ISSN:0730-7268    

DOI:10.1002/etc.5620100101

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe 1‐octanol/water partition coefficient (Kow) of methylmercury was determined at pH 7 in water and in aqueous solutions ranging from 0.0003 to 0.6000 M in sodium chloride. It was also determined over a pH range of 2 to 10 with a fixed sodium chloride concentration of 0.0045 M. In these experiments,Kowwas seen to increase with increasing chloride concentrations in the range 0.0 to 0.075 M and to decrease with increasing pH above 7. Results were similar whether low levels of methylmercuric chloride or methylmercuric hydroxide were used as the starting materials. Partitioning was not affected by changes in ionic strengt

ISSN:0730-7268    

DOI:10.1002/etc.5620100102

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractTwo sparging devices have been designed, built, and tested. They can be used to estimate the concentration of truly dissolved chemical in water and thus the potential for diffusive transfer by volatilization. Samples of air, and air contacted to achieve equilibrium with the water, are analyzed to give an unequivocal determination of the displacement of equilibrium between air and water. Essentially, the chemical's fugacity or partial pressure is measured. A theoretical treatment is presented. Exploratory test results in a wind‐wave tank and in the field are described and discussed. It is believed that these devices are of value for assessing the sorbed vs. dissolved condition of hydrophobic chemicals in natural waters that influences not only volatilization but also other diffusive processes such as bioconcentratio

ISSN:0730-7268    

DOI:10.1002/etc.5620100103

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractIngestion of contaminated food is considered the primary route of exposure in birds to agricultural chemicals. Routes of exposure other than ingestion are not often considered in risk assessments of agricultural chemicals to avian wildlife. However, recent studies demonstrated anorexic or avoidance behaviors in birds exposed to organophosphate (OP) insecticides. These behaviors would tend to limit exposure if ingestion alone were considered. The contribution, if any, of dermal, preening, and respiratory pathways to the exposure of birds to pesticides under field conditions is unknown. In addition, oral exposures are currently assessed in artificial environments that do not reflect real‐life exposure scenarios. To determine the relative contribution of these pathways and to assess exposures under ecological conditions, 270 northern bobwhite (Colinus virginianus) were exposed to simulated aerial crop applications of methyl parathion in an environmentally controlled wind tunnel. The wind tunnel environment consisted of a 25‐cm cotton plant canopy, a 5‐cm‐thick floor of silt‐loam, a temperature of 25°C, 50% RH, UV intensity similar to summer sunlight, and a wind speed of 3.2 km/h. Inhalation, preening, and dermal routes were isolated in groups of birds exposed to each application. Five birds from each group were collected at 1, 4, 8, 24, and 48 h post‐spray to determine cholinesterase (ChE) response to the exposures. Contaminated and uncontaminated darkling beetle (Tenebrio molitar) larvae were presented to free‐ranging sprayed birds in the wind tunnel to assess oral uptake. ChE response was determined at 4, 8, 24, and 48 h postspray. All exposures were replicated. All four routes contributed to the inhibition of brain ChE at different post‐spray periods. Dermal uptake and preening were major contributors to the overall dose and toxic response of birds to methyl parathion. Inhalation was the major route of exposure at 1 h post‐spray. At 4 h post‐spray, uptake through preening caused the greatest inhibition of brain ChE activity. Oral ingestion resulted in less than 20% inhibition of brain ChE during the test. Routes of uptake in order of contribution to toxicologic response from 8 to 48 h post‐spray were dermal>pree

ISSN:0730-7268    

DOI:10.1002/etc.5620100104

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractAmphipods,Diporeiasp., were exposed to a reference sediment dosed with two radiolabeled polycyclic aromatic hydrocarbons (PAHs) and sediments dosed with a mixture of PAHs at four concentrations: 21.4, 41.0, 119.6, and 327.0 nmol g−1dry sediment, as the molar sum of the PAH congeners.Diporeiasp. were sampled for mortality and toxicokinetics for up to 26 d. Significant sediment avoidance was observed at the highest dose out to 6 d of exposure. The toxicity for the mixture was 38 ± 3% after 19 d of exposure at the highest dose, 327 nmol g−1dry sediment as the molar sum of the PAHs. The measured organism concentration required to produce the mortality at day 19 was 2.9 μmol g−1as the sum of the bioaccumulated PAHs. The uptake clearance (g dry sediment g−1organism h−1) from sediments for the radiotracers increased with dose to an apparent plateau. Uptake clearance is the conditional constant relating the contaminant flux into the organism to the contaminant concentration in the referenced environmental compartment, in this case the sediment. This enhanced bioavailability with dose occurred even in the absence of overt effects and in the absence of changes in the measured partition coefficients for phenanthrene (273 ± 98) and pyrene (540 ± 212), between the freely dissolved radiotracers in interstitial water and the sediment particles. These changes in bioavailability with changes in PAH concentration suggest that predictions of bioaccumulation of PAH congeners from sediments under different field concentration conditions will not be possible with standard partitioning

ISSN:0730-7268    

DOI:10.1002/etc.5620100105

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThis study evaluated the technical feasibility of a shorter alternative to the U.S. Environmental Protection Agency (EPA)‐recommended 7‐d chronic toxicity test withCeriodaphnia dubia.The results of 4‐d and 7‐dCeriodaphnia dubiatoxicity tests, conducted concurrently, were compared using treated municipal effluent, metals, PCP, ethylene glycol, phenol and surfactants. The experimental technique was similar for both studies with the exception of the duration and age of the test species at test initiation. The 4‐d static‐renewal test was initiated with 3‐day‐oldCeriodaphnia dubia, and 1‐day‐old organisms were used in the 7‐d tests. The chronic values of the replicated studies, based on survival and young production, were within a factor of two in approximately 70% of the total tests conducted and in all tests conducted with municipal effluent. Based on the available results, the 4‐d toxicity study appears to be a technically valid alternative to the EPA‐recommended 7‐day test, particularly for treated municipal effluent. An important factor in toxicity testing is the use of valid statistical procedures. The validity of the various methods forCeriodaphnia dubiadepends upon their appropriate use; however, it is difficult to justify the widespread use of multiple comparison methods, parti

ISSN:0730-7268    

DOI:10.1002/etc.5620100106

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractIn this investigation the effects of chlorophenols on rat liver mitochondrial respiratory parameters were determined and compared to the toxicities of those compounds in a variety of biological systems currently being used for toxicity testing. Mitochondrial fractions were exposed to six concentrations of five different chlorophenols in a semiclosed, 2‐ml reaction vessel. Respiratory parameters were measured polarographically with an oxygen electrode and compared to control experiments. The toxicity of the chlorophenols, as measured by the concentration reducing the respiratory control ratio of the control to 50% (RCR50), increased with increasing chloro substitution. RCR50 concentrations ranged from 599 μM with 2‐chlorophenol to 0.110 μM with pentachlorophenol.The RCR50 concentrations for the five chlorophenols were compared to six physicochemical parameters for the same chlorophenols; high degrees of correlation between the RCR50 concentrations and the physicochemical parameters were found (r≥ 0.890). The highest correlation coefficient obtained was with then‐octanol/water partition coefficient (r= 0.991), indicating that the ability of chlorophenols to partition into the lipid mitochondrial membrane plays a significant role in eliciting its toxic effect. RCR50 concentrations were also compared to nine currently existing short‐term toxicity tests. High degrees of correlation were obtained with several of the tests, including algal, bacterial, and fish bioassays. This suggests that the uncoupling of oxidative phosphorylation may be the major mechanism by which chlorophenols cause toxicity to intact cells as well as more complex organisms.The use of mitochondrial respiratory parameters appears to offer a complementary approach as a short‐term toxicity test for this class of compounds. Further development and testing with a variety of other toxicants

ISSN:0730-7268    

DOI:10.1002/etc.5620100107

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractWater quality‐based limits are receiving greater emphasis in National Pollutant Discharge Elimination System permits. These permits often contain requirements for conducting acute or chronic toxicity tests of wastewater and/or ambient receiving waters. In this paper, we analyze the effort (in person‐hours per test‐ph/t) required to conduct the 7‐d fathead minnow (Pimephales pro‐melas) larval survival and growth test, the 7‐dCeriodaphnia dubiasurvival and reproduction test, and various tasks that are associated with these two static‐renewal tests (e.g., maintaining cultures of the test animals, water chemistry analyses, quality assurance/quality control needs, sampling, and reporting). This analysis shows that all of these tasks require 53.6 ph/t. For six samples (e.g., five ambient samples plus a control, or five concentrations of an effluent plus a control), the fathead minnow test requires 6.9 ph/t and theCeriodaphniatest requires 5.8 ph/t. The effort needed to maintain fathead minnow cultures is approximately equal to that needed to maintainC. dubiacultures (5.6 vs. 5.8 ph/t). Effort expended on other components of the testing includes 7.0 ph/t for water chemistry analyses (six samples), 5.5 ph/t for test preparation and takedown, 4.0 ph/t for QA/QC, 6.0 ph/t for report writing, and 7.0 ph/t for sampling. In addition, the analysis explores the economies of scale in conducting the two toxicity tests. Finally, the study provides guidance for those who plan to conduct these tests and for those sponsors who may need a better understanding of the basis for the c

ISSN:0730-7268    

DOI:10.1002/etc.5620100108

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractLaboratory bioassay experiments were conducted with juvenile rainbow trout (Oncorhynchus mykiss) to determine the acute lethal (96‐h LC50) values of the forest‐use herbicides Garlon 3A®, Garlon 4®, and Vision® with 15% and 10% surfactant formulations, and the threshold concentrations of these herbicides that would cause behavioral effects. A Y‐maze apparatus was used to determine the threshold concentration of each herbicide that elicited either an avoidance or a preference reaction from rainbow trout fry after a one‐hour exposure period. Rainbow trout fry were observed for qualitative behavioral changes (e.g., increased coughing and ventilatory rates, loss of equilibrium, etc.) over a four‐day period of exposure to a wide range of chemical strengths. Nominal concentrations of the herbicides eliciting threshold avoidance reactions in test fish were 150 ppm Vision‐10% surfactant, 54 ppm Vision‐15% surfactant, 19.2 ppm Garlon 4, and 800 ppm Garlon 3A, which were, respectively, 2, 2, 8, and 2 times the 96‐h LC50 values determined for each herbicide. Preferential reactions to the herbicide solutions were not observed. Qualitative behavioral changes were observed in rainbow trout fry at levels from 25% (Garlon 4) to 50% (Garlon 3A, Vision‐10% and ‐15% surfactants) of the 96‐h LC50 values. Nominal concentrations of the herbicides causing threshold changes in fish behavior were 37.5 ppm Vision‐10% surfactant, 13.5 ppm Vision‐15% surfactant, 0.60 ppm Gar

ISSN:0730-7268    

DOI:10.1002/etc.5620100109

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractJuvenile coho salmon (Oncorhynchus kisutch) were exposed for 4 h to sublethal concentrations of the herbicides Garlon 4®, Garlon 3A®, and Vision®. Trials were performed in a closed‐system respirometer that measured oxygen consumption of fish prior to and during a 4‐h exposure. At the end of the exposure period, plasma glucose and lactate concentrations, hematocrit, and leucocrit were measured as indicators of acute physiological stress. There were no biologically significant indications of acute physiological stress in fish exposed to Garlon 4, Garlon 3A, or Vision at 5 to 80% of the 96‐h LC50 concentrations. The results suggest that threshold herbicide concentrations causing physiological stress in short‐term exposure (4 h) in juvenile coho salmon may be higher than the 96‐h LC50 value for those herbicides. It was concluded that sublethal concentrations of Garlon and Vision herbicides do not induce significant physiological stress responses in juvenile coho salmon during a 4‐h e

ISSN:0730-7268    

DOI:10.1002/etc.5620100110

出版商:Wiley Periodicals, Inc.    

年代:1991

数据来源: WILEY