bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metier (modular ecotoxicity tests incorporating ecological relevance) for difficult substances: Aedes aegypti (diptera: culicidae) initial module test development using 3,4-dichloroaniline
Authors: Ribeiro Rui , Lima Luís M. , Gonçalves Fernando , Scares Amadeu M.V.M. 
Published: March 2010

Abstract
There is an urgent need to develop regulatory guidelines for compounds classed as “difficult substances” - poorly water-soluble, volatile, readily biodegradable or photodegradable, or hydrolytically unstable compounds. The project METIER (modular ecotoxicity tests incorporating ecological relevance) aims to develop a series of ecologically relevant toxicity tests allowing the full breadth of response of aquatic organisms to chemical contaminants to be assessed under realistic exposure scenarios. This involves the development of a standard flow-through exposure system and a series of modular toxicity tests linked to a mechanistic physiological model of contaminant effects. This paper addresses the initial stages of the development and test design of the module with Aedes aegypti larvae (Diptera: Culicidae), using 3,4–dichloroaniline (3,4–DCA), a poorly water-soluble compound included in the European Community Priority 1 List of Chemicals. A viable culture system, suitable test medium, and the experimental design for loading effects and test duration are investigated. Moreover, the dissolution process and stability of the 3,4–DCA solutions are presented. Up to 50 mg L−1 3,4-DCA was dissolved without the use of a carrier. There was no loss of chemical during 4 d after dissolution. Use of one larva per vessel in 96-h acute toxicity tests is recommended. Also, 24-, 48-, 72-, and 96-h acute toxicity tests were run in low and high volumes of medium. Results of these tests reveal that A. aegypti larvae are more sensitive in higher volumes of test medium and belong to a moderately tolerant group of organisms regarding 3,4-DCA acute toxicity.
Tests for bioequivalence of control media and test media in studies of toxicity
Authors: Erickson Wallace P. , McDonald Lyman L. 
Published: March 2010

Abstract
Statistical tests of the classical (null) hypothesis–that there is no difference in effects of control media and test media– are commonly used to make statistical inferences toward the no-observed-adverse-effect concentration. However, failing to reject this hypothesis is not considered as scientific proof the hypothesis is true. An effect may exist, but high variation due to inadequate replication, variation in experimental units, or imprecise measurement techniques may yield data for which the hypothesis is not rejected. An experiment may also be too precise, yielding effects that are statistically significant but not biologically important. We propose the use of tests of bioequivalence of control media and test media to alleviate these unsatisfactory characteristics of tests of the classical hypotheses for regulatory decisions. We review and illustrate the test for bioequivalence using acute and chronic toxicity data. We also define a procedure for determining the level of effect at which there will be high power to refute the hypothesis that there is a lack of bioequivalence if in fact the biological response in the control media is identical to the response in the test media.
Reversed-phase separation of estuarine interstitial water fractions and the consequences of C18 retention of organic matter
Authors: Ozretich Robert J. , Smith Lawrence M. , Roberts Fredrick A. 
Published: March 2010

Abstract
Data are presented on the application of the reversed-phase separation technique for the determination of dissolved organic compounds in estuarine interstitial water. Thirty-seven neutral, nonpolar organic compounds were equilibrated with interstitial water, extracted by emulsion-free gentle liquid-liquid extraction, and quantified using surrogate internal standards. The extraction and quantitation procedures were insensitive to dissolved organic carbon concentration (DOC, 1 to 55 mg C/L). Gross dissolved organic carbon retention by the C18 matrix (7 ± 2%) was similar to the range reported for fresh water; significant regressions of apparent, DOC-normalized, partition coefficients (K′doc) versus compound solubility and octanol/water partition coefficients (Kow) were determined. An inverse relationship between K′doc and DOC concentrations, similar to that reported in fresh water, was found, but was reduced or eliminated for many compounds by accounting for the retained bound compound in the calculation of K′doc; failure to account for C18 retention of DOM in determining freely dissolved concentrations of high K′ow organic compounds could result in overestimates of this fraction. Partition coefficients of selected compounds between Aldrich humic acid and distilled water were similar to those found in other studies using radiolabeled compounds.
Biodegradation of glycol ethers in soil
Authors: Gonsior Stanley J. , West Robert J. 
Published: March 2010

Abstract
Because of the widespread use of glycol ethers in applications ranging from consumer products to use as chemical intermediates, there is a need to better understand the fate of these compounds in the environment. Soil biodegradation studies were conducted for three propylene glycolethers: 1-methoxy-2-propanol, 1-phenoxy-2-propanol, and 1-methoxy-2-propanol acetate. The test compounds were labeled with carbon-14 at either the methoxy or phenoxy substituents. Biodegradation of the three compounds was observed in two sandy loam soils. The time required for disappearance of 50% of the test compounds ranged from &lt;1 d at 0.2 ppm (w/w) to &lt;7 d at 107 ppm. Degradation rates were slower in a sandy soil, reflecting the lower concentration of microorganisms present. No significant accumulation of intermediate products was observed, and ultimate yields of 14CO2 were in the range of 40 to 65% of the initial concentration. Results indicated that the glycol ethers were degraded in a variety of soils under aerobic conditions.
Fate and effects of triclopyr ester in a first-order forest stream
Authors: Thompson Dean G. , Kreutzweiser David P. , Capell Scott S. , Thomas David R. , Staznik Bozena , Viinikka Ty 
Published: March 2010

Abstract
The fate and the effects of triclopyr butoxyethyl ester (TBEE) were investigated in a first-order forest stream. Quantification of TBEE in stream-water samples showed maximal concentration of 0.848 and 0.949 μg ml−1 at sampling stations nearest two discrete injection points. Average TBEE concentrations ranged from 0.32 μg ml−1 at stations nearest injection points to 0.02 μg ml−1 approximately 225 m downstream. Periods of exposure to aqueous TBEE concentrations in excess of 0.001 μg ml−1 ranged from 55 min in fast-flowing upstream locations to 120 min at slower, downstream sampling locations. Simultaneous quantitation of triclopyr acid (TRI) residues in stream-water samples indicated that natural degradative mechanisms rapidly converted TBEE to TRI, and that sorption to natural allochthonous materials occurred as chemical pulses moved downstream. Chemical behaviour resulted in short-term, pulse-type exposures to TBEE, with decreasing magnitude and slightly increasing duration in relation to downstream distance. Short-term, low-level exposures generated in this stream treatment resulted in slightly elevated drift (∼3- to 4-fold increase) for up to 36 h, but no measurable reductions in abundance of benthic invertebrates. Increases in chlorophyll a concentrations in epilithic periphyton from treated sections indicated short-term eutrophication or growthregulation effects of the herbicide applications.
Spatial and temporal trends of contaminants in eggs of wading birds from San Francisco Bay, California
Authors: Hothem Roger L. , Marois Katherine C. , Wainwright Susan E. , Roster Douglas L. , King Kirke A. , Keldsen Timothy J. 
Published: March 2010

Abstract
Between 1989 and 1991, reproduction by black-crowned night-herons (Nycticorax nycticorax) and snowy egrets (Egretta thula) was studied at sites in San Francisco Bay. Eggs were collected from these and other bay sites and from South Wilbur Flood Area, a reference site in California's San Joaquin Valley. Eggs were analyzed for inorganic trace elements, organochlorine pesticides, and polychlorinated biphenyls (PCBs). Results were compared among sites and years and with results of previous studies. There was some evidence of impaired reproduction, but concentrations of contaminants were generally lower than threshold levels for such effects. Egg hatchability was generally good, with predation being the factor that most limited reproductive success. Mean PCB concentrations were generally higher in eggs from the south end of San Francisco Bay than from the north, but the only temporal change, an increase, was observed at Alcatraz Island. There were spatial differences for p,p′-DDE in night-heron eggs in 1990, but the highest mean concentration of DDE was in night-heron eggs from South Wilbur in 1991. Temporal declines in maximum concentrations of DDE in eggs were observed in the bay, but means did not change significantly over time. At Bair Island in the southern end of the bay, mean concentrations of mercury decreased while selenium increased in night-heron eggs over time, but there were no clear bay-wide spatial or temporal trends for either element.
An inexpensive fathead minnow egg incubation and toxicant exposure system
Authors: Diamond Stephen A. , Oris James T. , Guttman Sheldon I. 
Published: March 2010

Abstract
We report on an inexpensive, easily constructed system for hatching fathead minnow eggs and maintaining hatched larvae for growth and survivorship studies. Data are presented to illustrate the use of the system for toxicant exposures. This system has applications for both field and laboratory studies.
Adaptation to fluoranthene exposure in a laboratory population of fathead minnows
Authors: Diamond Stephen A. , Oris James T. , Guttman Sheldon I. 
Published: March 2010

Abstract
Tolerance of toxicant exposure is common in polluted sites in nature. However, in most cases, the processes underlying tolerance acquisition are not well understood. In the case of exposure to polycyclic aromatic hydrocarbons (PAHs) in particular, reports are lacking on the capacity for tolerance acquisition. To evaluate the potential for adaptation to this class of contaminants we exposed a large laboratory population of fathead minnows to fluoranthene, commonly a major constituent of PAH contamination. The exposure concentration chosen did not cause mortality but was sufficient to diminish reproductive capacity in exposed breeding fish relative to a control population. This level of exposure also significantly diminished hatching success and larval survivorship in the exposed population. The estimated value of selection against susceptibility (the product of all assessments of effect) was 0.67. Tests for tolerance acquisition included comparative larval 96-h LC50 determinations, and comparative juvenile median time to death (LT50) determinations. Enhanced tolerance was not apparent in the LC50 determinations, although an examination of the concentration-response distribution suggested an adverse effect due to egg and larval exposure to fluoranthene prior to the test. In contrast, results of the comparative LT50 determination indicated that the exposed population was approximately 30% more tolerant, relative to the control population, when exposed to an acutely toxic concentration of fluoranthene. These results suggest that tolerance to PAH exposure can occur in nature and that this population-level response needs to be examined relative to other recognized effects in PAH-contaminated areas.
Relative sensitivity of five benthic invertebrate species to reference toxicants and resin-acid contaminated sediments
Authors: Hickey Christopher W. , Martin Michael L. 
Published: March 2010

Abstract
Five sediment-dwelling native New Zealand freshwater invertebrate species (amphipod, Chaetocorophium c.f. lucasi; clam, Sphaerium novaezelandiae; oligochaete, Lumbriculus variegatus; tanaid, Tanais standfordi; and the burrowing mayfly, Ichthybotus hudsoni) were assessed for their suitability for sediment toxicity testing by comparison of sensitivity to reference toxicants [phenol and pentachlorophenol (PCP)] and contaminated sediments. The 96-h EC50 values at 20°C showed a greater range in test sensitivity for phenol (30-fold range) from the most sensitive test, amphipod (8.1 mg/L), to the least sensitive one, clam (243 mg/L), compared with PCP (14-fold range), with amphipod the most sensitive test species (0.13 mg/L) and tanaid the least sensitive (1.8 mg/L). Clam reburial was a more sensitive end point than was lethality for phenol (by 20-fold) and PCP (by 2.4-fold). Four of the test species, excluding the tanaid, showed good 10-d survival in reference muds (≥87%) but lower survival in sand sediments (≥79%). Bleached kraft mill sediment containing high resin-acid concentrations (total 1,900 mg/kg dry weight) showed significant reductions in amphipod survival (15%), clam reburial (30%), and oligochaete survival (17%), and reproduction (49%). Amphipods, clams, and oligochaetes were the most promising species for sublethal test development.
Use of loading rates to establish dioxin criteria for land application of sludge
Authors: Thiel David A. , Martin Stephen G. , Goodman Beth B. , Sullivan John R. 
Published: March 2010

Abstract
A methodology derived from empirical field and laboratory data on wildlife toxicology, chemical concentrations, and loading rates is developed for defining criteria for protecting wildlife exposed to landspread materials containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and TCDD-like compounds. The method controls mass loading, giving it clear advantages over soil-concentration-based criteria in situations where material is spread in a relatively thin layer on the surface and not incorporated into the soil. It also controls dioxin toxic equivalents in the target organism rather than in the landspread material. It achieves a high level of protection for bird embryos by applying a safety factor to a no-observed-adverse-effect level (NOAEL) derived from egg toxicity data and combining this adjusted NOAEL with bioaccumulation data from the most efficient avian accumulator of TCDD on a landspread site. Assuming that bird embryos are among the most sensitive organisms to TCDD in the terrestrial environment, dioxin restrictions adequate to safeguard eggs will protect other wildlife inhabiting landspread sites. Using this methodology, the Wisconsin Department of Natural Resources has derived the following wildlife dioxin criterion for surface spreading (i.e., no incorporation) a paper industry sludge: The sum of the mass of TCDD plus 0.0013 times the mass of 2,3,7,8-tetrachlorodibenzofuran (TCDF) shall not exceed 1.3 mg per hectare.
Hydrolysis of para-substituted benzonitriles in water
Authors: Masunaga Shigeki , Lee Wolfe N. , Hayase Kohji 
Published: March 2010

Abstract
The transformation of para-substituted benzonitriles was studied in buffered distilled water. The elevated temperature experiments revealed that benzonitriles are hydrolyzed to the corresponding benzoic acids through benzamide intermediates. For 4-chlorobenzonitrile, the pseudo-first-order rate constants adhered to the Arrhenius equation with an activation energy of 40.5 kJ · mol−1 and collision frequency of In 6.23 × 104. Alkaline hydrolysis was dominant at pH values above 8, while neutral hydrolysis was important between pH 5 and 7. The quantitative structure-reactivity relationship (QSRR) analysis of 14 para-substituted benzonitriles showed that the first-order rate constants obtained in phosphate buffer (pH 7.7) at 85°C, based on a combination of neutral and alkaline hydrolysis, were correlated with Hammett σp constants.
Parameters affecting the adsorption of hexachlorobenzene to natural sediments
Authors: Jepsen Rich , Borglin Sharon , Lick Wilbert , Swackhamer Deborah L. 
Published: March 2010

Abstract
Many of the toxic contaminants introduced into aquatic systems are hydrophobic and, because of this, they are transported with the suspended sediments and eventually incorporated into the bottom sediments. Understanding the dynamics of contaminant sorption to sediments is therefore important in understanding and predicting the transport and fate of contaminants. In the present study, the adsorption and the partitioning of hexachlorobenzene (a hydrophobic organic chemical) to natural sediments from the Detroit River were investigated by means of batch mixing experiments. Experiments were conducted over a long period (2 to 5 months) to reach a steady-state equilibrium and at different sediment concentrations (10, 100, 500, 2,000, and 10,000 mg/L). It was found that the adsorption rate was greatest for small time and decreased to zero as time increased. For all concentrations, a steady-state equilibrium was always attained. Experiments quantitatively demonstrate the time-dependent effects of hexachlorobenzene dissolution, of the flocculation of colloidal matter in the water, and of the flocculation of the suspended sediments. Although a solids concentration effect on the partition coefficient was observed, it is shown to be due to the above processes. From the data, a true equilibrium partition coefficient as well as the approximate times to equilibrium can be determined.
Hexazinone effects on stream periphyton and invertebrate communities
Authors: Kreutzweiser David P. , Capell Scott S. , Sousa Brian C. 
Published: March 2010

Abstract
Experiments were conducted in laboratory test chambers and outdoor stream channels to measure the effects of hexazinone on stream periphyton and macroinvertebrate communities. All experimental units were treated at the nominal concentration of 2.7 mg/L, which represents the maximum expected environmental concentration in water from forest vegetation management applications. In laboratory flow-through tests, a 12-h exposure of stream periphyton on natural substrates to hexazinone resulted in a significant reduction in net photosynthetic activity, but no significant effects on periphyton biomass (chlorophyl-a concentration). Recovery from toxic effects was rapid, with no significant differences in photosynthetic activity among treated and control units within 3 h after the hexazinone concentrations were cleared. In stream channels treated for 12 h with hexazinone, there were no significant effects on periphyton biomass and no significant differences in invertebrate drift, compared to control channels. There were also no indications of adverse treatment effects on the invertebrate communities in the stream channels 14 d after the application. The treated and control channels differed in invertebrate community structure, as determined by a stepwise discriminant analysis [Wilks' lambda F equivalent (3,2) = 127.6, p = 0.007], and this was supported by a two-way ANOVA which showed a significant difference in abundance of macroinvertebrates [F(1, 56) = 10.5, p = 0.002] between treated and control channels, averaged over all taxa. However, subsequent pairwise t tests, when adjusted for multiple comparisons, were unable to identify significant differences between treatment levels for any of the 14 taxa with sufficient data for analysis. Although not significant, the comparison of means showed that abundance of most taxa was higher in the treated channels than in the controls.
The response of biota in experimental stream channels to a 24-hour exposure to the herbicide Velpar L®
Authors: Schneider Judith , Morin Antoine , Pick Frances R. 
Published: March 2010

Abstract
Outdoor experimental stream channels were used to examine the short-term impact of Velpar L® on periphyton and macroinvertebrates. Velpar L was added to five channels for 24 h while five additional, alternating channels served as controls. The concentration and the duration of the Velpar L treatment were chosen to mimic the pulse of herbicide carried to streams during rain events subsequent to Velpar L spraying. The mean concentration of hexazinone, the active ingredient, in the treatment channels varied over time from 145 μg L−1 to 432 μg L−1. Periphyton chlorophyll-a-specific productivity was reduced by 80% during the Velpar L addition. Within 24 h after the termination of the Velpar L addition, periphyton productivity returned to control levels. The 4-h EC50 value, 3.6 μg L−1 of hexazinone, for chlorophyll-a-specific productivity was lower than published bioassay results from single species tests. Mean periphyton biomass (chlorophyll-a per unit area of gravel substrate) and mean macroinvertebrate biomass, density, length, and drift were not significantly affected by the Velpar L addition. Although it appears that lotic systems are resilient to short-term exposure to Velpar L, the effects of repeated and chronic exposures on stream biota remain unexplored.
Validation of models on uptake of organic chemicals by plant roots
Authors: Polder Marieke D. , Hulzebos Etje M. , Jager D. Tjalling 
Published: March 2010

Abstract
The fate of a substance is governed by the distribution of the substance among soil, water, air, and biota, and by the concentration of the substance and its altered forms existing over a period of time in these media. As vegetable food forms a major part of the diet of both human beings and of cattle, the contamination of plants will have a large influence on the total daily intake of a substance. In this report the application of soil-plant transfer factors is investigated. The main goal was to find sufficient experimental data in the available literature, if possible adjusted for differences in experimental design, that could be used to evaluate the currently applied method in the uniform system for the evaluation of substances (USES). In this approach, concentrations in plant root and stem are estimated on the basis of an empirical relationship with the octanol/water partitioning coefficient. It was concluded that, for the purposes set in USES, the root concentration factor is an appropriate instrument for the estimation of residues in roots, whereas the application of the stem concentration factor is insufficient. Consequently, for aboveground plant parts, other approaches need to be explored, which can then be applied in the general risk assessment of substances.