bluuebunny/crossref_metadata_2025 huggingface dataset:
Toxicokinetics and toxicity of zinc under time-varying exposure in the guppy (Poecilia reticulata)
Authors: Widianarko Budi , Kuntoro Felix X S , van Gestel Cornelis A M , van Straalen Nico M
Published: March 2010

Levels of toxic substances released into the environment are often highly variable and fluctuate over time. The present study deals with a simple type of time-variable exposure, diluted pulse. We determined toxicokinetic parameters of zinc in guppy fish (Poecilia reticulata) and evaluated the applicability of a toxicokinetics-based survival model developed earlier. In the toxicokinetics experiment, zinc was rapidly taken up and released again; the half-life in fish was only 1.5 d. In the toxicity experiments with diluted-pulse exposure, survival leveled off to a baseline level, which in accordance with the model is explained by the dilution of zinc. The model fitted reasonably well for the lower initial concentrations but tended to overestimate survival rates at the higher concentrations. Toxicokinetic parameters estimated from changes in survival were close to values estimated from measured zinc concentrations in water. Elimination rates during pulse exposure varied from 0.434 to 0.488 d−1 and corresponded very well to the elimination rate during constant exposure (0.463 d−1). Ultimate LC50 values were estimated as 6.40 and 9.10 mg/L. These results suggest that toxicity experiments with a simple, time-varying exposure can be used as an alternative to conventional, constant-exposure experiments. Toxicokinetic parameters and toxicological endpoints can still be estimated in static bioassays with decreasing exposure if the concentration in the medium is measured. At the same time, diluted-pulse experiments may simulate exposure from discharges in the field better than constant-exposure experiments.
Toxicity of boron to rainbow trout: A weight-of-the-evidence assessment
Authors: Loewengart Gordon
Published: March 2010

From the large data set available on the toxicity of boron to aquatic organisms, the toxicity of boron to the early life stages of rainbow trout (Oncorhyncus mykiss) is the seminal issue relative to setting water quality criteria and effluent standards. Issues associated with the early life stage studies are the flat concentration-response curve, the low threshold of toxicity, and teratogenic effects observed. Recent laboratory and field studies offer new experimental data that make a weight-of-the-evidence assessment timely. In a re-examination of the effect of boron on the embryo-larval stage in rainbow trout and zebrafish, adverse effects due to boron deficiency are observed which decrease with increasing dose. It was found that low concentrations of boron stimulate embryonic growth in rainbow trout and increase the viability and survival of embryonic zebrafish. As boron concentration is further increased, the dose-response curve becomes flat as homeostatic processes are active; this is followed at higher doses by a new adverse response that increases with increasing dose. As a result, the dose-response relationship is U shaped, consistent with the characteristic shape of an essential micronutrient. Thus, effects originally reported to be toxicity at low exposures rather may be due to boron deficiency. Water analyses in trout hatcheries and field studies in wild trout streams add additional information on the toxicity of boron to trout. Of particular note is a controlled field study carried out in the Firehole River in Yellowstone Park (WY, USA), where trout populations survive and reproduction successfully occurs in natural water containing boron concentrations up to and in some cases greater than 1.0 mg B/L. Teratogenic effects due to boron exposure were not observed in any of these more recent studies.
Assessment of sublethal endpoints for toxicity testing with the nematodeCaenorhabditis elegans
Authors: Anderson Gary L , Boyd Windy A , Williams Phillip L.
Published: March 2010

Toxicity tests in invertebrates often use sublethal endpoints, which may exhibit different sensitivity for various toxicants. Our objective was to characterize the sensitivity of movement, feeding, growth, and reproduction as endpoints for heavy metal toxicity testing with Caenorhabditis elegans. Growth and feeding were assessed in the same nematode samples used to assess movement and reproduction. Median effective concentrations (EC50s) for 24-h exposures to Pb, Cu, and Cd were determined for movement, feeding, and growth and a 72-h EC50 was derived for reproduction. The order of toxicity was Cu > Pb > Cd for each endpoint, including lethality and movement. There were no differences in sensitivity among endpoints for any metal. When exposed for 4 h at (sublethal) concentrations that were 14 times the 24-h EC50 value, Pb and Cu reduced feeding to the same extent while movement was reduced significantly more by Pb than by Cu. Thus, a difference in sensitivity of endpoints was apparent at 4 h, which was not evident at 24 h. These observations suggest potentially different mechanisms of toxicity for 24- and 4-h tests.
Frequently co-occurring pesticides and volatile organic compounds in public supply and monitoring wells, southern New Jersey, USA
Authors: Stackelberg Paul E , Kauffman Leon J , Ayers Mark A , Baehr Arthur L
Published: March 2010

One or more pesticides were detected with one or more volatile organic compounds (VOCs) in more than 95% of samples collected from 30 public supply and 95 monitoring wells screened in the unconsolidated surficial aquifer system of southern New Jersey, USA. Overall, more than 140,000 and more than 3,000 unique combinations of pesticides with VOCs were detected in two or more samples from the supply and monitoring wells, respectively. More than 400 of these combinations were detected in 20% or more of the samples from the supply wells, whereas only 17 were detected in 20% or more of the samples from the monitoring wells. Although many constituent combinations detected in water from the supply and monitoring wells are similar, differences in constituent combinations also were found and can be attributed, in part, to differences in the characteristics of these two well types. The monitoring wells sampled during this study yield water that typically was recharged beneath a single land-use setting during a recent, discrete time interval and that flowed along relatively short paths to the wells. Public supply wells, in contrast, yield large volumes of water and typically have contributing areas that are orders of magnitude larger than those of the monitoring wells. These large contributing areas generally encompass multiple land uses; moreover, because flow paths that originate in these areas vary in length, these wells typically yield water that was recharged over a large temporal interval. Water withdrawn from public supply wells, therefore, contains a mixture of waters of different ages that were recharged beneath various land-use settings. Because public supply wells intercept water flowing along longer paths with longer residence times and integrate waters from a larger source area than those associated with monitoring wells, they are more likely to yield water that contains constituents that were used in greater quantities in the past, that were introduced from point sources, and/or that are derived from the degradation of parent compounds along extended flow paths.
Assessment of biological effects of chlorinated hydrocarbons in osprey chicks
Authors: Elliott John E. , Wilson Laurie K , Henny Charles J , Trudeau Suzanne F , Leighton Frederick A , Kennedy Sean W , Cheng Kimberly M
Published: March 2010

Osprey(Pandion haliaetus) eggs were collected during 1995 and 1996 at seven sites along the Fraser and Columbia River systems of British Columbia, Canada, and Washington and Oregon, USA. Fifty-four eggs were placed into a laboratory incubator. Thirty-eight of the hatched chicks were sacrificed within 24 h. Hatching success did not differ among sites and therefore between treatment and reference areas. Residual yolk sacs of eggs collected downstream of the large bleached-kraft pulp mill at Castlegar contained greater mean concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 2,930 ng/kg lipid) compared with reference sites such as the Nechako River, an upper tributary of the Fraser system (33.7 ng/kg). Total polychlorinated biphenyls (PCBs) in yolk sacs were also higher at Castlegar and in samples from the Columbia River downstream of Portland, Oregon, compared with those from the Nechako River. Concentrations of measured chemicals, including TCDD toxic equivalents (TEQs), total PCBs, p, p′-dichlorodiphenylethylene (p, p′-DDE), and other organochlorines were not different in eggs that failed to hatch compared with calculated whole-egg values for hatched eggs. There were significant biochemical responses; a hepatic cytochrome P4501A (CYP1A) cross-reactive protein was detected in all samples tested and correlated positively with ethoxyresorufin o-deethylase (EROD) activity and yolk sac concentrations of TEQs and total PCBs. Tissue concentrations of vitamin A compounds varied among sites and correlated positively with yolk sac concentrations of TEQs and PCBs. Morphological, histological, and other physiological parameters, including chick growth, edema, deformities, and hepatic and renal porphyrin concentrations, neither varied among sites nor showed concentration-related effects.
Chlorophyll fluorescence as a bioindicator of effects on growth in aquatic macrophytes from mixtures of polycyclic aromatic hydrocarbons
Authors: Marwood Christopher A , Solomon Keith R , Greenberg Bruce M.
Published: March 2010

Chlorophyll-a fluorescence induction is a rapid technique for measuring photosynthetic electron transport in plants. To assess chlorophyll-a fluorescence as a bioindicator of effects of polycyclic aromatic hydrocarbon mixtures, chlorophyll-afluorescence parameters and plant growth responses to exposure to the wood preservative creosote were examined in the aquatic plants Lemna gibba and Myriophyllum spicatum. Exposure to creosote inhibited growth of L. gibba (EC50 = 7.2 mg/L total polycyclic aromatic hydrocarbons) and M. spicatum (EC50 = 2.6 mg/L) despite differences in physiology. Creosote also diminished maximum PSII efficiency (Fv/Fm) (EC50 = 36 and 13 mg/L for L. gibba and M. spicatum) and the effective yield of photosystem II photochemistry (ΔF/F′m) (EC50 = 13 and 15 mg/L for L. gibba and M. spicatum). The similarity between growth and chlorophyll-a fluorescence EC50s and slopes of the response curves suggests a close mechanistic link between these end points. The predictive power of chlorophyll-a fluorescence as a bioindicator of whole-organism effects applied to complex contaminant mixtures is discussed.
Correlation of Tetrahymena and Pimephales toxicity: Evaluation of 100 additional compounds
Authors: Sinks Glendon D , Schultz T Wayne
Published: March 2010

In the summary/recommendations for the Ecotoxicology Session of Test Smart—A Humane and Efficient Approach to Screening Information Data Sets (SIDS) Data Workshop, it was recommended that more population growth impairment data using Tetrahymena be generated and compared with available lethality data for the fathead minnow. To comply with this recommendation, 100 additional chemicals were tested in the ciliate assay. Toxicity values for the 96-h Pimephales promelas mortality assay (log[LC50−1]) and the 2-d Tetrahymena pyriformis growth assay (log[IGC50−1]) were compared. Each chemical was a priori assigned a mode of action. The majority of compounds were classified as either narcotics (n = 46) or direct-acting electro(nucleo)philes (n= 43), while 11 chemicals were listed as carboxylic acids, diesters, proelectrophiles, or weak acid respiratory uncouplers. Toxicities for narcotics showed an excellent relationship between endpoints with the coefficient of determination (r2) being 0.93. A weaker relationship, r2 = 0.78, was observed for the electro(nucleo)philes. The poorer fit for the covalent-reacting electro(nucleo)philes is attributed to differences in protocol, in particular, to test-medium composition and exposure scheme. Those chemicals whose potency is mediated by metabolism in fish (diesters and proelectrophiles) as well as the acids exhibited poor correlation between endpoints, with toxicity in the fish assay being greater than that predicted from the ciliate data. The regression analysis between endpoints, regardless of mode or mechanism of toxic action, yielded the model log(LC50−1) = 1.12(log[IGC50−1]) + 0.46, with n= 92, r2 = 0.82, s (root of the mean square error) = 0.87, F = 399, and p > F = 0.0001. A result for the present investigation supports earlier findings that, with noted exceptions, there is a strong relationship between toxicity potency as quantified by P. promelas mortality and T. pyriformis growth impairment.
Biodegradation of poly(tetramethylene succinate-cotetramethylene abdicate) and poly(tetramethylene succinate) through water-soluble products
Authors: Kitakuni Eiichi , Yoshikawa Katsuyuki , Nakano Katsuharu , Sasuga Junji , Nobiki Masayoshi , Naoi Hiroshi , Yokota Yoshihisa , Ishioka Ryoji , Yakabe Yoshiyuki
Published: March 2010

Poly(tetramethylene succinate-co-tetramethylene adipate) (PBSA) and poly(tetramethylenesuccinate) (PBS) were hydrolyzed experimentally into water-soluble oligomers and monomers by Chromobacterium extracellular lipase. The oligomers were identified by high-performance liquid chromatography–mass spectrometry and 1H-nuclear magnetic resonance, which indicated that a total of 28 oligomer species were liberated from PBSA, and that 13 of them were identical to the hydrolysates from PBS. Moreover, 20 of the species were polyester-based compounds of monomer units, and the other 8 species were small amounts of diurethane compounds. Bis(hydroxybutyl) succinate (BSB) and bis(hydroxybutyl) hexamethylene dicarbamate (BHB) were the typical oligomers and were chemically synthesized. Biodegradability of BSB and BHB was examined for 28 d in the activated sludge, and analysis of the results of this study indicated that the final conversion rate of constituent carbon to carbon dioxide was estimated at 80 mol% for BSB and 10 mol% for BHB. The remaining amount of carbon in the undegraded BHB was 20 mol%. In the presence of BSB, the biodegradability of BHB was increased by about 1.5 times. The suggestion was made that BSB induced a growth of microorganisms and helped BHB degradation. This is consistent with the observation that the biodegradation of BHB in native soil for 60 d reached > 60%.
Isomeric effects on thiosulfate transformation and detoxification of 1,3-dichloropropene
Authors: Wang Qiquang , Gan Jianying , Papiernik Sharon K , Yates Scott R
Published: March 2010

The fumigant 1,3-dichloropropene (1,3-D) is one of the most heavily used pesticides but also a suspected carcinogen. Previous research has shown that 1,3-D was rapidly transformed and detoxified by ammonium thiosulfate (ATS), a sulfur and nitrogen fertilizer. As common formulations contain cis and trans isomers at roughly equivalent ratios, this study was conducted to understand isomeric differences in thiosulfate transformation and detoxification of 1,3-D. Under the same conditions, reaction of cis-1,3-D with thiosulfate was more than three times faster than trans-1,3-D, which was correlated with a lower reaction activation energy for the cis isomer. The trans isomer was considerably more toxic to the luminescent bacteria Vibrio fisheri than the cis isomer, but the toxicity was reduced by 14 times after thiosulfate transformation. Mutagenic activity to strains of Salmonella typhimurium was observed for trans-1,3-D but was not detected after thiosulfate transformation. These results suggest that thiosulfate transformation detoxifies 1,3-D primarily by deactivating the trans isomer, and the reaction is toxicologically beneficial, as it negates the potential harmful effects of 1,3-D to the environment and human health.
Atrazine uptake, elimination, and bioconcentration by periphyton communities and Daphnia magna: Effects of dissolved organic carbon
Authors: Nikkilä Anna , Paulsson Maria , Almgren Klara , Blanck Hans , Kukkonen Jussi V K
Published: March 2010

The bioconcentration and toxicokinetics of atrazine in three different periphyton communities and in laboratory reared Daphnia magna were studied in natural and artificial waters with different dissolved organic carbon (DOC) concentrations and qualities. The exposure concentrations were similar to those short-lived peak concentrations found in contaminated waters. Atrazine uptake and elimination were very fast, and the bioconcentration was low both in periphyton and D. magna. The bioconcentration factors in D. magna were approx. 16% of those in periphyton. The uptake and elimination rates were also higher in periphyton than in Daphnia. The periphyton properties affected the bioconcentration of atrazine more than the DOC concentration and water quality. A steady state was reached within a few hours of uptake by the periphyton and within 24 h by D. magna. A residue of atrazine was left in the periphyton and D. magna after an 8-h biphasic depuration with clearly distinct fast and slow phases. In D. magna, atrazine may be eliminated during the normal life span of the organism. These results suggest that DOC has a minor influence on the toxicokinetics of atrazine.
Uptake and diverse effects of polycyclic aromatic hydrocarbons on the metabolic activity of Elliptio complanata measured by calorespirometry
Authors: Cheney Marcos A , Birdsall Karen , Kukor Jerome J
Published: March 2010

Polycyclic aromatic hydrocarbons (PAHs) are important contaminants of world water resources, with effects on aquatic life. Metabolic responses to short-term acute toxicities of naphthalene, anthracene, and chrysene were investigated in the freshwater bivalve mollusk Elliptio complanata using differential scanning calorespirometry coupled with uptake and scanning electron microscopy. Comparing the uptakes of naphthalene, anthracene, and chrysene with that of inulin, which is known to occupy only extracellular space, showed that all compounds studied were taken up. The PAHs studied had diverse effects on the metabolic activity of E. complanata. Naphthalene and, to a lesser degree, chrysene caused stimulation of heat rates, possibly due to uncoupling of oxidative metabolism. Differential scanning calorespirometry coupled with studies of rates of oxygen consumption by the gill tissue exposed to the PAHs showed similar diverse patterns of respiratory rate stimulation and inhibition. Analysis of results of scanning electron microscopy suggested that irreversible damage to the gill tissue occurred in the presence of anthracene but not in the presence on naphthalene or chrysene. The batch calorespirometric method coupled with uptake and spectroscopy proved to be a useful technique to assess the toxicity of PAHs on the control of energy flux in gills of a freshwater bivalve mollusk.
Relative potencies of polychlorinated dibenzo-p-dioxin, dibenzofuran, and biphenyl congeners to induce cytochrome P4501A mRNA in a zebrafish liver cell line
Authors: Henry Tala R , Nesbit Dorothy J , Heideman Warren , Peterson Richard E
Published: March 2010

Induction of cytochrome P4501A (CYP1A) mRNA by polychlorinated dibenzo- p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), and polychlorinated biphenyl (PCB) congeners was measured in a zebrafish liver (ZF-L) cell line. The ZF-L cells were far less sensitive to PCDD, PCDF, and PCB congeners than were other fish cell lines. The 2,3,7,8-PCDDs, 2,3,7,8-PCDFs, and PCB 126 caused dose-related induction. All other PCBs tested, including other coplanar as well as ortho-substituted congeners, were ineffective at inducing CYP1A. The potency of each congener that gave a response, relative to 2,3,7,8-tetrachlo-rodibenzo-p-dioxin, was determined. The ZF-L cell–derived relative potency values (REPs) are similar to other in vitro REPs in that the ZF-L cell–derived REPs are generally higher than those derived from in vivo models. Furthermore, the ZF-L cell–derived REPs are generally within fivefold of REPs determined in a variety of rainbow trout systems when the same endpoint in the same tissue are compared. Analysis of these data indicates that REPs based on molecular and biochemical responses in sensitive and insensitive species are similar, but overestimate relative in vivo toxicity in the rainbow trout. The ZF-L cell–derived REPs expand the database of REPs, providing additional information that will be useful in quantifying the uncertainty associated with applying consensus fish-specific toxic equivalency factors in ecological risk assessment.
Atrazine remediation in wetland microcosms
Authors: Runes Heather B , Bottomley Peter J , Lerch Robert N , Jenkins Jeffrey J
Published: March 2010

Laboratory wetland microcosms were used to study treatment of atrazine in irrigation runoff by a field-scale-constructed wetland under controlled conditions. Three experiments, in which 1 ppm atrazine was added to the water column of three wetland, one soil control, and one water control microcosm, were conducted. Atrazine dissipation from the water column and degradate formation (deethylatrazine [DEA]; deisopropylatrazine [DIA]; and hydroxyatrazine [HA]) were monitored. Atrazine dissipation from the water column of wetland microcosms was biphasic. Less than 12% of the atrazine applied to wetland microcosms remained in the water column on day 56. Atrazine degradates were observed in water and sediment, with HA the predominant degradate. Analysis of day 56 sediment samples indicated that a significant portion of the initial application was detected as the parent compound and HA. Most probable number (MPN) assays demonstrated that atrazine degrader populations were small in wetland sediment. Wetland microcosms were able to reduce atrazine concentration in the water column via sorption and degradation. Based on results from this study, it is hypothesized that plant uptake contributed to atrazine dissipation from the water column.
Development of a freshwater aquatic toxicity database for ambient water quality criteria for methyl tertiary-butyl ether
Authors: Wong Diana C L , Arnold W Ray , Rausina Gary A , Mancini Eugene R , Steen Alexis E
Published: March 2010

The detection of methyl tertiary-butyl ether (MTBE) in groundwater and surface water in recent years has drawn attention to its potential effects in aquatic ecosystems. To address concerns regarding MTBE environmental effects and to establish safe concentrations in surface waters, a collaborative effort was initiated in 1997 to develop aquatic toxicity databases sufficient to derive ambient water quality criteria for MTBE consistent with United States Environmental Protection Agency (U.S. EPA) requirements. Acute toxicity data for six species, chronic toxicity data for a fish and an invertebrate, and plant toxicity data were developed in order to complete the freshwater database. The toxicity tests followed U.S. EPA and American Society for Testing and Materials (ASTM, Philadelphia, PA, USA) procedures and were conducted in accordance with U.S. EPA Good Laboratory Practice guidelines. Based on measured exposure concentrations, acute toxicity endpoints ranged from 472 to 1742 mg MTBE/L, while chronic endpoints (IC25) were 57 to 308 mg MTBE/L. Aquatic invertebrates were generally more sensitive than fish to MTBE in both acute and chronic exposures. Acute-to-chronic ratios for fathead minnows and Daphnia magna were 3.4 and 11.3, respectively. The measured acute and chronic toxicity were within a 10-fold factor of toxicity predicted from quantitative structure–activity relationships for baseline toxicity or nonpolar narcosis typical of ether compounds. The data developed in this study were consistent with existing data and showed that MTBE has low acute and chronic toxicity to freshwater organisms. Reported environmental concentrations of MTBE are several orders of magnitude lower than concentrations observed to cause effects in freshwater organisms.
Tumor prevalence and biomarkers of exposure in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed
Authors: Pinkney Alfred E , Harshbarger John C , May Eric B , Melancon Mark J
Published: March 2010

Associations between contaminant exposure and liver and skin tumor prevalence were evaluated in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed. Thirty bullheads (≥ age 3) were collected from Quantico embayment, near a Superfund site that released organochlorine contaminants; Neabsco Creek, a tributary with petroleum inputs from runoff and marinas; and Anacostia River (spring and fall), an urban tributary designated as a Chesapeake Bay region of concern, that was contaminated with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides. Fish were collected from the Tuckahoe River, as a reference. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide and PCB concentrations were measured in randomly selected individuals and sediment contaminants were analyzed. We found statistically significant differences in liver tumor prevalences: Anacostia (spring), 50%; Anacostia (fall), 60%; Neabsco, 17%; Quantico, 7%; and Tuckahoe, 10%. Skin tumor prevalences were significantly different: Anacostia (spring), 37%; Anacostia (fall), 10%; Neabsco, 3%; Quantico, 3%; and Tuckahoe, 0%. Tumor prevalence in Anacostia bullheads warrants concern and was similar to those at highly contaminated sites in the Great Lakes. Evidence was found of higher PAH exposure in Anacostia fish but a cause-effect linkage could not be established. Fish tumor surveys, with histopathologic examination of internal and external organs, are recommended for monitoring the status of regions of concern.
Evaluation and use of sediment toxicity reference sites for statistical comparisons in regional assessments
Authors: Hunt John W , Anderson Brian S , Phillips Bryn M , Newman John , Tjeerdema Ronald S , Fairey Russell , Puckett H Max , Stephenson Mark , Smith Robert W , Wilson Craig J , Taberski Karen M
Published: March 2010

Sediment reference sites were used to establish toxicity standards against which to compare results from sites investigated in San Francisco Bay (California, USA) monitoring programs. The reference sites were selected on the basis of low concentrations of anthropogenic chemicals, distance from active contaminant sources, location in representative hydrographic areas of the Bay, and physical features characteristic of depositional areas (e.g., fine grain size and medium total organic carbon [TOC]). Five field-replicated sites in San Francisco Bay were evaluated over three seasons. Samples from each site were tested with nine toxicity test protocols and were analyzed for sediment grain size and concentrations of trace metals, trace organics, ammonia, hydrogen sulfide, and TOC. The candidate sites were found to have relatively low concentrations of measured chemicals and generally exhibited low toxicity. Toxicity data from the reference sites were then used to calculate numerical tolerance limits to be used as threshold values to determine which test sites had significantly higher toxicity than reference sites. Tolerance limits are presented for four standard test protocols, including solid-phase sediment tests with the amphipods Ampelisca abdita and Eohaustorius estuarius and sea urchin Strong ylocentrotus purpuratus embryo/larval development tests in pore water and at the sediment-water interface (SWI). Tolerance limits delineating the lowest 10th percentile (0.10 quantile) of the reference site data distribution were 71% of the control response for Ampelisca, 70% for Eohaustorius, 94% for sea urchin embryos in pore water, and 87% for sea urchins embryos exposed at the SWI. The tolerance limits are discussed in terms of the critical values governing their calculation and the management implications arising from their use in determining elevated toxicity relative to reference conditions.
Gill lesions and death of bluegill in an acid mine drainage mixing zone
Authors: Henry Theodore B , Irwin Elise R , Grizzle John M , Brumbaugh William G , Wildhaber Mark L
Published: March 2010

The toxicity of an acid mine drainage (AMD) mixing zone was investigated by placing bluegill (Lepomis macrochirus) at the confluence of a stream contaminated by AMD and a stream having neutral pH. A mixing channel receiving water from both streams was assembled in the field, during July and October 1996, to determine the toxicity of freshly mixed and aged water (2.9–7.5 min). The AMD stream had elevated concentrations of Al and Fe, which precipitated upon mixing, and of Mn, which did not precipitate in the mixing zone. Fish exposed to freshly mixed water had higher mortality than fish exposed to water after aging. Precipitating Al, but not Fe, accumulated on the gills of bluegill, and accumulation was more rapid early during the mixing process than after aging. Fish exposed for 3.5 h to freshly mixed water had hypertrophy and hyperplasia of gill filament and lamellar epithelial cells. Similar lesions were observed after 6.0 h in fish exposed to water aged after mixing. Results demonstrated that Al was the predominant metal accumulating on the gills of fish in this AMD mixing zone, and that mixing zones can be more toxic than AMD streams in equilibrium.
Effects of nutrient loading and planktivory on the accumulation of organochlorine pesticides in aquatic food chains
Authors: Ridal Jeffrey J. , Mazumder Asit , Lean David R S
Published: March 2010

The effects of nutrients and planktivory on the accumulation of hydrophobic organic contaminants (HOCs) in aquatic food chains were investigated in large lake enclosures. Food-chain compositions in the enclosures were manipulated by additions of planktivorous fish (+F), nutrients (+N), both nutrients and fish (+NF), or received no additions (-NF). The treatments resulted in higher plankton but lower zooplankton biomass in the +NF enclosures than in the other enclosures. Once enclosure communities were established, a suite of organochlorine pesticides (α-hexachlorocyclohexane, methoxychlor, heptachlor, cis- and trans-chlordane, cis- and trans-nonachlor, and mirex) was added to all enclosures in amounts sufficient to obtain initial concentrations in the epilimnion of approximately 15 ng/L. Dissipation of HOCs from the water and accumulation in phytoplankton, zooplankton, and fish were monitored for four months. The HOC concentrations in plankton did not differ significantly across treatments. However, on a total-mass basis, greater amounts of HOCs were sorbed to phytoplankton in the +NF enclosures (20%) than in the three other sets of enclosures. Concentrations in zooplankton of some HOCs differed significantly between treatments as a function of nutrient loading. Chlordane and nonachlor concentrations were greater in zooplankton from enclosures with no fish (+N, -NF) than in those from enclosures with fish (+F, +NF). The HOC residues in fish were highest in low-nutrient enclosures. The results demonstrate that fish predation and nutrient loading can modify the size-related processes of HOC partitioning and affect its accumulation in the aquatic food chain.
Evaluation of basal micronucleus frequency and hexavalent chromium effects in fish erythrocytes
Authors: de Lemos Clarice Torres , Rödel Patrícia Milan , Terra Nara Regina , Erdtmann Bernardo
Published: March 2010

Hexavalent chromium (Cr [VI]) genotoxicity was studied using fish micronucleus analysis in peripheral blood erythrocytes from Pimephales promelas, the fathead minnow. Forty-five- to 60-d-old fish were used to assess the spontaneous level of genotoxic damage. The genotoxic effect of Cr (VI) obtained from potassium dichromate (K2Cr2O7) in tests performed for 7-, 14-, and 21-d exposure periods was estimated. Significant micronucleated erythrocyte (MNE) induction was detected in fish exposed for 7 d to 2.5 mg/L of Cr (VI), and induction decreased after 21 d of exposure. The results suggest a handling effect in fish manipulated compared to those not manipulated, thus demonstrating the importance of including parallel negative controls in experimental design. Basal levels of MNE are reported, providing laboratory values for future assay quality control. The importance of determining the period with the highest expression of the genotoxic effects in this assay system was also confirmed.
Identification of androstenedione in a river containing paper mill effluent
Authors: Jenkins Ronald , Angus Robert A , McNatt Heather , Howell W Mike , Kemppainen Jon A , Kirk Marion , Wilson Elizabeth M
Published: March 2010

Effluent from a paper mill discharging into the Fenholloway River, Taylor County, Florida, USA, contains chemicals that masculinize females of the resident population of eastern mosquitofish (Gambusia holbrooki), as evidenced in females by elongated anal fins, which is normally a male-specific trait. To identify androgenic components in the effluent, water collected from the Fenholloway River and a control tributary was fractionated using solid-phase extraction and reverse-phase high-performanceliquid chromatography. Two Fenholloway River fractions induced androgen receptor-dependent transcriptional activity in transient transfection cell culture assays. Of these, androstenedione was confirmed by liquid chromatography-mass spectrometry with multiple reaction monitoring.
Effect of beringite on cadmium and zinc uptake by plants and earthworms: More than a liming effect?
Authors: Oste Leonard A , Dolfing Jan , Ma Wei-chun , Lexmond Theo M
Published: March 2010

Metal-contaminated soils are potentially harmful to plants, animals, and humans. Harmful effects are often related to the free-metal concentration in the soil solution. Immobilization is a potentially useful method to improve the quality of metal-contaminated soils by transforming free-metal ions into species that are less mobile and less toxic. The effect of many immobilizing products can be attributed to sorption on the surface of the material. Alkaline materials also enhance adsorption to soil particles by decreasing proton competition. Immobilization should preferably be evaluated independently of soil pH to discriminate between these processes. In this study, the immobilizing effect of beringite, an alkaline alumino silicate, was compared with that of lime. Plants (Swiss chard [Beta vulgaris L. var. cicla]) were grown on a soil contaminated with cadmium and zinc and treated with graded amounts of beringite or lime. Metal availability, as determined by a 0.01 M CaCl2 extraction, and metal uptake by plants strongly decreased in all treated soils. Beringite did not reduce metal availability more than liming when the obtained pH levels were similar. The effect of beringite can, therefore, be explained as a liming effect, at least for the duration of our experiment (10 weeks). The effect of beringite and lime on metal accumulation by earthworms (Eisenia veneta and Lumbricus rubellus) was small or not significant, although the CaCl2-extractable metal concentration in treated soils decreased by more than 90%. We conclude that immobilizing agents based on a liming effect can decrease metal uptake by plants, but they will hardly affect metal uptake by earthworms. Hence, these materials can reduce negative ecological effects of metal contamination on plants and herbivores, but not on earthworm predators.
Pyrene bioaccumulation, effects of pyrene exposure on particle-size selection, and fecal pyrene content in the oligochaeteLimnodrilus hoffmeisteri(Tubificidae, Oligochaeta)
Authors: Millward Rod N , Fleeger John W , Reible Danny D , Keteles Kristen A , Cunningham Brian P , Zhang Li
Published: March 2010

The oligochaete Limnodrilus hoffmeisteri Cleparéde was exposed to sediment-amended pyrene (0–1,196 nmol/g dry wt) for 2, 5, and 10 d to investigate sediment particle-size preference, tissue pyrene bioaccumulation (using biota-sediment accumulation factor, BSAF), fecal pyrene concentrations (using fecal-sediment accumulation factor, FSAF), and pyrene biotransformation. In non-pyrene-amended sediment, L. hoffmeisteri preferentially ingested finer sediment particles (<3.5 μm). However, pyrene concentrations >199 nmol/g dry weight resulted in a decreased preference for finer particles, presumably reducing pyrene exposure. Particle selectivity also changed with time such that after 10 d, worms showed an increased preference for finer particles. At high pyrene exposure, tissue pyrene concentrations rapidly attained equilibrium (maximum body residue 4.4 μmol/g wet wt, close to values cited for hydrocarbon critical body residues). Levels of biotransformation were low (mean 14%) and independent of time or pyrene concentration. Biota-sediment accumulation factor showed a negative relationship with sediment pyrene concentration; this trend may be due to reduced availability at high sediment pyrene concentrations or due to reductions in both ingestion rate and selectivity for fine, pyrene-rich particles. Fecal pyrene concentrations were depleted compared to sediment levels, suggesting removal of pyrene during gut passage by absorption. Fecal-sediment accumulation factor showed a negative relationship with increasing sediment pyrene levels.
Sediment chemical contamination and toxicity associated with a coastal golf course complex
Authors: Lewis Michael A , Foss Steven S , Harris Peggy S , Stanley Roman S , Moore James C
Published: March 2010

The increasing density of golf courses represents a potential source of sediment contamination to nearby coastal areas, the chemical and biological magnitude of which is almost unknown. The objective of this study was to determine the concentrations of contaminants and toxicities of sediments impacted by a coastal golf course complex. Sediment contaminant concentrations were determined at least twice during the two-year study period at 14 sampling stations. In addition, a combination of acute and chronic bioassays were conducted exposing four invertebrate test species to whole sediments and associated pore waters. Overall, the Florida, USA, golf course complex had a measurable impact on sediment chemical quality, particularly in near-field areas. Higher concentrations of several trace metals and organochlorine pesticides were detected in many golf course-associated sediments compared with reference areas; however, concentrations decreased seaward and only a few, primarily chlorinated pesticides, exceeded proposed sediment quality guidelines. Chromium, zinc, and mercury were detected more frequently than other trace metals. The DDT and associated metabolites, dieldrin and chlordane, were the more commonly detected organic contaminants. Acute toxicity was uncommon and occurred consistently for sediment collected from one coastal location. In contrast, chronic toxicity occurred at several study sites based on the response of Mysidopsis bahia. It was concluded that the impact of golf course runoff on sediment quality may be subtle and sensitive biological assessment methods, such as chronic toxicity tests, will be needed to detect adverse effects.
The power of size. 1. Rate constants and equilibrium ratios for accumulation of organic substances related to octanol-water partition ratio and species weight
Authors: Hendriks A. Jan , van der Linde Alex , Cornelissen Gerard , Sijm Dick T H M
Published: March 2010

Most of the thousands of substances and species that risk assessment has to deal with are not investigated empirically because of financial, practical, and ethical constraints. To facilitate extrapolation, we have developed a model for accumulation kinetics of organic substances as a function of the octanol-water partition ratio (Kow) of the chemical and the weight, lipid content, and trophic level of the species. The ecological parameters were obtained from a previous review on allometric regressions. The chemical parameters, that is, resistances that substances encounter in water and lipid layers of organisms, were calibrated on 1,939 rate constants for absorption from water for assimilation from food and for elimination. Their ratio was validated on 37 laboratory bioconcentration and biomagnification regressions and on 2,700 field bioaccumulation data. The rate constant for absorption increased with the hydrophobicity of the substances with a Kow up to about 1,000 and then leveled off, decreasing with the weight of the species. About 39% of the variation was explained by the model, while deviations of more than a factor of 5 were noted for labile, large, and less hydrophobic molecules as well as for algae, mollusks, and arthropods. The efficiency for assimilation of contaminants from food was determined mainly by the food digestibility and thus by the trophic level of the species. A distinction was made between substances that are stable, that is, with a minimum elimination only, and those that are labile, that is, with an excess elimination probably largely due to biotransformation. The rate constant for minimum elimination decreased with the hydrophobicity of the substance and the weight of the species. About 70% of the variation was explained by the model, while deviations of more than a factor of 5 were noted for algae, terrestrial plants, and benthic animals. Labile substances were eliminated faster than isolipophilic stable compounds, but differences in laboratory elimination and accumulation were small compared with those in field accumulation. Excess elimination by vertebrates was faster than by invertebrates. Differences between terrestrial and aquatic species were attributed to water turnover rates, whereas differences between trophic levels were due to the food digestibility. Food web accumulation, expressed as organism-organic solids and organism-food concentrations ratios could be largely explained by ecological variables only. The model is believed to facilitate various types of scientific interpretation as well as environmental risk assessment.
The power of size. 2. Rate constants and equilibrium ratios for accumulation of inorganic substances related to species weight
Authors: Hendriks A. Jan , Heikens A.
Published: March 2010

Most of the thousands of substances and species that risk assessment has to deal with are not investigated empirically because of financial, practical, and ethical constraints. To facilitate extrapolation, we have developed a model for concentration kinetics of inorganic substances as a function of the exposure concentration of the chemical and the weight and trophic level of the species. The ecological parameters and the resistances that substances encounter during diffusion in water layers were obtained from previous reviews. The other chemical parameters (the resistances for permeation of lipid layers) were calibrated in the present study on 1,062 rate constants for absorption from water, for assimilation from food, and for elimination. Data on all elements and species were collected, but most applied to aquatic species, in particular mollusks and fish, and to transition metals, in particular group IIB (Zn, Cd, Hg). Their ratio was validated on 92 regressions and nine geometric averages, representing thousands of (near-)equilibrium accumulation ratios from laboratory and field studies. Rate constants for absorption and elimination decreased with species weight at an exponent of about −0.25, known from ecological allometry. On average, uptake-rate constants decreased with about the reciprocal square root of the exposure concentration. About 71 and 30% of the variation in absorption and elimination was explained by the model, respectively. The efficiency for assimilation of elements from food appeared to be determined mainly by the food digestibility and the distribution over egested and digested fractions. (Near-)equilibrium accumulation and magnification ratios also decreased with the reciprocal square root of the exposure concentration. The level of the organism-solids concentrations ratios roughly varied between one and two orders of magnitude, depending on the number of elements and species groups investigated. Metal concentrations did not increase at higher trophic levels, with the exception of (methyl-)mercury. Organism-solids concentration ratios for terrestrial species tended to be somewhat lower than those for their aquatic equivalents. Food web accumulation, expressed as organism-organic solids and organism-food concentrations ratios, can therefore be only partly explained by ecological variables. The model is believed to facilitate various types of scientific interpretation as well as environmental risk assessment.
Aircraft and runway deicers at General Mitchell International Airport, Milwaukee, Wisconsin, USA. 1. Biochemical oxygen demand and dissolved oxygen in receiving streams
Authors: Corsi Steven R , Booth Nathaniel L , Hall David W
Published: March 2010

Aircraft and runway deicers are used during cold weather at many of the world's airports to facilitate safe air travel. Propylene glycol-, ethylene glycol-, and urea-based deicers are known to have very high biochemical oxygen demand. At General Mitchell International Airport (GMIA) in Milwaukee, Wisconsin, USA, deicer application, water chemistry, and dissolved oxygen (DO) data were collected for two deicing seasons in order to evaluate and define premanagement water quality parameters prior to the implementation of a glycol management program. Calculations using stream-monitoring data during a controlled release of deicer provided an estimate of 0.8/d for the first-order decay rate constant, substantially higher than published laboratory test results. For eight precipitation events with deicing activities, between 2.4 and 99% of propylene and ethylene glycol applied to aircraft was delivered directly to receiving streams. The percentage of glycol runoff during an event increased with increasing storm-flow volume. Elevated concentrations of glycol and biochemical oxygen demand were measured downstream from the airport. However, the frequency of low DO concentrations in the receiving streams is comparable with that at an upstream reference site. This is possibly due to slowed bacteria metabolism at low water temperatures, short travel times, and dilution from downstream tributaries.
On the validity of classifying chemicals for persistence, bioaccumulation, toxicity, and potential for long-range transport
Authors: Mackay Don , McCarty Lynn S , MacLeod Matthew
Published: March 2010

It is argued that chemical substances can be meaningfully ranked or classified according to their persistence (P), bioaccumulation (B), toxicity (T), and potential for long-range transport (LRT) only if these attributes can be shown to be intensive, as distinct from extensive, properties of the substance, i.e., they are independent of quantity of substance. It is shown that P, B, and LRT can be considered intensive or quasi-intensive properties, but toxicity is more problematic. To obtain an intensive metric of toxicity requires selection of one of several possible extensive quantities that define exposure or dose. Ranking of a group of chemicals by toxicity is shown to be very dependent on which quantity is selected. It is suggested that toxicity metrics, such as lethal concentration to 50% of the population (LC50), lethal dose to 50% of the population (LD50), and threshold limit value (TLV) suffer the severe disadvantage of being dependent on the efficiency of delivery of the substance to the site(s) of toxic action in the organism. The use of measured or calculated internal dose is a preferable measure of toxicity since it reduces ambiguities inherent in the other metrics. Also, the primary concern is not the quasi-intensive property of toxicity; rather, it is the risk of toxic effects, an extensive quantity. To adequately assess the risk of toxic effects, both the toxic hazard and the degree of exposure must be characterized. Since exposure cannot be estimated without knowledge of the emission rate of chemicals to the environment, a compelling case can be made that screening to identify priority P, B, T, and LRT substances should be expanded to include quantity released to the environment as an additional factor.