Showing papers by "United States Environmental Protection Agency published in 1984"
TL;DR: With some additional analytical improvements, isomer-specific PCB analysis can be utilized to determine the composition of commercial PCBs and accurately follow the fate and distribution of these pollutants within the global ecosystem.
Abstract: The synthesis and spectroscopic properties of all the mono-, di-, tri-, tetra-, penta-, hexa-, and heptachlorobipheynls are reported and the synthesis of all 209 polychlorinated biphenyls (PCBs) is completed. The retention times and molar response factors of the 209 PCBs were determined relative to a reference standard, octachloronaphthalene. The retention times for these compounds generally increased with increasing chlorine content, and it was apparent that within a series of isomers there was an increase in retention time with increasing meta and para and decreasing ortho substitution. By use of a 50-m narrow bore fused silica capillary column coated with SE-54, it was possible to separate 187 PCB congeners, and only 11 pairs of compounds were not fully resolved. With some additional analytical improvements, isomer-specific PCB analysis can be utilized to determine the composition of commercial PCBs and accurately follow the fate and distribution of these pollutants within the global ecosystem.
568 citations
TL;DR: There are several broad classes of mathematical models used to apportion the aerosol measured at a receptor site to its likely sources as discussed by the authors, including tracer element, linear programming, ordinary linear least squares, effective variance least squares and ridge regression.
429 citations
TL;DR: A three-brood life cycle test for Ceriodaphnia reticulata, using renewal techniques, that can be completed in 7 d is described, convenient when samples to be tested are limited in volume or when time is especially important, such as in on-site effluent testing.
Abstract: A three-brood life cycle test for Ceriodaphnia reticulata, using renewal techniques, that can be completed in 7 d is described. The test is convenient when samples to be tested are limited in volume or when time is especially important, such as in on-site effluent testing. The cladoceran C. reticulata is easily cultured and is not bothered by handling; control survival in tests has not been a problem.
230 citations
TL;DR: Methods are presented for using Daphnia magna, Hyalella azteca, Gammarus lacustris, Chironomus tentans and Hexagenia limbata to screen freshwater sediments for acute and chronic toxicity, bioaccumulation potential and in situ toxicity.
Abstract: Methods are presented for using Daphnia magna, Hyalella azteca, Gammarus lacustris, Chironomus tentans and Hexagenia limbata to screen freshwater sediments for acute and chronic toxicity, bioaccumulation potential and in situ toxicity. The 48-h Daphnia tests are recommended as inexpensive, uncomplicated and sensitive acute methods. Hyalella and Chironomus are the recommended benthic test organisms, as they are easy to rear and test, they remain in intimate contact with the sediment and they exhibit high control survival. Verification studies (published elsewhere) evaluating the recommended methods and organisms are briefly summarized.
196 citations
TL;DR: In this article, a model that considers both carboxyl and weakly acidic groups of humus as continuous binding site distributions in which individual ligand concentrations are normally distributed with respect to the log K values for proton binding is proposed.
155 citations
121 citations
TL;DR: Blue mussels raised from eggs in the laboratory to the age of 2·5 months were continuously exposed to 0, 1, 5 and 10μg/liter of either silver (nitrate) or copper (chloride) and sampled at 12, 18 and 21 months for growth studies, measurements of metal accumulation and histopathological examination.
118 citations
TL;DR: The modified method used appears to be suitable for testing the mutagenicity of azo dyes, and it may also be useful for monitoring the presence of mutagenic or potentially carcinogenic impurities in otherwise nonmutagenic azos dyes.
Abstract: We have evaluated the mutagenic activity of a series of diazo compounds derived from benzidine and its congeners o-tolidine, o-dianisidine and 3,3'-dichlorobenzidine as well as several monoazo compounds. The test system used was a modification of the standard Ames Salmonella assay in which FMN, hamster liver S9 and a preincubation step are used to facilitate azo reduction and detection of the resulting mutagenic aromatic amines. All of the benzidine and o-tolidine dyes tested were clearly mutagenic. The o-dianisidine dyes except for Direct Blue 218 were also mutagenic. Direct Blue 218 is a copper complex of the mutagenic o-dianisidine dye Direct Blue 15. Pigment Yellow 12, which is derived from 3,3'-dichlorobenzidine, could not be detected as mutagenic, presumably because of its lack of solubility in the test reaction mixture. Of the monoazo dyes tested, methyl orange was clearly mutagenic, while C.I. Acid Red 26 and Acid Dye (C.I. 16155; often referred to as Ponceau 3R) had marginal to weak mutagenic activity. Several commercial dye samples had greater mutagenic activity with the modified test protocol than did equimolar quantities of their mutagenic aromatic amine reduction products. Investigation of this phenomenon for Direct Black 38 and trypan blue showed that it was due to the presence of mutagenic impurities in these samples. The modified method used appears to be suitable for testing the mutagenicity of azo dyes, and it may also be useful for monitoring the presence of mutagenic or potentially carcinogenic impurities in otherwise nonmutagenic azo dyes.
111 citations
TL;DR: Several chemicals were highly correlated with each other in personal air samples, indicating possible common sources of exposure and some, but not all, of the potentially occupationally exposed individuals had significantly higher workplace exposures to several chemicals.
110 citations
TL;DR: In this article, the important numerical models are reviewed and possibilities for future development are discussed, as well as possible future development of numerical models for predicting the thermal response after exposure to electromagnetic (EM) radiation.
Abstract: For humans exposed to electromagnetic (EM) radiation, the resulting thermophysiologic response is not well understood. Because it is unlikely that this information will be determined from quantitative experimentation, it is necessary to develop theoretical models which predict the resultant thermal response after exposure to EM fields. These calculations are difficult and involved because the human thermoregulatory system is very complex. In this paper, the important numerical models are reviewed and possibilities for future development are discussed.
109 citations
TL;DR: Skin tumor development was dependent upon 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion whereas lung tumor induction was not, and previous observations of carcinogenic activity of acrylamide in the skin of SENCAR mice and lungs of strain A/J mice to a third strain of mouse, the ICR-Swiss.
TL;DR: Natural freshwater sediments from two Oregon sites were spiked with copper in the laboratory and two static toxicity tests were conducted with series of copper concentrations ranging from 59 to 10,600 mg/kg of dry sediment to introduce test animals in solid-phase sediment toxicity bioassays.
Abstract: Natural freshwater sediments from two Oregon sites were spiked with copper in the laboratory and two static toxicity tests were conducted with series of copper concentrations ranging from 59 to 10,600 mg/kg of dry sediment. Water (800 ml) was added to 1-liter test beakers over the sediment (200 ml) and repeatedly removed and replaced to lower the aqueous copper concentrations. When copper concentrations stabilized, i.e., attained equilibrium between water and sediment, the midge Chironomus tentans, the cladoceran Daphnia magna and the amphipods Hyalella azteca and Gammarus lacustris were introduced as test animals in solid-phase sediment toxicity bioassays. Based on dry-weight sediment copper concentrations, LC50 values (48-h for Daphnia, 10-d for other organisms) ranged from 681 to 2,296 mg/kg.
TL;DR: In this article, the biodegradabilite des surfactants et leur toxicite envers les microorganismes is discussed. But le toxicite is not considered.
TL;DR: In this paper, the authors investigated the dietary transfer of PCBs from contaminated harbor sediments in a laboratory food chain consisting of sediments, polychaetes (Nereis virens) and a predatory fish (Leiostomus xanthurus).
TL;DR: Experimental studies of the interactions within microbial communities have been a standard banner of microbial ecologists for many years and their emphasis has been to bridge the gap between pure culture studies in the laboratory and field observations in natural ecosystems as discussed by the authors.
Abstract: Experimental studies of the interactions within microbial communities have been a standard banner of microbial ecologists for many years. Their emphasis has been to bridge the gap between pure culture studies in the laboratory and field observations in natural ecosystems. Concern over the long-term effects of pollution on ecosystem processes has continuously challenged existing knowledge about the types, rates, and extents of these interactions, including their resistance and resilience to a large array of man-made perturbations.
TL;DR: The occurrence of structural changes in chloride cells during exposure to acid water suggests that chloride cells may be involved in acclimation to acid stress.
Abstract: Fathead minnows, Pimephales promelas, were exposed for 129 days to Lake Superior water acidified with sulfuric acid by means of a flow-through toxicant injection system. The effects of chronic acid stress (pH 6.5, 6.0, 5.5, 5.0) on gill histology were examined. Most of the histological effects were seen at pH 5.5 and 5.0 and were confined primarily to changes in numbers, distribution, and morphology of chloride cells. At low pH levels there tend to be more chloride cells in the gill epithelium and an increased percentage of these cells in the secondary lamellae. In contrast to normal chloride cells, chloride cells from fish exposed to low pH frequently had apical pits while some had bulbous apical evaginations. The occurrence of structural changes in chloride cells during exposure to acid water suggests that chloride cells may be involved in acclimation to acid stress.
01 Jan 1984
TL;DR: The waterborne transmission of G. lamblia was suggested as early as 1946 by an epidemiologic investigation of an outbreak of amebiasis attributed to sewage contamination of a water supply in a Tokyo apartment building.
Abstract: Giardiasis is endemic in many countries of the world including the United States, and in recent years, Giardia lamblia has been identified as the etiologic agent in numerous common-source outbreaks. The waterborne transmission of G. lamblia was suggested as early as 1946 by an epidemiologic investigation of an outbreak of amebiasis attributed to sewage contamination of a water supply in a Tokyo apartment building (Davis and Ritchie, 1948). Entamoeba histolytica and G. lamblia were recovered from 96 (64%) and 116 (77%) occupants, respectively; G. lamblia was isolated from 86% of the occupants who experienced diarrhea with abdominal discomfort and had stools that were negative for E. histolytica.
TL;DR: In this article, three sets of simulated aerosol compositional data were prepared to assess the current state of the art of source apportionment procedures and provide initial sets of test data to aid method development.
TL;DR: This report will review studies on the doses of different viruses required to initiate infection in animals and man and highlight the importance of the minimum infectious dose.
Abstract: The potential for spread of viral and other infectious diseases is a function of the dose required to initiate an infection with either clinical or sub‐clinical sequelae. This is especially important for environmental spread where dilution and natural die‐off are generally assumed to play prominent roles in the control of disease. The use of disinfectants and other methods of pathogen destruction are common in certain instances but often a few survivors will eventually find routes back to their hosts. The importance of the minimum infectious dose is, therefore, evident. This report will review studies on the doses of different viruses required to initiate infection in animals and man.
TL;DR: In this paper, a flow-through acute toxicity test was conducted with 24 organic compounds using fathead minnows Pimephales promelas as test organisms and the tested toxicants consisted of 11 substituted phenols, four substituted benzenes and nine esters.
TL;DR: In this paper, an aerosol characterization, visibility, and receptor modeling study was conducted in the Shenandoah Valley, VA between 14 July and 15 August 1980, where the authors determined the origin of the ambient particles, determined the major chemical species contributing to the light extinction coefficient, and evaluated analytical methods to characterize aerosols and provide data for comparison with chemical composition of aerosols collected in the Great Smoky Mountains and in the Abastumani Mountains of Georgian Soviet Socialist Republic.
TL;DR: Four larval instars of the midge Chironomus tentans Fabricius were exposed to copper to determine their relative sensitivities and the impact of copper on adult emergence and effect of exposure time on LC50 values were determined.
Abstract: The four larval instars of the midge Chironomus tentans Fabricius were exposed to copper to determine their relative sensitivities. The impact of copper on adult emergence and effect of exposure time on LC50 values were also determined. First-instar larvae appeared to be the most sensitive to acute exposure, with a 96-h LC50 of 298 μg/L copper, followed by second-instar (LC50 = 773 μg/L), third-instar (LC50 = 1,446 μg/L) and fourth-instar (LC50 = 1,690 μg/L) larvae, at a water hardness of 71 to 84 mg/L. Adults emerged successfully from fourth-instar larvae and pupae that survived 20-d copper exposures of up to 235 μg/L; the 20-day EC50 was 77.5 μg/L.
Methods for continuous culture of C. tentans in a flow-through rearing facility using Cerophyl, a commercially available powdered grass product, as food and substrate are presented.
TL;DR: In this paper, the authors evaluated the relationship between surface area and reaction rate and found that the rate of CaS formation increases exponentially with the specific surface area of CaO in micrometer size particles and that the effect of surface area on reactivity is at least as great as that expected for pure diffusion control.
Abstract: Details are presneted of a new limestone injection multistage burner as an economical and practical method of reducing emissions from existing power plants by 50%. The process involves injection of pulverized limestone into coal burners that are designed to minimize NO/sub x/ formation by staged combustion. The reaction of CaO with SO/sub 2/ following combustion is the principal mechanism of sulfur capture in the LIMB process. The relationship between surface area and reaction rate is evaluated. It was found that the rate of CaS formation increases exponentially with the specific surface area of CaO in micrometer size particles. The effect of surface area on reactivity is at least as great as that expected for pure diffusion control. The activation energy of CaO reaction with H/sub 2/S or COS is 31 kcal/mol for the limestone studied. On the basis of the activation energy measured between 600/sup 0/ and 900/sup 0/C, and the reaction rates measured for CaO of 40 m/sup 2//g surface area, efficient sulfur capture would be predicted at 1250/sup 0/C in a dispersed-particle system if the kinetics of CaS formation is the only limitation.
TL;DR: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been detected at levels ranging from 20 to 173 parts per trillion in adipose tissue from three Vietnam veterans who were "heavily exposed to Herbicide Orange".
TL;DR: Any of the 4 water miscible solvents or a sonicated suspension of corn oil in serum met the criteria of a non-toxic and non-teratogenic water insoluble compound delivery system for in vitro embryo culture.
TL;DR: 1-Nitropyrene and 3-hydroxy-1-nitropyrene were activated primarily by the 'classical' nitroreductase, while the other compounds, particularly in the presence of S9 metabolic activation, were dependent on transesterification for expression of their mutagenicity.
Abstract: The mutagenicity and activation requirements of purified synthetic derivatives and potential metabolites of 1-nitropyrene have been characterized in the Ames plate incorporation assay with the Salmonella tester strains TA98, TA98NR and TA98/1,8-DNP 6 , in the presence or absence of exogenous metabolic activation provided by Aroclor-induced rat liver S9. All the compounds tested (1-aminopyrene, N -acetyl-1-aminopyrene, N -hydroxy- N -acetyl-1-aminopyrene, 3-hydroxy-1-nitropyrene, 6-hydroxy-1-nitropyrene, and 8-hydroxy-1-nitropyrene) exhibited mutagenic activity under one or more assay conditions. 1-Nitropyrene was metabolized to 3-hydroxy-1-nitropyrene, 6- or 8-hydroxy-1-nitropyrene, 1-aminopyrene, N -acetyl-1-aminopyrene and other unidentified products (including some bound to protein) by an S9 preparation analogous to that used for exogenous metabolic activation in the Ames assay. 1-Nitropyrene and 3-hydroxy-1-nitropyrene were activated primarily by the ‘classical’ nitroreductase, while the other compounds, particularly in the presence of S9 metabolic activation, were dependent on transesterification for expression of their mutagenicity.
TL;DR: The metabolic fate of the bacterial mutagen, environmental pollutant and potential carcinogen 1-nitropyrene (NP) has been investigated in the rat and mutagenic activity was detected in the urine of rats dosed with NP.
Abstract: The metabolic fate of the bacterial mutagen, environmental pollutant and potential carcinogen 1-nitropyrene (NP) has been investigated in the rat. Over half of an i.p. dose (10 mg/kg) of 1-nitro[14C]pyrene was excreted within 24 h of dosing, 15% of the dose in urine and 40% in the faeces. After 96 h greater than 80% of the dose had been recovered. The urinary and fecal metabolites of NP were separated and quantitated by h.p.l.c., then identified by high resolution gas chromatography/mass spectrometry (h.r.g.c./m.s.) and comparison with synthetic reference compounds, where available. Very little (less than 5%) of the dose was excreted unchanged. Urinary metabolites were all excreted in conjugate form, mainly with glucuronic acid. Among the principal metabolite fractions identified were 3-hydroxy-1-nitropyrene and 8-hydroxy-1-nitropyrene (already known as hepatic in vitro metabolites of 1-nitropyrene) and the hitherto unreported metabolites 6-hydroxy-N-acetyl-1-aminopyrene and 8-hydroxy-N-acetyl-1-aminopyrene. Mutagenic activity was detected, by means of the Ames Salmonella (strain TA 98) plate incorporation assay, in the urine of rats dosed with NP. This mutagenicity, unlike that of NP itself, required exogenous metabolic activation. It was predominantly associated with 6-hydroxy-N-acetyl-1-aminopyrene and with the nitropyrene phenols (specific mutagenicity 600 and 700 rev/nmol respectively in the presence of 0.6 mg of S9 protein per plate). The majority of the residual metabolites were polar, refractory to enzymic hydrolysis, and of low mutagenicity. The major proportion of the 14C in feces was not extractable or amenable to enzymic hydrolysis; the extractable fecal metabolites were similar in nature to those in urine.