Showing papers by "United States Environmental Protection Agency published in 1981"
TL;DR: In this article, a method for estimating the equilibrium sorption behavior of hydrophobic pollutants was developed for estimating KOC from water solubility (including crystal energy) and octanol/water partition coefficients.
1,221 citations
TL;DR: The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated.
Abstract: This paper reviews the ability of a number of chemicals to induce sister-chromatid exchanges (SCEs). The SCE data for animal cells in vivo and in vitro, and human cells in vitro are presented in 6 tables according to their relative effectiveness. A seventh table summarizes what is known about the effects of specific chemicals on SCEs for humans exposed in vivo. The data support the concept that SCEs provide a useful indication of exposure, although the mechanism and biological significance of SCE formation still remain to be elucidated.
576 citations
TL;DR: The report reviews and evaluates the current literature on chemically induced specific locus mutations in the V79 Chinese hamster lung cell line, and discusses the protocols for quantitative mutation studies including measurements of cytotoxicity, mutant expression times, mutant selection agents, cell densities during selection, and the stability and verification of mutant phenotypes.
Abstract: The report reviews and evaluates the current literature (about 125 primary publications) on chemically induced specific locus mutations in the V79 Chinese hamster lung cell line. The V79 cell is convenient to use for mutagenesis studies since it has a rapid growth rate, high plating efficiency, and a stable karyotype. Mutation can be easily measured at either the hypoxanthine-guanine phosphoribosyl transferase or the Na+/K+ ATPase locus, both of which have been well characterized. Other less-studied markers are also described. We discuss the protocols for quantitative mutation studies including measurements of cytotoxicity, mutant expression times, mutant selection agents, cell densities during selection, and the stability and verification of mutant phenotypes. Mutations in the V79 cells by chemicals that require activation can be tested after their metabolism by cell homogenates or by intact cells, and the results with each type of activation are compared. For purposes of analysis, we classified a compound as mutagenic if it induced a mutation frequency that is at least 3 times higher than the spontaneous mutant frequency reported for that specific experiment. By this criterion two-thirds of the chemicals analyzed were mutagenic--; 11% with and 55% without metabolic activation. Of the 191 chemicals examined; 119 were polycyclic aromatic hydrocarbons; 25 were nitro or nitroso compounds, 9 were alkyl halides; 7 were purine or pyrimidine derivatives and the remaining 31 were from other chemical classes. We also defined mutagenic potency as the concentration of a compound that increases the mutant frequency by 10 times the spontaneous frequency. Mutagenic potencies of the compounds examined varied over a range of 5 X 10(6). We have also found large interlaboratory variations in the mutagenic potencies. Such variation in potency could be reduced by normalizing the results to a standard mutagen such as N-methyl-N'-nitro-N-nitrosoguanidine. The role of the V79 assay in mutagenicity and carcinogenicity testing is discussed and recommendations are suggested for future investigation.
293 citations
TL;DR: In this paper, a number of different estimation methods have been developed to use these data in conjunction with available concentration data to calculate pollutant loadings for a typical major tributary.
220 citations
TL;DR: In this paper, it was shown that the photoproducts were the same in colored natural waters and in solutions of soil-derived humic substances, including those obtained commercially.
197 citations
TL;DR: In this paper, the authors derived specific absorption coefficients for humic substances at wavelengths λ from 300 to 500 nm for 12 water bodies in the US and found that the results can be used to compute photolysis rates of pollutants as a function of depth in natural water bodies.
162 citations
TL;DR: In this application to remotely monitor chlorophyll a concentrations in fresh waters, the Raman-corrected chlorophyLL a fluorescence measurements were found to be highly correlated with chlorophyh a ground truth data.
Abstract: Airborne laser fluorosensor measurements of fluorophore concentrations in surface waters are highly sensitive to interference from changes in optical attenuation. This interference can be eliminated by normalizing the fluorescence signal with the concurrent water Raman signal. In our application to remotely monitor chlorophyll a concentrations in fresh waters, the Raman-corrected chlorophyll a fluorescence measurements were found to be highly correlated with chlorophyll a ground truth data. Also, the reciprocal of the water Raman signal was seen to vary directly as the beam attenuation coefficient. It is suggested that this latter relationship be exploited as a means for remotely sensing changes in the optical attenuation of surface waters.
157 citations
TL;DR: Live-oak plants were subjected to various levels of CO2, water stress or photosynthetic photon flux density to test the hypothesis that isoprene biosynthesis occurred only under conditions of restricted CO2 availability, indicating that isobrene is a normal plant metabolite.
Abstract: Live-oak plants (Quercus virginiana Mill.) were subjected to various levels of CO2, water stress or photosynthetic photon flux density to test the hypothesis that isoprene biosynthesis occurred only under conditions of restricted CO2 availability. Isoprene emission increases as the ambient CO2 concentration decreased, independent of the amount of time that plants had photosynthesized at ambient CO2 levels. When plants were water-stressed over a 4-d period photosynthesis and leaf conductance decreased 98 and 94%, respectively, while isoprene emissions remained constant. Significant isoprene emissions occurred when plants were saturated with CO2, i.e., below the light compensation level for net photosynthesis (100 μmol m-2 s-1). Isoprene emission rates increased with photosynthetic photon flux density and at 25 and 50 μmol m-2 s-1 were 7 and 18 times greater than emissions in the dark. These data indicate that isoprene is a normal plant metabolite and not — as has been suggested — formed exclusively in response to restricted CO2 or various stresses.
156 citations
TL;DR: In this paper, the size of the P reservoir in the profundal zone (at water depths > 6.5 m) was estimated, and a significant fraction of the available P was potentially mobile (NaOH extractable).
Abstract: Phosphorus budget calculations for Shagawa Lake show that significant increases in lake P during July and August 1971-1975 originated from within the lake basin. Mass increases of 2,000-2,900 kg (3550 pgeliter-‘) were measured, corresponding to internal supply rates of 240-680 kg* wk-’ over a 3-9-week interval. After anaerobi : conditions developed in late June, release from the profundal zone sediments contributed :ignificant amounts of P to lake water. Sediment chemical properties were determined to estimate: the size of the P reservoir in the profundal zone (at water depths > 6.5 m). The P content of the surficial profundal zone sediments was 0.2-0.5% (dry wt) and a significant fraction \fas potentially mobile (NaOH extractable). We calculate that the upper 10 cm of these sediments contain 50,000 kg of potentially mobile P, of which a small fraction is released each summer. Although external sources of phosphorus have been reduced by about 80%, the feedback ofP from the sediments is supporting the productivity of Shagawa Lake and may continue to do so for many years.
151 citations
150 citations
TL;DR: The reliability of second-order rate constants for assessing microbial degradation kinetics in natural waters was examined by using three compounds that undergo hydrolytic degradation, and indicated that the rate conformed to second- order kinetics.
Abstract: The reliability of second-order rate constants for assessing microbial degradation kinetics in natural waters was examined by using three compounds that undergo hydrolytic degradation. The butoxyethyl ester of 2,4-dichlorophenoxyacetic acid was studied in water samples from 31 sites, malathion was examined in water from 14 sites, and chlorpropham was studied in samples from 11 sites. The coefficient of variation for rate constants for each compound was less than 65% over all sites. Additional studies indicated that the rate conformed to second-order kinetics; that is, the rate was proportional to both bacterial and xenobiotic concentrations.
TL;DR: It seems likely that λ and σ mutants result from 2 different mutational mechanisms that may be distinguished on the basis of mutant colony morphology, possibly related to the type of chromosomal damage sustained.
Abstract: The L5178Y/TK+/− → TK−/− mouse lymphona mutagen assay, which allows selection of forward mutations at the autosomal thymidine kinase (TK) locus, uses a TK+/− heterozygous cell line, TK+/− 3.7.2C. Quantitation of colonies of mutant TK−/− cells in the assay forms the basis for calculations of mutagenic potential of test compounds. We have evaluated the banded karyotypes of the parent TK+/− heterozygous cell line, as well as homozygous TK−/− mutants, in order to relate the genetic and morphological properties of mutant colonies. The parent cell line displays karyotype homogeneity, all cells containing normal mouse chromosomes, readily identifiable chromosome rearrangements, and cell line specific marker chromosomes. Mutant TK−/− colonies of the TK+/− 3.7.2C cell line form a bimodal frequency distribution of colony sizes for most mutagenic or carcinogenic test substances. Large-colony (λ) TK−/− mutants with normal growth kinetics appear karyotypically identical within and among clones and with the TK+/− parental cell line. In contrast, most slow-growing small-colony (σ) TK−/− mutants have readily recognizable chromosome rearrangements involving chromosome 11, which contains the thymidine kinase gene locus. It is possible that the heritable differences in growth kinetics and resultant colony morphology in λ and σ mutants are related to the type of chromosomal damage sustained. Large-colony mutants receive minimal damage, possibly in the form of point mutations at the TK locus, while small-colony mutants receive damage to other genetic functions coordinately with loss of TK activity, implying gross insult to chromosomal material. It seems likely that λ and σ mutants result from 2 different mutational mechanisms that may be distinguished on the basis of mutant colony morphology.
TL;DR: In this article, the authors reveal patterns of response of major United States crops to sulfuric acid rain (pH 3.0, 3.5 or 4.6) at harvest, the weights of the marketable portion, total aboveground portion and roots were determined for 28 crops.
TL;DR: In this article, mussels were transplanted to four sites along a pollution gradient in Narragansett Bay and their physiological responses (oxygen consumption, feeding rate, absorption efficiency and ammonia excretion) were measured under controlled laboratory conditions.
TL;DR: The CRC Critical Reviews in Microbiology as mentioned in this paper, Vol. 8, No. 3, pp. 205-228, was the first critical review of this paper, with a focus on organic pollution from aquatic systems.
Abstract: (1981). Microbial Bioconcentration of Organic Pollutants from Aquatic Systems — A Critical Review. CRC Critical Reviews in Microbiology: Vol. 8, No. 3, pp. 205-228.
TL;DR: A realistic and statistically tractable model is developed for the evaluation of Ames-type data and its performance is demonstrated on data from organic extracts of various environmental contaminants.
Abstract: Despite the value and widespread use of the Ames test, little attention has been focused on standardizing quantitative methods of analyzing these data. In this paper, a realistic and statistically tractable model is developed for the evaluation of Ames-type data. The model assumes revertant colony formation at a any dose follows a Poisson process, while the mean number of revertants per plate is a nonlinear functions of up to 4 parameters. An exponential decay term can be included in the model to adjust for toxicity. The resultant system of nonlinear equations is solved using a modified Gauss-Newton iterative scheme to obtain maximum likehood estimates of the model parameters. Significance of the key parameters is tested by fitting reduced models and using likelihood ratio tests. The model's performance is demonstrated on data from organic extracts of various environmental contaminants. Among the advantages of the proposed model are (1) no data is discarded in the parameter estimation process, (2) no arbitrary constants need to be added to zero counts or doses, and (3) no mathematical transformation of the data is required.
TL;DR: In this paper, the photochemical oxygenation of 2,5-dimethylfuran (DMF) in water was studied under a variety of reaction conditions employing various humic substances as photosensitizers.
TL;DR: In this paper, the Octanol/Water partition coefficients (Kow's) of organic solutes are estimated with reasonable accuracy (standard deviation ± 0.25 log Kow units) by elution from a C-18 column with 75:25 (v/v) MeOH-H2O, based on results with 37 test compounds.
TL;DR: Snails, Helix aspersa, were chosen to examine the entrance of cadmium into terrestrial food chains and the effects of accumulation, acute toxicity, and behavioral, reproductive and growth responses with increasing levels of Cadmium are determined.
Abstract: Spreading treated municipal wastes on agricultural and forest lands is becoming an established method of disposal. However, there is concern about the deleterious effects of toxicants, particularly cadmium, in the sludges. Cadmium concentrations in sewage sludge have been reported as high as 1500 ppM. The work reported here is a part of a larger project to investigate the ecological effects of municipal wastes on forest lands. Snails, Helix aspersa, were chosen to examine the entrance of cadmium into terrestrial food chains. This experiment was designed to determine cadmium accumulation, acute toxicity, and behavioral, reproductive and growth responses with increasing levels of cadmium.
TL;DR: This acute test series was conducted with a variety of phenolic compounds and provides data on the toxic effects in Lake Superior water, which is a major freshwater body in the USA.
Abstract: Because of the wide, high-volume usage of phenolics it behooves us to be aware of their toxicity in the environment. This awareness must include a knowledge of the effects on freshwater bodies and more specifically, an appreciation of the importance of differences in the physical properties of the water. The variability of the data on some phenolics makes it difficult to separate toxicity values that vary widely from others because of different test methods rather than different physical properties of the water. Data were lacking on some of the compounds we tested, and thus our data contribute significantly to the basic informtion on these chemicals. This acute test series was conducted with a variety (12) of phenolic compounds. Test conditions were kept as uniform as possible so that the toxicities of the compounds could be attributed to the differences in toxicity rather than to differences in test conditions. In addition, the tests provide data on the toxic effects in Lake Superior water, which is a major freshwater body in the USA.
TL;DR: Evidence of pathological responses was found which included impaired development of reproductive tissues, degeneration and loss of symbiotic zooxanthellae, and atrophy of mucous secretory cells and muscle bundles.
TL;DR: Giardia lamblia cysts obtained from human symptomatic and asymptomatic donors were excysted in vitro and excystation averaged 87% for cysts from symptomatic donors and 70% forCysts from asymPTomatic donors.
Abstract: Giardia lamblia cysts obtained from human symptomatic and asymptomatic donors were excysted in vitro Excystation averaged 87% for cysts from symptomatic donors and 70% for cysts from asymptomatic donors
TL;DR: It is concluded that weights of external transmitters in water should be less than 1.5% of the fish weight and design considerations should include streamlining components and an anterior attachment wire at the extreme leading edge of an external transmitter to prevent entanglement of the tag in surrounding vegetation.
Abstract: Yellow perch (Perca flavescens) and largemouth bass (Micropterus salmoides) were studied to determine the effects of externally attached radio transmitter tags. Perch that had been tagged with dummy radio tags were more susceptible to predation and more sensitive to environmental stress than were controls. Feeding and respiration rates were similar among dummy tagged and control groups of perch over a 6-week period. The feeding rate of dummy tagged largemouth bass was lower than that of untagged fish over a 3.5-week period. On the basis of these studies, we conclude that weights of external transmitters in water should be less than 1.5% of the fish weight. Design considerations should include streamlining components and an anterior attachment wire at the extreme leading edge of an external transmitter to prevent entanglement of the tag in surrounding vegetation.
TL;DR: In this paper, a multi-class, phytoplankton simulation model was developed and calibrated to an extensive set of field data acquired on Saginaw Bay, Lake Huron, during 1974.
TL;DR: The binding of chemical carcinogen and mutagen hemoglobin would appear to be generic so that it could be developed into a dose monitor for a large number of known carcinogens and mutagens.
TL;DR: It is indicated that cytochrome P-450-dependent microsomal metabolism of cyclophosphamide is required for the embryotoxic and teratogenic effects observed in vitro.
TL;DR: In this article, 8500 observations of atmospheric turbidity, taken at Raleigh, North Carolina from July 1969 to July 1975 are analyzed for within-day and day-to-day variations and their dependence on meteorological parameters.
Abstract: Some 8500 observations of atmospheric turbidity, taken at Raleigh, North Carolina from July 1969 to July 1975 are analyzed for within-day and day-to-day variations and their dependence on meteorological parameters. The annual average turbidity of 0.147 (0.336 aerosol optical thickness) is near the highest non-urban turbidity in the United States. A distinct diurnal turbidity cycle was evident with a maximum in early afternoon. Annually, highest turbidity and day-to-day variation occurred during summer with lowest values and variation during winter. Daily averages revealed an asymmetric annual cycle, with a minimum on 1 January and a maximum on 1 August. Turbidity showed a slight inverse dependence on surface wind speed. Aside from winter, highest turbidities occurred with southeast surface winds. Turbidity was directly proportional to both humidity and dew point. Correlations between turbidity and local visibility were best for visibilities <7 mi. Air mass trajectories arriving at Raleigh were us...
TL;DR: Consideration of the epidemiological evidence on radiogenic lung cancer in uranium miners and of the incidence of the disease generally leads to an upper estimate for the lifetime risk of 10−4 cases per working level month for the general population.
Abstract: Consideration of the epidemiological evidence on radiogenic lung cancer in uranium miners and of the incidence of the disease generally leads to an upper estimate for the lifetime risk of 10−4 cases per working level month for members of the general population.
TL;DR: Monitoring of juvenile coho salmon production in 12 laboratory streams confirmed that habitats of salmonid juveniles, as well as spawning areas, should be protected against fine sediments.
Abstract: Juvenile coho salmon (Oncorhynchus kisutch) production (tissue elaboration) was monitored in 12 laboratory streams under six replicate treatment levels of fine sedimentation. Increasing sedimentation suppressed fish production. Our data confirm that habitats of salmonid juveniles, as well as spawning areas, should be protected against fine sediments. Substrate Score, a visual technique for evaluating stream substrate quality, correlated closely with both the geometric mean particle size of the substrate and fish production, and can be easily applied in the field.
TL;DR: In this article, the authors describe some of the important sources of specification errors in logit models, present numerical illustrations of the errors' effects on forecasts of travel behavior, and evaluates the ability of several informal and formal statistical procedures to identify and diagnose the errors.
Abstract: Multinomial logit models of travel demand are subject to a variety of specification errors that can severely affect the accuracy the models' forecasts. This paper describes some of the important sources of specification errors in logit models, presents numerical illustrations of the errors' effects on forecasts of travel behavior, and evaluates the ability of several informal and formal statistical procedures to identify and diagnose the errors. Among the tests considered, the most powerful are a test against a probit model and the McFadden, Tye and Train (1976) test based on the universal logit method. The least powerful tests are a test based on extrapolating the logit model and informal tests based on examination of the signs, t -statistics and ratios of the estimated parameters of the logit function.