bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intra- and intertreatment variability in reference toxicant tests: Implications for whole effluent toxicity testing programs
Authors: Moore Dwayne RJ , Warren-Hicks William , Parkhurst Benjamin R , Teed R Scott , Baird Rodger B , Berger Robert , Denton Debra L , Pletl James J 
Published: March 2010

AbstractWole effluent toxicity tests are used in permitting programs across the United States to determine whether effluents are potentially toxic to aquatic biota in receiving environments. In cases where whole effluent toxicity tests indicate unacceptable toxicity, corrective measures or further testing (e.g., field tests) may be required. To be consistent and fair to permit holders, whole effluent toxicity test outcomes (e.g., pass or fail) should not be strongly influenced by intra- and interlaboratory variability. In this study, we quantified intra- and interlaboratory variability for four species–data type combinations using the results of reference toxicant tests compiled from many laboratories in recent years. For each set of test results, we conducted a regression analysis using the generalized linear models framework. The results indicated that the coefficient of variation (CV) for intralaboratory 25% effective concentration (i.e., EC25) values varied from 15.7% for number of young of Ceriodaphnia dubia in laboratory CD4 to 122% for mortality of Menidia beryllina (inland silverside) in laboratory MB3. Interlaboratory variability was small for both mortality (CV = 17.3%) and number of young (CV = 13.4%) of C. dubia. Interlaboratory variability for mortality (CV = 65.8%) and biomass (CV = 117%) of M. beryllina, however, was very high. Our study shows that permit toxicity limits can be exceeded because of factors other than effluent toxicity, particularly when the limits are based on testing of M. beryllina.
Investigating the Incidence of type i errors for chronic whole effluent toxicity testing usingCeriodaphnia dubia
Authors: Moore Timothy F , Canton Steven P , Grimes Max 
Published: March 2010

AbstractThe risk of Type I error (false positives) is thought to be controlled directly by the selection of a critical p value for conducting statistical analyses. The critical value for whole effluent toxicity (WET) tests is routinely set to 0.05, thereby establishing a 95% confidence level about the statistical inferences. In order to estimate the incidence of Type I errors in chronic WET testing, a method blank-type study was performed. A number of municipal wastewater dischargers contracted 16 laboratories to conduct chronic WET tests using the standard test organism Ceriodaphnia dubia. Unbeknownst to the laboratories, the samples they received from the wastewater dischargers were comprised only of moderately hard water, using the U.S. Environmental Protection Agency's standard dilution water formula. Because there was functionally no difference between the sample water and the laboratory control/dilution water, the test results were expected to be less than or equal to 1 TUc (toxic unit). Of the 16 tests completed by the biomonitoring laboratories, two did not meet control performance criteria. Six of the remaining 14 valid tests (43%) indicated toxicity (TUc &gt; 1) in the sample (i.e., no-observed-effect concentration or IC25 &lt; 100%). This incidence of false positives was six times higher than expected when the critical value was set to 0.05. No plausible causes for this discrepancy were found. Various alternatives for reducing the rate of Type I errors are recommended, including greater reliance on survival endpoints and use of additional test acceptance criteria.
Effects of several variables on whole effluent toxicity test performance and interpretation
Authors: Markle Philip J , Gully Joseph R , Baird Rodger B , Nakada Kenneth M , Bottomley Jay P 
Published: March 2010

Abstract
Protocol changes and options contained within U.S. Environmental Protection Agency whole effluent toxicity tests represent variables that have the potential to affect bioassay performance and interpretation of results. Variables evaluated in this study include: the change in allowable age in the Pimephales promelas acute bioassay from up to 90 d to a maximum of 14 d, age-specific acute responses of P. promelas among the allowable ages of 1 to 14 d, change in the chronic growth endpoint definition from final mass to biomass, differences between hemacytometer and fluorometer measurements in the Selenastrum capricornutum protocol, and options for statistical interpretation of species sensitivity in multiple test/species screening bioassays. Clear age-related sensitivity and precision differences were observed in acute responses of P. promelas. Results obtained using the younger age classes were typically more variable in studies of both 1- to 14-d-old and 14- to 90-d-old P. promelas. In the experiments on 1-to 14-d-old organisms, larvae at 1 d of age were significantly less sensitive. In the tests on 14- to 90-d-old organisms, the 14-d-old organisms were significantly less sensitive. The change in endpoint definition in the P. promelas chronic bioassay resulted in an apparent increase in toxic response in the inhibition concentration (ICp) value for each bioassay, evaluated by the biomass method, with no general improvement in statistical intertest precision estimates and no predictable impact on the no-observed-effect concentration endpoint. Fluorometric scoring in the Selenastrum bioassay was significantly more precise and better capable of estimating counts than hemacytometer measurements. Discrepancies associated with commonly used statistical endpoints used to determine the most sensitive species were identified, and potential solutions were proposed.
Effect-based interpretation of toxicity test data using probability and comparison with alternative methods of analysis
Authors: Gully Joseph R , Baird Rodger B , Markle Philip J , Bottomley Jay P 
Published: March 2010

AbstractA methodology is described that incorporates the intra- and intertest variabilityand the biological effect of bioassay data in evaluating the toxicity of single and multiple tests for regulatory decision-making purposes. The single- and multiple-test regulatory decision probabilities were determined from t values (n − 1, one-tailed) derived from the estimated biological effect and the associated standard error at the critical sample concentration. Single-test regulatory decision probabilities below the selected minimum regulatory decision probability identify individual tests as noncompliant. A multiple-test regulatory decision probability is determined by combining the regulatory decision probability of a series of single tests. A multiple-test regulatory decision probability below the multiple-test regulatory decision minimum identifies groups of tests in which the magnitude and persistence of the toxicity is sufficient to be considered noncompliant or to require enforcement action. Regulatory decision probabilities derived from the t distribution were compared with results based on standard and bioequivalence hypothesis tests (t tests and no-observed-effect concentrations) using single- and multiple-concentration toxicity test data from an actual national pollutant discharge elimination system monitoring program. The analysis demonstrates that the use of regulatory decision probabilities effectively incorporated the precision of the effect estimate into regulatory decisions at a fixed level of effect. Also, probability-based interpretation of toxicity tests provides incentive to laboratories to produce, and permit holders to use, high-quality, precise data, particularly when multiple tests are used in regulatory decisions. These results are contrasted with standard and bioequivalence hypothesis tests in which the intratest precision is a determining factor in setting the biological effect used for regulatory decisions.
An empirical comparison of effective concentration estimators for evaluating aquatic toxicity test responses
Authors: Bailer A. John , Hughes Michael R , Denton Debra L , Oris James T 
Published: March 2010

Abstract
Aquatic toxicity tests are statistically evaluated by either hypothesis testing procedures to derive a no-observed-effect concentration or by inverting regression models to calculate the concentration associated with a specific reduction from the control response. These latter methods can be described as potency estimation methods. Standard U.S. Environmental Protection Agency (U.S. EPA) potency estimation methods are based on two different techniques. For continuous or count response data, a nominally nonparametric method that assumes monotonic decreasing responses and piecewise linear patterns between successive concentration groups is used. For quantal responses, a probit regression model with a linear dose term is fit. These techniques were compared with a recently developed parametric regression-based estimator, the relative inhibition estimator, RIp. This method is based on fitting generalized linear models, followed by estimation of the concentration associated with a particular decrement relative to control responses. These estimators, with levels of inhibition (p) of 25 and 50%, were applied to a series of chronic toxicity tests in a U.S. EPA region 9 database of reference toxicity tests. Biological responses evaluated in these toxicity tests included the number of young produced in three broods by the water flea (Ceriodaphnia dubia) and germination success and tube length data from the giant kelp (Macrocystis pyrifera). The greatest discrepancy between the RIp and standard U.S. EPA estimators was observed for C. dubia. The concentration–response pattern for this biological endpoint exhibited nonmonotonicity more frequently than for any of the other endpoint. Future work should consider optimal experimental designs to estimate these quantities, methods for constructing confidence intervals, and simulation studies to explore the behavior of these estimators under known conditions.
Using single-species toxicity tests, community-level responses, and toxicity identification evaluations to investigate effluent impacts
Authors: Maltby Lorraine , Clayton Sophie A , Yu Hongxia , McLoughlin Nathan , Wood Robert M , Yin Daqiang 
Published: March 2010

Abstract
Whole effluent toxicity (WET) tests are increasingly used to monitor compliance of consented discharges, but few studies have related toxicity measured using WET tests to receiving water impacts. Here we adopt a four-stage procedure to investigate the toxicity and biological impact of a point source discharge and to identify the major toxicants. In stage 1, standard WET tests were employed to determine the toxicity of the effluent. This was then followed by an assessment of receiving water toxicity using in situ deployment of indigenous (Gammarus pulex) and standard (Daphnia magna) test species. The third stage involved the use of biological survey techniques to assess the impact of the discharge on the structure and functioning of the benthic macroinvertebrate community. In stage 4, toxicity identification evaluations (TIE) were used to identify toxic components in the effluent. Receiving-water toxicity and ecological impact detected downstream of the discharge were consistent with the results of WET tests performed on the effluent. Downstream of the discharge, there was a reduction in D. magna survival, in G. pulex survival and feeding rate, in detritus processing, and in biotic indices based on macroinvertebrate community structure. The TIE studies suggested that chlorine was the principal toxicant in the effluent.
Bioequivalence approach for whole effluent toxicity testing
Authors: Shukla Rakesh , Wang Qin , Fulk Florence , Deng Chunqin , Denton Debra 
Published: March 2010

Abstract
Increased use of whole effluent toxicity (WET) tests in the regulatory arena has brought increased concern over the statistical analysis of WET test data and the determination of toxicity. One concern is the issue of statistical power. A number of WET tests may pass the current hypothesis test approach because they lack statistical power to detect relevant toxic effects because of large within-test variability. Additionally, a number of WET tests may fail the current approach because they possess excessive statistical power, as a result of small within-test variability, and detect small differences that may not be biologically relevant. The strengths and limitations of both the traditional hypothesis test approach and the bioequivalence approach for use in the National Pollutant Discharge Elimination System program were evaluated. Data from 5,213 single-concentration, short-term chronic WET tests with Ceriodaphnia dubia provided the database for analysis. Comparison of results between the current approach and the bioequivalence approach indicates that the current approach to WET testing is generally sound but that adopting the proposed bioequivalence approach resolves concerns of statistical power. Specifically, within this data set, applying the bioequivalence approach resulted in failure for tests with relatively large test variability and a pass for tests with relatively small within-test variability.
Adjusting for mortality effects in chronic toxicity testing: Mixture model approach
Authors: Wang Shin Cheng David , Smith Eric P 
Published: March 2010

AbstractChronic toxicity tests, such as the Ceriodaphnia dubia 7-d test are typically analyzed using standard statistical methods such as analysis of variance or regression. Recent research has emphasized the use of Poisson regression or more generalized regression for the analysis of the fecundity data from these studies. A possible problem in using standard statistical techniques is that mortality may occur from toxicant effects as well as reduced fecundity. A mixture model that accounts for fecundity and mortality is proposed for the analysis of data arising from these studies. Inferences about key parameters in the model are discussed. A joint estimate of the inhibition concentration is proposed based on the model. Confidence interval estimation via the bootstrap method is discussed. An example is given for a study involving copper and mercury.
Toxicity of total dissolved solids associated with two mine effluents to chironomid larvae and early life stages of rainbow trout
Authors: Chapman Peter M , Bailey Howard , Canaria Edmund 
Published: March 2010

Abstract
Asessment of total dissolved solids (TDS) represents anintegrated measure of the concentrations of common ions (e.g., sodium, potassium, calcium, magnesium, chloride, sulfate, and bicarbonate) in freshwaters. Toxicity related to these ions is due to the specific combination and concentration of ions and is not predictable from TDS concentrations. Short-term chronic toxicity tests were conducted with larval chironomids and trout (eggs and swim-up fry) to assess their TDS tolerance relative to effluents from two Alaskan mines. Both effluents are characterized by high TDS content but differ with respect to concentrations of specific ions and alkalinity. The toxicity tests were conducted with synthetic effluents formulated to match the ionic composition of each mine discharge. No toxicity was observed at &gt;2,000 mg of TDS/L with embryos or developing fry, but chironomids exhibited effects above 1,100 mg of TDS/L. These tests, together with information on the health of field populations (fish and benthic invertebrates), are appropriate and relevant for determining site-specific whole effluent TDS concentrations.
Insecticide-caused toxicity toCeriodaphnia dubia(CLADOCERA) in the Sacramento–San Joaquin River delta, California, USA
Authors: Werner Ingeborg , Deanovic Linda A , Connor Valerie , de Vlaming Victor , Bailey Howard C , Hinton David E 
Published: March 2010

AbstractIn recent years, populations of resident aquatic species in California's Sacramento–San Joaquin Delta, USA, have declined appreciably in numbers. The cause of these declines is not known, but has been attributed to a number of factors including water diversions, loss of habitat, introduced exotic organisms, and toxic compounds. To detect and characterize the spatial extent, severity, frequency, and causes of potential toxicity caused by anthropogenic pollutants, a monitoring study was conducted over a period of two years (1993–1995). Sites were monitored on a monthly basis using the standardized U.S. Environmental Protection Agency freshwater toxicity test with the zooplankton species Ceriodaphnia dubia. Twenty-four sites were sampled in 1993 to 1994. During the 1994 to 1995 sampling season, the number of sampling sites was restricted to 20, with special emphasis placed on back sloughs, delta island agricultural drains, and main-stem river sites. Significant mortality or reproductive toxicity in C. dubia was detected in 9.8% of 400 water samples tested. Ecologically important back sloughs had the largest percentage of toxic samples. Of 71 and 103 samples collected from back sloughs during 1993 to 1994 and 1994 to 1995, respectively, 14.1% and 19.6% were toxic. To determine the causative chemical(s), toxicity identification evaluations (TIEs) were conducted on 23 toxic samples. These included eight follow-up samples taken to determine whether toxicity at the respective site persisted. Organophosphate (chlorpyrifos, diazinon, malathion) and carbamate (carbofuran, carbaryl) pesticides were identified as primary toxicants. Chlorpyrifos was present at toxic concentrations in 87% of samples tested by TIE. Analysis of data from the follow-up samples suggested that toxicity may have persisted over periods of several days to weeks.
The role of calcium and sodium in toxicity of an effluent to mysid shrimp (Mysidopsis bahia)
Authors: Kline Edward R , Stekoll Michael S 
Published: March 2010

AbstractThe source of acute toxicity of an aged gold mill effluent to juvenile mysid shrimp (Mysidopsis bahia [Americamysis bahia]) was identified. Effluent osmolality was equivalent to that of 12 ppt seawater. At five effluent concentrations ranging from 4 to 100% (v/v), using 12 ppt seawater for dilution, the onset of responses was most rapid at 37% effluent. Simulated effluent was created by adding Na+, Ca2+, Mg2+, K+, Cl−, and SO42− to distilled water at concentrations equal to those measured in the effluent. The unusual finding of a more rapid onset of responses at 37% than at 100% effluent was duplicated with simulated effluent, demonstrating that responses of M. bahia to effluent were attributable to one or more of the six ions that were included in simulated effluent. Proportionally, excess Ca2+ and Na+ deficiency were among the greatest differences in the ionic composition of effluent relative to seawater. Manipulation of Ca2+ and Na+ concentrations in effluent and in simulated effluent, along with the results of the previous experiments, demonstrated that excess Ca2+ was the sole source of effluent toxicity and that Na+ deficiency, relative to the proportion in seawater, reduced Ca2+ toxicity.
Application of a fish DNA damage assay as a biological toxicity screening tool for metal plating wastewater
Authors: Choi Kyungho , Zong Moonshik , Meier Peter G 
Published: March 2010

AbstractThe utility of a fish DNA damage assay as a rapid monitoring tool was investigated. Metal plating wastewater was chosen as a sample because it contains various genotoxic metal species. Fish DNA damage assay results were compared to data generated from the conventional whole effluent toxicity (WET) test procedure. The Microtox® assay (Azur Environmental, Carlsbad, CA, USA) using Vibrio fischeri was also employed. Eleven samples from two metal plating companies were collected for this evaluation. For the fish DNA damage assay, 7-d-old fathead minnow larvae, Pimephalespromelas, were utilized. They were exposed to a series of dilutions at 20°C for 2 h. Whole effluent toxicity tests conducted in this study included two acute toxicity tests with Daphnia magna and fathead minnows and two chronic toxicity tests with Ceriodaphnia dubia and fathead minnows. The fish DNA damage assay showed good correlations with both the acute and chronic WET test results, especially with those obtained with fathead minnows. The kappa values, an index of agreement, between the fish DNA damage assay and WET tests were shown to be acceptable (kappa ≥ 0.55). These findings imply that this novel fish DNA damage assay has use as an expedient toxicity screening procedure since it produces comparable results to those of the acute and chronic fathead minnow toxicity tests.
Sporadic mortality in chronic toxicity tests using Pimephales promelas (rafinesque): Cases of characterization and control
Authors: Downey Patrick J , Fleming Kari , Guinn Richard , Chapman Norris , Varner Patricia , Cooney John D 
Published: March 2010

Abstract
In whole effluent toxicity tests, organisms are exposed to various effluent concentrations for a specific time period to estimate the potential effects of an effluent on a receiving stream. Laboratories typically have good success performing valid chronic toxicity tests. However, some difficulty in conducting valid chronic whole effluent toxicity tests with Pimephales promelas (fathead minnow) has been encountered as a result of sporadic control mortality. Some investigators report an interference that causes anomalous patterns of survival in chronic fathead minnow tests. This interference has been termed sporadic mortality phenomenon. Characteristics of sporadic mortality phenomenon include high variability among replicates, nonmonotonic dose responses, mortality beginning on or about day 4 of the test, and fungal growths often observed on the larvae. Histopathologic examinations often indicate bacterial and/or fungal infections on fish exhibiting symptoms of sporadic mortality phenomenon. The most plausible explanation of sporadic mortality phenomenon is a naturally occurring pathogen or pathogens that interfere with the test method. This interference may invalidate tests or falsely indicate toxicity. Sporadic mortality phenomenon can be reduced or eliminated by sample treatments intended to inactivate (heating, antibiotics, or ultraviolet light) or remove (filtration) pathogenic microorganisms. These methods must be used with forethought because of their potential to alter the toxicity of a sample.
Biokinetics of cesium in Perna viridis
Authors: Yu Peter K. N. , Lam Paul K S , Ng Ben K P , Li Ashley M Y 
Published: March 2010

Abstract
The biokinetics of Cs in four compartments in the green-lipped mussel Perna viridis, namely, gill, viscera, adductor muscle, and foot, were studied. First-order linear differential equations were set up for these four compartments, and their solutions were used to fit the experimental data. The parameters governing the biokinetics, which depend on the elimination rate from each compartment and the transfer coefficient between compartments, were found. These are useful in understanding the physiology of Perna viridis, in predicting the activity of cesium in each compartment of Perna viridis from a contamination history, or in using Perna viridis as a sentinel organism for surveying and monitoring radioactive contamination. The results showed that the viscera should be represented by more than one compartment. Concentration factors for the four compartments and for Perna viridis were also determined, and these agreed well with reported values in the literature.