bluuebunny/crossref_metadata_2025 huggingface dataset:
The fate of atrazine and a hexachlorobiphenyl isomer in naturally-derived model stream ecosystems
Authors: Lynch Thomas R. , Johnson Howard E. , Adams William J.
Published: March 2010

Current emphasis in hazard assessment is being placed on the development of quick and inexpensive methods to identify chemicals with potentially harmful properties. The present study was designed to test the validity of simple microcosms that have been proposed to predict chemical behavior in aquatic systems.

Six laboratory streams were used to study the fate and effects of atrazine and 2, 4, 5, 2′, 4′, 5′, - hexachlorobiphenyl (HCBP) in a naturally derived aquatic community during one annual period. Two streams were treated with the HCBP (0.100 μg/L), two received atrazine (25 μg/L) and two streams served as solvent controls. The chemicals were administered for 30 days during the fall, winter, spring, and summer; a 60 day depuration phase followed each treatment.

The substrates and benthic organisms accumulated HCBP rapidly and concentrations increased with duration of exposure. Uptake of HCBP by the biota was biphasic; the most rapid rate of accumulation occurred during the initial three hours of exposure. Maximum HCBP concentrations in the biota occurred on day 30. Bioaccumulation factors at this time ranged from 300,000 for amphipods to 1200 for clams. Fish, crayfish and other macroinvertebrates had intermediate values. There was no evidence that residue concentrations were increased by trophic transfer.

Atrazine was not accumulated in the laboratory stream communities. Atrazine bioaccumulation factors in the biota ranged from 3.5 in annelids to 480 in mayfly nymphs. Residue concentrations declined to pretreatment levels within a few days of depuration.

These results are significant in that (1) they are consistent with predictions derived from physical-chemical data and (2) the compounds behaved similarly to closely related compounds in simpler model systems. Based on our results, simpler model ecosystems and/or models based on physicalchemical data are probably adequate for predicting the fate of toxicants in aquatic systems.
Ecological toxicology: Experimental analysis of toxic substances in ecosystems
Authors: Hendrix Paul F.
Published: March 2010

Premanufacture testing of new chemicals is considered as an applied problem in biogeochemistry, consisting of experimentation at several complimentary levels of resolution. A descending sequential testing protocol is proposed which begins with combined fate and effects experiments in ecosystems (e.g., laboratory microcosms) followed by studies of processes and species which are hypothesized to be important at finer levels of resolution.
Physical, chemical and physiological factors influencing entry of xenobiotics into the body via the pulmonary system
Authors: Lubawy William C.
Published: March 2010

The respiratory system has an extremely large surface area covered with a thin aqueous film of either mucus or a lipoprotein surfactant-containing fluid. The large total surface area and minute separation between the air space and the blood make the lung an efficient organ for the rapid, systemic absorption of xenobiotics with a variety of physicochemical characteristics.

Gases are absorbed throughout the entire respiratory system, the dominant driving force being diffusion. Highly water soluble gases are rapidly absorbed and may be cleared significantly through the surfaces of the upper respiratory tract before penetrating the deeper recesses of the lung.

Inhaled particles are deposited in the respiratory system according to their size. Particles with aerodynamic diameters of 5 to 30 μm are similarly trapped in the nasopharyngeal region; those from 1 to 5 μm are largely deposited in the tracheal and bronchiolar regions, the major portion of particles smaller than 1 μm penetrate to the alveoli.

Solute absorption studies indicate that the respiratory epithelium behaves like a lipoid–pore type membrane. Lipid soluble compounds are most rapidly absorbed at rates roughly related to their lipid/water partition coefficient at pH 7.4. Lipid insoluble substances are absorbed by nonsaturable diffusion with absorption rates related to the size of the molecules, i.e., the higher the molecular weight, the slower is the absorption. Organic ions can be absorbed by diffusion and by saturable, carrier-mediated processes. Pulmonary exposure to substances known to produce lung damage, i.e., ozone, silica, or acids, can alter carrier-mediated absorption of solutes and increase the passive absorption of lipid insoluble compounds alone or of both lipid soluble and lipid insoluble compounds.

Age appears to be an important factor in absorption rate of lipid insoluble compounds. The lungs of 3- to 12-day-old rats absorb lipid insoluble compounds twice as rapidly as those of 18- to 27-day-old or adult animals. Age is unimportant, however, in the absorption of lipid soluble compounds.

Species differences also exist for the absorption rates of lipid insoluble compounds but not for those of lipid soluble compounds. Mice will absorb lipid insoluble compounds 2 to 3 times more rapidly than rats, while rats absorb 1.3 to 3 times more rapidly than the rabbit.
Diagnosis of anticholinesterase poisoning in birds: Effects of environmental temperature and underfeeding on cholinesterase activity
Authors: Rattner Barnett A.
Published: March 2010

Brain cholinesterase (ChE) activity has been used extensively to monitor exposure to organophosphorus (OP) and carbamate (CB) insecticides in wild birds. A series of factorial experiments was conducted to assess the extent to which noncontaminant-related environmental conditions might affect brain ChE activity and thereby confound the diagnosis of OP and CB intoxication. Underfeeding (restricting intake to 50% of control for 21 d or fasting for 1–3 d) or exposure to elevated temperature (36 ± 1°C for 1 d) caused only slightreductions (10–17%)in brain AChE activity in adult male Japanese quail (Coturnix coturnix japonica). This degree of “reduction” in brain AChE activity is considerably less than the 50% “inhibition” criterion employed in the diagnosis of insecticide-induced mortality, but nevertheless approaches the 20% “inhibition” level used as a conservative estimate of sublethal exposure to a known insecticide application.
Predictability of chronic toxicity from acute toxicity of chemicals in fish and aquatic invertebrates
Authors: Kenaga Eugene E.
Published: March 2010

The relationship of the acute LC50 of chemicals to their chronic toxicity for aquatic animals can be expressed as the acute chronic ratio (ACR). Based on ACR data accumulated from the literature, the size ranges of ACRs for various chemicals were determined for different species. The relationship and significance of the size of the ACR for various species, LC50 values, bioconcentration factors, classes of chemicals and their uses and mode of toxic action are given. Eighty-six percent of the LC50 acute toxicity data were less than two orders of magnitude different from the chronic toxicity no-effect concentration for the same chemicals and species. Among the industrial organic chemicals (i.e., excluding pesticides and metals) the average ACR for four species of organisms was 12. Ninety-three percent of these ACR values were 25 or below. Industrial organic chemicals have a higher percentage of ACR values below 25 do than pesticides and heavy metals. These data offer a statistical basis for the prediction of chronic toxicity from acute toxicity.
Early life-stage toxicity test with tidewater silversides (Menidia Peninsulae) and chlorine-produced oxidants
Authors: Goodman Larry R. , Middaugh Douglas P. , Hansen David J. , Higdon Peggy K. , Cripe Geraldine M.
Published: March 2010

Early life-stage toxicity tests (continuous exposure from embryonic stage to 3 weeks or more into the exogenous feeding stage) with North American marine fishes have been conducted almost exclusively with cyprinodontids. In this report, we present methods for testing a representative of another family, Atherinidae. Embryos of the tidewater silverside Menidia peninsulae (Goode and Bean) were obtained by a laboratory spawning procedure that required lighting and tidal (current) stimuli. A 28-d toxicity test with chlorine-produced oxidants (CPO) began with stage 21 and 22 embryos (approximately 36 h old). Average measured CPO concentrations in exposure water were nondetectable (< 0.01 mg/L) in the control and in the two lowest exposure concentrations, and 0.01, 0.04 and 0.21 mg/L. Survival of embryos to hatching averaged 99%, with no significant difference among treatments. Although no fish survived exposure to 0.21 mg CPO/L, survival was ≥ 88% in the control and the four other CPO treatments. Average wet weights of individual fish ranged from 11.7 mg in 0.04 mg/L to 13.2 mg in 0.01 mg/L, with no significant difference among treatments.
Brain cholinesterase activity and brain and liver residues in wild birds of a forest sprayed with acephate
Authors: Zinkl Joseph G. , MacK Paul D. , Mount Michael E. , Shea Patrick J.
Published: March 2010

In May 1981, acephate (O,S-dimethyl-acetylphosphoramidothioate) was applied at 0.85 kg [a.i. (active ingredient)]/ha in a ponderosa pine (Pinus ponderosa Douglas) forest of northern Arizona for suppression of a pandora moth (Coloradia pandora Blake) infestation. Brain cholinesterase (ChE) activity was determined in six species of wild birds, and brain and liver residues were determined in five species. Brain ChE was not inhibited on the day of spraying, but ChE was significantly inhibited 2 d after acephate application. The species of birds which presumably had the smallest territories and therefore would be more likely to be confined to the relatively small spray plots (about 250 ha) had the greatest ChE inhibition, both in magnitude and in numbers of birds with inhibition. Acephate and methamidophos (O,S-dimethyl-phosphoramidothioate) residues in brain and liver were highest on the day of spraying and decreased to undetectable concentrations 14 d after application. No correlation between brain ChE activities and brain or liver residue concentrations was found. The results of this study suggest that brain ChE inhibition found after acephate application is a better indicator of exposure than is tissue residue analysis. Brain ChE inhibition is probably due to a metabolite of acephate that is not detected by the methods used. Birds exposed to acephate in the wild may suffer as yet undetermined sublethal effects, but it is unlikely that acephate applied at 0.85 kg/ha or less will kill many birds.
Organic pollution and the macrobenthos of Raritan Bay
Authors: Stainken Dennis M.
Published: March 2010

The Raritan Bay—Lower New York Bay complex was surveyed to examine xenobiotic—sediment—benthic relationships. The macrofauna, sediment granulometry, extractable hydrocarbons, polychlorinated biphenyls (PCB) and polynuclear aromatic hydrocarbons (PAH) were surveyed concomitantly. PCB and PAH in molluscs and PAH in bottom waters were also measured.

A total of 126 species was identified, principally molluscs, polychaetes and crustacea. Mya arenaria, Mercenaria mercenaria, Nereis virens and Glycera dibranchiata were the most abundant. Numerous xenobiotics were detected in the sediments and bivalves at all stations. Correlations of diversity indices, and numbers of bivalve species and polychaete species with specific sediment pollutants were poor or absent. Trends of decreasing diversity and density with increased pollution and/or silt-clay were observed, with more species generally occurring in the lower bay area. The dominant feature determining the distribution and abundance of the fauna appeared to be the sediment characteristics (substrate) and prevailing local currents within areas (zones) of the bay. These factors were further modified by the total hydrocarbon—xenobiotic loading of the sediments.
Sensitivity of agricultural ecological system models and implications for vulnerability to toxic chemicals
Authors: Kickert Ronald N.
Published: March 2010

Published results of sensitivity experiments on agricultural models by international authors are analyzed with a simple univariate sensitivity index. Values for system parameter and response-effects at ratios greater than 2.0 or 3.0 are presented for different crop plants, ecosystem components and processes. Responses are ranked according to their level of sensitivity to direct and indirect changes that conceivably could be imposed by manufactured chemicals. Of several hundred agricultural modeling publications, only 8.5% was found to contain results from sensitivity analysis experiments performed by their original authors. This low proportion means that environmental interactions and biological species other than those for which such results are published might be of equal or greater sensitivity and importance if comprehensive sensitivity analyses were available across all crops and ecological processes.

Results imply that hydrological flows, soil nutrient losses, and pesticide losses might all be quite vulnerable to disruption if indirect effects could be transferred through ecosystems by changes in weather and climate. Below-ground primary production processes in agroecosystems such as cotton, semiarid range pastureland, perennial ryegrass and sugar yield of sugar beets might be vulnerable to potential, direct, sublethal effects of chemical substances. If climatic processes were changed, indirect effects could be expected in cotton and pasture root growth, and potato yields. Results also indicate that vegetative growth of corn, alfalfa, soybean and perennial ryegrass might all be extremely vulnerable to any indirect effects from chemically induced climatic changes. Reproductive parts that could be especially vulnerable to possible potential direct effects from chemical substances include seed yield of annual semiarid pastures, fruit quality of hardwood trees and, specifically, apple fruit production. If any indirect effects are possible, it appears that grain sorghum and grain corn yields, and apple fruit yields might be very vulnerable. All these results are limited to the particular designs of the models used and the response variables on which data are available from simulations.
Partitioning of naphthalene, methylnaphthalenes and biphenyl between wastewater treatment sludges and water
Authors: Southworth George R. , Keller Jenny L.
Published: March 2010

Partition coefficients (Kp) describing the partitioning of naphthalene, methylnaphthalenes and biphenyl between organic-rich wastes and water were determined using 14C-tracer techniques as well as high performance liquid chromatographic analysis of the wastes and their aqueous extracts. Results of the two procedures were in good agreement. The concentrations of the specific organics in the wastes were not good predictors of concentrations in aqueous extracts, since Kp varied among the materials tested. Predictions of Kp based on organic carbon partition coefficient (Koc) and organic carbon content of the sludges were well below observed values. Oil content of the wastes and oil-water partition coefficients appeared to be important factors in determining Kp.
Derivation of site-specific water quality criteria for cadmium and the St. Louis River Basin, Duluth, Minnesota
Authors: Spehar R. L. , Carlson A. R.
Published: March 2010

Several freshwater aquatic species were exposed to cadmium in site and laboratory water to evaluate a protocol recommended by the U.S. Environmental Protection Agency for deriving site-specific water quality criteria. The recalculation, indicator species and resident species procedures of this protocol were used to modify the national cadmium criteria. These procedures were used to account for differences in species sensitivity and in the biological availability and/or toxicity of cadmium due to physical and/or chemical characteristics of the site water.

The site-specific maximum concentration derived from the recalculation procedure was slightly lower (1.3 as compared with 2.2 μg/L) than the national criterion. The maximum concentration derived from the indicator species procedure was 7.0 μg/L and was calculated by using a water effect ratio from tests conducted in both site and laboratory water. Acute tests with several species demonstrated that cadmium was less toxic in site water than in laboratory water. The site-specific maximum concentration derived from the resident species procedure (from eight species exposed to cadmium in site water) was 1.9 μg/L. The 30-d average concentrations were the same as the maximum concentrations in the procedures in which the national acute/chronic ratio was used in the calculation. These concentrations were much lower when the site-specific acute/chronic ratio was applied.

Acute tests conducted monthly in site water showed that cadmium toxicity varied by more than a factor of 3 over the year. This indicates the need for considering seasonal changes in physical and chemical characteristics of the site water when deriving criteria to protect aquatic life.
Toxicity of ammonia to early life stages of the smallmouth bass at four pH values
Authors: Broderius Steven , Drummond Robert , Fiandt James , Russom Christine
Published: March 2010

Early life stages of smallmouth bass (Micropterus dolomieui Lacepede) were exposed to ammonia concentrations at four different pH values (from 6.5 to 8.7). Acute lethal tests were conducted with juveniles, and partial chronic tests were initiated at the late embryo stage and extended through 32 d of exposure.

The 96-h LC50 ammonia concentrations at pH 6.53, 7.16, 7.74 and 8.71 were 371, 117, 39.5 and 7.43 mg/L total ammonia-N (NH3-N) and 0.694, 1.00, 1.20 and 1.78 mg/L un-ionized NH3, respectively. The acute toxicity of ammonia in terms of NH3-N was directly related to test pH, and in terms of NH3 was inversely related to pH.

Embryo through preswim-up larvae were the most resistant early life stages studied during chronic exposures. Survival of embryos to larvae 7 d post hatch was unaffected by ammonia concentrations ranging from 0.236 to 0.865 mg/L NH3 at pH values of 6.60 to 8.68. Adverse effects on early developmental stages demonstrated that survival to 14 d and growth to 32 d were among the most sensitive indicators of ammonia toxicity. The estimated 32-d no-observed-effect concentrations, defined as the geometric means of the maximum no-effect and minimum effect concentrations determined from statistically significant decreases in growth (wet weight), were calculated to be 17.4, 14.4, 14.6 and 2.40 mg/L total NH3-N and 0.0437, 0.148, 0.599 and 0.612 mg/L un-ionized NH3 at pH values of 6.60, 7.25, 7.83 and 8.68, respectively. The acute to chronic ratios, as calculated from NH3 concentrations and acute results adjusted to the above pH values for chronic tests, were 16.7, 7.03, 2.07 and 2.89, respectively.
Modification of the neubauer technique to assess toxicity of hazardous chemicals in soils
Authors: Thomas J. M. , Cline J. F.
Published: March 2010

The Neubauer technique was modified to provide a sensitive and economical phytoas-say for soils and surface waters obtained from a chemical waste site. Use of individual plastic enclosures allowed safe handling and disposal over the course of our experiments. Laboratory tests showed that water from a holding basin was toxic to wheat plants at dilutions of less than 1% and that our modified Neubauer technique produced results compatible with both pot culture and the standard Neubauer test. Further testing of several inorganic constituents of the basin water pointed to an organic toxicant, even though the original water contained high levels of sodium, copper and other elements.

The results of testing 26 samples from an abandoned waste pond were negative insofar as toxicity to wheat and lettuce seeds, whereas samples from an abandoned ditch allowed us to determine areal toxicity as well as toxicity as a function of depth and suggested that more than one species should be tested.
Quantitative structure-activity relationships in aquatic toxicity studies of chemicals and complex mixtures of chemicals
Authors: Hermens Joop , Musch Aalt , Köunemann Hans , Leeuwangh Peter
Published: March 2010

Several quantitative structure-activity relationships (QSARs) are presented that describe the aquatic toxicity of three different groups of organic chemicals. In QSARs for nonreactive organic chemicals, hydrophobicity as the only parameter gives excellent results. For anilines, hydrophobicity and the Hammet constant were used for the QSAR, whereas for reactive organic halogen compounds, the aquatic toxicities correlated very well with the chemical reactivities. In addition, some remarks on the applicability of QSARs are made.
Water solubility behavior of binary hydrocarbon mixtures
Authors: Burris David R. , Macintyre William G.
Published: March 2010

The aqueous solubility equilibrium behavior of seven medium molecular weight, liquid, binary hydrocarbon mixtures has been determined at 20°C. Binary hydrocarbon mixtures containing structurally similar compounds exhibited ideal solution behavior, but deviations from ideality by as much as a factor of 2.5 at 0.1 mole-fraction occurred with aromatic-aliphatic mixtures. The ratio of concentrations of hydrocarbon solutes appears to be independent of the degree of saturation of the binary hydrocarbon mixture with water. This independence implies that the equilibrium phenomena observed could be applicable under nonequilibrium conditions.
Metabolic diversity and activity of heterotrophic bacteria in ground water
Authors: Ventullo Roy M. , Larson Robert J.
Published: March 2010

The number and metabolic diversity of bacteria were studied in groundwaters collected in the United States and Canada. Bacterial numbers were determined by acridine orange direct counts, viable plate counts and 14C most-probable-number counts. Metabolic diversity was determined by heterotrophic activity and biodegradation potential assays using several classes of natural and xenobiotic substrates. Rates of metabolism in diversity studies (uptake and/or mineralization to carbon dioxide) were measured by radiotracer techniques and rate data were analyzed by nonlinear regression models to generate appropriate kinetic constants. Overall, the density and activity of groundwater bacteria were comparable to values reported for oligotrophic marine and freshwater systems. Bacterial numbers ranged from approximately 102 to 106 cells/ml, depending on the enumeration technique used and the particular sample tested. Turnover times for natural compounds in heterotrophic activity assays (i.e., glucose, amino acids) ranged from less than 100 to more than 2,000 h. Degradation half-lives for xenobiotic and natural substrates in biodegradation potential studies exhibited a comparable range of values. In general, our results indicate that groundwater bacteria have the potential to metabolize several classes of natural and xenobiotic substrates, although at reduced rates compared with those of surface water systems.
Ration and toxicant preexposure influence dieldrin accumulation by rainbow trout (Salmo gairdneri)
Authors: Shubat Pamela J. , Curtis Lawrence R.
Published: March 2010

Whole body accumulation and tissue distribution of dieldrin in rainbow trout were studied through oral-dose disposition tests and subchronic exposures via water (0.04 and 0.08 μg dieldrin/L) and/or diet (0.087 μg dieldrin/g fish/d). Growth and no-growth (maintenance) rations of 4 and 2% body weight per day were employed. In subchronic tests, apparent steady-state residue concentrations depended on ration and exposure concentration after 8 weeks of exposure. At 16 weeks, mean whole fish residue concentrations ranged from 120 to 1,400 ng dieldrin/g fish. Combination food and water exposures at a growth ration produced the highest accumulation values (1,300–1,400 ng dieldrin/g fish). Maintenance rations apparently limited accumulation to a maximum of 360 ng dieldrin/g fish. Whole body dieldrin concentration, calculated on the basis of total lipids, greatly reduced the differences in residue levels due to ration.

Tissue distribution of a single oral dose of [14C]dieldrin was determined in naive (no pretreatment) fish and those preexposed via the diet for 2, 4 or 6 weeks. Tissue concentrations of the tracer dose were determined 48 h following administration. Retention of the [14C]dieldrin was similar in most tissues of naive, 2- or 6-week dieldrin-pretreated fish with a slight downward trend with duration of pretreatment. Retention of 14C in the bile of fish receiving maintenance and growth treatments increased two- and five-fold, respectively, in 6-week pretreated as compared with naive fish. After 4 weeks of pretreatment, 14C concentrations peaked in all tissues except the bile, gut, and gut contents.
Patterns of metal pollution in soils: A comparison of the values obtained by atomic absorption spectrophotometry and x-ray fluorescence
Authors: Smith G.H. , Lloyd O. Ll.
Published: March 2010

In the town of Armadale in central Scotland, where high rates of mortality and high birth sex ratios (males/females) have been observed, the main industry is steel production. Previous studies have shown a geographical relationship between the foundry, air pollution by metals as measured by low-technology biomonitors, and the epidemiological abnormalities. In this study, the patterns of pollution in Armadale were investigated by taking soil cores from 29 sites within the town. The concentrations of metals in all samples were measured by means of atomic absorption spectrophotometry, and 19 of the samples were analysed using x-ray fluorescence. The results extended the knowledge about the pattern of pollution in Armadale, and also allowed the direct comparison of these two methods of analysis in a study of soil pollution.
Toxicity of five alkyl-aryl phosphate ester chemicals to four species of freshwater fish
Authors: Cleveland Laverne , Mayer Foster L. , Buckler Denny R. , Palawski Donald U.
Published: March 2010

The toxicities of five phosphate ester compounds — Fyrquel GT, Kronitex 200, Phosflex 31P, Pydraul 50E and Santicizer 148—were evaluated in acute toxicity tests with rainbow trout (Salmo gairdneri), fathead minnows (Pimephales promelas), channel catfish (Ictalurus punctatus) and bluegills (Lepomis macrochirus) and in 90-d partial life-cycle tests with fathead minnows. Nominal exposure concentrations were 0, 0.06, 0.12, 0.25, 0.5 and 1.0 mg/L in the partial life-cycle tests with Fyrquel GT, Kronitex 200, Phosflex 31P and Pydraul 50E, and 0, 0.05, 0.09, 0.19, 0.38 and 0.75 mg/L in the test with Santicizer 148.

The 96-h LC50 values for rainbow trout, fathead minnows, channel catfish and bluegills exposed to the five phosphate esters ranged from less than 0.3 to greater than 72 mg/L. The LC50 values may be directly related to the percentage of triphenyl phosphate contained in each of the compounds. The phosphate esters generally showed similar chronic toxicities to fathead minnows, and adverse toxic effects occurred at nominal exposure concentrations of 0.38 to 1.0 mg/L. Comparison of available environmental concentration data for phosphate esters with the effect concentrations obtained for fish in the present study indicated that phosphate ester compounds may not now pose a threat to fish populations.
Comparison of pesticide root zone model predictions with observed concentrations for the tobacco pesticide metalaxyl in unsaturated zone soils
Authors: Carsel Robert F. , Nixon Will B. , Ballantlne Larry G.
Published: March 2010

The pesticide root zone model (PRZM) was developed to evaluate pesticide leaching threats to ground water for different crops under varying climatic conditions, soil characteristics and cropping practices. In this study, PRZM was evaluated to establish its predictive capability by comparing observed metalaxyl concentration profiles with predicted concentration profiles using field-averaged pesticide data and best estimates for several hydrologic characteristics and pesticide transport properties at field sites in Florida and Maryland. Coefficients of determination for the Florida site at 26, 55 and 85 d after application of 0.33, 0.90 and 0.95, respectively, were obtained when field observations were regressed against model predictions. An overall coefficient of determination for the Maryland site of 0.75 was determined for 14 samplings after metalaxyl application.

Pesticide transformation in the Florida soil was best described by a first-order model. A first-order degradation rate in soil of 0.014 d−1 was estimated. Pesticide transformation in the Maryland soil was best described by a phased first-order model. A phase determination point that occurred 30 d after metalaxyl application was used to estimate soil degradation rates. Differences were attributed to the timing of rainfall events and soil infiltration characteristics. Estimated phased first-order degradation rates in soil for the Maryland site were 0.046 and 0.0045 d−1 before and after the phase determination point.

Evaluation of PRZM, using best estimates for transport and transformation properties of metalaxyl and limited calibration for water balance, suggests that the model effectively simulates the important processes operating on the pesticide.
Validation trial of predictive fate models using an aquatic herbicide (endothall)
Authors: Reinert K. H. , Rodgers J. H.
Published: March 2010

Environmental risk assessment of pesticides in aquatic environments requires predictions of their persistence and compartmentalization. A strategy for developing confidence in predictive fate models, such as the Exposure Analysis Modeling System (EXAMS) and the Simplified Lake and Stream Analysis model (SLSA), is to test the models using carefully chosen chemicals in semi-controlled and field situations. For example, endothall, a relatively water-soluble aquatic herbicide, essentially has a sole fate process, biotransformation. This dicarboxylic acid was used to test the predictive capabilities of EXAMS and SLSA and to identify sources of variance in those predictions. The models were parameterized using laboratory, experimental pool and field measurements. Persistence and compartmentalization of endothall in the water, sediments and aquatic plants (Eurasian watermilfoil—Myriophyllum spicatum L.) contained in experimental pools were measured using gas chromatography. Both EXAMS and SLSA predicted aqueous compartment half-lives ranging from 7.3 to 7.8 d, whereas an aqueous half-life of 4 d was observed in the experimental pools. Endothall was introduced to areas within Pat Mayse Lake, a 2,400-ha reservoir in north central Texas, as part of an aquatic plant management program for M. spicatum. Concentrations of endothall were below detection limits (0.002 mg L−1 water, 0.01 mg kg−1 sediment) in 2 to 3 d and in 4 d in the water and sediment compartments, respectively. EXAMS and SLSA predicted half-lives ranging from 3 to 6 d in the water column. Observed aqueous half-lives ranged from 0.1 to 0.23 d. Horizontal dispersion and dilution contributed significantly to the dissipation of endothall at these sites. Predicted concentrations of endothall in sediment were similar to the measured concentrations. This study is one validation trial of EXAMS and SLSA in which the models were not considered validated.
Evaluation of the archiannelid Dinophilus gyrociliatus for use in short-term life-cycle toxicity tests
Authors: Carr Robert Scott , Curran Mark D. , Mazurkiewicz Michael
Published: March 2010

The use of the archiannelid Dinophilus gyrociliatus O. Schmidt in short-term (7 to 10 d) life-cycle tests with reference toxicants and industrial effluents was evaluated. Culture techniques and test protocols were developed and evaluated. The life history of this archiannelid was also studied and is described. Because this species has a very short life cycle (10 d from juvenile to juvenile at 20°C and 30%+ salinity), reproductive information can be obtained during a short-term test. The results of tests with industrial effluents and reference toxicants indicate that this species is suitable for toxicity testing and appears to be quite sensitive to the industrial effluents tested in this study. The animals are easily cultured and the testing procedure requires very little time for setup and maintenance (1 to 2 h/d). It has been determined that reproductive information can be obtained during a 7-d test that starts with newly emerged juveniles.
Relation of survival to other endpoints in chronic toxicity tests with fish
Authors: Mayer Foster L. , Mayer Kathleen S. , Ellersieck Mark R.
Published: March 2010

Hazard assessments of chemicals in aquatic organisms often include chronic toxicity testing. The evaluation of exposure duration and of the life stages tested according to standard test methods has led to the development of shorter chronic toxicity tests. A similar evaluation of biological endpoints (i.e., survival, growth and reproduction) could result in tests that are more economical. We analyzed endpoints for 28 chemicals and seven fish species in 34 chronic toxicity studies. When all endpoints were compared, survival was equal to or more sensitive than all other endpoints 56 to 69% of the time. Individual endpoints were more sensitive than survival 19 to 61% of the time, except for reproduction, which was always more sensitive (although there were few observations). The no observed effect concentration (NOEC) for growth could be predicted from the NOEC for survival by using interendpoint correlations (r = 0.949 to 0.974). Ratios of NOECs for survival to those for all other endpoints examined were 5 or less in 93 to 96% of the comparisons (specific endpoint comparisons ranged from 80 to 100%).

The determination of the survival endpoint requires less time and money than does the determination of most other endpoints, and it appears adequate for hazard assessments in the initial stage of estimating chronic toxicity. However, a factor of at least 0.2 should be applied to the estimated no-effect concentrations for survival to include other potential biologically significant effects at least 95% of the time. The factor of 0.2 is based on frequency analyses that resulted in the NOECs for survival being 5 times or less than the NOECs for most other endpoints about 95% of the time. Univariate analyses, however, indicated a range of 0.13 to 0.22 for the factor. A thorough evaluation of other published studies that contain endpoints other then survival should be conducted to define the appropriate factor more accurately.
Simultaneous evaluation of the acute effects of chemicals on seven aquatic species
Authors: Ewell William S. , Gorsuch Joseph W. , Kringle Robert O. , Robillard Kenneth A. , Spiegel Richard C.
Published: March 2010

A cost-effective testing procedure is described that measures the acute aquatic effects of a single test chemical on seven aquatic species simultaneously: Asellus intermedius (pillbug), Daphnia magna (water flea), Dugesia tigrina (flatworm), Gammarus fasciatus (sideswimmer), Helisoma trivolvis (snail), Lumbriculus variegatus (segmented worm) and Pimephales promelas (fathead minnow). These species were chosen because of their ecological importance, diversity and amenability to laboratory culturing. Twenty-seven commercial inorganic and organic chemicals were tested using the simultaneous exposure procedure. The 96-h LC50 values were derived for each species and the results compared with literature values. The reproducibility of the results achieved using this testing procedure was shown to be very good. The results compare favorably with 96-h LC50 values from single-species tests.

The susceptibility of test animals as a function of species and chemical compound was evaluated. Water fleas were found to be as susceptible as, or more so than, the other aquatic organisms for all compounds tested. The relative sensitivities of the other test species were found to be highly chemical dependent.
Comparative toxicology of phenolic compounds using root elongation method
Authors: Wang Wuncheng C.
Published: March 2010

The U.S. Environmental Protection Agency and the Organization for Economic Cooperation and Development both recommend cucumber, lettuce, radish, red clover and wheat as plant species for terrestrial toxicity tests. In Illinois, millet is common in the Illinois River Valley and toxicity testing using this plant species has been reported previously. The objective of this study was to compare the toxicities of several phenolic compounds to cucumber, lettuce and millet seeds concurrently. Phenol, 2-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol were tested.

Millet seeds were shown to be superior over cucumber and lettuce seeds; they exhibited regular and predictable toxic responses to all four compounds. Millet seeds, in addition, were the most sensitive. Excellent results were obtained for the structure-toxicity relationships between millet EC50s and the molecular weights of the phenols (R = 0.999), and between millet EC50s and n-octanol/water partition coefficients (R = 0.999). It is recommended, consequently, that millet be included in level 1 biological tests.
Evaluation of proadifen HCL as a synergist for temporary immobilization and toxicity of eight chemicals in coturnix quail
Authors: Cunningham D. J. , Otis D. L. , Schafer E. W.
Published: March 2010

Proadifen HCl (SKF-525A), a hepatic microsomal enzyme inhibitor, was evaluated as a synergist for eight chemicals that produced temporary immobilization (TI) at sublethal levels in birds. Probit analysis showed that Proadifen HCl administered orally and concurrently at 100 mg/kg to quail (Coturnix coturnix japonica) with four of the test chemicals (alpha-chloralose, chlordiaz-epoxide, nicotine sulfate and phencyclidine) significantly lowered (p = 0.05) the estimated median lethal (LD50) and/or temporary immobilization response (TI50). Proadifen HCl reduced the LD50 dose for alpha-chloralose 1.56-fold and the TI50 2.03-fold; the TI50 dose for chlordiazepoxide HCl 2.47-fold; the LD50 dose for nicotine sulfate 4.10-fold and the TI50 2.98-fold; and the LD50 dose for phencyclidine HCl 2.35-fold and the TI50 27.5-fold. The synergism exhibited by Proadifen HCl with metomidate and tribromoethanol was less or negative. The LD50 of metomidate was reduced 1.96-fold, but the TI50 was not affected. The LD50 of tribromoethanol was increased 1.15-fold, but the TI50 was reduced by a factor of 1.48. There was no synergism between Proadifen HCl and methiocarb or pentobarbital. These data show that the LD50 and/or TI50 of temporary immobilizing agents for birds can be affected by the use of a synergist such as Proadifen HCl, and indicate that synergism between bird control chemicals or pesticides and drugs could be used to improve efficacy, lower application rates and reduce environmental contamination.
Exposure of forestry ground workers to 2,4-D, picloram and dichlorprop
Authors: Lavy T. L. , Mattice J. D. , Marx D. B. , Norris L. A.
Published: March 2010

Urine samples from 80 forest workers applying 2,4-D [(2,4-dichlorophenoxy)acetic acid] plus dichlorprop [(±)-2-(2,4-dichlorophenoxy)propanoic acid] or picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) by ground techniques were monitored to determine the dose of chemical absorbed. Four crews of 20 workers each were studied to compare the exposures during application by backpack, injection bar, Hypohatchet or a hack-and-squirt method. Total urine output was analyzed to compare the absorbed dose to each worker under two operational modes. In the first, designated T-1, the workers wore their usual clothing and followed the work habits they ordinarily used on the job. In the second mode, designated T-2 and conducted 6 d after the first, workers were given new leather gloves and boots and asked to take all feasible precautions to prevent herbicide exposure and to wash immediately if they come into contact with the chemical.

For all application methods except that with backpacks, the T-2 treatment decreased the absorbed dose. During both T-1 and T-2 the clothing of backpack sprayers often became saturated with spray, dew or perspiration, and these workers received a higher absorbed dose of 2,4-D (0.04–0.24 mg/kg body weight) than did workers in other crews. The absorbed dose of dichlorprop ranged from undetectable to 0.18 mg/kg. Hypohatchet workers received a greater dose than did injection bar or hack-and-squirt workers. The absorbed dose of picloram ranged from undetectable to 0.02 mg/kg. If equal dermal penetration of 2,4-D and picloram is assumed, this represents much less dermal absorption than would have been predicted from the relative amounts of 2,4-D and picloram in Tordon 101-Rr̀.
Effects of chronic exposure to acidified water on chemoreception of feeding stimuli in fathead minnows (Pimephales promelas): Mechanisms and ecological implications
Authors: Lemly A. Dennis , Smith R. J. F.
Published: March 2010

A computer-automated behavioral assay was used to assess the effects of reduced ambient pH on the response of fathead minnows to chemical feeding stimuli. The testing system quantified eight behavioral parameters based on the activity level of individual fish before and after exposure to a single-pulse dose of a feeding stimulus—a tissue culture medium (1 ml; Eagle minimum essential medium with Earl's salts and L-glutamine) — injected into the water circulation. Twentyfive adult minnows were tested after exposure to one of five pH levels: 8.0 (control), 7.0, 6.5, 6.0 and 5.5. Complete elimination of the feeding response occurred at pH = 6 and lower; responses at higher pH levels were not statistically different from those in the controls. Differences in water hardness (<10 mg/L CaCO3 versus > 160 mg/L CaCO3) and duration of exposure (72 h versus 30 d) had no influence on the pattern or degree of the pH effects. Scanning electron microscopy revealed no pathological or gross morphological correlates of the behavioral changes. To test for possible recovery, minnows that did not respond at pH = 6 were placed in water of control pH (8.0) for 24 h and then tested again; a statistically significant response to the feeding stimulus was restored. These results indicate that acute and chronic sublethal levels of acidification caused a reversible impairment of chemoreception and that the impairment can occur at a relatively high pH. The toxic effect probably involves mechanical and chemical inhibition of receptor cells in the olfactory and gustatory epithelia rather than actual destruction of chemosensory tissue. In nature, reduction of pH to approximately 6.0 could impair feeding behavior and reduce food intake, fecundity and long-term survival of fathead minnow populations. Our results correspond well with environmental studies that show that fathead minnows are eliminated from natural waters when pH levels reach 5.8 to 6.0.
Toxic effects of selected bleached kraft mill effluent constituents on the sea urchin sperm cell
Authors: Cherr Gary N. , Shenker Jonathan M. , Lundmark Cathy , Turner Kenneth O.
Published: March 2010

The toxicities of chemicals found in bleached kraft pulp mill effluent were assessed using a sea urchin sperm toxicity test. Sperm of the purple sea urchin, Strongylocentrotus purpuratus, were preincubated with 12 individual compounds, including resin acids, unsaturated fatty acids, their chlorinated derivatives and chlorinated guaiacols. Sperm were then coincubated with eggs and inhibition of fertilization and the effects on sperm motility were assessed. Resin acids, which are highly toxic to juvenile salmonids in freshwater, were less toxic in seawater (EC50s ranging from 2 to more than 20 mg/L). Unsaturated linoleic and linolenic fatty acids inhibited fertilization at lower concentrations (EC50s of 0.28 to 1.07 mg/L) than resin acids, although they are less toxic than resin acids to freshwater fishes. Oleic acid was not significantly toxic up to 75 mg/L. Chlorinated derivatives showed increasing toxicity with increasing chlorination, and chlorinated resin acids were more toxic than their unchlorinated parent compound. Dichlorostearic acid was the most toxic compound tested, with an EC50 of 0.057 mg/L. All compounds except fatty acids inhibited sperm motility.

These results indicate that some of the major constituents of pulp mill effluent exhibit very different levels of toxicity in seawater using a sea urchin sperm cell toxicity test as compared to freshwater bioassays using juvenile salmonids. In addition, mechanisms of action on the sperm appear to differ among the compounds. Accurate quantification of the compounds in effluent as well as the potential effect of the effluent on other marine organisms remains to be determined.
Detection of cadmium-binding proteins in fish chronically exposed to heavy metals
Authors: Benson William H. , Birge Wesley J.
Published: March 2010

Studies were undertaken to determine the presence of cadmium-binding proteins in fish from a metal-contaminated flyash disposal pond and relatively uncontaminated hatchery ponds. Fractionation of gill cytosolic proteins by gel filtration indicated three classes of cadmium-binding proteins. While no cadmium was detected in the metallothionein (MT)-like fraction of the hatchery fish, 1% of the cytosolic cadmium was detected in this fraction for ash pond fish. Cadmium concentrations in the flyash pond were previously reported as ranging from 0.30 to 0.98 μg/L. This level of exposure may be insufficient to induce significant biosynthesis of MT-like proteins.
Incorporating Daphnia magna into the seven-day Ceriodaphnia effluent toxicity test method
Authors: Knight John T. , Waller William T.
Published: March 2010

The experiments reported here describe the incorporation of Daphnia magna into the 7-d Ceriodaphnia toxicity test procedure of Mount and Norberg [1]. The addition of D. magna to the procedure increased the number of parameters on which decisions regarding sublethal effects could be determined without significantly increasing the workload. In addition to the survival and productivity measures of the Mount and Norberg procedure, length and weight of Ceriodaphnia dubia adults and D. magna adults and neonates were evaluated.

Methods for the culture and testing of both organisms using Selenastrum capricornutum Printz as the food source were described. An analysis of algal caloric content, chlorophyll a, cell number, mean cell volume, dry weight, number of bacteria, storage time, and time since the algae were “cleaned” was made to determine the characteristics of the feeding suspensions which most influenced the growth and productivity of the cladocerans.
Comparative toxicity and speciation of two hexavalent chromium salts in acute toxicity tests
Authors: Jop Krzysztof M. , Parkerton Thomas F. , Rodgers John H. , Dickson Kenneth L. , Dorn Philip B.
Published: March 2010

The comparative acute toxicity of potassium chromate and dichromate salts to six aquatic species including both freshwater and marine forms was investigated. A thermodynamic equilibrium model was developed to aid in interpreting toxicity data with respect to hexavalent chromium speciation. Although parallel acute toxicity tests conducted with both salts yielded similar LC50 values, toxicity differences tended to become more pronounced as the sensitivity of the test species to the chemical decreased. Observed changes in pH and predicted changes in chromium speciation that occurred between the two salts in tests with less sensitive species were postulated to explain these findings. The implication of the aqueous chromium species to the relative toxicity of the hexavalent chromium are discussed. If hexavalent chromium is widely adopted as a standard reference toxicant for aquatic toxicity testing then the chromate salt should be used since it does not appreciably alter the initial pH of the dilution water and subsequent speciation to the extent that would be expected if the dichromate salt was employed. Standardization of the source of hexavalent chromium used in reference tests will facilitate intralaboratory comparison of toxicity data.