As(III)), accounting for nearly all of the identified arsenic in periods of high mobilization. Additionally, two methylated metabolites, methylarsonic acid and dimethylarsinic acid were observed. Mobilization of arsenic is attributed to the biological reduction of As(V) to As(III) since literature data indicates that As(III) is more weakly adsorbed to AA compared to As(V). Batch and continuous assays confirmed that VFA, present in landfill leachates, served as an electron donating substrate supporting enhanced rates of As(V) reduction to As(III). Two control columns, lacking inoculum and/or VFA in the feed displayed low mobilization of arsenic compared to the fully biologically active column. Therefore, leachates generated in MSW landfills could potentially result in the biologically catalyzed mobilization of arsenic from As(V)-laden drinking water residuals.

Adsorption↗
PubMed2006

Treatability of chloro-s-triazines by conventional drinking water treatment technologies.

Recent research shows that herbicide atrazine (ATZ), simazine (SIM), and propazine (PROP), as well as their three chlorinated degrades-desethylatrazine (DEA), deisopropylatrazine (DIA), and didealkylatrazine (DDA)-may cause a common toxic effect in terms of endocrine disruption. The US Environmental Protection Agency (EPA) is currently considering a regulatory trigger based on the sum of these concentrations of these six chloro-s-triazines. While limited removal data exists for the parent compounds, little information is available for the degrades formed biologically and/or chemically in the environment and in the treatment plants. It is therefore critical to assess the removal efficiency in a typical water plant of the parent herbicides, as well as the daughter products. In this work, conventional drinking water treatment technologies were evaluated under typical water treatment plant conditions to determine their effectiveness in removing six chloro-s-triazines: ATZ, SIM, PROP, DEA, DIA, and DDA. Experiments were conducted using synthetic solutions prepared by spiking both distilled water and Missouri River water with the study compounds. Two powder activated carbons (PAC)--Calgon WPH and Norit HDB-were shown to be partially effective in removing the studied chloro-s-triazines. Ozonation efficiency varied, depending on different water sources, with respect to the removal of atrazine and didealkylatrazine. Coagulation/flocculation/sedimentation with alum and iron salts, excess lime/soda ash softening, and disinfection by free chlorine were all ineffective methods for removing chloro-s-triazines. It appears that chloro-s-triazine compounds are not readily removed by most conventional drinking water treatment processes, with the exception of use of activated carbon.

Herbicides↗
PubMed2003

Dioxin and cancer: a critical review.

2,3,7,8-tetrachlordibenzo-p-doxin (TCDD) would not have been designated as a Group 1 carcinogen by IARC had there not been a change in the criteria used for inclusion in this category. Furthermore, there is no precedent for indicating, as did IARC, that a single chemical acts as a pluripotential carcinogen by modestly increasing human risk for all cancer while not increasing the risk for any single cancer at least moderately. IARC moved TCDD to Group 1 based on mechanistic considerations focusing on the Ah receptor. However, while occupancy of the Ah receptor by TCDD may be necessary for its toxicity, it is not sufficient for toxicity or for potential carcinogenicity. Animal evidence relating TCDD exposure to cancer is much stronger than that for humans. However, the large inter-species variation in the relevant dose-response slopes severely limits generalizations from animals to humans. The epidemiologic studies of occupational exposures, pesticide applicators, and community exposures following industrial accidents, notably Seveso, have generated overall relative risks of all cancer of about 1.0. Only case-control studies of soft-tissue sarcoma and non-Hodgkin's lymphoma, all by the same investigator, reported elevated risk from TCDD exposure. However, these results have not been replicated. The representation that a chemical compound (TCDD) would be a late-stage carcinogen for all types of cancer has no precedent and lacks biological foundation. Virtually all late-stage or promoting carcinogens (e.g., hepatitis-C virus, asbestos, and estrogens) cause a very limited number of forms of cancer. The exposure-response meta-analysis of TCDD and cancer developed by the United States Environmental Protection Agency (USEPA) is seriously compromised by its failure to adequately fit the data. The studies used by the USEPA also likely underestimate TCDD body burdens and may be confounded by smoking and other occupational exposures. Furthermore, the use of a linear dose-response model by the USEPA is scientifically unjustified since the underlying model of TCDD as a human carcinogen is based primarily on its supposed receptor-mediated, non-genotoxic (or promotional) mode of action. There are few examples of an agent being suspected as a human carcinogen for decades and then eventually moving into the category of "known" human carcinogens. In contrast, there are hundreds of compounds that remain for decades on lists of "suspected" human carcinogens despite the lack of confirming evidence. The long-term accumulation of negative, weak, and inconsistent findings suggests that TCDD eventually will be recognized as not carcinogenic for humans.

Animals↗
PubMed2004

An evaluation of benchmark dose methodology for non-cancer continuous-data health effects in animals due to exposures to dioxin (TCDD).

The U.S. Environmental Protection Agency (EPA) has conducted extensive reviews and analyses of health effects associated with exposures to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. Because the carcinogenicity of TCDD has received considerable attention from EPA and others, this paper focuses on animal data for non-cancer health effects that sometimes appear to be almost as sensitive as cancer to TCDD exposures. Benchmark dose (BMD) methodology can be used to identify point-of-departure (POD) estimates for use in derivation of reference doses or evaluation of margins of exposure. However, selection of an appropriate BMD methodology for assessment of non-cancer data, which are usually continuous (non-quantal), needs to be considered. One option available for a benchmark dose is to use a small percentage change in the mean response relative to the estimated maximum effect of TCDD at large doses. The benchmark based on a change estimated to equal 1% of the estimated maximum change from background to the asymptotic response at large doses (denoted as the relative ED01) was used by EPA in a reassessment of TCDD health risks. A lower confidence limit (LED01) could serve as a point of departure for setting a reference dose (RfD). This is a somewhat arbitrary effect level, generally within the background range of variation among unexposed animals, with an unknown risk. An alternative approach is recommended in which the risk of abnormal levels can be estimated. For continuous-data effects, a low and/or high percentile (e.g., 1st and/or 99th) in unexposed control animals can be used to define abnormal (not necessarily adverse) levels. From a dose-response curve and the standard deviation, it is possible to estimate the excess risk (proportion) of animals with abnormal levels as a function of dose for normally distributed levels. With this approach, the risk-based benchmark dose (BMD01) represents the dose with an estimated excess risk of 1% of the animals in the abnormal range rather than an arbitrary change in the value of the measured endpoint. Values for the relative and risk-based benchmark doses are computed from published data for a variety of non-cancer health effects associated with exposure to TCDD. For the 30 cases investigated, the BMD01 tended to vary around the lowest experimental dose tested, whereas the relative ED01 tended to be about a factor of three below the lowest dose, and the BMD01 was more precisely estimated than the ED01 as reflected by narrower confidence intervals. The BMDL01 values were on average more than fivefold higher than the corresponding LED01 values. However, these values still provide a conservative assessment for POD assessment, because the BMDL01 tends to be about an order of magnitude lower (more conservative) than the no-observed-adverse-effect level. This analysis demonstrates the potential impact of alternative choices in benchmark dose methodology. In combination with selection of appropriate adverse health effect endpoint(s) and studies, use of the risk-based BMD results in identification of more valid and meaningful POD estimates for non-cancer effects compared to the use of the relative ED approach.

Animals↗
PubMed1984

Product sterilization. Why industry uses radiation.

Industry uses gamma radiation sterilization because of its superior reliability, safety, and cost savings over the EO fumigation method. EO has many processing variables and is toxic and expensive. The Environmental Protection Agency has recently declared EO to be both mutagenic and carcinogenic. The residual EO in hospital products has been reported to adversely affect hospital workers. Unlike EO fumigation, radiation sterilization imparts no toxic residuals. The coloration and embrittlement problems experienced earlier with some products sterilized by gamma radiation are being overcome with the introduction of new manufacturing materials and lower radiation dosages. Other benefits of radiation sterilization include the option of sterilizing some materials that could not otherwise be sterilized and using new types of packaging to better protect the products and increase shelf-life. The emphasis now being placed on cost containment for health care products will be another significant part of the answer to why industry uses gamma radiation sterilization.

Bacteria↗
PubMed2000

Cryogen free automated gas chromatography for the measurement of ambient volatile organic compounds.

An automated gas chromatographic system was constructed for measuring ambient volatile organic compounds (VOCs). Preconcentration of the VOCs was performed by using two separated sorbent traps of different combinations with each designated for either low or high boiling VOCs. Both traps and their associated valve systems were integrated as a complete system sharing a common sample inlet. Precise temperature controls for desorption relied on the use of a process controller with proportional-integral-derivative algorithm to throttle the current supply. No additional cryo-focusing stage prior to the column was needed owing to the flash heating capability for desorption. Other than the cryogen free preconcentration and focusing, the separation of VOCs of large volatility difference was also performed without cryogen. The system employed an Al2O3/KCl porous-layer open tubular column for separating C3-C7 compounds; and a DB-1 column for C6-C12. This automated GC system has been deployed in a Taiwan Environmental Protection Agency urban air quality monitoring station of Taiwan for continuous measuring C3-C7 ozone precursors. Excellent correlation between the car exhaust type of compounds measured by our GC system and carbon monoxide measured by a non-dispersive infrared spectrometer was observed, suggesting the automated GC system was robust and reliable.

Automation↗
PubMed2000

Comparison of different sorbent materials for on-line solid-phase extraction with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry of phenols.

On-line solid-phase extraction (SPE) was interfaced to liquid chromatography with atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS) for the determination of US Environmental Protection Agency (EPA) phenols. The system, allowing fully automated operation, was used to evaluate different SPE cartridge materials and dimensions. Six different SPE materials (C18 HD, Polymer Labs PLRP-s, Hamilton PRP-1, Hysphere GP, Hysphere SH and Waters Oasis) were tested. Criteria for their comparison were first the recovery for the different phenols and its reproducibility, but also chromatographically relevant items like peakshape in the on-line elution mode. High recoveries and good relative standard deviations were obtained particularly for the newer, strongly retaining SPE materials that have become commercially available recently (the Hysphere materials and Waters Oasis) compared to the well known silica-based and weaker polymeric adsorbents like PLRP-s and PRP-1. These advantages are, however, traded in for good chromatographic peakshape, since the stronger adsorbents give rise to notable peak broadening in on-line elution. This is particularly true when using APCI-MS detection which on the one hand offers excellent selectivity and sensitivity, but imposes additional restrictions on the mobile phase composition in order not to suppress the response significantly. The influence of these parameters on the on-line-SPE-HPLC-MS determination of EPA phenols is discussed and present limitations are pointed out.

Atmospheric Pressure↗
PubMed2000

Pressurised liquid extraction of ketones of polycyclic aromatic hydrocarbons from soil.

Pressurised liquid extraction (PLE) was used in the extraction of three ketones of polycyclic aromatic hydrocarbons from the sample of a soil highly contaminated with polycyclic polyaromatic compounds. The choice of solvent was the only factor that considerably influenced the extraction efficiency of PLE under the conditions recommended in Method 3545A promulgated by the United States Environmental Protection Agency. The dichloromethane-ethanol solvent mixture was found to be the most efficient solvent. PLE using this mixture provided better recoveries of all analysed ketones relative to Soxhlet extraction.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Simultaneous determination of cyanogen chloride and cyanogen bromide in treated water at sub-microg/L levels by a new solid-phase microextraction-gas chromatographic-electron-capture detection method.

A headspace solid-phase microextraction (HS-SPME) procedure has been developed and applied for the determination of cyanogen halides in treated water samples at microg/L concentrations. Several SPME coatings were tested, the divinylbenzene-Carboxen-polydimethylsiloxane fiber being the most appropriate coating. GC-electron-capture detection was used for separation and quantitation. Experimental parameters such as sample volume, addition of a salt, extraction time and desorption conditions were studied. The optimized method has an acceptable linearity, good precision, with RSD values <10% for both compounds, and it is sufficiently sensitive to detect ng/L levels. HS-SPME was compared with liquid-liquid microextraction (US Environmental Protection Agency Method 551.1) for the analysis of spiked ultrapure and granular activated carbon filtered water samples. There was good agreement between the results from both methods. Finally, the optimized procedure was applied to determine both compounds at the Barcelona water treatment plant (N.E. Spain). Cyanogen chloride in treated water was <1.0 microg/L and cyanogen bromide ranged from 3.2 to 6.4 microg/L.

Adsorption↗
PubMed2001

Characterization and identification of a "mystery" oil spill from Quebec (1999).

This paper describes a case study in which advanced chemical fingerprinting and data interpretation techniques were used to characterize the chemical compositions and determine the source of an unknown spilled oil from Quebec. On 28 February 1999, significant amounts of oil was reported on the river banks of St. Laurence River in front of a company named "Thermex" (in a town - Beauharnois, Quebec, about 50 km northwest of Montreal). The spilled oil was suspected to be released from a nearby factory. In response to this specific site investigation needs, a tiered analytical approach using GC-MS and GC-flame ionization detection was applied. A variety of diagnostic ratios of "source-specific marker" compounds, in particular isomers of biomarkers and alkylated series of polycyclic aromatic hydrocarbons within the same alkylation groups, were determined and analyzed. The hydrocarbon analysis results reveal the following: (1) the spilled oil is very "specific", and is significantly different from most crude oils in chemical composition; (2) the oil in samples come from the same source, however, the spill sample 2569 was identified to contain a small amount (approximately 10%) of diesel; (3) the spilled oil was relatively "fresh", its chemical composition has not undergone significant alteration yet; (4) the spilled oil showed unusually high concentration of the US Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs). The "Pyrogenic Index" values were determined to be as high as 0.11-0.13, significantly higher than crude oils (<0.010) and heavy Bunker type fuels (0.015-0.060). This indicates significant contribution of PAH composition from pyrogenic components; (5) biomarkers were also detected, but their concentrations were unusually low in comparison to most crude oils.

Chromatography, Gas↗
PubMed2001

Fast determination of phenols in contaminated soils.

An extraction method for the determination of phenols in contaminated soils, based on the application of solid-phase microextraction (SPME) coupled with GC-flame ionization detection analysis, was developed and tested. This method was developed using a natural soil spiked with phenol to a concentration level typical of an acute contamination event that can occur in an industrial site. The effects of the extraction parameters (pH, extraction time and salt concentration) on the extraction efficiency were studied and the method was then applied to determine the pollutant concentration at the beginning and during the biological treatment of a soil, contaminated with phenol and 3-chlorophenol, respectively. The SPME results were validated by comparison with those obtained with an US Environmental Protection Agency certified extraction method. The SPME method was also successfully applied to the determination of the adsorption behavior of 3-chlorophenol on a natural clay soil and was shown to be suitable for different matrices and phenolic compounds. Application of SPME technique results in a sharp reduction of the extraction times with negligible solvent consumption.

Chromatography, Gas↗
PubMed2001

On-line flow sample stacking in a flow injection analysis-capillary electrophoresis system: 2000-fold enhancement of detection sensitivity for priority phenol pollutants.

A flow injection analysis-capillary electrophoresis system has been used for on-line flow stacking of 11 US Environmental Protection Agency priority phenol pollutants. Samples containing low concentrations of phenols dissolved in deionised water are continuously delivered to the capillary opening by means of a peristaltic pump. The sample components stack at the boundary between the highly conductive separation electrolyte and the introduced sample. By selecting an appropriate electrolyte and stacking conditions the movement of the electrolyte solution inside the capillary can be reduced, thereby improving the stacking efficiency. The electrolyte used here contained 20 mM phosphate, 8% 2-butanol, and 0.001% hexamethonium bromide at pH 11.95, and the stacking was carried out at 2 kV for 240 s. These conditions allowed up to 2000-fold preconcentration of the selected phenols. No matrix removal was necessary.

Electrophoresis, Capillary↗
PubMed2001

Solid-phase extraction of polycyclic aromatic hydrocarbons in surface water. Negative effect of humic acid.

The effect of humic acid on solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from surface water was studied. The hydrophobic PAHs show significant association with humic acid, and this was confirmed to be the cause of negative effect when conventional reversed-phase solid-phase extraction (RP-SPE) was employed to extract the analytes from aqueous samples. As an alternative, dynamic ion-exchange (DIE) SPE could simultaneously extract both the fraction of the analytes which was associated with humic acid, and that which was freely dissolved. Using the 16 US Environmental Protection Agency priority PAHs as model compounds, the recoveries of the highly hydrophobic components by DIE-SPE were 10-30% higher than those by RP-SPE for a 1000-ml water sample dissolved with Aldrich humic acid (of 4.1 mg/l dissolved organic carbon content). A similar result was also obtained for 500 ml of natural surface water although the difference in recoveries between the two methods for this sample was smaller than that for the simulated sample. For validation of the method, the artifacts in connection with DIE-SPE in extracting the fraction of analytes which was freely dissolved and that which was associated with humic acid were investigated.

Humic Substances↗
PubMed2001

On-site solid-phase extraction and laboratory analysis of ultra-trace synthetic musks in municipal sewage effluent using gas chromatography-mass spectrometry in the full-scan mode.

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography-mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of 1-1 samples. Full-scan mass spectra are required to verify that a target analyte has been found by comparison with the mass spectra of fragrance compounds in the National Institute of Standards and Technology (NIST) mass spectral library. A 1-1 sample usually provides insufficient analyte for full scan data acquisition. This paper describes an on-site extraction method developed at the US Environmental Protection Agency (Las Vegas, NV, USA) for synthetic musks from 60 l of wastewater effluent. Such a large sample volume permits high-quality, full-scan mass spectra to be obtained for a wide array of synthetic musks. Quantification of these compounds was achieved from the full-scan data directly, without the need to acquire SIM data. The detection limits obtained with this method are an order of magnitude lower than those obtained from liquid-liquid and other solid-phase extraction methods. This method is highly reproducible, and recoveries ranged from 80 to 97% in spiked sewage treatment plant effluent. The high rate of sorbent-sample mass transfer eliminated the need for a methanolic activation step, which reduced extraction time, labor, and solvent use. More samples could be extracted in the field at lower cost. After sample extraction, the light-mass cartridges are easily transported and stored.

Fatty Acids, Monounsaturated↗
PubMed2001

Monofluorinated polycyclic aromatic hydrocarbons as internal standards to monitor trace enrichment and desorption of their parent compounds during solid-phase extraction.

Solid-phase extraction (SPE) is an established sample-preparation technique for clean-up procedures of polycyclic aromatic hydrocarbons (PAHs). The suitability of monofluorinated polycyclic aromatic hydrocarbons (F-PAHs) as a novel set of internal standards, was tested for two widely used SPE sorbents, octyl-bonded silica and styrene-divinylbenzene copolymer. The elution profiles of eight F-PAHs and their parent PAHs, taken from the priority pollutant list of the US-Environmental Protection Agency, were compared for demineralized water and waste water. In both instances, the match of the elution profiles was exceptionally close. The eight F-PAHs and the corresponding PAHs were determined by reversed-phase liquid chromatography using acetonitrile-water gradient elution with UV detection at 254 nm. The UV spectra of the F-PAHs show a small bathochromic shift compared with the parent PAHs.

Chromatography, Liquid↗
PubMed2001

Quantitative analysis of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants.

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge. Due to their persistence and toxic potential, information about their presence in sewage sludge is needed in order to assess applicability on agricultural land. A method for the gas chromatographic-mass spectrometric (GC-MS) determination was developed and applied to the trace determination of PAHs present in sewage sludge samples from six wastewater treatment plants (WWTPs) differing in the type of treatment and the origin of wastewater. PAHs were extracted from freeze-dried samples by a dichloromethane-methanol (2:1) mixture in a sonication bath. The sludge extracts were cleaned-up by an alumina column. The method showed recovery values varying from 60 to 98%. Four surrogate standards ([2H8]naphthalene, [2H10]anthracene, [2H12]benzo[a]anthracene, and [2H12]benzo[ghi]perylene) were used for quantitation by GC-MS. A reference sludge sample was analysed in order to validate the method. The sum of the 16 US Environmental Protection Agency PAHs analysed in the sewage sludge samples varied from 1.13 to 5.52 mg/kg. No significant difference between the different WWTPs was found.

Calibration↗
PubMed2002

Determination of aldehydes in drinking water using pentafluorobenzylhydroxylamine derivatization and solid-phase microextraction.

A headspace solid-phase microextraction (HS-SPME) procedure followed by gas chromatography and electron capture detection (GC-ECD) has been developed for the determination of aldehydes in drinking water samples at microg/l concentrations. A previous derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) was performed due to the high polarity and instability of these ozonation by-products. Several SPME coatings were tested and the divinylbenzene-polydimethylsiloxane (DVB-PDMS) coating in being the most suitable for the determination of these analytes. Experimental SPME parameters such as selection of coating, sample volume, addition of salt, extraction time and temperature of desorption were studied. Analytical parameters such as precision, linearity and detection limits were also determined. HS-SPME was compared to liquid-liquid microextraction (proposed in US Environmental Protection Agency Method 556) by analyzing spiked water samples; a good agreement between results obtained with both techniques was observed. Finally, aldehydes formed at the Barcelona water treatment plant (N.E. Spain) were determined at levels of 0.1-0.5 microg/l. As a conclusion, HS-SPME is a powerful tool for determining ozonation by-products in treated water.

Aldehydes↗
PubMed2002

Solid-phase extraction and sample stacking-capillary electrophoresis for the determination of quaternary ammonium herbicides in drinking water.

Conditions for the simultaneous determination of paraquat, diquat and difenzoquat by capillary zone electrophoresis were established by combining two preconcentration procedures. Off-line solid-phase extraction was used for the isolation and preconcentration of quats in drinking water. Quats were then analysed by capillary electrophoresis using sample stacking with matrix removal as on-column preconcentration procedure. Two different porous graphitic carbon cartridges were compared. The breakthrough volumes of the three herbicides were calculated and the loading capacity of the sorbents was compared. Recoveries higher than 80% for difenzoquat and around 40% for paraquat and diquat were obtained when a sample volume of 250 ml was percolated. For the stacking-capillary electrophoresis analysis of quats, 50 mM acetic acid-ammonium acetate (pH 4.0), 0.8 mM cetyltrimethylammonium bromide with 5% (v/v) methanol as carrier electrolyte was used. Detection limits, based on a signal-to-noise ratio of 3:1, were lower than 0.3 microg l(-1) for standards in Milli-Q water, and lower than 2.2 microg l(-1) for drinking water samples. Run-to-run and day-to-day precision of the method were established. The two preconcentration procedures used together was successfully applied to the analysis of the three herbicides in spiked drinking water at concentrations below the maximum admissible US Environmental Protection Agency levels.

Electrophoresis, Capillary↗