bluuebunny/crossref_metadata_2025 huggingface dataset:
A steady-state fugacity-based pharmacokinetic model with simultaneous multiple exposure routes
Authors: Paterson Sally , MacKay Donald
Published: March 2010

A physiologically based human pharmacokinetic model of chemical intake via ingestion of food and water and inhalation of air is presented. The model takes the form of a series of algebraic equations that describe the steady state, constant exposure, transport rates and physiological distribution in arterial and venous blood, lung, fat, skin, muscle, liver, gut tissue, gut lumen and richly perfused tissues. It is assembled using the fugacity concept and is applied to a hexachlorobiphenyl and styrene. It is suggested that the model can be used to elucidate how tissue concentrations respond to these intake routes and thus should contribute to better assessment of the hazards or effects of exposure to organic chemicals on humans and other mammals.
Methods for waste load allocation of municipal sewage sludge at the 106-mile ocean disposal site
Authors: Walker Henry A. , Paul John F. , Bierman Victor J.
Published: March 2010

Methods for modeling short-term (time-variable) and long-term (time-averaged) exposures in the upper mixed layer that may result from the proposed disposal of sewage sludge at the 106-Mile Ocean Disposal Site are presented. The models have not been field validated at the 106-Mile Site, but they do provide decision makers with “upper-bound” estimates of risk to the upper water column from municipal sludge loadings currently projected for disposal at the site. The methods are believed to be useful in managing disposal site operations and in determining if future loadings to the site would be permissible.

The models are two-dimensional in the horizontal plane and assume complete mixing over a prescribed mixed-layer depth. Upper-bound estimates of sludge contaminant concentrations in the upper mixed layer were based on summer hydrographic conditions and an annual disposal rate of 7.2 million metric wet tons of sludge. Preliminary assessments of the potential effects of the sludge disposal were made using U.S. Environmental Protection Agency marine water quality criteria, the Food and Drug Administration tolerance level for polychlorinated biphenyl residues in edible portions of fish tissue and whole-sludge toxicity test results. Within the framework of the assumptions and limitations of this analysis, and based on the projected loading rate, the overall results indicate that there would be no violations of these criteria. The margins of safety relative to the specified criteria were estimated.
Measurement of attenuation coefficients in natural water columns
Authors: Winterle John S. , Tse Doris , Mabey William R.
Published: March 2010

Light scattering and light absorption by particulates and humic substances in natural waters can significantly affect the photoreaction rates of chemicals in aquatic systems. These scattering and absorption processes are quantitatively described by the use of an empirical parameter, the diffuse attenuation coefficient, K. We have tested actinometric and radiometric methods for measuring the diffuse attenuation coefficient K which can be used to calculate the depth averaged rate constant (kpavg) in a specific water body. The two methods were found to give excellent agreement. We found the method using a chemical actinometer system to be the most practical and convenient for use in field studies, but that more studies in other water systems and with other test cheimcals are needed to more rigorously test the method. We calculated kpavg equal to 0.33 ±0.17d−1 for carbazole in a 1-m test pond.
Toxicity of brass powder in soil to the earthworm Lumbricus terrestris
Authors: Wentsel Randall S. , Guelta Mark A.
Published: March 2010

The earthworm Lumbricus terrestris was exposed to brass powder (70% Cu, 30% Zn) contaminated soils at concentrations ranging from 0 to 430 μg/g. A 14-d LC50 of 190 μg/g with 95% fiducial limits of 169 and 220 μg/g was determined. Sublethal effects, measured as weight loss, were significantly different (p < .05) from the control at 120 μg/g and above.
Bioavailability and toxicity of metals leached from lead-mine tailings to aquatic invertebrates
Authors: Besser John M. , Rabeni Charles F.
Published: March 2010

Erosion and leaching of abandoned deposits of lead-mine tailings in southeast Missouri have resulted in the heavy metal contamination of surface waters, sediments and aquatic biota. We examined how cover materials added to stabilize tailings deposits might influence the mobilization of metals in mine tailings leachates by monitoring metal bioaccumulation and toxic effects in aquatic invertebrates (Orconectes nais, Hexagenia limbata and Chironomus riparius) exposed to leachates from test plots of tailings that had been given various cover treatments. Bioaccumulation of lead and cadmium increased significantly, and survival, growth and development were impaired in one or more invertebrate taxa during chronic (10–120 d) exposures to leachates from cover treatments of vegetation and organic mulches. Metal bioaccumulation and toxicity were greatest in a maple leaf cover treatment. Leachate from the leaf treatment had high metal concentrations because of the formation of metal/organic complexes. Lesser responses were observed in treatments of seed + fertilizer, bluegrass sod and dried sewage sludge, all of which resulted in the establishment of varying amounts of vegetative cover on the tailings. Bioaccumulation of lead, but not cadmium, was significantly correlated with the dissolved metal concentrations in the leachates. Toxic effects on invertebrate survival, growth and development were significantly correlated with the metal concentrations in leachate samples and, for lead, with body burdens in invertebrates. The results indicated that leachates from mine tailings deposits can adversely affect aquatic invertebrates, and that cover materials that release organic complexing agents can increase the mobilization of toxic metals in leachates. Vegetative cover would probably reduce future runoff and erosion from tailings deposits, but conditions similar to those in this study may favor the mobilization of metals from tailings already present in riparian habitats and stream sediments.
Bisphenol a: Acute aquatic toxicity
Authors: Alexander Howard C. , Dill Dennis C. , Smith Ladd W. , Guiney Patrick D. , Dorn Philip
Published: March 2010

The Society of the Plastics Industry, Inc., ad hoc Bisphenol A Task Group determined that freshwater and saltwater environmental effects testing on bisphenol A should be conducted. This decision was based upon the nation's high production capacity for bisphenol A, which is manufactured at many sites, its potential for entering the environment in substantial quantities and the general lack of relevant ecological effects data. The freshwater test results were as follows: the 96-h EC50 algal toxicity to Selenastrum capricornutum was 2.7 mg/L based on cell count, and 3.1 mg/L based on cell volume; the 48-h EC50 to the invertebrate Daphnia magna was 10 (9.2–11) mg/L; and the 96-h LC50s to the fathead minnow, Pimephales promelas, was 4.7 (4.0–5.5) mg/L in a static test and 4.6 (3.6 to 5.4) mg/L in a flow-through test. The saltwater test results were as follows: the 96-h EC50 algal toxicity to the diatom Skeletonema costatum was 1.0 mg/L based on cell count and relative fluorescence, and 1.8 mg/L based on chlorophyll a content; the 96-h LC50 to the mysid Mysidopsis bahia was 1.1 (0.92 to 1.2) mg/L; and the 96-h LC50 to the Atlantic silverside, Menidia menidia, was 9.4 (8.3 to 11) mg/L.

According to current U.S. Environmental Protection Agency standard evaluation procedures, bisphenol A was moderately to slightly toxic to the fish and invertebrates tested, with LC50 or EC50 values of from 1.1 to 10 mg/L. These data did not trigger freshwater or saltwater chronic tests. The acute toxicity data together with the fact that bisphenol A rapidly biodegrades in surface waters indicate a low potential for chronic exposure or toxicity.
An indirect test of correlation
Authors: Lower W. R. , Thompson W. A.
Published: March 2010

Measurements are frequently made of two unpaired dependent variables, Y and Z, at levels of a common independent variable, x. However, the relationship of primary interest may not be between Y and x or Z and x, but between Y and Z. Since Y and Z are not paired it is not possible to directly regress Y on Z or Z on Y, calculate a partial correlation coefficient or perform a covariance analysis with x as a covariate. A method based on normal theory has been developed to indirectly test for correlation from regression analysis of two or more dependent variables when they share a common independent variable. Examples of application of the technique are taken from field studies of the toxic effects of the emissions of a lead smelter on a variety of biological systems.
Effects of dimilin® on freshwater litter decomposition
Authors: Swift Michael C. , Cummins Kenneth W. , Smucker Richard A.
Published: March 2010

The pesticide Dimilin® (diflubenzuron) is widely used on forests in Maryland to control gypsy moths, and it may enter streams via leaf litter. We measured the effects of Dimilin on stream leaf litter processing using artificial leaf packs treated with the pesticide. Over the entire study period (464 degree days) the Dimilin-treated packs were processed more rapidly than control packs. There was a continuous loss of Dimilin from the packs, apparently due to leaching. Both Dimilin-treated and control packs were quickly colonized by macroinvertebrates and the maximum total macroin-vertebrate biomass occurred when about 50% of the leaf-pack biomass remained. The macroinvertebrate community in the leaf packs was typical for western Maryland. There was little difference in the macroinvertebrate communities on the Dimilin-treated and the control packs; any possible differences between treatments were probably obscured by recolonization of the packs by invertebrate drift. Bioassays were conducted using two shredder macroinvertebrates (Tipula abdominalis and Platycentropus radiatus) to compare growth and mortality when they were fed untreated and Dimilin-treated tulip poplar leaves. Mortality was significantly higher and growth significantly lower in the shredders fed Dimilin-treated leaves.
The acute toxicity of thiocyanate and cyanate to rainbow trout as modified by water temperature and pH
Authors: Speyer M. R. , Raymond P.
Published: March 2010

Acute 96-h static bioassays were conducted with juvenile rainbow trout (Salmo gairdneri) to assess the toxicity of thiocyanate (CNS) and cyanate (CNO), as potassium salts, under several pH and temperature regimes. Bioassays were conducted at pH 6 or 8 and at temperatures of 5 or 12°C. Mean 96-h LC50 values for CNS ranged between 177 and 264 mg/L, and for CNO, between 15 and 81 mg/L, depending on test conditions. The data suggested that pH influenced the toxicity of both CNS and CNO more than did temperature. Stressing of fish at the end of each bioassay resulted in almost instantaneous mortalities in most CNS-exposed fish, but no stress effects were observed in CNO-exposed fish. There were indications that water hardness reduced CNS and CNO toxicity.
Application of cellulolytic activity of asiatic clams (CorbiculaSP.) to in-stream monitoring of power plant effluents
Authors: Farris Jerry L. , Van Hassel John H. , Belanger Scott E. , Cherry Donald S. , Cairns John
Published: March 2010

Rigorous testing schemes in field-located artificial streams and in-stream monitoring provided evidence for use of Corbicula cellulolytic activity as a highly sensitive and efficient approach to effluent assessment. Cellulolytic (exo- and endocellulase) activity of the Asiatic clam, Corbicula sp., determined in 30-d, field-located artificial stream exposures at the New River, Virginia to single components of power plant effluents (copper [Cu] and zinc [Zn] separately) was compared with cellulolytic responses in caged clams from within an impacted area of the Clinch River, Virginia below power plant effluents. Cellulolytic responses were then compared to conventional biomonitoring responses (Hester-Dendy macroinvertebrate community structure), water quality monitoring in the Clinch River, and laboratory artificial stream bioassays. Clam enzyme activity was significantly reduced in 10 to 20 d (α = 0.05) at 16 and 87 μg Cu and Zn/L, respectively, in field-located artificial streams. Cellulolytic activity of clams caged at stations within power plant outfalls (metal concentrations of 47–78 μg Zn/L and 80–345 μg Cu/L) was significantly reduced to levels as low as 9 to 52% of upstream activity levels. Reduction in cellulolytic activity in Corbicula was more sensitive after 14 d of in-stream monitoring than reduction in diversity of macroinvertebrate assemblages after 28 d. Bioassay exposures as long as 30 d were needed to provide toxicity data comparable to enzyme impairment seen as early as 10 d.
Predicting acidification effects on fish populations, using laboratory data and field information
Authors: Christensen Sigurd W. , Breck James E. , Van Winkle W.
Published: March 2010

We developed a framework of linked models that uses lake levels of pH, Al, and Ca to predict the occurrence of fish species on a regional scale. As a first step, statistical models are fitted to laboratory data on brook trout (Salvelinus fontinalis). The resulting functions predict mortality and reduction in fecundity resulting from chemical conditions (pH, Al, and Ca). The second step applies a life-cycle model to results from the first step to estimate the reproductive potential expected for fish living in lakes with specified chemical conditions relative to that expected for fish living under nonstressful chemical conditions. Use of the framework requires field data on the presence or absence of brook trout in lakes having measured pH, Al, and Ca. The chemical conditions for each lake are processed through the first two steps to estimate the relative reproductive potential for brook trout in that lake. After, obtaining estimates for all lakes, a logistic regression model is fitted, with probability of occurrence as the dependent variable and relative reproductive potential as the independent variable. The resulting function, representing the calibrated framework, relates the probability of brook trout occurrence in high-elevation Adirondack (New York) lakes to relative (i.e., reduced) reproductive potential attributable to chemical stress. This function, when tested against additional data, can be used to predict changes in brook trout population status in relation to changed chemical conditions, stocking, or altered fishing pressure.
Toxic contaminants in rainfall in Canada: 1984
Authors: Strachan William M. J.
Published: March 2010

Replicate rain samples for most of the 1984 wetfall season were collected from four widely separated sites in Canada, and concentrations and loadings of a number of polychlorinated biphenyls and organochlorine pesticides were determined for each location. Comparisons were made among the sites and with results from other years.

The major contaminants in 1984 were, in order of concentration, α-hexachlorocyclohexane (α-HCH or α-BHC), lindane and polychlorinated biphenyls (PCBs). Found at lower levels were dieldrin, methoxychlor (in the Lake Superior area), DDT residues, endrin (especially at Kouchibouguac), heptachlor epoxide and hexachlorobenzene. The loading of the α-HCH/lindane pair was higher at the Atlantic coastal site than at the other locations, possibly because of the greater precipitation there. No geographic trend for PCBs was apparent. For the other substances, no significant pattern to the differences between sites can be discerned. The qualitative similarities of concentrations and loadings at the widely separated locations, however, suggest long-range atmospheric transport.

A comparison between results from two Lake Superior sites indicated no shoreline effect on the concentrations of over-lake versus shoreline samples. The differences observed were in accord with those observed in 1983 and were attributed to lack of replenishment from the lake surface.
Some reactions of naturally occurring nucleophiles with haloalkanes in water
Authors: Haag Werner R. , Mill Theodore
Published: March 2010

Rate constants for the reactions of a variety of naturally occurring nucleophiles with 1-bromohexane and, to a lesser extent, three other haloalkanes were studied in order to assess their importance relative to hydrolysis in determining the environmental fate of haloalkanes. HS− is generally the most important nucleophile because it is moderately reactive and, among the reactive sulfur nucleophiles, is usually present in the highest concentration. When elemental sulfur is present, polysulfides will be more important for the consumption of 1-bromohexane than HS− at pH above approximately 7 because they are 60 times more reactive and their equilibrium concentrations increase with increasing pH. A nucleophilicity scale valid in pure water was established for environmental nucleophiles, using 1-bromohexane as a reference reactant.
Effects of culture conditions on the sensitivity of a phoxocephalid amphipod,rhepoxynius abronius, to cadmium in sediment
Authors: Robinson Anja M. , Lamberson Janet O. , Cole Faith A. , Swartz Richard C.
Published: March 2010

Experiments were conducted to determine (a) the feasibility of maintaining laboratory cultures of the infaunal phoxocephalid amphipod Rhepoxynius abronius (Barnard), (b) the relative sensitivities of cultured versus freshly collected adult animals, (c) the sensitivities of adult versus juvenile R. abronius to cadmium in sediment and (d) the effect of handling on cultured amphipods. R. abronius held in sediment in a flow‒through seawater system for various lengths of time showed high survival, growth and sexual maturation for periods of up to 180 d. Cultured amphipods appeared normal and survived well (93%) under control toxicity test conditions, but were more sensitive to cadmium in sediment (LC50 = 4.4) than were freshly collected amphipods (LC50 = 8.7). Differences in cadmium LC50s between size classes (LC50 = 8.2 for juveniles and 11.5 for adults) were statistically significant, but not substantial. We recommend that large juveniles and adults (3 to 5 mm) be used in sediment toxicity tests because they are available from natural populations throughout the year, and that amphipods be collected within 14 d of use in sediment toxicity tests to minimize the interaction between culture and contaminant stresses.
A comparative ecological and toxicological investigation of a secondary wastewater treatment plant effluent and its receiving stream
Authors: Birge Wesley J. , Black Jeffrey A. , Short Terry M. , Westerman Albert G.
Published: March 2010

A comparative ecological and toxicological investigation was conducted on a secondary wastewater treatment plant point—source discharge and the receiving system, a fourth—order freshwater stream in the Kentucky River basin. Biological, chemical, hydrological and on—site toxicological studies were performed at 10 monitoring stations, including reference sites. The principal objectives were to assess downstream persistence of aquatic contaminants, to quantify their effects on structure and function of aquatic communities and to evaluate the 8—d fathead minnow embryo—larval test for measuring instream toxicity and estimating chronic effects on aquatic biota. The principal ecological endpoints included species richness, diversity (H'), density and dominance (D) of macroinvertebrates and diversity of fish species. Macroinvertebrates were further analyzed by trophic groups. Marked downstream gradients existed for effluent dilution, decreasing concentration of selected chemicals, improvement in ecological conditions and decreasing toxicity, as measured in on—site static—renewal tests. A good predictive correlation was found between embryo—larval survival and independent ecological parameters, especially species richness of macroinvertebrates. In addition, static—renewal and flow—through toxicity tests were performed with effluent dilutions to determine LC50 and toxicity threshold values (LC1), expressed as percent effluent by volume. The estimated toxicity thresholds correlated closely with the actual percent instream effluent dilution observed at the first downstream station at which no ecological impact was discernible.
Degradation of nitroguanidine wastewater components in soil
Authors: Williams Richard T. , Sisk Wayne E. , MacGillivray A. Ronald
Published: March 2010

The degradation of nitroguanidine (NQ) wastewater components was studied using continuous-flow and perfusion soil columns. After 271 d of operation of the continuous-flow columns and 84 d of operation of the perfusion columns, only some components of NQ wastewater were completely or partially removed. Guanidine nitrate and sulfate were the most readily transformed. NQ, however, was only partially removed. Carbon supplements enhanced the transformation of both sulfate and NQ. Transformation products included nitrosoguanidine and ammonia, but not cyanoguanidine or melamine. Microbial adaptation to wastewater components was not demonstrated. Based on test data, land application of untreated wastewater is not recommended.
Relationship between the soil sorption constants for pesticides and their physicochemical properties
Authors: Kanazawa Jun
Published: March 2010

Soil sorption constants based on the organic carbon content (Koc) of 15 pesticides were measured using two soils at three concentrations. Significant correlations were found between the Koc value and water solubility (WS), octanol/water partition coefficient (Kow), retention time in reversed-phase HPLC (Rt) and molecular weight (mol. wt.). Thus the soil sorption constants of nonionic pesticides can be predicted by these four parameters.
Relative developmental toxicities of nine diphenyl ethers related to nitrofen
Authors: Francis B. Magnus
Published: March 2010

Outbred Swiss mice (Mus musculus) were treated with 2,3-dichlorophenyl 4′-nitrophenyl ether (23-DCN), 2,5-dichlorophenyl 4′-nitrophenyl ether (25-DCN), 2,6-dichlorophenyl 4′-nitrophenyl ether (26-DCN), 3,4-dichlorophenyl 4′-nitrophenyl ether (34-DCN), 3,5-dichlorophenyl 4′-nitrophenyl ether (35-DCN), 2,4,5-trichlorophenyl 4′-nitrophenyl ether (245-TCN), 2,4,6-trichlorophenyl 4′-nitrophenyl ether (CNP), 3-chlorophenyl 4′-nitrophenyl ether (3-MCN) or phenyl 4-bromophenyl ether (4-BR) at dosages that are highly teratogenic when the known teratogen nitrofen (2,4-dichlorophenyl 4′-nitrophenyl ether) is administered. The Chernoff/Kavlock screen was used to assess both prenatal and postnatal toxicity; in addition, effects of each chemical on Harderian glands were evaluated. The monochlorinated analogs and the five dichlorinated nitrofen analogs were inactive at the doses given. 4-BR was inactive at levels of up to 1,000 mg/kg/d. The trichlorinated analogs caused missing Harderian glands in pups exposed to 10 or 20 mg/kg/d 245-TCN, 50 or 100 mg/kg/d nitrofen or 250 or 500 mg/kg/d CNP; significant perinatal mortality in litters exposed to 20 mg/kg/d 245-TCN or 100 mg/kg/d nitrofen; and a high incidence of prenatal mortality in litters exposed to 500 or 750 mg/kg/d CNP. Maternal toxicity other than decreased weight gain was not seen with any compound, even at doses that caused significant prenatal or perinatal mortality. The data demonstrate that the position of chlorine substituents, as well as the number of such substituents, is critical in determining the developmental toxicity of diphenyl ethers.
Fate of fenthion in salt-marsh environments: I. Factors affecting biotic and abiotic degradation rates in water and sediment
Authors: Cripe C. R. , O'Neil E. J. , Woods M. E. , Gilliam W. T. , Pritchard P. H.
Published: March 2010

Fenthion (Baytex), an organophosphate insecticide, is frequently applied to salt-marsh environments to control mosquitoes. Shake-flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or water-sediment (500 mg dry weight/L) slurries from salt marshes located along the Northwest Florida Gulf Coast were used. Flasks contained 200 μg fenthion/L, and degradation rates were determined by following decrease of fenthion over time. Hydrolysis and biodegradation in water were relatively insignificant fate processes; fenthion disappeared from flasks containing water, formalin-sterilized water, or formalin-sterilized sediment very slowly (half-life ≥ 2 weeks). The presence of nonsterile sediment resulted in a rapid exponential disappearance of fenthion (half-life ≥ 3.8 d). Biodegradation was assumed since sterile sediment systems showed a much slower decrease of fenthion, and the production of polar compounds (hexane-unextractable) from radiolabeled fenthion was greater in the presence of sediment than sterilized sediment. The effect of environmental pH levels (5.0–7.0) on degradation was insignificant. No biotic degradation occurred at low oxygen concentration. An 8°C decrease in incubation temperature decreased the rate of sediment biodegradation 2.5-fold. Light caused a slight, but significant, increase in the biotic and abiotic degradation rates of fenthion in water. A two-fold variation in sediment-mediated degradation was noted among sediment samples from three stations within one field site. Inclusion of whole marsh plants or plant parts increased the disappearance rate of fenthion in test systems.
Measurement of zinc amelioration of cadmium toxicity in Chlorella pyrenoidosa using turbidostat culture
Authors: Bennett William N. , Brooks Arthur S.
Published: March 2010

The amelioration of cadmium toxicity by zinc was measured in terms of changes in the maximum specific growth rate (μmax) of a Chlorella pyrenoidosa population using turbidostat culture. In this continuous culture system, μmax is a dependent variable that responds directly to toxic effects. At a sublethal cadmium concentration (2.05 μM Cd) in the medium, the population μmax was in steady state at 70% of control values. When zinc was added to the medium to a concentration of 4.08 μM Zn, μmax increased immediately to a rate of 2.2% of control μmax/generation for seven generations, reaching steady state at 90% of the control. Additional increases in zinc did not elicit further increases in μmax. Full recovery of μmax subsequently occurred after five generations in control medium. Mean cell size and percentage dry mass also changed during periods of toxicity and amelioration. Mechanisms of the amelioration process are discussed.
Toxic effects of boron on mallard reproduction
Authors: Smith Gregory J. , Anders Velora P.
Published: March 2010

Boron, a naturally occurring trace element generally considered environmentally innocuous, was documented to severely impair mallard reproduction. Boron is leached from irrigated agricultural soils and transported in drainage water that contaminates wetlands. Until now, only the selenium accumulated in aquatic food chains has been documented to pose a toxic hazard to wildlife in drainage water wetlands. Adult mallard (Anas platyrhynchos) ducks were fed diets supplemented with 0, 30, 300 or 1,000 ppm boron (fresh weight; diets contained about 10% moisture). The hatching success of fertile eggs was significantly reduced by 1,000 ppm boron, less than one-third the highest boron concentrations found in plants in California's San Joaquin Valley. Hatching weights, duckling survival and duckling weight gain were also reduced by 1,000 ppm boron. Boron concentrations in mallard egg, liver and brain tissues were dose-related. Boron did not affect adult survival or egg fertility. Management of drainage water-contaminated environments must now also consider the adverse effects of boron, as well as the possible interactions of drainage water contaminants.
Computer data bases for carcinogenicity and risk assessment
Authors: Sidhu Kirpal S.
Published: March 2010

This paper reviews information on computer data bases for carcinogenicity and risk assessment. The data bases included were Chemical Evaluation Search and Retrieval System (CESARS), Hazardous Substances Data Bank (HSDB), Registry of Toxic Effects of Chemical Substances (RTECS), Toxicology Information Online (TOXLINE), Cancer Literature (CANCERLIT), Chemical Carcinogenesis Research Information System (CCRIS), Public Health Risk Evaluation Database (PHRED) and Integrated Risk Information System (IRIS). Chemical records included in CESARS, HSDB and RTECS contain general information on carcinogenicity. TOXLINE and CANCERLIT are bibliographic data bases for toxicological and cancer studies. CCRIS contains detailed information on carcinogenicity studies for formulation of risk assessment. PHRED contains toxicological information and cancer potency factors for formulation of risk assessment. IRIS provides detailed information for carcinogenicity assessments, slope factors, unit risks and concentrations at specified risk levels for chronic exposures to carcinogens. IRIS serves as the best source of information for risk assessment for environmental contaminants.
Responses of green frog (Rana Clamitans) tadpoles to lead-polluted water
Authors: Taylor Douglas H. , Steele Craig W. , Strickler-Shaw Shari
Published: March 2010

Green frog (Rana clamitans) tadpoles were exposed to 0, 500, 750 and 1,000 μg Pb/L (as lead nitrate) for 6 d (144 h). Previous studies have shown that similar exposure to 750 or 1,000 μg Pb/L produces deficiencies in both acquisition and retention of learned responses in green frog tadpoles. We examined preference/avoidance responses and spontaneous locomotor activity of Pb-exposed and control tadpoles to plumes of Pb-polluted water at each concentration in an octagonal fluviarium. Results indicated no significant preference or avoidance of Pb by either control or Pb-exposed animals, and no significant effects on the amount of locomotor activity. However, there was significantly greater (p < 0.05; folded Ftest) variability in locomotor activity for tadpoles exposed to 750 and 1,000 μg Pb/L compared to control animals and to those exposed to 500 μg Pb/L.
Ambient toxicity dynamics: Assessments using Ceriodaphnia dubia and fathead minnow (Pimephales promelas) larvae in short-term tests
Authors: Stewart A.J. , Kszos L.A. , Harvey B.C. , Wicker L.F. , Haynes G.J. , Bailey R.D.
Published: March 2010

Seven-day-static-renewal tests with fathead minnow larvae (Pimephales promelas) and Ceriodaphnia dubia were conducted monthly and results were used to assess spatiotemporal patterns in toxicity at 15 sites in five streams that receive discharges from the Oak Ridge National Laboratory (ORNL). The stream-water samples were also analyzed for pH, conductivity, alkalinity, hardness and total residual chlorine (TRC). Relationships between the ambient toxicity test results and the chemical data were evaluated by (a) examining correlations between the two data sets across all site-test combinations and (b) principal components analyses (PCA). These approaches proved to be more appropriate than procedures typically used to evaluate effluent toxicity (e.g., analysis of variance followed by Dunnett's test or Fisher's exact test).

On average, P. promelas growth and C. dubia fecundity differed little from site to site, but survival of the two species varied greatly from test to test at some sites. Mean survival and its site-specific C.V. were inversely related both for C. dubia and P. promelas (r = -0.857 and -0.810, respectively), and the slope of this relationship was greater for C. dubia than it was for P. promelas. Thus, (a) mortality patterns for both test species suggested that episodic events controlled overall patterns in ambient toxicity and (b) the C. dubia test appeared to be more sensitive than the P. promelas test.

PCA identified two water quality factors (axis I, associated with hardness–conductivity, and axis II, strongly associated with TRC) that accounted for 60.5 and 17.6%, respectively, of the total variance in the chemical data. Multiple regression analyses of toxicity test response variables in relation to the two PCA factors showed that C. dubia survival was linked to axis II (p = 0.001) but not to axis I (p = 0.10). C. dubia fecundity was linked significantly to both (p = 0.011 and p = 0.019 for axes I and II, respectively). Neither survival nor growth of P. promelas was linked statistically to either axis. Occurrence-frequency distributions for TRC showed that concentrations high enough to kill either species were exceeded, on average, twice monthly at sites where survival of C. dubia and P. promelas tended to be low. Thus, TRC, which enters ORNL streams primarily as drinking water used in once-through cooling systems, was implicated as a toxicant governing the ambient toxicity test outcomes.
QSAR analysis of the acute fish toxicity of organic phosphorothionates using theoretically derived molecular descriptors
Authors: Schüürmann Gerrit
Published: March 2010

The 14-d LC50 toxicity to the guppy of ten O,O-dimethyl O-phenyl phosphorothionate pesticides is analyzed with respect to linear two-parameter quantitative structure-activity relationship (QSAR) models containing partitioning and reactivity descriptors. The use of quantum chemical parameters within the modified neglect of diatomic overlap (MNDO) scheme leads to QSAR models with correlation coefficients up to 0.95 that are based solely on theoretically derived descriptors. Furthermore, the results show that quantum chemical descriptors have a particular value in modeling chemical reactivity within homologous series of compounds.
Ecological fate, effects and prospects for the elimination of environmental polychlorinated biphenyls (PCBs)
Authors: Hooper Scott W. , Pettigrew Charles A. , Sayler Gary S.
Published: March 2010

Polychlorinated biphenyls (PCBs) present an environmental health hazard of global scale and man-made origin. Their impact on nearly every member of the biota results in a wide range of interacting negative effects. Due to their chemical nature, these recalcitrant toxicants are poised to enter and bioaccumulate in the food web. Recent advances in biodegradation research and molecular biology have shown that natural microorganisms and genetically modified bacterial strains could be used to decontaminate PCB-containing sites. The aim of this review is to summarize the chemistry, environmental fate and toxicological effects of PCBs and to evaluate the currently available technologies for nondisruptive elimination of PCBs from the environment.
Biodegradation of 2-furaldehyde under nitrate-reducing and methanogenic conditions
Authors: Knight Elaine V. , Novick Norman J. , Kaplan Donna L. , Meeks J. R.
Published: March 2010

Nitrate-reducing and methanogenic microbial consortia capable of using 2-furaldehyde (furfural) as a sole source of carbon and energy were isolated from a mixture of soil and municipal sewage and from municipal anaerobic digestor sludge, respectively. Under nitrate-reducing conditions, more than 97% of the furfural was biodegraded in 0.25, 1.5, 4 and 32 d at initial substrate concentrations of 0.5, 5, 50 and 500 ppm, respectively. In all cases microbial populations were able to reduce furfural levels to less than the detection limit of 20 ppb as measured by HPLC. At 500 ppm, there was a 12-d lag period before detectable activity was noted, while there was no lag period at the lower concentrations tested. When the disappearance of both furfural (50 ppm) and nitrate was measured, the molar ratio of nitrate to furfural consumed was approximately 4.2:1, Which is in good agreement with the theoretical ratio of 4.0:1. The biodegradation of furfural was generally more rapid under methanogenic than under nitrate-reducing conditions. The methanogenic consortium was able to metabolize 97% of the furfural in 2, 4, 48 and 144 h at initial concentrations of 0.5, 5, 50 and 500 ppm, respectively. No lag period was noted at any concentrations tested. As under nitrate-reducing conditions, populations were able to reduce furfural levels to less than 20 ppb. Complete metabolism of furfural in cultures that received an initial concentration of 50 ppm resulted in the production of 0.056 mM methane or 43% of the theoretical yield that would result from complete conversion of the material to carbon dioxide and methane. This is the first report of the biodegradation of furfural under nitrate-reducing conditions.
Influence of light intensity and photoadaptation on the toxicity of PCB to a marine diatom
Authors: Ruben Howard J. , Cosper Elizabeth M. , Wurster Charles F.
Published: March 2010

An investigation of the influence of light intensity and photoadaptation on the toxicity of polychlorinated biphenyls (PCBs) to the marine diatom, Ditylum brightwellu, was undertaken Cultures were adapted to six light intensities (30, 50, 75, 100, 125 and 150 μEm 2s−1) for a period of three months During this time a significant decrease in cell size occurred at the lower light intensities (The cultures grown at 30, 100 and 150 μEm 2s−1 were then tested for sensitivity to 10 μg/L PCB ) Rates of growth and photosynthesis (uptake of [14C]HCO3/μg Chl a/h) and cellular concentrations of chlorophyll a and carotenoids, as well as cell size, were measured

PCB toxicity was greatest at the higher light intensities Adapted cultures were less sensitive to PCB than unadapted cultures indicating that photoadaptation increased tolerance to PCB In the unadapted cultures growth rates and photosynthetic activity were significantly depressed by all PCB treatments In the adapted cultures growth rate at 150 μEm 2s−1 was the only measurement to show a significant decrease with PCB treatment Cellular concentrations of chlorophyll a and carotenoids varied with adaptation history, light intensity and PCB treatment

[14C]PCB (Aroclor 1254) accumulation was compared in adapted and nonadapted cultures The nonadapted cultures accumulated an order of magnitude more PCB, and the greatest accumulations correlated with reduced rates of photosynthesis and growth in cultures grown at the highest light levels
Human health effects of metals in drinking water: Relationship to cultural acidification
Authors: Nordberg Gunnar F.
Published: March 2010

Under certain conditions high concentrations of lead or cadmium in drinking water have occurred as a result of contamination from piping and distribution systems Contamination has led to acute and chronic toxicity in humans Metal concentration is increased when the acidity and corrosivity of water increase due to cultural acidification Adverse health effects have occurred in sen sitive subsections of human populations exposed to lead contaminated acidic water Neutralization of the acidity can reduce these problems Acidic water may also dissolve copper from piping systems Cirrhosis of the liver has been reported in children in India (Indian Childhood Cirrhosis – ICC), commonly with fatal outcome High liver copper levels in ICC cases have been related to copper exposure from cooking utensils Some rare cases reported from Germany and Italy have been partly attributed to high concentrations of copper in drinking water and partly to a special sensitivity to copper toxicity Elevated aluminum concentrations may occur in acidified natural waters and as a result of the aluminum chemicals used in drinking water purification Use of water con taming high aluminum levels for dialysis may give rise to dialysis dementia and disorders of bone mineral metabolism A possible relationship between aluminum in drinking water and Alzheimer's disease requires further investigation
Control of cadmium levels in Holopedium gibberum (crustacea, cladocera) in canadian shield lakes
Authors: Yan Norman D. , Mackie Gerald L. , Grauds Peter
Published: March 2010

Cadmium concentrations (Cd-h) of Holopedium gibberum (Crustacea, Cladocera) collected from 26 Canadian Shield lakes with positive alkalinity ranged from 0.9 to 31 μg/g. Levels were positively correlated with aqueous Cd concentrations (Cd-aq) and negatively correlated with clutch size. Animals collected from acidified lakes did not have elevated Cd-h concentrations despite elevated Cd-aq levels. In three intensive study lakes, the presence of eggs lowered Cd-h concentrations and Cd-h levels frequently increased with increases in body size. In two of these lakes, many H. gibberum occupied waters rich in particulate iron just above the anoxic interface. Cd-h levels fell when animals were experimentally confined to this layer, presumably because much of the Cd-aq was adsorbed by the particulate iron and was unavailable for uptake. We suggest that the behavior of animals, specifically their movement to light-scattering layers just above the anoxic interface, influences the accumulation of Cd by H. gibberum in Canadian Shield lakes.
Partitioning and bioavailability of mercury in an experimentally acidified wisconsin lake
Authors: Wiener James G. , Fitzgerald William F. , Watras Carl J. , Rada Ronald G.
Published: March 2010

We studied the partitioning of mercury (Hg) among air, water, sediments and fish at Little Rock Lake, a clear water seepage lake in north-central Wisconsin. The lake was divided with a sea curtain into two basins, one acidified with sulfuric acid to pH 5.6 for two years and the other an untreated reference site (mean pH 6.1), to document the effects of acidification. Trace-metal-free protocols were used to measure Hg at the picomolar level in air and water. Total gaseous Hg in air samples averaged 2.0 ng/m3. Total Hg in unfiltered water samples collected in 1986 after the fall overturn averaged about 1 ng/L in the acidified and reference basins. Mercury in surficial sediments was strongly correlated with volatile matter content and ranged from 10 to about 170 ng/g (dry weight) in both basins. Total Hg concentrations in whole, calendar age-1 yellow perch (Perca flavescens), sampled after one year of residence in the lake, averaged 114 ng/g (fresh weight) in the reference basin and 135 ng/g in the acidified basin – a highly significant (p < 0.01) difference. The mean whole-body burden (quantity) of Hg in age-1 perch did not differ between basins after the first year, but was significantly greater in the treatment basin than in the reference basin after the second year of acidification. Differences between the two basins in the bioaccumulation of Hg were attributed to internal (within-lake) processes that influence the bioavailability of the metal. An initial Hg budget for the treatment basin of Little Rock Lake showed that atmospheric deposition and sedimentary remobilization of Hg are potentially important processes influencing its biogeochemical cycling and uptake by fish.
Effect of body size on the uptake and bioconcentration of di-2-ethylhexyl phthalate in rainbow trout
Authors: Tarr Bryan D. , Barron Mace G. , Hayton William L.
Published: March 2010

Three groups of rainbow trout (Salmo gairdneri) having average body weights of 2.9, 61 and 440 g were exposed at 12°C by the water to di-2-ethylhexyl phthalate (DEHP). The kinetics of uptake and bioconcentration were characterized in each group using a compartmental model. Most of the model parameters, when expressed per unit body weight, were similar in the three sizes of fish. The two major exceptions were the uptake rate parameter, a measure of the capacity of the gill to extract DEHP from water and the apparent size (volume of distribution) of the large DEHP storage compartment, which is a measure of the capacity of the fish to accumulate DEHP. The values of these parameters declined as body weight increased; they followed the allometric equation with body weight exponents of 0.44 and 0.77, respectively. The body weight-associated changes in the pharmacokinetic parameters caused the bioconcentration factor to decline as body weight increased, from 51.5 to 1.6.
Comparative evaluation of five toxicity tests with sediments from san francisco bay and tomales bay, california
Authors: Long Edward R. , Buchman Michael F. , Bay Steven M. , Breteler Ronald J. , Carr R. Scott , Chapman Peter M. , Hose Jo Ellen , Lissner Andrew L. , Scott John , Wolfe Douglas A.
Published: March 2010

The relative sensitivity, analytical precision, discriminatory power and concordance among endpoints and with sediment chemistry were compared among five sediment toxicity tests. The tests were performed with aliquots of 15 composited, homogenized sediment samples. Survival and a variety of sublethal endpoints were determined in tests performed with the amphipods Rhepoxynius abronius and Ampelisca abdita, embryos of the mussel Mytilus edulis, embryos of the urchin Strongylocentrotus purpuratus, and the polychaete Dinophilus gyrociliatus. Each sample was also tested for trace metal and organic compound concentrations, organic carbon content and texture. Two of the five tests (survival among M. edulis and survival among R. abronius) were highly sensitive to the samples and had relatively high precision, but the results were correlated most highly with sedimentological variables. One of the tests (survival among A. abdita) was relatively insensitive, but the results were highly correlated with only the concentrations of toxic chemicals. The test with S. purpuratus indicated mutagenicity in several samples that had high hydrocarbon concentrations. The test of pore water with D. gyrociliatus was intermediate in sensitivity and precision and not correlated highly with the results from the other tests.
Are laboratory-derived toxicity data for freshwater algae worth the effort?
Authors: Lewis Michael A.
Published: March 2010

Algal toxicity test results are increasingly being considered in the evaluation of the environmental safety of chemicals and effluents. The ability of the current standard toxicity test methods to provide data useful in the safety assessment process was reviewed. It was concluded that there are too few data supporting the environmental relevance of those results derived using the standard methods in their present format. The current algal toxicity data base shows that interspecific variation in response to chemicals is significant and that field-validation of most laboratory-derived results is lacking. Therefore, multiple test species should be used in algal toxicity tests and the biological significance of the recommended end points, including stimulation, needs definition before the results can be expanded to natural algal communities and be useful in predicting environmental impact.