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PubMed2001

U.S. Chemical program: purpose, challenges, and evolution.

This article explores long-term issues and problems that have seriously undermined the U.S. Chemical Testing Program established by the Environmental Protection Agency (EPA) under the Toxic Substances Control Act. This program is meant to gather information needed to protect human health and the environment from damaging exposure to toxic chemicals. Despite seemingly broad and impressive authority under the statute, there are a number of inherent difficulties, as well as substantial political constraints, that impede comprehensive oversight of chemicals in U.S. commerce. The article discusses several approaches that EPA has adopted to overcome statutory and political limitations and increase chemical testing information. The most recent and promising of these efforts has involved international negotiations to harmonize testing approaches with OECD nations and to cooperate on an agenda that will better share the testing burden on an international level.

Journal Article↗
PubMedDate not supplied

Remote site production of sterile purified water from available surface water.

A water purification and sterilization device was tested for its functional capabilities. Challenge water consisting of potable water augmented with bacteria, endotoxin, virus, suspended solids, and dissociable ions (sodium chloride, lead or arsenic salts) was passed through the device. The product water quality attributes were analyzed. The device demonstrated reduction in bacteria of >7 logs, endotoxin was reduced by >4 logs, virus was reduced by >4 logs, and dissociable ions were reduced by >3 logs. The product water of the device met the limits for a range of chemical entities specified by the United States Pharmacopeia and Association for the Advancement of Medical Instrumentation. The product water met the quality attributes of Sterile Water for Injection, USP, Sterile Purified Water, USP, and the Water for Dialysis. The device provides a logistical advantage in reducing the weight of transport of packaged water by 83% and the cube by 67%. It operates manually by gravity and is disposable after a single use. The device provides an effective alternative to the transport and use of packaged sterile water in remote locations by production of sterile water at the point-of-need using available water. It also is capable of producing safe drinking water following the production of clinical waters. This device has been cleared by the US Food and Drug Administration for production of three liters Sterile Purified Water, USP from Environmental Protection Agency (EPA) grade drinking water.

Communicable Disease Control↗
PubMed2000

Synthesis and evaluation of a molecularly imprinted polymer for selective on-line solid-phase extraction of 4-nitrophenol from environmental water.

A molecularly imprinted polymer (MIP) able to bind 4-nitrophenol (4-NP) was prepared using noncovalent molecular imprinting methods and evaluated as a selective sorbent in molecularly imprinted solid-phase extraction (MISPE) on-line coupled to a reversed-phase HPLC. It has been shown that the conditions chosen for washing the MIP and for eluting the analyte in the MISPE process are extremely important for ensuring good selectivity and recovery. River water samples, spiked with the 11 Environmental Protection Agency phenolic compounds at microgram per liter levels, were preconcentrated on-line using this MIP, and 4-NP was selectively extracted. The humic acid interference was simultaneously reduced considerably. The MIP was also compared with a commercially available highly cross-linked polymer (LiChrolut EN) and the former yielded cleaner extracts.

Chromatography, High Pressure Liquid↗
PubMed2000

Determination of perchlorate at trace levels in drinking water by ion-pair extraction with electrospray ionization mass spectrometry.

Perchlorate has been added to the U.S. Environmental Protection Agency's Drinking Water Contaminant Candidate List (CCL). The present work describes the analysis of perchlorate in water by liquid-liquid extraction followed by flow injection electrospray mass spectrometry (ESI/MS). Cationic surfactants, mostly alkyltrimethyl-ammonium salts, are used to ion-pair aqueous perchlorate, forming extractable ion pairs. The cationic surfactant associates with the perchlorate ion to form a complex detectable by ESI/MS. The selectivity of the extraction and the mass spectrometric detection increases confidence in the identification of perchlorate. The method detection limit for perchlorate based on 3.14 sigma n-1 of seven replicate injections was 100 ng L-1 (parts per trillion). Standard addition was used to quantitate perchlorate in a drinking water sample from a contaminated source, and the concentration determined agreed within experimental error with the concentration determined by ion chromatography.

Flow Injection Analysis↗
PubMed1977

Development of a chemical use classification system to facilitate reporting under the Toxic Substances Control Act.

A classification system was developed to enable manufacturers and processors of industrial chemicals to report categories of proposed categories of use of such chemicals to the Environmental Protection Agency in accordance with the Toxic Substances Control Act. To accommodate the two aspects of chemical use (i.e., function and application), a faceted classification scheme was designed. The function facet contains categories denoting the action for which a chemical is specially fitted or used, for example, adhesives or fuels. The application facet contains categories denoting the process or product in which a chemical is used, such as synthetic rubber manufacture. Linking these two facets in a single notation code provides a comprehensive indication of a chemical's use or uses. A variety of existing relevant classification schemes and reference tools were used as input sources for the chemical use classification. The practicability of the classification system was tested using a small sample of manufacturing and processing companies.

Chemical Phenomena↗
PubMed2001

Estimating the long-term trend in the extreme values of tropospheric ozone using a multivariate approach.

This paper deals with the identification and estimation of the long-term trend in the extreme values of tropospheric ozone after allowing for the confounding effects of meteorological conditions. The U. S. Environmental Protection Agency's (EPA's) National Ambient Air Quality Standard for ozone is stated in terms of exceedances of a specified threshold level. Therefore, the EPA is concerned with the long-term trend in the probability of an exceedance. A multivariate nonparametric probit regression model estimated within the framework of a hierarchical Bayes model is used to model the probability of an exceedance after allowing for the effects of changing meteorological conditions. There are three advantages to using this model. First, the trends estimated at each site in a region can be separated into a city-wide component that is common to all sites and a site-specific component that is unique to the individual site. Second, the hierarchical Bayes framework allows for combining information across monitoring sites to increase the information available regarding the trend at each individual site. Third, the nonparametric model does not require the a priori specification of the functional forms relating the probability of an exceedance to the meteorological variables. Ozone data from four Houston, Texas monitoring sites for the period 1981-1997 are analyzed. We find that there is a downward trend in the probability of an exceedance in the 1980s followed by a relatively flat trend in the 1990s.

Air Pollutants↗
PubMed2003

Toxicity characteristic leaching procedure and iron treatment of brass foundry waste.

The Toxicity Characteristic Leaching Procedure (TCLP) is used by the United States Environmental Protection Agency to determine if wastes contain extractable components subject to hazardous waste regulations. This paper examines the limitations of the TCLP and the way it is used by studying a particular example. Waste casting sand from brass foundries to which iron metal has been added passes the TCLP test but when placed in a landfill for several years may start to leach lead, copper, and zinc. Results of TCLP tests of waste sand alone and with the additives iron metal, zinc metal, hydrous ferric oxide, and hematite are reported. Three processes were studied: reduction by metallic iron, sorption by hydrous ferric oxide, and precipitation of hydroxides. Lead, copper, and zinc behave differently with respect to these three processes, and their measurement allows some deductions as to what is occurring in a TCLP test or a landfill. Iron addition does not result in long-term stabilization of a waste placed in the ground. The chemistry of a laboratory extraction can be very different from the chemistry of a waste placed in the environment. Wastes that are treated to pass the TCLP test, but are not permanently stabilized, are a threat to the environment.

Hazardous Waste↗
PubMed2004

Halonitromethane drinking water disinfection byproducts: chemical characterization and mammalian cell cytotoxicity and genotoxicity.

Halonitromethanes are drinking water disinfection byproducts that have recently received a high priority for health effects research from the U.S. Environmental Protection Agency (EPA). Our purpose was to identify and synthesize where necessary the mixed halonitromethanes and to determine the chronic cytotoxicity and the acute genotoxicity of these agents in mammalian cells. The halonitromethanes included bromonitromethane (BNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM), dibromochloronitromethane (DBCNM), bromodichloronitromethane (BDCNM), chloronitromethane (CNM), dichloronitromethane (DCNM), and trichloronitromethane (TCNM). Low- and high-resolution gas chromatography/mass spectrometry (GC/MS) was used to identify the mixed chloro-bromonitromethanes in finished drinking waters, and analytical standards that were not commercially available were synthesized (BDCNM, DBCNM, TBNM, CNM, DCNM, BCNM). The rank order of their chronic cytotoxicity (72 h exposure) to Chinese hamster ovary (CHO) cells was DBNM > DBCNM > BNM > TBNM > BDCNM > BCNM > DCNM > CNM > TCNM. The rank order to induce genomic DNA damage in CHO cells was DBNM > BDCNM > TBNM > TCNM > BNM > DBCNM > BCNM > DCNM > CNM. The brominated nitromethanes were more cytotoxic and genotoxic than their chlorinated analogues. This research demonstrated the integration of the procedures for the analytical chemistry and analytical biology when working with limited amounts of sample. The halonitromethanes are potent mammalian cell cytotoxins and genotoxins and may pose a hazard to the public health and the environment.

Animals↗
PubMed2004

Full-scale chamber investigation and simulation of air freshener emissions in the presence of ozone.

Volatile organic compound (VOC) emissions from one electrical plug-in type of pine-scented air freshener and their reactions with O3 were investigated in the U.S. Environmental Protection Agency indoor air research large chamber facility. Ozone was generated from a device marketed as an ozone generator air cleaner. Ozone and oxides of nitrogen concentrations and chamber conditions such as temperature, relative humidity, pressure, and air exchange rate were controlled and/or monitored. VOC emissions and some of the reaction products were identified and quantified. Source emission models were developed to predict the time/concentration profiles of the major VOCs (limonene, alpha-pinene, beta-pinene, 3-carene, camphene, benzyl propionate, benzyl alcohol, bornyl acetate, isobornyl acetate, and benzaldehyde) emitted bythe air freshener. Gas-phase reactions of VOCs from the air freshener with O3 were simulated by a photochemical kinetics simulation system using VOC reaction mechanisms and rate constants adopted from the literature. The concentration-time predictions were in good agreement with the data for O3 and VOCs emitted from the air freshener and with some of the primary reaction products. Systematic differences between the predictions and the experimental results were found for some species. Poor understanding of secondary reactions and heterogeneous chemistry in the chamber is the likely cause of these differences. The method has the potential to provide data to predict the impact of O3/VOC interactions on indoor air quality.

Air Pollution, Indoor↗
PubMed2005

Inactivation of Ascaris suum and poliovirus in biosolids under thermophilic anaerobic digestion conditions.

There is considerable interest in the United States in production of Class A (low pathogen content) biosolids from the treatment of municipal wastewater sludge. Current requirements imposed by the U.S. Environmental Protection Agency make it difficult for thermophilic anaerobic digestion, in its simplest process configurations, to achieve Class A status. In particular, the time-temperature requirements necessitate long batch treatment times at temperatures associated with thermophilic anaerobic digestion. The time-temperature requirements are meant to ensure extensive inactivation of helminth eggs and enteric viruses, considered to be the most heat-resistant of the relevant pathogen classes. However, data on inactivation kinetics of these pathogens at precisely controlled and well-characterized temperatures are scarce. We measured inactivation of vaccine-strain poliovirus and eggs from the helminth Ascaris suum at temperatures from 49 to 55 degrees C in a lab-scale batch reactor containing biosolids from a continuous-flow thermophilic anaerobic digester. Both microbes were inactivated rapidly, with Ascaris more resistant to inactivation than poliovirus, and the relationships between inactivation rate and temperature were steep. The Arrhenius correlation between inactivation rate and temperature over the range 49-53 degrees C is consistent with protein denaturation as the inactivation mechanism for both microbes. The least stringent of the EPA time-temperature equations for thermal processes requires batch treatment times more than 2 orders of magnitude greater than would be required for three-log reduction of Ascaris at the rates we measured, suggesting an overly conservative regulatory approach. Such a grossly conservative approach can hinder full-scale implementation of thermophilic anaerobic digestion.

Anaerobiosis↗
PubMed2006

A predictive model to correlate fuel specifications with on-road vehicles emissions in Mexico.

Mexico is currently in the process of implementing its third air management program, which includes control measures targeting emissions reductions from mobile, point, and area sources. Achieving the program goals will require changes in the composition and in physical properties of gasoline and implementing an emissions reduction schedule. For that purpose a study was undertaken to support understanding of the effect of gasoline fuel parameters on exhaust emissions. Specifically, the relative impacts of Reid vapor pressure, distillation parameters, oxygen, sulfur, olefins, and aromatic contents on the exhaust emissions of in-use vehicles of the metropolitan area of Mexico City were investigated. The results were used to develop a model to predict CO, nitrogen oxides, total hydrocarbons, and toxic emissions such as benzene, 1,3-butadiene, formaldehyde, and acetaldehyde. Also a statistical model that predicts evaporative emissions was built. Results of the present model are compared with those obtained using the complex model of the United States Environmental Protection Agency.

Air Pollutants↗
PubMed2006

Iron-mediated oxidation of antimony(III) by oxygen and hydrogen peroxide compared to arsenic(III) oxidation.

Antimony is used in large quantities in a variety of products, though it has been declared as a pollutant of priority interest by the Environmental Protection Agency of the United States (USEPA). Oxidation processes critically affect the mobility of antimony in the environment since Sb(V) has a greater solubility than Sb(lll). In this study, the cooxidation reactions of Sb(lIl) with Fe(ll) and both O2 and H2O2 were investigated and compared to those of As(III). With increasing pH, the oxidation rate coefficients of Sb(lll) in the presence of Fe(ll) and O2 increased and followed a similar pH trend as the Fe(ll) oxidation by O2. Half-lives of Sb(lll) were 35 and 1.4 h at pH 5.0 and pH 6.2, respectively. The co-oxidation with Fe(ll) and H2O2 is about 7000 and 20 times faster than with Fe(ll) and O2 at pH 3 and pH 7, respectively. For both systems, *OH radicals appear to be the predominant oxidant below approximately pH 4, while at more neutral pH values, other unknown intermediates become important. The oxidation of As(lll) follows a similar pH trend as the Sb(lll) oxidation; however, As(lll) oxidation was roughly 10 times slower and only partly oxidized in most of the experiments. This study shows that the Fe(ll)-mediated oxidation of Sb(Ill) can be an important oxidation pathway at neutral pH values.

Antimony↗
PubMed2006

Metal distributions in New Orleans following hurricanes Katrina and Rita: A continuation study.

In late October 2005, twenty-seven metals were determined in soils and sediment layers deposited by floodwaters (flood sediments) within New Orleans, Louisiana. Samples originated from 43 sites along four transects, at an industrial canal, and near the Superdome. The sampling design encompassed flooded and nonflooded areas as well as differing economic strata within the city. Results from this effort confirmed findings of our previous study designed to quantify contaminant profiles in the aftermath of Hurricane Katrina. The expanded sampling from this most recent investigation revealed that arsenic (As) and lead (Pb) concentrations exceeded United States Environmental Protection Agency (USEPA) soil screening criteria indiscriminately throughout the city. However, As and Pb concentrations were lower along St. Charles Avenue, an area largely unaffected by hurricane related flooding. Toxicant concentrations did not exceed soil screening criteria values for lead within any flood sediments or for 32 of 37 soil samples, but arsenic concentrations in 40 of 43 samples exceeded screening criteria.

Arsenic↗
PubMed2006

Survey of catalysts for oxidation of mercury in flue gas.

Methods for removing mercury from flue gas have received increased attention because of recent limitations placed on mercury emissions from coal-fired utility boilers by the U. S. Environmental Protection Agency and various states. A promising method for mercury removal is catalytic oxidation of elemental mercury (Hg0) to oxidized mercury (Hg2+), followed by wet flue gas desulfurization (FGD). FGD cannot remove Hg0, but easily removes Hg2+ because of its solubility in water. To date, research has focused on three broad catalyst areas: selective catalytic reduction catalysts, carbon-based materials, and metals and metal oxides. We review published results for each type of catalyst and also present a discussion on the possible reaction mechanisms in each case. One of the major sources of uncertainty in understanding catalytic mercury oxidation is a lack of knowledge of the reaction mechanisms and kinetics. Thus, we propose that future research in this area should focus on two major aspects: determining the reaction mechanism and kinetics and searching for more cost-effective catalyst and support materials.

Air Pollutants↗
PubMed2006

Human adenoviruses in water: occurrence and health implications: a critical review.

Adenoviruses are important human pathogens that are responsible for both enteric illnesses and respiratory and eye infections. Recently, these viruses have been found to be prevalent in rivers, coastal waters, swimming pool waters, and drinking water supplies worldwide. United Sates Environmental Protection Agency (USEPA) listed adenovirus as one of nine microorganisms on the Contamination Candidate List for drinking water because their survival characteristic during water treatment is not yet fully understood. Adenoviruses have been found to be significantly more stable than fecal indicator bacteria and other enteric viruses during UV treatment. Adenovirus infection may be caused by consumption of contaminated water or inhalation of aerosolized droplets during water recreation. The goal of this review is to summarize the state of technology for adenovirus detection in natural and drinking waters and the human health risk imposed by this emerging pathogen. The occurrence of these viruses in natural and treated waters is summarized from worldwide reports.

Adenoviridae Infections↗
PubMed2006

Sorption of Sb(III) and Sb(V) to goethite: influence on Sb(III) oxidation and mobilization.

Antimony is an element of growing interest for a variety of industrial applications, even though Sb compounds are classified as priority pollutants by the Environmental Protection Agency of the United States. Iron (Fe) hydroxides appear to be important sorbents for Sb in soils and sediments, but mineral surfaces can also catalyze oxidation processes and may thus mobilize Sb. The aim of this study was to investigate whether goethite immobilizes Sb by sorption or whether Sb(III) adsorbed on goethite is oxidized and then released. The sorption of both Sb(III) and Sb(V) on goethite was studied in 0.01 and 0.1 M KClO4 M solutions as a function of pH and Sb concentration. To monitor oxidation processes Sb species were measured in solution and in the solid phase. The results show that both Sb(III) and Sb(V) form inner-sphere surface complexes at the goethite surface. Antimony(III) strongly adsorbs on goethite over a wide pH range (3-12), whereas maximum Sb(V) adsorption is found below pH 7. At higher ionic strength, the desorption of Sb(V) is shifted to lower pH values, most likely due to the formation of ion pairs KSb(OH)6 degrees. The sorption data of Sb(V) can be fitted by the modified triple-layer surface complexation model. Within 7 days, Sb(III) adsorbed on goethite is partly oxidized at pH 3, 5.9 and 9.7. The weak pH-dependence of the rate coefficients suggests that adsorbed Sb(III) is oxidized by 02 and that the coordination of Sb(III) to the surface increases the electron density of the Sb atom, which enhances the oxidation process. At pH values below pH 7, the oxidation of Sb(III) did not mobilize Sb within 35 days, while 30% of adsorbed Sb(III) was released into the solution at pH 9.9 within the same time. The adsorption of Sb(III) on Fe hydroxides over a wide pH range may be a major pathway for the oxidation and release of Sb(V).

Adsorption↗
PubMed2005

Screening mercury levels in fish with a selective fluorescent chemosensor.

Societal concerns over toxic mercury accumulation in humans from fish and other dietary and environmental sources provide motivation to develop new tools and tactics for mercury detection in a wide range of laboratory and field settings. Here we report the synthesis, properties, and application of a selective and sensitive small-molecule chemosensor for fluorescence screening of mercury levels in fish. Mercuryfluor-1 (MF1) is a water-soluble, fluorescein-based reagent that features excellent selectivity for Hg2+ over competing analytes and the largest turn-on fluorescence response to date (>170-fold increase) for reporting this heavy metal ion in aqueous solution. Combining this chemoselective Hg2+ probe with a microwave digestion protocol provides a facile method for assaying mercury levels in fish samples with mercury concentrations spanning 0.1 to 8 ppm, a range well matched with the United States Environmental Protection Agency (U.S. EPA) standard for the maximum safe level of mercury in edible fish (0.55 ppm).

Animals↗
PubMed2002

Dissipation of the herbicide [14C]dimethenamid under anaerobic conditions in flooded soil microcosms.

The objective of this research was to investigate the dissipation of the herbicide dimethenamid under anaerobic redox conditions that may develop in the soil environment. Soil-water biometers were prepared with a saturated soil and made anaerobic by either glucose pretreatment (according to the Environmental Protection Agency registration study for anaerobic fate) or N2 sparging. Treatments included glucose pretreatment, NO3- + SO42- amendment, unamended, and autoclaved. Volatile, aqueous, extractable, and bound (unextractable) 14C-residues were quantified and characterized. The redox potential decreased over time, and evidence of denitrifying, iron-reducing, sulfate-reducing, and methanogenic conditions was observed, depending on the amendments. Anaerobic degradation of 14C-dimethenamid occurred in all treatments, and the time observed for 50% disappearance (DT50) was 13-14 days for nonautoclaved treatments. 14C-metabolites accumulated to up to 20% of applied 14C. At least two major metabolites were observed in nonautoclaved treatments, whereas only one was observed in autoclaved microcosms. More than 50% of the applied 14C was eventually incorporated into soil-bound residue.

Acetanilides↗

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