bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human toxicity potentials for life-cycle assessment and toxics release inventory risk screening
Authors: Hertwich Edgar G , Mateles Sarah F , Pease William S , McKone Thomas E 
Published: March 2010

Abstract
The human toxicity potential (HTP), a calculated index that reflects the potential harm of a unit of chemical released into the environment, is based on both the inherent toxicity of a compound and its potential dose. It is used to weight emissions inventoried as part of a life-cycle assessment (LCA) or in the toxics release inventory (TRI) and to aggregate emissions in terms of a reference compound. Total emissions can be evaluated in terms of benzene equivalence (carcinogens) and toluene equivalents (noncarcinogens). The potential dose is calculated using a generic fate and exposure model, CalTOX, which determines the distribution of a chemical in a model environment and accounts for a number of exposure routes, including inhalation, ingestion of produce, fish, and meat, and dermal contact with water and soil. Toxicity is represented by the cancer potency q1* for carcinogens and the safe dose (RfD, RfC) for noncarcinogens. This article presents cancer and noncancer HTP values for air and surface-water emissions of 330 compounds. This list covers 258 chemicals listed in U.S. Environmental Protection Agency TRI, or 79 weight-% of the TRI releases to air reported in 1997.
Ecotoxicological effects of hexahydro-1,3,5-trinitro-1,3,5-triazine on soil microbial activities
Authors: Gong Ping , Hawari Jalal , Thiboutot Sonia , Ampleman Guy , Sunahara Geoffrey I 
Published: March 2010

Abstract
Although hexahydro-1,3,5-trinitro-1,3,5-triazine (also called RDX or hexogen) is a potentially toxic explosive compound that persists in soil, its ecotoxicological effects on soil organisms have rarely been assessed. In this study, two uncontaminated garden soils were spiked with 10 to 12,500 mg RDX/kg dry soil. Soil microbial activities, i.e., potential nitrification, nitrogen fixation, dehydrogenase, basal respiration, and substrate-induced respiration were chosen as bioindicators and were determined after 1-, 4-, and 12-weeks of exposure. Experimental results indicate that RDX showed significant inhibition (up to 36% of control) on indigenous soil microbial communities over the period of this study. All five bioindicators responded similarly to the RDX challenge. The length of exposure also affected the microbial toxicity of RDX, with 12-week exposure exerting more significant effects than the shorter exposure periods, suggesting that soil microorganisms might become more vulnerable to RDX when exposure is extended. The estimated lowest observable adverse effect concentration of RDX was 1,235 mg/kg. No biodegradation products of RDX were detected at all three sampling times. Compared with 2,4,6-trinitrotoluene (TNT), RDX is less toxic to microbes, probably because of its resistance to biodegradation under aerobic conditions, which precludes metabolic activation of nitro groups.
Effect of bile salts, lipid, and humic acids on absorption of benzo[a]pyrene by isolated channel catfish (Ictalurus punctatus) intestine segments
Authors: Weber Lynn P , Lanno Roman P 
Published: March 2010

Abstract
Dietary absorption of lipophilic contaminants may be a significant route of exposure in aquatic organisms. Bile salts, lipids, and humic acids are important factors that may influence the intestinal absorption of a contaminant such as benzo[a]pyrene (BaP). We hypothesized that bile salts, monoglycerides, and free fatty acids would increase BaP intestinal absorption, while triglycerides, humic acids, and sediment would decrease BaP intestinal absorption. We have established and validated an in vitro model to examine modification of 3H-BaP absorption in everted intestinal segments from channel catfish (Ictalurus punctatus). Uptake of BaP into the everted intestinal segments continued to increase over the times examined in this study (60 min) and apparently occurs passively; thus, fugacity-based models of uptake are supported. Absorption of BaP into intestinal cells was significantly decreased by the addition of monoglycerides and free fatty acids to bile salts in the incubation media. Addition of triglycerides decreased BaP absorption even further. Humic acids may have decreased BaP intestinal absorption, while natural sediment may have increased BaP absorption. The results of this study suggest that all lipids may decrease intestinal uptake of lipophilic contaminants if they remain in unabsorbable excess in the intestinal lumen by retaining BaP in lipid/bile micelles. In contrast, if triglycerides are hydrolyzed into monoglycerides/free fatty acids prior to absorption, lipophilic contaminant uptake will likely be facilitated. Thus, it may be the hydrolytic state of lipids that determines its effects on BaP absorption. Humic acids alone may decrease dietary uptake of BaP, but our results suggest that other components in natural sediment may counteract this effect to cause a slight enhancement of BaP uptake. Further studies are needed to determine the dietary conditions necessary for bio-accumulation to contribute significantly to lipophilic contaminant body burdens in benthivorous fish. Finally, the everted intestinal segment technique has the potential to be used in other species and with different contaminants.
Toxicant- and response-specific comparisons of statistical methods for estimating effective concentrations
Authors: Hughes Michael R. , Bailer A John , Denton Debra L 
Published: March 2010

Abstract
Standard U.S. Environmental Protection Agency (U.S. EPA) statistical analyses of whole effluent toxicity tests involve the estimation of the concentration associated with a specified level of inhibition relative to control responses. Current U.S. EPA estimation methods (linear interpolation or probit-based methods) are compared to a recently developed parametric regression-based estimator, the relative inhibition concentration estimator RIp. The RIp estimation technique, with level of inhibition p = 25%, is applied to a series of chronic toxicity test data from a U.S. EPA Region 9 database of reference toxicity tests. Tests on marine species are conducted with one reference toxicant, while the freshwater tests are conducted with several reference toxicants. While the U.S. EPA estimators and the RIp estimator are highly correlated for red abalone larval shell development, the degree of correlation for fathead minnow responses varies with reference toxicant tested. The strength of the relationship between the RIp and the standard U.S. EPA estimators varies as a function of the reference toxicant. Correlations range between 0.67 and 0.99. For all biological responses included in this evaluation (fathead minnow growth or survival and red abalone larval development), experiments occurred where the RIp is estimable, while the standard U.S. EPA estimators are not. Nonestimability of the standard EPA methods appears to be related, in part, to the failure of models to account for enhanced responses, such as a hormesis effect prior to toxicity being manifest. The ability to account for such enhanced responses is a strength of the RIp method. Finally, a variance component analysis suggests that lab-to-lab variability is relatively low for the red abalone but relatively high for the fathead minnow.
Characterization of enzymes involved in biotransformation of polycyclic aromatic hydrocarbons in terrestrial isopods
Authors: de Knecht Joop A , Stroomberg Gerard J , Tump Cornelis , Helms Martine , Verweij Rudo A , Commandeur Jan , van Gestel Cornelis A M , van Straalen Nico M 
Published: March 2010

Abstract
Little is known about the capacity of terrestrial invertebrates to transform organic soil pollutants such as polycyclic aromatic hydrocarbons (PAHs). Studies were designed to characterize microsomal mixed function oxygenase and accompanying conjugation enzymes from the hepatopancreas of the terrestrial isopods Porcellio scaber and Oniscus asellus using pyrene and 1-hydroxypyrene as model substrates. The hydroxylation of pyrene and the formation of pyreneglucoside and pyrenesulfate appeared to be sensitive measures for the activity of cytochrome P450 aryl hydrocarbon hydroxylase (AHH), uridinediphosphateglucosyltransferase (UDPGT), and aryl sulfotransferase (ST), respectively. Treatment with the antibiotic riphampicine demonstrated that the enzyme activities originate from the animals themselves and not from symbiotic microflora present in the hepatopancreas and the gut. In both species, ST has a very high affinity for 1-hydroxypyrene with Km values two orders of magnitude lower than that of UDPGT. The Vmax values of UDPGT, however, are 10- to 20-fold higher than that of ST. Taking the P450 activities into consideration, both species are expected to transform PAHs in an equally effective way. When the isopods were fed with food containing benzo[a]pyrene and 3-methyl-cholanthrene, none of the enzyme activities appeared to be inducible except for a small enhancement of UDPGT in O. asellus. Our findings indicate that terrestrial isopods have a high, noninducible capacity for biotransformation of PAHs and that the sulfate conjugation pathway is as important as the carbohydrate conjugation pathway. This conclusion is consistent with the low body residues of parent PAHs found in the field.
Effects of parathion on acetylcholinesterase, butyrylcholinesterase, and carboxylesterase in three-spined stickleback (Gasterosteus aculeatus) following short-term exposure
Authors: Wogram Jörn , Sturm Armin , Segner Helmut , Liess Matthias 
Published: March 2010

Abstract
The sensitivity of butyrylcholinesterase (BChE) toward the inhibition by the organophosphorus insecticide (OP) parathion-ethyl was compared with that of other esterases in the fish three-spined stickleback. Earlier field and in vitro results had suggested the higher sensitivity to OPs of stickleback BChE when compared with acetylcholinesterase (AChE). In the present study, stickleback were exposed in vivo under environmentally realistic conditions using a short duration of exposure (1 h) and parathion concentrations of 0.01, 0.1, and 1.0 μg/L. Seventy and 80% of nominal concentrations, respectively, were measured in the 0.01 and 0.1 μg/L treatments. Following exposure, stickleback were maintained in clean water for 48 h (recovery), allowing the metabolic activation of parathion. After recovery, the activities of BChE (axial muscle, gills, liver), AChE (brain, axial muscle, gills), and carboxylesterase (CaE, liver) were determined. Following exposure to 1 μg/L parathion, the BChE activity was significantly decreased in liver (∼60%) and axial muscle (∼30%), while its decrease in gills (∼30%) was not significant. No effects on BChE activity were observed with 0.1 and 0.01 μg/L parathion. The AChE and CaE activities remained unaffected with all parathion concentrations used. The results are discussed with respect to the potential application of stickleback BChE as a biomarker of OP exposure.
The relationship of Chironomus riparius larval Se body burden and body concentration to larval dry mass and effects on sensitivity to selenium
Authors: Beaty T. Vernon , Hendricks Albert C 
Published: March 2010

Abstract
Selenium as selenite was added to laboratory cultures of Chironomus riparius. In two sets of cultures, substrate-bound Se concentrations were typically 103 times dissolved Se concentrations, while in the other set dissolved Se concentrations were about 10 to 50 times substrate-bound Se concentrations. Body burdens of individual second-, third-, and fourth-instar larvae and eviscerated fourth-instar larvae were measured. Regressions of Se body burden on larval dry mass found evidence for separate intercepts but common slopes for each instar, and Se body concentrations were diluted by growth. The derivation of body concentration from body burden as a function of larval dry mass was used to derive a model of body burden and body concentration as a function of instar. Toxicity tests were performed to check for a change in sensitivity to Se as a function of culture Se concentration. Larval Se concentrations were highly correlated with dissolved Se concentrations but not with substrate-bound Se concentrations. Increases in Se in substrate caused no sensitization, while increases in dissolved Se caused desensitization. We concluded that covariates such as larval dry mass should be incorporated when deriving water quality criteria.
Determination of microcystins in cyanobacterial blooms by solid-phase microextraction-high-performance liquid chromatography
Authors: Poon Ka-Fai , Lam Michael Hon-wah , Lam Paul K S , Wong Bryan S F 
Published: March 2010

Abstract
A solid-phase microextraction (SPME) method was applied to study microcystin (MC) profiles in a natural Microcystis sp. bloom in a freshwater pond in Guangzhou, China. Three dominant MC variants, namely MC-LR, MC-YR, and MC-RR, were quantified. Simultaneous study of their total, extracellular, and intracellular profiles was made possible using SPME coupled to high-performance liquid chromatography. The total and intracellular concentrations of MC-LR in the bloom were 8.67 × 10−2 μg/ml and 1.93 mg/g, respectively. The corresponding concentrations of MC-YR were 1.20 × 10−3 μg/ml and 0.06 mg/g, respectively, and those of MC-RR were 5.57 × 10−2 μg/ml and 1.49 mg/g, respectively. Only MC-LR was detectable in the extracellular phase (1.49 × 10−2 μg/ml) of the bloom, and its concentration was 14% of the intracellular content. Mass balance consideration revealed that only 71.1% of total MC-LR, 36.0% of total MC-YR, and 67.4% of total MC-RR within the cyanobacterial cells were released into the aqueous phase immediately after cell lysis.
Effects of fungicides on thyroid function, metabolism, and thermoregulation in cotton rats
Authors: Tomasi Thomas E , Ashcraft John , Britzke Eric 
Published: March 2010

Abstract
Among the myriad of recent studies on endocrine-disrupting chemicals, relatively few involve thyroid disruption, and most of these address exposure/disruption during embryonic life. Of those involving adult vertebrates, the endpoints examined are thyroid measurements. Even though thyroid disruption could potentially interfere with energy metabolism and thermoregulation such that over-winter survival might be compromised, the possible energetic consequences of these thyroid perturbations have not been investigated. We assessed thyroid function and measured resting metabolic rates of cotton rats chronically exposed to the fungicides vinclozolin or mancozeb. In addition, we measured norepinephrine-induced nonshivering thermogenesis and cold-induced thermogenesis and then cold-acclimated the mancozeb animals. Although thyroid hormone concentrations generally decreased, this was compensated for by an increase in thyroxine turnover (vinclozolin study only) such that thyroxine utilization rate was not different. In addition, there was no difference between the treated and control animals in any of the metabolic parameters measured. It is concluded that wild rodents exposed to these compounds are not energetically compromised.
Assessing the potential for pesticide leaching for the pine forest areas of Tenerife
Authors: Diaz-Diaz Ricardo , Loague Keith 
Published: March 2010

Abstract
Currently, no guidelines cover use of pesticides in the forested areas of the Canary island of Tenerife. An index-based model (Li) was used to rank the leaching potential of 50 pesticides that are, or could be, used for management purposes in the pine forest areas of Tenerife. Once the pesticides with the greatest leaching potential were identified, regional-scale groundwater vulnerability assessments, with consideration for data uncertainties, were generated using soil, climatic, and chemical information in a geographic information system framework for all pine forest areas of the island. Process-based simulations with the pesticide root zone model for the areas and pesticides of highest vulnerability were conducted to quantitatively characterize the leaching potentials. Carbofuran, hexazinone, picloram, tebuthiuron, and triclopyr were each identified as being potential leachers.
The sheepshead minnow as an in vivo model for endocrine disruption in marine teleosts: A partial life-cycle test with 17α-ethynylestradiol
Authors: Zillioux Edward J , Johnson Isabel C , Kiparissis Yiannis , Metcalfe Chris D , Wheat Jeff V , Ward Scott G , Liu Hui 
Published: March 2010

AbstractThe sheepshead minnow (Cyprinodon variegatus Lacépède), an estuarine fish species, was exposed to 17α-ethynyl-estradiol (EE2) at nominal test concentrations of 0.2, 2, 20, 200, 400, 800, 1,600, and 3,200 ng/L. Fish were exposed for up to 59 d, from subadult stages to sexual maturity, under flow-through conditions. The exposure period was followed by an evaluation of reproductive success and survival of progeny. The reproductive success of exposed sheepshead minnows, as determined from data on egg production from two subsequent spawning trials, was reduced in fish exposed to 200 ng/L EE2 and, in one spawning trial, in the 20-ng/L treatment. Hatching success was reduced in the progeny of fish exposed to 200 ng/L EE2, but survival was good among fry that successfully hatched. Histological examination indicated generalized edema, damage to gill epithelia, hepatic toxicity, fibrosis of the testis, and evidence of sex reversal, including testes–ova and spermatagonia-like cells in ovaries. The maximum acceptable toxicant concentration (MATC) for gonadal development in males was within the normal range of EE2 concentrations in sewage treatment plant effluents. The exposure regimen and choice of test organism, combined with histological examination, allowed independent evaluation of ecologically significant acute, reproductive and estrogenic endpoints. Estrogen receptor–mediated effects occurred at concentrations where reproductive effects were measurable under standard reproduction assays. The sheepshead minnow appears to be a sensitive in vivo model for partial life-cycle testing of compounds that have the potential to disrupt the endocrine system as well as reproduction in estuarine and coastal marine fish species.
Phototoxicity of anthracene and pyrene to glochidia of the freshwater musselUtterbackia imbecillis
Authors: Weinstein John E , Polk Kevin D 
Published: March 2010

AbstractThe acute toxicity of photoactivated anthracene and pyrene to the glochidial larvae of the paper pondshell (Utterbackia imbecillis) was characterized in the laboratory using two sets of experiments. Acute toxicity tests designed to determine the overall sensitivity of glochidia to anthracene and pyrene were conducted under simulated sunlight (ultraviolet [UV]-A = 70 ± 0.5 μW/cm2 [mean ± standard deviation]). The median lethal concentration (LC50) and median lethal dose (LD50) of anthracene at 24 h were 1.93 (95% CI, 0.87–3.02) μg/L and 1.94 (1.87–2.00) μg/g glochidia, respectively. The LC50 and LD50 for pyrene at 24 h were 2.63 (2.38–2.90) μg/L and 6.36 (5.82–6.94) μg/g glochidia, respectively. Acute toxicity tests designed to delineate the relationship between the rate of mortality and UV intensity were conducted under one of four different UV intensities (UV-A = 15, 31, 50, and 68 μW/cm2). Regression analyses revealed that time to death decreased as tissue residue concentrations and UV intensity increased for both compounds. Based on measured tissue residues, anthracene was 1.5-fold more potent than pyrene and 3-fold more potent than fluoranthene. The lower potency of fluoranthene is in agreement with previously developed structure–activity relationships; however, these relationships predict equal potency between anthracene and pyrene. These findings suggest that glochidia of freshwater mussels are sensitive to photoactivated anthracene and pyrene at environmentally relevant concentrations, that the time-dependent mortality of glochidia can be accurately predicted through evaluating the product of tissue residue and light intensity, and that species-dependent factors may alter the predicted relative potencies of anthracene and pyrene.
Vertical distribution profiles of linear alkylbenzene sulfonates and their long-chain intermediate degradation products in coastal marine sediments
Authors: León Victor M , González-Mazo Eduardo , Pajares Jesus M. Forja , Gómez-Parra Abelardo 
Published: March 2010

Abstract
The variation with depth of the concentration of linear alkylbenzene sulfonates (LASs) and of the long-chain sulfophenyl carboxylic acids (SPCs) resulting from LAS biodegradation was determined in coastal sediments. We analyzed samples of sediment cores taken from three locations in a littoral zone subjected to the discharge of untreated urban effluents in the Bay of Cádiz in the southwestern part of the Iberian Peninsula. The vertical profile of LAS concentrations showed a sharp reduction with depth, whereas the concentration of long-chain SPCs (6–13 carbon atoms) was greatest at 10 to 14 cm depth. At this depth, the conditions in the interstitial water are strictly anoxic (Eh = −380 mV). The partition coefficients between the solid phase of the sediment versus the interstitial water are very different for LAS and for its degradation intermediates. For LAS, the organic carbon-based partition coefficient values were between 2.4 × 103 and 6.6 × 1055 L/kg for the C10 and C13 homologues, respectively; these values are similar to those obtained from laboratory tests for the sorption of LAS onto marine sediments. For the long-chain SPCs, the partition coefficients are several orders of magnitude less as a consequence of their lower hydrophobicity.
Toxicity of atrazine to the estuarine phytoplankterPavlovasp. (Prymnesiophyceae): Increased sensitivity after long-term, low-level population exposure
Authors: Pennington Paul L , Scott Geoffrey I 
Published: March 2010

AbstractPhytoplankton are potentially more at risk to the adverse effects of herbicides than many other organisms in estuarine ecosystems. The focus of this study was to characterize the toxicity of a widely used herbicide, atrazine, to a single species of phytoplankton. The nanoplankter Pavlova sp. was grown under controlled laboratory conditions and was used to elucidate short-term, high-level population effects of atrazine. Secondly, a long-term, multigenerational population exposure was performed with a low level of atrazine followed by an additional short-term, high-level exposure on the same population with no recovery period. The 96–h growth rate of 50% effective concentration (EC50) for Pavlova sp. was 147 μg/L (95% CI = 116.4–178.7 μg/L). Long-term exposure at 20 μg/L for four (batch culture) growth cycles (∼20 generations) had no significant effect on the growth rate of Pavlova sp. except during the fourth growth cycle. However, a subsequent short-term, high-level 96–h exposure inoculated from the long-term, low-level exposed population showed increased sensitivity to atrazine (96–h growth rate EC50 = 96.0 μg/L, 95% CI = 90.2–103.7 μg/L). Multigenerational exposure to atrazine appeared to render phytoplankton significantly more sensitive (35%) to atrazine effects. Given the documented persistence of atrazine in surface waters, long-term exposure to low levels of atrazine without recovery may lead to shifts in species sensitivity and potential alterations in phytoplankton population dynamics.