bluuebunny/crossref_metadata_2025_split huggingface dataset:
Existing chemical testing for environmental fate and effects under TSCA section 4: A case study with octamethylcyclotetrasiloxane (OMCTS)
Authors: Hobson James F. 
Published: March 2010

Abstract
Octamethylcyclotetrasiloxane (OMCTS, or D4) is a highly volatile, cyclic silicone that is an important intermediate in the synthesis of polydimethylsiloxanes and other higher-molecular-weight silicones. As a category of chemicals, silicones have generated substantial scientific and regulatory interest over the last few years. OMCTS, one of the first silicones considered for regulatory review, was recommended for testing in the 15th Report of the Interagency Testing Committee (ITC) in 1984 based on its high volume of production, alleged presence in aquatic environments, and the general lack of environmental fate and effects information for this type of compound. As a result, the environmental effects and fate of OMCTS have been extensively evaluated in a series of laboratory toxicity and environmental fate studies, fate modeling studies, and field monitoring studies. Most of these studies were conducted as part of a negotiated consent order (CO) under Section 4 of the Toxic Substances Control Act (TSCA). Applying the principles of ecological risk assessment (ERA) to the OMCTS program, the current paper presents the problem-formulation phase of the ERA process including stressor characteristics, identification of the ecosystem potentially at risk, and development of a conceptual model. In addition, the planning phase with interactions among the industry representatives, the risk assessors, and the risk managers are discussed. OMCTS was one of the first chemicals to reach the RM1 (risk management) level of regulatory analysis under TSCA, which resulted in a determination that no additional data was needed. Application of ERA principles in this program were instrumental in this favorable determination.
Bioaccumulation of dietary 2,2′,4,4′,5,5′-hexachlorobiphenyl and induction of hepatic arylhydrocarbon hydroxylase in rainbow trout (Oncorhynchus mykiss)
Authors: da Costa Emmanuel G. , Curtis Lawrence R. 
Published: March 2010

Abstract
Juvenile rainbow trout (Oncorhynchus mykiss) were fed either 5 or 20 μg 2,2′,4,4′,5,5′-hexachlorobiphenyl (245-HxCB)/g diet (wet wt.) for 4, 8, or 12 weeks. Hepatic xenobiotic-metabolizing enzyme activities and dietary 245-HxCB accumulation in liver, muscle, and remaining carcass were determined. Liver-to-body weight ratios were not altered by either of the two 245-HxCB concentrations. Relative growth rate increased with time but was not altered by 245-HxCB concentration. Bioaccumulation of 245-HxCB was dose and time dependent in all tissues without reaching apparent steady state. Hepatic arylhydrocarbon hydroxylase (AHH) activities increased with 245-HxCB dose and with time. Ethoxyresorufin-O-deethylase (EROD) activities also increased in fish fed 20 μg 245-HxCB/g diet. No 245-HxCB-induced changes in uridine diphosphoglucuronosyl transferase (UDP-GT) or NADPH-cytochrome-c reductase (NCCR) activities were determined. High-resolution GC-MS analysis of the 245-HxCB standard revealed trace (0.4-0.5%) contamination by two mono-ortho pentachlorobiphenyls (PnCBs): 2,3,3′,4,4′-PnCB and 2,3,4,4′,5-PnCB. Total liver accumulation of these contaminants was inversely related with corresponding EROD and AHH activities and estimated to contribute minimally to their induction. Results from this study suggested that long-term dietary 245-HxCB exposures induced cytochrome P4501A activities in rainbow trout liver.
Fathead minnow reproduction in outdoor microcosms: A comparison to bluegill sunfish reproduction in large mesocosms
Authors: Shaw Jennifer L. , Maund Stephen J. , Hill Ian R. 
Published: March 2010

Abstract
Large-scale aquatic mesocosm studies were formerly required by the U.S. Environmental Protection Agency (EPA) for ecological risk assessment in pesticide registration. However, the use of bluegill sunfish (Lepomis macrochirus Rafinesque) to evaluate pesticide effects on fish reproduction in large mesocosms (&gt;300 m3) resulted in over-exploitation of invertebrates by large numbers of young-of-the-year (YOY) bluegill, thus confounding the interpretation of pesticide effects. As an alternative, a reproduction study with fathead minnows (Pimephales promelas Rafinesque) was conducted in 17-m3 outdoor microcosms. The objective of this research was to evaluate the effects of varying sex ratios of 20 adult fathead minnows (FHMs) on their reproduction during a 4.5-month period. The outcome of this study was compared to a bluegill reproduction study in 400-m3 mesocosms conducted synchronously. The logistics of monitoring the microcosms were simpler, and harvesting FHMs from microcosms took considerably less effort in comparison to harvesting bluegills from mesocosms. The FHMs produced a smaller number of larger young in comparison to bluegills, which produced large numbers of less mature YOY. The variability in total fish biomass between replicates was greater in the bluegill study, resulting in less statistical power to detect biomass effects. The FHM sex ratios significantly affected reproduction and growth, thus altering the fish population structure, despite similar stocking densities. Sex ratios with similar numbers of males and females produced a lower total biomass and number of YOY. There was no evidence of system carrying-capacity constraints on FHM growth or reproduction.
Use of coded wire tags to identify fathead minnow (Pimephales promelas rafinesque) adults in an outdoor microcosm study designed to evaluate consistency in reproduction
Authors: Shaw Jennifer L. , Copeland John R. , Johnson J. Keith 
Published: March 2010

Abstract
Fathead minnows (Pimephales promelas) were evaluated for use as a test species in ecosystem-level studies investigating pesticide effects on fish reproduction. Twenty adult fathead minnows (8 females: 12 males) were stocked in four, 17-m3 outdoor microcosms and collected 98 d later. Each fish was identified with a coded wire tag (CWT). In a preliminary indoor experiment, survival was 100% and tag retention was 93%, 33 d after tagging. At the end of the field study, 100% of surviving stocked adults had tags in three of the four replicates. In these microcosms, stocked adults could be differentiated from young-of-the-year (YOY) because there was no size overlap of YOY with the larger stocked adults, whereas in the fourth replicate the YOY grew to maturity. Fathead minnow reproduction was compared to a study conducted the preceding season utilizing the same experimental systems and incorporating the same 8F:12M sex ratio at stocking. Reproduction was consistent for identical sex ratios in the different seasons despite differences in water conditions. In both years, fathead minnow fecundity was similar, and fish size distributions had equivalent attributes. Furthermore, the relationship between fish number and biomass was comparable, and regressions of weight on length were equal.
Long-term fate and bioavailability of sediment-associated polychlorinated dibenzo-p-dioxins in aquatic mesocosms
Authors: Segstro Mark D. , Muir Derek C.G. , Servos Mark R. , Webster G.R. Barrie 
Published: March 2010

Abstract
The long-term fate of four polychlorinated dibenzo-p-dioxin (PCDD) congeners in sediments and their bioavailability to benthic invertebrates were studied in littoral enclosures located in a small lake at the Experimental Lakes Area in northwestern Ontario. The PCDDs sorbed on sediment particles were added to the 5-m-diameter enclosures on June 12, 1985, and concentrations in sediment cores (0 to 6 cm) were determined over 1,800-d (˜ 5 years). Concentrations of 1,3,6,8-TCDD, 1,3,7,9-TCDD, HpCDD, and OCDD in the sediment declined, with half-lives of 4.4±1.7, 4.6±1.9, 6.2±3.1, and 6.0±2.8 year, respectively. Evaluation of the data for 1,3,6,8-TCDD and OCDD using a sediment-water exchange model suggested that the decline in PCDD concentrations was due to losses to the water column via diffusion of DOC-associated PCDDs in pore water and via particle resuspension. After 5 years the PCDDs remained bioavailable to freshwater mussel (Anodonta grandis) and crayfish (Orconectes virilis) exposed to sediments for up to 78 d. The crayfish had higher mean biota-sediment accumulation factors (BSAFs) for 1,3,6,8-TCDD and 1,3,7,9-TCDD (0.31–0.53) than did mussels (0.07–0.13), whereas BSAFs for HpCDD and OCDD in the two species were similar (0.03–0.09).
Toxicity and bioaccumulation of sediment-associated contaminants using freshwater invertebrates: A review of methods and applications
Authors: Ingersoll Christopher G. , Brunson Eric L. , Dwyer F. James , Ankley Gerald T. , Benoit Duane A. , Norberg-King Teresa J. , Burton G. Allen , Hoke Robert A. , Landrum Peter F. , Winger Parley V. 
Published: March 2010

Abstract
This paper reviews recent developments in methods for evaluating the toxicity and bioaccumulation of contaminants associated with freshwater sediments and summarizes example case studies demonstrating the application of these methods. Over the past decade, research has emphasized development of more specific testing procedures for conducting 10-d toxicity tests with the amphipod Hyalella azteca and the midge Chironomus tentans. Toxicity endpoints measured in these tests are survival for H. azteca and survival and growth for C. tentans. Guidance has also been developed for conducting 28-d bioaccumulation tests with the oligochaete Lumbriculus variegatus, including determination of bioaccumulation kinetics for different compound classes. These methods have been applied to a variety of sediments to address issues ranging from site assessments to bioavailability of organic and inorganic contaminants using field-collected and laboratory-spiked samples. Survival and growth of controls routinely meet or exceed test acceptability criteria. Results of laboratory bioaccumulation studies with L. variegatus have been confirmed with comparisons to residues (PCBs, PAHs, DDT) present from synoptically collected field populations of oligochaetes. Additional method development is currently underway to develop chronic toxicity tests and to provide additional data-confirming responses observed in laboratory sediment tests with natural benthic populations.
Acute and subchronic toxicity of naturally weathered Exxon valdez crude oil in mallards and ferrets
Authors: Stubblefield William A. , Hancock Gregg A. , Ford William H. , Ringer Robert K. 
Published: March 2010

Abstract
The toxic properties of naturally weathered Exxon Valdez crude oil (WEVC) were assessed in a battery of acute and subchronic toxicity tests using mallards, Anas platyrhynchos, and European ferrets, Mustela putorius. Adult mallard acute oral toxicity study results indicated no mortalities or signs of toxicity, i.e., no-observed-adverse-effect level (NOAEL) and median lethal dose (LD50) &gt; 5,000 mg/kg. Acute oral feeding and food avoidance tests with ducklings also indicated no toxicity (NOAEL and LC50 &gt; 50,000 mg/kg diet) with no evidence of food avoidance (FAC50 &gt; 20,000 mg/kg diet). No mortalities or toxic signs were noted in a 14-d feeding study with adult birds at dietary concentrations up to 100,000 mg WEVC/kg diet. Among clinical and physiological end points evaluated, the only significant difference noted was an increase in liver:body weight ratios in the 100,000-mg WEVC/kg diet dose group. No differences in clinical chemistry or hematological parameters were noted, and there were no consistent differences in histological evaluations of organ tissues. Daily oral doses of up to 5,000 mg/kg of WEVC over 5 d resulted in minimal effects on ferrets. Increased serum albumin concentrations were observed in the 5,000-mg/kg dose group females and decreased spleen weights were noted in females of all WEVC treatment groups. No other significant observations were noted.
Chronic toxicity of 14 phthalate esters toDaphnia magnaand rainbow trout (Oncorhynchus mykiss)
Authors: Rhodes Jon E. , Adams William J. , Biddinger Gregory R. , Robillard Kenneth A. , Gorsuch Joseph W. 
Published: March 2010

AbstractChronic toxicity studies were performed with commercial phthalate esters and Daphnia magna (14 phthalates) and rainbow trout (Oncorhynchus mykiss) (six phthalates). For the lower-molecular-weight phthalate esters–dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and butylbenzyl phthalate (BBP)–the results of the studies indicated a general trend in which toxicity for both species increased as water solubility decreased. The geometric mean maximum acceptable toxicant concentration (GM-MATC) for D. magna ranged from 0.63 to 34.8 mg/L. For the higher-molecular-weight phthalate esters–dihexyl phthalate (DHP), butyl 2-ethylhexyl phthalate (BOP), di-(n-hexyl, n-octyl, n-decyl) phthalate (610P), di-(2-ethylhexyl) phthalate (DEHP), diisooctyl phthalate (DIOP), diisononyl phthalate (DINP), di-(heptyl, nonyl, undecyl) phthalate (711P), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), and ditridecyl phthalate (DTDP)-the GM-MATC values ranged from 0.042 to 0.15 mg/L. Survival was equally sensitive and sometimes more sensitive than reproduction. The observed toxicity to daphnids with most of the higher-molecular-weight phthalate esters appeared to be due to surface entrapment or a mode of toxicity that is not due to exposure to dissolved aqueous-phase chemical. Early life-stage toxicity studies with rainbow trout indicated that survival (DMP) and growth (DBP) were affected at 24 and 0.19 mg/L, respectively. This pattern of observed toxicity with the lower-molecular-weight phthalate esters and not the higher-molecular-weight phthalate esters is consistent with previously reported acute toxicity studies for several aquatic species.
ΣPAH: A Model to predict the toxicity of polynuclear aromatic hydrocarbon mixtures in field-collected sediments
Authors: Swartz Richard C. , Schults Donald W. , Ozretich Robert J. , Lamberson Janet O. , Cole Faith A. , Ferraro Steven P. , Dewitt Theodore H. , Redmond Michele S. 
Published: March 2010

Abstract
The ΣPAH model estimates the probability of toxicity of PAH-contaminated sediments using a combination of equilibrium partitioning, QSAR, toxic unit, additivity, and concentration-response models. The sediment concentration of organic carbon and 13 PAH (polynuclear aromatic hydrocarbon) compounds were measured. Interstitial water concentrations (PAH1W) of the 13 compounds were predicted by equilibrium partitioning. The 10-d LC50 of each compound in interstitial water (10-d LC501W) was predicted by a QSAR regression of 10-d LC501W (from spiked sediment tests) to Kow. Toxic unit concentrations of individual compounds (TU1) were predicted as PAH1w/10-d LC501w. The total number of toxic units of the 13 compounds (ΣTU1) was calculated assuming the additivity of toxic effects of PAHs. ΣTU1 was used to predict the probability of toxicity to marine and estuarine amphipods using a concentration-response model derived from spiked sediment toxicity tests. The ΣPAH model was verified by comparing predicted and observed toxicity in field-collected sediment samples. There was 86.6% correspondence and no significant difference between predicted and observed toxicity at PAH-contaminated sites. Ecological-effect levels predicted by theΣPAH model correspond with several sediment-quality guidelines.
Prediction of adsorption of divalent heavy metals at the goethite/water interface by surface complexation modeling
Authors: Kooner Zorawar S. , Cox Chris D. , Smoot James L. 
Published: March 2010

Abstract
The triple-layer model was used to model the adsorption behavior of Cu(II), Pb(II), and Zn(II) onto goethite as a function of pH, total dissolved metal (Me) concentration, surface area, and ionic strength. A single reaction involving adsorption of Me2+ onto negative surface sites as an inner-sphere complex proved successful in describing adsorption of all three metals under the experimental conditions. The calibrated model was validated by comparing model predictions to independent data reported in the literature. A linear-free-energy relationship between the intrinsic surface complexation and the first-hydrolysis equilibrium constants was determined and was used to predict the intrinsic surface complexation constants for Co(II) and Hg(II). The triple-layer model, using the predicted constants, quantitatively described the adsorption of Co(II), but significantly over-predicted the extent of Hg(II) adsorption.
Comparison of the 10-day freshwater sediment toxicity tests usingHyalella AztecaandChironomus Tentans
Authors: Becker Scott D. , Bigham Gary N. , Rose Curt D. 
Published: March 2010

AbstractComparisons were made of the performance of the 10-d fresh water sediment toxicity tests using the amphipod Hyalella azteca and midge Chironomus tentans. Sediments were collected from eight stations in Onondaga Lake, New York, and represented a wide range of toxicity. The biological end points were survival, biomass, and body length. The two tests were compared on the basis of correspondence among relative values of the end points and ability to statistically discriminate adverse effects relative to control responses (i.e., discriminatory ability). Minimum detectable differences (MDDs) and adverse response ranges of the end points were used to further evaluate the discriminatory ability of the end points. Relative responses and discriminatory abilities of the end points of both tests were similar, despite numerous differences that exist among characteristics of the test species and end points. Significant concordance was found among all end points with respect to relative toxicity of sediments from the eight stations. Although MDDs and adverse response ranges of the various end points differed substantially, the observed positive correlation between those two variables resulted in all end points having similar discriminatory ability. Although amphipod biomass and body length have rarely been used as end points in 10-d tests, both end points provided results comparable to those of the other end points evaluated in the present study.
Reduction of the explosive 2,4,6-trinitrotoluene by enzymes from aquatic sediments
Authors: Van Beelen Patrick , Burris David R. 
Published: March 2010

Abstract
Enzymes were extracted from aquatic sediments. Some of these enzymes reduced 2,4,6-trinitrotoluene (TNT) with nicotinamide adenosine dinucleotide phosphate (NADPH) as an electron donor under aerobic conditions. The origin of these enzymes was not clear as the enzymes were extracted from a sediment containing plant roots and microorganisms. Aquatic plants were determined to be a source of TNT-reducing enzymes. Chemical reduction was not a rate-limiting process in the assays as the enzymatic activity was inhibited by heating or the addition of proteases. Enzymatic activity in the extracts was further characterized. Partial purifications of enzymes from the sediment extracts shows that several proteins capable of reducing TNT with NADPH were present. The enzymes did not require flavins and preferred NADPH over NADH as the electron donor. The pH optimum for the stability of the enzymes was near neutral, and the temperature optimum was in the 37 to 45°C range. Addition of dithiothreitol improved the stability of the enzymes. The enzymes reduced 2,4,6-trinitrotoluene to 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, and 2,6-diamino-4-nitrotoluene under aerobic conditions with NADPH. When used as a starting substrate, the aminodinitrotoluenes were not reduced by the enzymes. It might be possible that the hydroxylaminodinitrotoluenes are reduced to di[hydroxylamine]nitrotoluenes prior to the formation of the diamino-nitrotoluenes. Sediments from 11 surface water bodies were examined for the presence of TNT-reducing enzymes, and 10 were found to have activity. These enzymes appear to be ubiquitous and are present in both freshwater and saltwater sediments. Reduction of TNT by sediment enzymes can be a significant environmental fate process for TNT in aquatic systems.
Avian plasma carboxylesterase activity as a potential biomarker of organophosphate pesticide exposure
Authors: Bartkowiak Donna J. , Wilson Barry W. 
Published: March 2010

Abstract
Plasma cholinesterase (ChE) and carboxylesterase (CaE) activities were measured in pigeons (Columba hvia), captive and wild American kestrels (Falco sparveius), red-tailed hawks (Buteo jamaicensis), Swainson's hawks (Buteo swainsoni), Cooper's hawks (Accipiter cooperit), and red-shouldered hawks (Buteo lineatus). The effect of organophosphate (OP) insecticides on pigeon ChE and CaE activities was determined. Pigeon plasma CaE activity showed distinct groups averaging 12.4 and 138 nmol/min/ml plasma. The CaE activity for raptors was less than 20 nmol/min/ml plasma. Both ChE and CaE activities were inhibited by 0.4 mg/kg ethyl parathion, but CaE activity was not inhibited by 10 mg/kg methidathion. There was no difference in the blood ChE activities of pigeons with low or high blood CaE after treatment with parathion. In general, CaE activity was less severely depressed and recovery was less predictable than was ChE activity.
An ecological risk assessment of lead shot exposure in non-waterfowl avian species: Upland game birds and raptors
Authors: Kendall Ronald J. , Lacker Thomas E. , Bunck Christine , Daniel Bernard , Driver Crystal , Grue Christian E. , Leighton Frederick , Stansley William , Watanabe Philip G. , Whitworth Molly 
Published: March 2010

Abstract
There is increasing concern that birds in terrestrial ecosystems may be exposed to spent lead shot. Evidence exists that upland birds, particularly mourning doves (Zenaida macroura), ingest spent lead shot and that raptors ingest lead shot by consuming wounded game. Mortality, neurological dysfunction, immune suppression, and reproductive impairment are documented effects of exposure to lead in birds. An ecological risk assessment on the impact of lead shot exposure in upland birds was conducted and is presented in the context of the new United States Environmental Protection Agency's Ecological Risk Assessment Paradigm. A considerable amount of spent lead shot is released into the environment each year from shooting and hunting. Doves collected from fields that are cultivated to attract mourning doves for hunting activities show evidence of ingestion of spent lead shot. Because lead can cause both acute and chronic toxicity if ingested by birds, and because there is evidence of widespread deposition of lead shot in terrestrial ecosystems, concern for impacts on upland game birds and raptors seems warranted. Although this ecological risk assessment does not clearly define a significant risk of lead shot exposure to upland game birds, this issue merits continued scrutiny to protect our upland game bird and raptor resources.