bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic pollutants in the coastal environment off San Diego, California. 1. Source identification and assessment by compositional indices of polycyclic aromatic hydrocarbons
Authors: Zeng Eddy Y , Vista Cherrie L
Published: March 2010

Samples collected in January and June 1994 from the Point Loma Wastewater Treatment Plant (PLWTP) effluent, Tijuana River runoff, and microlayer, sediment trap, and surface sediment at several locations adjacent to the PLWTP outfall, mouth of the Tijuana River, and San Diego Bay were analyzed in an attempt to identify and assess the sources of hydrocarbon inputs into the coastal marine environment off San Diego. Several compositional indices of polycyclic aromatic hydrocarbons (PAHs), for example, alkyl homologue distributions, parent compound distributions, and other individual PAH ratios, were used to identify the sources of PAHs. Partially due to the decline of PAH emission from the PLWTP outfall, PAHs found in the sea surface microlayer, sediments, and water column particulates near the PLWTP outfall were predominantly derived from nonpoint sources. The sea microlayer near the mouth of the Tijuana River appeared to accumulate enhanced amounts of PAHs and total organic carbon and total nitrogen, probably discharged from the river, although they were in extremely low abundance in the sediments at the same location. Surprisingly, PAHs detected in the microlayer and sediments in San Diego Bay were mainly derived from combustion sources rather than oil spills, despite the heavy shipping activities in the area.
Contaminant concentrations and biomarker response in great blue heron eggs from 10 colonies on the upper Mississippi River, USA
Authors: Custer Thomas W , Hines Randy K , Melancon Mark J , Hoffman David J , Wickliffe Jeffrey K , Bickham John W , Martin James W , Henshel Diane S
Published: March 2010

In 1993, great blue heron (Ardea herodias; GBH) eggs were collected from 10 colonies on the upper Mississippi River (UMR). They were then artificially incubated until pipping and analyzed for mercury, selenium, and organochlorines. Livers of embryos were analyzed for hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity and four measures of oxidative stress. Brains were measured for asymmetry and blood was measured for the coefficient of variation of DNA (DNA CV). Organochlorine concentrations were generally low (geometric mean DDE = 1.3 μg/g wet weight; polychlorinated biphenyl [PCB] = 3.0 μg/g; 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD] = 11.5 pg/g). Eggshell thickness was negatively correlated with DDE concentrations. Mercury (geometric mean = 0.8 μg/g dry weight) and selenium (3.1 μg/g dry weight) concentrations in GBH eggs were within background levels. EROD activity was not correlated with total PCBs, TCDD, or toxic equivalents (TEQs), based on the relative contribution of individual PCB congeners, dibenzodioxins (PCDDs), and dibenzofurans (PCDFs) to total calculated TEQs. Three of the four measures of oxidative stress were correlated with mercury concentrations. Twenty of 43 (47%) embryo brains were asymmetrical and the embryos with asymmetrical brains had higher EROD concentrations in the liver and higher DNA CV in the blood than embryos with symmetrical brains.
Accumulation of seleno-amino acids in legume and grass plant species grown in selenium-laden soils
Authors: Wu Lin , Guo Xun , Banuelos Gary S
Published: March 2010

Seleno-amino acid accumulation was studied for two legume and two grass species grown in Selenium (Se)-laden soils. An antagonistic relationship was found between the tissue Se-amino acid concentration and the corresponding sulfur-amino acid concentration. This relationship demonstrates a competitive interaction between Se and sulfate at the amino acid synthesis level. The nonsulfur-containing amino acids were not substantially affected by the increase of tissue Se concentration. Sour clover (Melilotus indica L.) was able to accumulate much greater tissue Se concentration than the other three species. Tissue methionine concentration of sour clover, rabbitfoot grass (Polypogon monspeliensis L.), and tall fescue (Festuca arundinacea Schreb.) was not significantly affected by the increase of tissue selenomethionine concentration, but a highly significant negative correlation was found in alfalfa (Medicago sativa L.). This discrepancy suggests that a less antagonistic effect on sulfur-amino acids under the increase of Se-amino acid analogues in the tissue might be able to minimize Se toxicity to the plant. Both Se-methylselenocysteine (nonprotein amino acid) and selenomethionine (protein amino acid) accumulated in the plants when grown in Se-laden soils. Possible effects of these Se-amino acids accumulated by plants on animal health should be tested before the plants are used for forage supplementation.
Accumulation and toxicokinetics of fluoranthene in sediment bioassays with freshwater amphipods
Authors: Driscoll Susan Kane , Harkey Gail A , Landrum Peter F
Published: March 2010

Two freshwater amphipods, Hyalella azteca and Diporeia sp., were exposed to sediment spiked with radiolabeled fluoranthene at nominal concentrations of 0.1 (trace) to 1,270 nmol fluoranthene/g dry weight. In two experiments, uptake kinetics and mortality were determined over 30-d exposures. Concentrations of fluoranthene in sediment and pore water were also measured. Mean survival of H. azteca was generally high, greater than 90% after 10 or 16 d, and greater than 74% after 30 d. Mean survival was lower for Diporeia, 14% after a 30-d exposure to the highest sediment concentration in experiment 1, and 53% in experiment 2. Tissue concentrations in Diporeia were as high as 2 to 4 μmol/g wet weight, a body burden that could be expected to result in death by narcosis. Hyalella azteca did not typically accumulate more than 1 μmol/g wet weight, which is consistent with the lower observed mortality. Apparent steady-state biota–sediment accumulation factors (BSAFs, lipid- and organic-carbon-normalized) for sediment concentrations other than trace level tended to be higher for Diporeia (0.345–0.818) than for H. azteca (0.161–0.612). The BSAFs for trace levels tended to be lower for both species (0.045–0.436) in comparison to higher sediment concentrations. For both organisms, the internal concentration based on body residue was a more reliable indicator of toxicity than were equilibrium partitioning predictions.
Evaluation of the effects of dioxin and PCBs onFundulus heteroclituspopulations using a modeling approach
Authors: Munns Wayne R , Black Dianne E , Gleason Timothy R , Salomon Karen , Bengtson David , Gutjahr-Gobell Ruth
Published: March 2010

The U.S. Environmental Protection Agency (EPA) is reevaluating the risks associated with 2,3,7,8-tetrachlorodibenzo-p-dioxin and related chlorinated hydrocarbons (CHCs). Most information currently available concerning CHC toxic action and biological effects focuses on the responses of individual organisms, as opposed to the potential impacts of CHCs on populations, communities, or ecosystems. In support of EPA's reevaluation, survivorship and reproduction data from two previous studies involving the estuarine fish, Fundulus heteroclitus (Linnaeus), exposed as adults to either dioxin or polychlorinated biphenyls (PCBs), were interpreted at the population level using a stage-classified model of F. heteroclitus population dynamics. The studies differed with respect to the route of exposure of the parental stock: dietary exposure to dioxin in the laboratory and natural exposure to PCBs at the New Bedford Harbor, Massachusetts marine Superfund site. The CHC effects documented in these studies were used to modify fertility and survivorship in the population model. The finite population multiplication (growth) rate, estimated using the model, was used as the measure of population-level effect. In both cases, a negative relationship was observed between CHC dose (quantified as dioxin whole-body burden and liver burden of non-ortho- and mono-ortho-substituted PCB congeners) and population growth rate. The dose-response relationships developed in this study provide useful information for assessing the ecological risks of CHCs to estuarine fish populations.
Induction of testis-ova in Japanese medaka (Oryzias latipes) exposed to p-nonylphenol
Authors: Gray Michelle A , Metcalfe Chris D
Published: March 2010

4-Nonylphenol (NP) is a degradation product of nonylphenol polyethoxylates, a major group of nonionic surfactants. When Japanese medaka, Oryzias latipes were exposed from hatch to 3 months of age to aqueous solutions of NP at nominal concentrations of 10, 50, and 100 μg/L, 50% of the male fish in the 50-μg/L treatment and 86% of the males in the 100-μg/L treatment developed testis-ova, an intersex condition characterized by both testicular and ovarian tissue in the gonad. The ratios of males to females in the control treatment (2:1, M:F) and the 100-μg/L NP treatment (1:2, M:F) were also significantly different. The LOAEC for induction of testis-ova at a nominal concentration of 50 μg/L NP is slightly greater than the upper range of concentrations of NP that have been reported in final effluents from municipal sewage treatment plants. Studies on the environmental fate of nonylphenol ethoxylates and degradation products in the aquatic environment are needed to assess the significance of these data in terms of potential reproductive effects in feral fish populations.
A performance assessment of source correlation and weathering indices for petroleum hydrocarbons in the environment
Authors: Whittaker Martin , Pollard Simon J T
Published: March 2010

The source of petroleum contaminants in the environment and the extent to which these contaminants have weathered following deposition can often be determined through an empirical evaluation of oil n-alkanes, isoprenoids (pristane and phytane), and hopane and sterane biomarkers. Common source correlation and weathering indices have been calculated for three sets of oil samples: fresh, 25% (w/w) weathered, and 50% (w/w) physically weathered diesel standards, crude oils from different sources, and a set of representative heavy oils. For the weathered diesel oils, the C18: tricyclic terpanes and n-alkanes: tricyclic terpanes indices varied most significantly with diesel weathering. Awareness of this may be important when these indices are used to assess biotic routes of contaminant dissolution. For the crude oil samples, C18: phytane demonstrated low specificity between the oils. C18: 17α(H),21β(H)-Hopane and n-alkanes: 17α(H),21 β(H)-hopane differentiated between crude oils but would be expected to vary significantly during weathering due to the microbial amenability of the alkane numerators. Pristane: phytane, phytane: 17α, 21β-hopane and tricyclic terpanes: hopanes were considered to be the indices best able to distinguish between oils from different origins, based on these results. 17α(H), 21β(H)-Hopane: 17α(H), 21β(H)-norhopane did not adequately distinguish between the respective crude oil samples. Finally, the relationship between heavy oil composition and the index value was investigated. Here, the values of n-alkanes: 17α(H), 21β(H)-hopane, phytane: 17α(H), 21β(H)-hopane, and tricyclic terpanes: hopanes decreased as the combined total of polar and asphaltene compounds within oil samples increased. This relationship may be useful in assessing the degradation status of petroleum wastes.
Terrestrial isopods—a good choice for toxicity testing of pollutants in the terrestrial environment
Authors: Drobne Damjana
Published: March 2010

Terrestrial isopods are suitable invertebrates for testing the relative toxicities of chemicals present in the terrestrial environment. Terrestrial isopods respond in numerous ways to elevated concentrations of chemicals in their food, but only a few of these responses can be used as toxicological endpoints. The most suitable are changes in reproduction, food consumption, moult cycle duration, and structure of the digestive glands. These responses are able to provide accurate indications of sublethal toxicity. Toxicity tests with terrestrial isopods could be much more reliable through the use of positive controls. A positive control with a reference toxicant could also be supplemented by a reference endpoint. The most suitable reference endpoint is change of food consumption rate. Toxicity testing with terrestrial isopods is a very promising method for fast, routine, and inexpensive laboratory determination of the relative toxicities of chemicals in the terrestrial environment.
Optimization and performance evaluation of the continuous algal toxicity test
Authors: Chen Chung-Yuan , Lin Kuo-Ching
Published: March 2010

Responses of Selenastrum capricornutum to cadmium in a chemostat are evaluated under various test conditions defined by the nitrogen to phosphorus ratio, phosphate strength, dilution rate, and ethylenediaminetetraacetic acid content. Based on the test results, these parameters were optimized to achieve superior test sensitivity. This continuous system was also modified to allow testing on a weekly basis. The performance of the modified testing technique was evaluated, employing six different metal toxicants. Compared with batch test results reported by other researchers and our own experiment, the continuous test achieved superior sensitivities and reproducibility. The test method presented in this study is believed to be an ideal technique both for research and regulatory purposes.
Biomarker sensitivity for polynuclear aromatic hydrocarbon contamination in two marine fish species collected in Galveston Bay, Texas
Authors: Willett Kristine L , McDonald Susanne J , Steinberg Michael A , Beatty Karla B , Kennicutt Mahlon C , Safe Stephen H
Published: March 2010

The Galveston Bay estuary exhibited a contamination gradient for polynuclear aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons, and the comparative sensitivity of various biomarkers in fish from different bay locations were determined. Two fish species, hardhead catfish (Arius felis) and Atlantic croaker (Micropogon undulatus), were collected from four stations where sediment total PAHs ranged from 68 to >1,000 ng/g. The induction of cytochrome P4501A-(CYP1A-) dependent hepatic ethoxyresorufin-O-deethylase (EROD) activity, CYP1A mRNA levels, or CYP1A immunoreactive protein in hardhead catfish was highly variable in the field-collected fish and in fish dosed with up to 15 mg/kg benzo[a]pyrene (BaP). In contrast, significant differences were seen in biliary concentrations of naphthalene, phenanthrene, and BaP metabolites in hardhead catfish from polluted versus less polluted areas. In croakers taken from the same four Galveston Bay locations, EROD and glutathione S-transferase activities, immunoreactive CYP1A protein, biliary PAH metabolites, and PAH–DNA adducts were higher at the contaminated stations compared with less polluted locations. These studies suggest that the croaker is a good species for monitoring contaminants that induce CYP1A-mediated responses. Biliary PAH metabolites and PAH–DNA adducts were also sensitive indicators of exposure to PAH contamination in both species of fish.
Inhibition of mercury methylation in anoxic freshwater sediment by group VI anions
Authors: Chen Yuan , Bonzongo Jean-Claude J , Lyons W Berry , Miller Glenn C
Published: March 2010

The addition of group VI anions to sediment slurries resulted in the inhibition of the rate of mercury (Hg) methylation. The ranking of inhibition is as follows: tellurate (TeO 2–4) > selenate (TeO 2–4) > molybdate (MoO 2–4) > tungstate (WO 2–4). In sediment slurries treated with TeO 2–4 and SeO 2–4, methylmercury (MeHg) formation was significantly inhibited (p < 0.05) at the concentrations >50 nM of TeO 2–4 and >270 nM of SeO 2–4, while the significant inhibition (p < 0.05) of Hg-methylation by MoO 2–4 and WO 2–4 was observed in slurries spiked at final concentrations ≥100 μM and ≥700 μM, respectively. Increasing the sulfate (SO 2–4) concentration while using fixed concentrations of inhibitors led to the partial reestablishment of some MeHg production in WO 2–4-treated slurries, whereas, no such significant change was noticed in sediment slurries treated with MoO 2–4 and TeO 2–4. These observations suggested that WO 2–4 inhibits Hg methylation by a competitive mechanism, while MoO 2–4 and TeO 2–4 are noncompetitive inhibitors. Selenate and SO 2–4 showed a qualitatively similar effect on Hg methylation at concentrations tested, in that each showed stimulation at low concentrations and inhibition at high concentrations. The depression of MeHg formation by group VI anions was not accompanied by an inhibition of general microbial activity, suggesting that only particular microorganisms, such as sulfate-reducing bacteria, are responsible for Hg methylation. Finally, in the concentration ranges encountered in most natural aquatic environments, the inhibition of MeHg production by group VI anions is unlikely, except in systems where those elements are found in anomalously high concentrations.
Effects of granular pesticide formulations and soil moisture on avian exposure
Authors: Stafford Tamara R , Best Louis B
Published: March 2010

Two experiments were conducted to evaluate the influence of granular carrier type, pesticide load per granule, and soil moisture on avian risk of adverse effects from granular pesticides. Bird behavior, survival, and brain and plasma cholinesterase activity were used to assess exposure. In the first experiment, silica and corncob granules formulated with fensulfothion at either 1/2 or 1/32 of the median lethal dose (LD50) were offered to captive house sparrows (Passer domesticus) in bands on dry soil. The corncob carrier and granules formulated with 1/2 the LD50 presented the greatest risk to birds. In the second experiment, fensulfothion was formulated on three carrier types (silica, clay, and corncob) and offered to house sparrows in bands on wet or dry soil. Overall, formulations with corncob as the carrier and dry soil conditions presented the greatest risk to birds. Wet soil conditions reduced the risk of adverse effects for all three granular carrier types, but the greatest risk reduction occurred with corncob and silica granules. Differences in adverse effects associated with various carrier types and soil moisture conditions can add complexity when assessing risk to birds from granular pesticides.
Stress protein synthesis and peroxidase activity in a submersed aquatic macrophyte exposed to cadmium
Authors: Siesko Melanie M , Fleming Walker J , Grossfeld Robert M
Published: March 2010

Sago pondweed (Potamogeton pectinatus L.) was exposed to CdCl, to evaluate peroxidase (POD) activity and stress protein (SP) synthesis as potential biomarkers of contaminant stress in an aquatic plant. Peroxidase activity did not increase in sago pondweed incubated for 24 h in a liquid culture medium containing 0.5, 0.75, or 1 mM CdCl,. By contrast, at each of these CdCl, concentrations, SPs of 162, 142, 122, 82, and 61 kDa were preferentially synthesized, and synthesis of a 66-kDa protein was reduced relative to controls. Peroxidase activity also did not change in sago pondweed rooted for 21 d in agar containing 1 mM CdCl2, despite the lower growth rate, lower protein content, and brown discoloration of the plants. Only when the plants were grown 7 or 21 d on agar containing 10 mM CdCl, were the growth retardation and phenotypic deterioration accompanied by significantly increased POD activity. In contrast, plants rooted for 7 d in agar containing 1 mM CdCl, were not significantly discolored or retarded in growth, yet they preferentially synthesized SPs of 122, 82, and 50 kDa and synthesized proteins of 59 and 52 kDa at reduced rates relative to controls. Similar changes in protein synthesis were accompanied by signs of depressed growth after 21 d of incubation with 1 mM CdCl, and with 7 or 21 d of exposure to 10 mM CdCl,. These data indicate that changes in SP synthesis may precede detectable alterations in growth of aquatic plants and, therefore, may be a potentially useful early biomarker of contaminant stress. However, further studies will be required to determine whether the SP response is measurable during exposure to environmentally relevant contaminant levels.
Development of a chronic sublethal sediment bioassay using the estuarine amphipod Leptocheirus plumulosus (Shoemaker)
Authors: Emery Vallen L , Moore David W , Gray Brian R , Duke B Maurice , Gibson Alfreda B , Wright Rachel B , Farrar J Daniel
Published: March 2010

Based on the need for a test to evaluate chronic sublethal toxicity in estuarine sediments, a 28-d sediment bioassay with the estuarine amphipod Leptocheirus plumulosus (Shoemaker) was developed. The test was initiated with animals less than 2 weeks old (i.e., 425–600 μm sieved size class). Test endpoints included survival, growth (μg dry weight/d), and reproduction (number of neonates/surviving female). Factors with the potential to influence test animal performance (i.e., nontreatment factors) such as artificial sea salts, salinity, food ration, size at test initiation, intraspecific density, sediment grain size, and diet were evaluated. For example, intraspecific densities between 10 and 60 animals/beaker (i.e., 0.18–1.4 animals/cm2) did not affect survival, growth, or reproduction. Similarly, L. plumulosus were tolerant of a wide range of sediment grain sizes with only extremely fine grained (e.g., >75% clay) or coarse grained (e.g., >75% sand) material significantly affecting survival, growth, and reproduction. Test performance criteria included control survival (>80%) and reproduction (production of offspring in all control replicates), and response to a reference toxicant test with cadmium chloride in a control chart format.
DDT-like effects as a result of corticosterone treatment in an anuran amphibian: Is DDT a corticoid mimic or a stressor?
Authors: Hayes Tyrone B , Wu Tzu Hao , Gill Tanya N
Published: March 2010

Exposure of tadpoles to dichlorodiphenyl trichloroethane (DDT) induces pathological development of the upper mandible. In the current study, we report a similar pathological development after tadpoles of the Senegal walking frog (Kassina senegalensis: Hyperolidae) were treated with the steroid hormone, corticosterone (CORT) for 5 d at 1.1 μM. Corticosterone-treated tadpoles developed a “hole” in the snout (mandibular fenestration) with complete loss of the upper keratinized beak, denticles, and oral papillae. Histological analysis revealed a loss of connective tissue, epidermis, and dermis, but remaining dermis, dermal skin glands, and epidermis appeared normal. Analysis of cleared and stained specimens showed that there was no loss of chondrocranial elements but that the cornu trabeculae was eroded, and the cartilago infrarostralis was repositioned and reshaped. The similarities in the effects of CORT reported in the current study and the previously reported effects of DDT suggest that DDT “mimics” CORT or that DDT acts as a “stressor” causing an increase in endogenous CORT. These data are important in defining the effects and mechanisms of pesticide action on anuran larval development.
A uniform procedure to estimate the predicted environmental concentration of the residues of veterinary medicines in soil
Authors: Spaepen Katrin R I , van Leemput Leo J J , Wislocki Peter G , Verschueren Christian
Published: March 2010

New guidelines to assess the environmental risk of veterinary medicines (VMs) have been proposed in the European Union. As in any risk assessment, exposure is a factor of critical importance. The predicted environmental concentration (PEC) in soil therefore is a pivotal decision parameter in the assessment procedures for VMs. As presently proposed, phases I and II of the assessment require a PEC at an appropriate level of refinement. Hence, it is necessary to calculate the PEC of VMs in a uniform way. The PEC for VMs depends on animal husbandry practices, on the use pattern of the product, on its kinetics in the treated animals and in soil, on physiological characteristics of these animals, and on the codes of good agricultural practices of excreta collecting, storage, and of fertilizing land. In this paper, basic calculations are presented to estimate the PEC from the concentration of residues in manure, the quantities of manure spread per unit land area, and the depth of incorporation into soil. Expanded calculations allow refinements for treatment of only part of the group of animals, metabolism, periods in house, transformation in manure or soil, and repeated application. Examples presented illustrate the dependence of the PEC on various parameters. The examples allow the examination of the regulatory framework of the phase I PEC and an alternative approach to judge the persistence during manure storage or the persistence in soil is proposed.
A method for evaluating consumer product ingredient contributions to surface and drinking water: Boron as a test case
Authors: Dyer Scott D , Caprara Robert J
Published: March 2010

Boron is a ubiquitous element that enters surface waters via two main routes, weathering of boron-containing rock (e.g., borosilicates) and release of boron in cleaning products through disposal to wastewater treatment systems. Recently, concentrations of boron deemed safe for humans and aquatic organisms, via drinking and surface water exposures, have been published. In comparison, however, little has been published regarding the concentrations and distribution of boron in surface waters. This manuscript describes the geographic distribution of boron in the U.S. and California and details a unique method for estimating the amount of boron in receiving waters from consumer product sources using ROUT, a novel deterministic U.S.-scale surface water modeling system, and the USEPA STORET database. ROUT is a national model that predicts chemical concentrations in U.S. rivers and streams and surface drinking water intakes that receive discharges from publically owned wastewater treatment plants (WWTPs). Over 500,000 river miles are systematically routed through the 18 major hydrologic regions of the continental U.S., excluding Alaska and Hawaii. A geographic information system interface coupled to ROUT provides a readily interpretable map of the predicted influences of environmental loadings on environmental concentrations. In addition, this capability allows for comparisons of ROUT output versus other water quality databases (i.e., STORET database) that are georeferenced. Further, for consumer product ingredients that are measured in surface waters, it may be possible to estimate the relative contribution of that ingredient in surface waters from consumer use. Concentrations of boron in receiving waters, predicted concentrations from consumer products, and the percentage of boron from consumer products were determined for California and the continental U.S. Over 55,000 records of dissolved boron were found in STORET between 1984 and 1993. At least one record was found in 667 counties in 44 states, most west of the Mississippi River. Based on all measurements, the median and 90th percentile boron concentrations for the U.S. were 0.076 and 0.387 mg B/L, respectively. The percent contribution of boron in surface waters from consumer product use and disposal to WWTPs was found to be dependent on the extent of sewage treatment plant effluent/receiving water dilution and natural background boron levels. Where background boron levels and dilution factors were lowest, the percent consumer-derived contributions were the greatest.
Equivalence of concentration–response relationships in aquatic toxicology studies: Testing and implications for potency estimation
Authors: Oris James T , Bailer A John
Published: March 2010

The purpose of this study was to describe statistical procedures to test the equivalence of concentration–response relationships in acute toxicology studies and to illustrate the implications of nonequivalence on potency endpoints such as LC10, LC50, or LC90. A logistic regression model for binary response endpoints such as mortality that allowed for the examination of equivalence of slopes and intercepts of the responses between populations is described. Test statistics were derived from comparing nested regression models. This procedure was used to test the equivalence of concentration versus acute mortality response relationships between two nonpolar, narcotic chemicals in a single population of fish and between two populations of fish with different exposure histories to a polycyclic aromatic hydrocarbon. These case studies illustrate different outcomes in the comparison of concentration–response relationships and demonstrate the need to consider more than a single endpoint (e.g., LC50) in a risk assessment context when nonparallel concentration–responses are observed.
A pharmacokinetic model of cadmium in rainbow trout
Authors: Thomann Robert V , Shkreli Frank , Harrison Scott
Published: March 2010

It has been previously observed that exposure of rainbow trout to Cd from water or food did not result in a steady state for key compartments such as the gill, liver, and kidney. Further, during depuration, the mass of Cd in the kidney continued to increase. A seven-compartment pharmacokinetic model of the disposition of cadmium in the rainbow trout was constructed to obtain insight into these observations. The model considers exchange across the gill from exposure to dissolved (available) Cd in the water and exchange of Cd across the gut wall due to exposure to Cd in the food source. Internal distribution of Cd is via Cd in blood exchanging with aqueous phase Cd in kidney, liver, and a storage compartment. Equilibrium partitioning is assumed between the aqueous phase Cd and bound tissue Cd in each compartment. The model is applied to a data set where trout were exposed under two conditions: Cd primarily in water and primarily in food. The model parameters were obtained from other published exposure experiments as well as calibration to the data. The parameters were not altered between the two exposure pathways. High surface gill sorption and gut biliary transfer were necessary in order to obtain reasonable model calibration. Reproduction of the observed increase in kidney Cd during depuration is obtained with a relatively high partitioning, and model flux calculations indicate a net flux into the kidney during the depuration phase. Model simulations for both water and food exposure routes indicated that the whole body Cd concentration was calculated to reach equilibrium in about 50 d. However, Cd did not achieve a steady state in the kidney where it reached a maximum concentration at seven times whole body. For assessment of Cd risk to trout target tissues, it is concluded that a pharmacokinetic model may be necessary.
Selective toxicity of chlorpyrifos to several species of fish during an environmental exposure: Biochemical mechanisms
Authors: Carr Russell L , Ho Lin Lin , Chambers Janice E
Published: March 2010

The organophosphorus insecticide chlorpyrifos is frequently used for termite control. A small pond near a construction site was contaminated with chlorpyrifos via runoff resulting in the death of several species of fish including largemouth bass, bluegill sunfish, and golden shiners, but not mosquitofish. Inhibition of acetylcholinesterase (AChE) and aliesterases (AliE) was determined in the tissues of exposed fish and the presence of chlorpyrifos was confirmed in fish livers by analytical chemistry. Brain AChE was inhibited 87 to 93% in bass, bluegill, and shiners but only 73% in mosquitofish. Skeletal muscle AChE was inhibited 91 to 97% in bass, shiners, and mosquitofish but only 77% in bluegill. Liver AChE and AliE were inhibited greater than 90% in bass, shiners, and mosquitofish but in bluegill, the activities were inhibited only 86% and 77%, respectively. After 60 d, brain AChE activity in exposed mosquitofish was fully recovered, and liver AliE activity was recovered to about 50% of control values, but there was little recovery of skeletal muscle and liver AChE activities. The sensitivity of these enzymes to inhibition by chlorpyrifos-oxon was assessed by determination of 50% inhibitory concentrations (IC50s). Mosquitofish brain and liver AChE and liver AliE were less sensitive to inhibition than the enzymes from the other species. In contrast, mosquitofish skeletal muscle AChE was more sensitive to inhibition compared to the other species. The lower inhibition of mosquitofish brain AChE and the lower in vitro sensitivity of mosquitofish brain AChE to inhibition by chlorpyrifos-oxon compared to the brain AChE of the other species suggest that the species difference in toxicity exhibited in this exposure resulted primarily from species differences in the sensitivity of brain AChE to inhibition by chlorpyrifos-oxon.
Power, sample size and taxonomic sufficiency for measures of impact in aquatic systems
Authors: Ammann Larry P , Waller William T , Kennedy James H , Dickson Kenneth L , Mayer Foster L
Published: March 2010

As part of a larger program to examine the relationships between laboratory and ambient toxicity, data from a series of 28 marine microcosm experiments, which included both laboratory and field studies, were reanalyzed. The statistical methods applied to the data include log-linear regression models (general and robust) for richness and taxa count data (kingdom, phylum, class, order, family, genus, and species) and Gaussian linear models (general and robust) for community metrics diversity and evenness (Shannon-Weiner's, Simpson's, and Brillouin's) and similarity (Bray-Curtis). In addition, taxonomic sufficiency was determined for each of the metrics examined. For each of the analyses performed, both the statistical power of the analysis and the sample sizes required to achieve a desired level of power were determined. New methods are presented to deal with zero count data. Suggestions on how the power of microcosm tests used in toxicity testing can be increased are provided. The statistical programs developed for the analyses applied to the data analyzed were done in S-PLUS. The programs and directions for their application have been placed on an anonymous FTP site at the University of North Texas.
Correlation of measures of ambient toxicity and fish community diversity in Chesapeake Bay, USA, tributaries—urbanizing watersheds
Authors: Hartwell S Ian , Dawson Celia E , Durell Eric Q , Alden Ray W , Adolphson Peter C , Wright David A , Coelho Gina M , Magee John A , Ailstock Steven , Norman Mike
Published: March 2010

This study was performed to evaluate ambient toxicity conditions in Chesapeake Bay tidal tributaries whose watersheds are impacted by urban development and to further evaluate an existing toxicological risk ranking model. A battery of water-column and sediment bioassays were employed with animals and plants. The study was conducted in coordination with a fish community sampling program. Tests were conducted monthly from April through August 1994 at five sample sites in each of four tidal tributaries. Mortality, reproduction, and growth rates in the water-column assays did not consistently indicate chemical contamination in any system. Chemical analyses did not indicate elevated levels of contaminants in the water column. Sediment bioassays demonstrated greater responses than water-column assays. Sediment in the upstream reaches of the South River demonstrated significant toxicity. Toxicity was also observed at the uppermost Severn River station and the middle Patuxent River station. Chemical analyses of composite sediment samples indicated elevated metals levels in the South River. Some metals were above threshold values in the Patuxent and Wicomico rivers. The AVS/SEM ratios in pore water were below 1 in all cases. Organic analyses demonstrated low level polycyclicaromatic hydrocarbon contamination in all four systems. The toxicological risk ranking model ranked the South River as the most contaminant-impacted site. The Patuxent and Severn rivers were ranked below the South River; however, the ranking model identified specific locations in the Severn and Patuxent rivers that indicate sediment contamination. The Wicomico River had the lowest overall risk score. The Patuxent River requires more intense sampling due to its relatively larger size. The toxicological risk ranking results for sediment were significantly correlated with species diversity forfish communities sampled by bottom trawl. Results were consistent with data from previous years. Regression analysis of 2 years of data indicate that fish community impairment can be predicted with ambient toxicity results.
Interrenal dysfunction in fish from contaminated sites: In vivo and in vitro assessment
Authors: Hontela Alice
Published: March 2010

Cortisol, synthesized in the interrenal cells of teleost head kidney, has a major role in the physiologic response to physical and chemical stressors. Plasma levels of cortisol increase in physiologically competent fish acutely exposed to stressors such as cadmium or mercury. The effects of chronic low level exposures are less well understood. We have diagnosed an endocrine impairment characterized by a reduced capacity to elevate plasma cortisol levels in response to an acute standardized capture stress in yellow perch (Perca flavescens) and in northern pike (Esox lucius) sampled at sites contaminated by mixtures of pollutants (heavy metals, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls), by heavy metals, or by bleached kraft mill effluent. Our studies with fish, as well as with amphibians at contaminated sites, demonstrated that low level chronic exposures impair secretion of corticosteroids. We have developed new tests for assessment of the functional integrity of teleost and amphibian interrenal tissue by using an adrenocorticotropic hormone (ACTH) challenge, in vivo and in vitro. The reduced ability to respond to ACTH indicates that the normal neuroendocrine response to stressors may be disrupted and that the ability to cope with biotic and abiotic stressors in the environment may be significantly reduced in the impaired animals.
Liver mercury and methylmercury concentrations in new England common loons (Gavia immer)
Authors: Pokras Mark A , Hanley Christopher , Gordon Zimra
Published: March 2010

Liver samples collected from common loons found dead were analyzed for mercury and methylmercury concentrations. Statistical analyses demonstrated no correlation between total mercury and methylmercury levels.
Factors affecting the biodegradation of phenanthrene initially dissolved in different nonaqueous-phase liquids
Authors: Carroquino Maria Jose , Alexander Martin
Published: March 2010

A study was conducted of the importance of measured partitioning rate, the nonaqueous-phase liquid (NAPL)–water interfacial area, and the toxicity of NAPLs to the biodegradation of constituents of NAPLs. Bacterial mineralization of phenanthrene was slower if the compound was initially dissolved in phthalate esters than in aliphatic hydrocarbons with several NAPL–water interfacial areas. The differences were not the result of toxicity of the test NAPLs. The rates of partitioning of phenanthrene from NAPLs to water were faster with larger interfacial areas, but a consistent influence of interfacial area on the rate of mineralization was not evident. The measured rates of partitioning from NAPLs to water under sterile conditions varied among the NAPLs, the mass transfer rates being slower with phthalate esters than with alkanes. The rates of mineralization of phenanthrene initially in NAPLs were correlated with measured partitioning rates, but the rates of biodegradation were sometimes faster than the partitioning rates measured under sterile conditions. Although the rates of biodegradation of a constituent of nontoxic NAPLs are generally related to rates of mass transfer determined under sterile conditions, we suggest that the partitioning rate determined in the absence of microorganisms is not an adequate predictor of the maximum rate of biodegradation of such constituents.
Validity of using linear alkylbenzenes as markers of sewage contamination with interference from tetrapropylene-based alkylbenzenes
Authors: Zeng Eddy Y , Cheng Darwin , Khan Azra R , Vista Cherrie L
Published: March 2010

A previously developed two-component model was used to estimate the magnitude of interference from tetrapropylene-based alkylbenzenes (TABs) in measuring linear alkylbenzene (LAB) concentrations in a sediment core collected from the Palos Verdes Shelf (Los Angeles, CA, USA). The magnitude of such interference generally increased with increasing sediment core depth and was fairly high in deeper sediments, where TABs were abundant relative to LABs. Usage of LABs as sewage markers in sediments is generally valid as long as the approximate ratio of TAB to LAB concentration is less than 10.
Fate of adsorbable organic halides from bleached laundering in septic tank systems
Authors: Braida Washington , Ong Say Kee , Smith William L , McCabe James W
Published: March 2010

A study was conducted to assess the fate of adsorbable organic halide (AOX) formed from the use of household bleach during laundering in a septic system. Experiments were conducted using laboratory-scale septic tanks and leachfield systems. Addition of feed water containing 20% of bleached or unbleached laundry wash water did not affect the performance of the septic tanks or the leach fields. Overall chemical oxidation demand (COD) and total organic carbon (TOC) removal rates through the septic systems were in the range of 90%. Adsorbable organic halide from unbleached laundry wash water with concentrations between 0.13 and 0.21 mg/L appeared to be removed in the septic tank but not in the leach field. The average overall AOX removal rate using unbleached laundry wash water was approx. 43%. In contrast, the overall removal rate of AOX generated from the use of sodium hypochlorite in bleached laundry wash water was between 87 and 94%. About one-third of the AOX was removed in the septic tank, and the rest was removed in the leach field. Analysis of the septic tank sludge and the soil in the leach field showed no accumulation of AOX from the use of hypochlorite, and the AOX was most likely removed by biodegradation and/or chemical degradation.
Using a spiked sediment bioassay to establish a no-effect concentration for dioxin exposure to the amphipodAmpelisca abdita
Authors: Barber Timothy R , Chappie Daniel J , Duda Deborah J , Fuchsman Phyllis C , Finley Brent L
Published: March 2010

A recent study conducted by the National Oceanic and Atmospheric Administration (NOAA) reported a highly significant correlation between 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) concentrations and amphipod (Ampelisca abdita) mortality in sediment samples collected from the lower Passaic River and Newark Bay. However, there is a paucity of data regarding the potential effects of 2,3,7,8-TCDD on benthic invertebrates under controlled laboratory exposures. In this study, 10-d whole-sediment bioassays using the marine amphipod A. abdita were conducted on spiked sediment samples representing a range of 2,3,7,8-TCDD concentrations (0–25 μg/kg dry weight). No effects on survival or growth relative to controls were observed at any test concentration. The highest 2,3,7,8-TCDD concentration reported from the NOAA study was 0.62 μg/kg. Therefore, the lack of 2,3,7,8-TCDD toxicity in this study indicates that the mortality observed in the NOAA study was probably due to factors or chemicals other than 2,3,7,8-TCDD. This study demonstrates the utility of spiked sediment bioassays in evaluating cause and effect relationships between sediment contamination and benthic invertebrate mortality.
Algal growth rate fluctuations observed under uniform ambient test conditions using static and semicontinuous assay techniques
Authors: Benjamin Richard B , Brown Ray , Fraizer Merideth , Joab Bruce M , Casey Ryan E , Klaine Stephen J
Published: March 2010

A simple, manually diluted, semicontinuous, 96-h algal growth assay technique was developed to measure changing rates of population growth following sublethal chemical exposure. Rates were estimated directly from changing cell counts in a fixed volume of cell suspension. Short-term rate fluctuations in exponential rate parameters were observed in Selenastrum capricornutum populations using this method and similar fluctuations were also documented by reanalyzing conventional static culture assay data. Replicate cultures tended to fluctuate in unison, and patterns of population increase were similar in static assays initiated on different dates. The latter suggested that nonuniform rates of S. capricornutum population increase were not due simply to environmental variation. All populations were preacclimated to test conditions, but growth lags were consistently observed for 12–24 h following inoculation. Subsequent rate fluctuations probably resulted from a high degree of cell-cycle synchronization. Treating systematic rate fluctuations as random error lowered measurement precision, especially with respect to estimates of rate changes over time. Systematic variance may be difficult to eliminate in practice, but repeated-measures regression methods can account for this effect and substantially reduce rate parameter confidence intervals. Findings are expected to apply to endpoints such as dry weight, total cell volume, chlorophyll, or DNA.
Availability of sludge-borne silver to agricultural crops
Authors: Hirsch Marianne P
Published: March 2010

Three green house studies were conducted to evaluate the availability of sludge-borne silver to a variety of agricultural crops. Two studies utilized anaerobically digested domestic sewage sludge that had been amended with silver sulfide in the laboratory prior to mixing the sludge with a screened topsoil. A third study utilized an aerobically digested, laboratory-prepared sludge synthesized by feeding sludge microorganisms a representative solution from a standard photoprocessing operation. The synthetic sludge was also mixed with screened topsoil. There were no differences in the mean number of days to emergence or percent emergence of seedlings grown in sludge-amended soils containing silver sulfide or seedlings grown in soils amended with silver-laden, waste-activated sludge. The growth and yields of corn, oat, and turnip plants were not affected by the presence of silver sulfide in sludge-amended soils at concentrations as high as 106 mg Ag/kg soil. The dry weights of Chinese cabbage plants grown in the sludge-amended soils containing silver sulfide at concentrations of ≥14 mg Ag/kg were significantly less than the controls. The presence of silver sulfide in the sludge-amended soils did not remove the beneficial effects of adding sludge to the soil as plant growth was greater in sludge-amended soils than in soil alone. The yields of lettuce, oat, turnip, and soybean plants grown in soils amended with the laboratory-prepared, silver-laden, waste-activated sludge were significantly greater than those of the controls. At maturity, selected tissues of each species were analyzed for silver. With the exception of lettuce, there were no significant differences in the silver concentrations of the edible tissues of the crops grown in soils containing silver sulfide when compared with controls. The results of these studies indicate that sludge-amended soils containing silver sulfide are not likely to affect adversely the growth of crops, and accumulation of low levels of silver may occur in the leaves of lettuce plants grown in soils containing silver.