The use of probabilistic risk assessment (PRA) for examining chemical impacts has become an impor... more The use of probabilistic risk assessment (PRA) for examining chemical impacts has become an important area of debate within the European Union. This paper describes a case study on probabilistic techniques to assess pesticide risks in the UK aquatic environment. The main aim of this paper is to demonstrate both the potential strengths and weaknesses of PRA for assessing pesticides when compared with the conventional deterministic approach, and to examine whether PRA is useful within the European regulatory context. The organophosphate insecticide, chlorpyrifos, was selected as a model compound and toxicity exposure ratios calculated using Monte Carlo analysis and different distributions of spray drift and toxicity values following application to top fruit. Chlorpyrifos is highly toxic to arthropods but less toxic to fishes. Species sensitivity followed a log-normal distribution when fitted to all toxicity data. Toxicity data quantity had little influence on species sensitivity distribution model parameters when n was greater than 10 species. Below this, estimates were less accurate and precise, possibly because of the inclusion of data from many different sources. Estimates of chlorpyrifos exposure derived from the standard spray drift model differed substantially from measurements of chlorpyrifos in European surface waters. When a distribution based on measured concentrations was used in a PRA, the risk of acute fish mortality was low, and the risk of acute arthropod mortality was lower than in other scenarios, although not negligible. If PRA is used to assess pesticides, risk managers need further guidance on how to conduct a PRA and what constitutes 'unacceptable risk' under EC Directive 91/414/EEC, as judgement is required when simple trigger values are no longer used.
Integrated environmental assessment and management, 2018
The US Environmental Protection Agency (USEPA) has historically used different methods to derive ... more The US Environmental Protection Agency (USEPA) has historically used different methods to derive an aquatic level of concern (LoC) for atrazine, though all have generally relied on an expanding set of mesocosm and microcosm ("cosm") studies for calibration. The database of results from ecological effects studies with atrazine in cosms now includes 108 data points from 39 studies and forms the basis for assessing atrazine's potential to impact aquatic plant communities. Inclusion of the appropriate cosm studies and accurate interpretation of each data point-delineated as binary scores of "effect" (effect score 1) or "no effect" (effect score 0) of a specific atrazine exposure profile on plant communities in a single study-is critical to USEPA's approach to determining the LoC. We reviewed the atrazine cosm studies in detail and carefully interpreted their results in terms of the binary effect scores. The cosm database includes a wide range of exp...
Chemical and physical differences between coal-derived oils (especially those produced by direct ... more Chemical and physical differences between coal-derived oils (especially those produced by direct liquefaction processes) and crude or refined petroleum would result in significant differences in the behavior of the oils after release into rivers or lakes. Phenolic compounds are abundant in many coal liquids but not in petroleum; these compounds dissolve rapidly in water and are toxic to aquatic life. Polycyclic aromatic hydrocarbons, aromatic amines, and other insoluble oil constituents could accumulate in bottom sediments, from which they could be taken up by organisms and cause long-term ecological effects. Through laboratory studies, simulation modeling, and field experiments, information has been developed that supports a preliminary evaluation of the potential environmental impacts of coal liquid spills. Releases of crude products into large rivers would probably cause relatively little immediate ecological damage, but spills in lakes, embayments, and other semienclosed water bodies could have serious effects. Product upgrading by hydrotreatment or distillation can be expected to reduce the environmental hazards of coal-derived oils.
Environmental Toxicology and Chemistry, Sep 1, 2002
Exposure to agrochemicals in the aquatic environment often occurs as time-varying or repeated pul... more Exposure to agrochemicals in the aquatic environment often occurs as time-varying or repeated pulses. Time-varying exposures may occur due to runoff events and spray drift associated with precipitation and application events. Hydrologic dilution, dispersion, and degradation also produce pulsed exposures. Standard laboratory toxicity tests using constant exposure concentrations typically do not investigate the toxicity of time-varying or repeated exposures. Detoxification, elimination, and recovery may occur within organisms or populations during the periods between exposures. The difficulty of estimating effects of realistic time-varying exposures from measurements made under constant exposure conditions is often an important source of uncertainty in ecological risk assessment of pesticides. This article discusses the criteria and tools for deciding whether time-varying exposures are relevant in a particular risk assessment, approaches for laboratory toxicity testing with time-varying exposure, modeling approaches for addressing effects oftime-varying exposure, deterministic and probabilistic ecological risk characterization of time-varyingexposures and toxicity, and uncertainty analysis.
ABSTRACT A derivative of musk xylene, 4-amino musk xylene, was tested for acute toxicity to Daphn... more ABSTRACT A derivative of musk xylene, 4-amino musk xylene, was tested for acute toxicity to Daphnia magna in laboratory water (hard water) and natural water (soft water). Tests with both water types were conducted using standard lighting and in continuous darkness. The 48-h EC50 ranged from 370 to 510 μg/l. These results are consistent with QSAR predictions and with previous results for 2-amino musk xylene, but inconsistent with a previous report for 4-amino musk xylene. The acute toxicity concentration for D. magna is approximately four orders of magnitude greater than concentrations of 4-amino musk xylene measured in surface waters and treated sewage.
Environmental toxicology and chemistry / SETAC, Jan 14, 2016
A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the ... more A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrins toxicity. PBO concentrations less than 4 µg/L caused no toxicity enhancement, while toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrins toxicity (decrease in median lethal concentration, LC50) of 1.4- to 1.6-fold and varied only slightly between 4 and 15 µg/L PBO, while direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. These results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. This article is protected by copyright. All rights reserved.
ABSTRACT A mesocosm study of pesticide effects was conducted between November 1987 and November 1... more ABSTRACT A mesocosm study of pesticide effects was conducted between November 1987 and November 1988 using 0 04-ha earthen ponds The bottoms of the ponds were covered with sediments from an old farm pond, filled with aged reservoir water, and stocked with fifty 11- to 17-cm blue-gill sunfish Importing mature communities rapidly produced taxonomically rich ecosystems Coefficients of variance among ponds for taxonomic richness and population densities were modest (typically 10–30%) and usually inversely related to abundance Unchecked bluegill reproduction resulted in expected effects on lower trophic levels Crustacean zooplankton were nearly eliminated, which led to poor growth of the juvenile bluegill Phytoplankton densities appeared to increase as grazing pressure from zooplankton was reduced Insect emergence was not obviously impacted by fish predation Potential indirect effects on fish, such as growth impairment caused by pesticide induced reduction of food supply, could be obscured if zooplankton were nearly eliminated by over-predation This suggests a need to control bluegill reproduction to achieve a more balanced ecosystem
Environmental Toxicology and Chemistry, May 1, 1996
... JEFFREY M. GIDDINGS,* RONALD C. BIEVER, MARIA F. ANNUNZIATO, and ALAN J. HOSMER Springbo... more ... JEFFREY M. GIDDINGS,* RONALD C. BIEVER, MARIA F. ANNUNZIATO, and ALAN J. HOSMER Springborn Laboratories, Inc., 790 Main Street, Wareham, Massachusetts 02571-1075, USA Ciba-Geigy Corporation, PO Box 18300 ... Phyto-plank-tonc Peri-phytond ...
The use of probabilistic risk assessment (PRA) for examining chemical impacts has become an impor... more The use of probabilistic risk assessment (PRA) for examining chemical impacts has become an important area of debate within the European Union. This paper describes a case study on probabilistic techniques to assess pesticide risks in the UK aquatic environment. The main aim of this paper is to demonstrate both the potential strengths and weaknesses of PRA for assessing pesticides when compared with the conventional deterministic approach, and to examine whether PRA is useful within the European regulatory context. The organophosphate insecticide, chlorpyrifos, was selected as a model compound and toxicity exposure ratios calculated using Monte Carlo analysis and different distributions of spray drift and toxicity values following application to top fruit. Chlorpyrifos is highly toxic to arthropods but less toxic to fishes. Species sensitivity followed a log-normal distribution when fitted to all toxicity data. Toxicity data quantity had little influence on species sensitivity distribution model parameters when n was greater than 10 species. Below this, estimates were less accurate and precise, possibly because of the inclusion of data from many different sources. Estimates of chlorpyrifos exposure derived from the standard spray drift model differed substantially from measurements of chlorpyrifos in European surface waters. When a distribution based on measured concentrations was used in a PRA, the risk of acute fish mortality was low, and the risk of acute arthropod mortality was lower than in other scenarios, although not negligible. If PRA is used to assess pesticides, risk managers need further guidance on how to conduct a PRA and what constitutes 'unacceptable risk' under EC Directive 91/414/EEC, as judgement is required when simple trigger values are no longer used.
Integrated environmental assessment and management, 2018
The US Environmental Protection Agency (USEPA) has historically used different methods to derive ... more The US Environmental Protection Agency (USEPA) has historically used different methods to derive an aquatic level of concern (LoC) for atrazine, though all have generally relied on an expanding set of mesocosm and microcosm ("cosm") studies for calibration. The database of results from ecological effects studies with atrazine in cosms now includes 108 data points from 39 studies and forms the basis for assessing atrazine's potential to impact aquatic plant communities. Inclusion of the appropriate cosm studies and accurate interpretation of each data point-delineated as binary scores of "effect" (effect score 1) or "no effect" (effect score 0) of a specific atrazine exposure profile on plant communities in a single study-is critical to USEPA's approach to determining the LoC. We reviewed the atrazine cosm studies in detail and carefully interpreted their results in terms of the binary effect scores. The cosm database includes a wide range of exp...
Chemical and physical differences between coal-derived oils (especially those produced by direct ... more Chemical and physical differences between coal-derived oils (especially those produced by direct liquefaction processes) and crude or refined petroleum would result in significant differences in the behavior of the oils after release into rivers or lakes. Phenolic compounds are abundant in many coal liquids but not in petroleum; these compounds dissolve rapidly in water and are toxic to aquatic life. Polycyclic aromatic hydrocarbons, aromatic amines, and other insoluble oil constituents could accumulate in bottom sediments, from which they could be taken up by organisms and cause long-term ecological effects. Through laboratory studies, simulation modeling, and field experiments, information has been developed that supports a preliminary evaluation of the potential environmental impacts of coal liquid spills. Releases of crude products into large rivers would probably cause relatively little immediate ecological damage, but spills in lakes, embayments, and other semienclosed water bodies could have serious effects. Product upgrading by hydrotreatment or distillation can be expected to reduce the environmental hazards of coal-derived oils.
Environmental Toxicology and Chemistry, Sep 1, 2002
Exposure to agrochemicals in the aquatic environment often occurs as time-varying or repeated pul... more Exposure to agrochemicals in the aquatic environment often occurs as time-varying or repeated pulses. Time-varying exposures may occur due to runoff events and spray drift associated with precipitation and application events. Hydrologic dilution, dispersion, and degradation also produce pulsed exposures. Standard laboratory toxicity tests using constant exposure concentrations typically do not investigate the toxicity of time-varying or repeated exposures. Detoxification, elimination, and recovery may occur within organisms or populations during the periods between exposures. The difficulty of estimating effects of realistic time-varying exposures from measurements made under constant exposure conditions is often an important source of uncertainty in ecological risk assessment of pesticides. This article discusses the criteria and tools for deciding whether time-varying exposures are relevant in a particular risk assessment, approaches for laboratory toxicity testing with time-varying exposure, modeling approaches for addressing effects oftime-varying exposure, deterministic and probabilistic ecological risk characterization of time-varyingexposures and toxicity, and uncertainty analysis.
ABSTRACT A derivative of musk xylene, 4-amino musk xylene, was tested for acute toxicity to Daphn... more ABSTRACT A derivative of musk xylene, 4-amino musk xylene, was tested for acute toxicity to Daphnia magna in laboratory water (hard water) and natural water (soft water). Tests with both water types were conducted using standard lighting and in continuous darkness. The 48-h EC50 ranged from 370 to 510 μg/l. These results are consistent with QSAR predictions and with previous results for 2-amino musk xylene, but inconsistent with a previous report for 4-amino musk xylene. The acute toxicity concentration for D. magna is approximately four orders of magnitude greater than concentrations of 4-amino musk xylene measured in surface waters and treated sewage.
Environmental toxicology and chemistry / SETAC, Jan 14, 2016
A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the ... more A series of acute toxicity tests with the amphipod Hyalella azteca was performed to quantify the synergistic effect of piperonyl butoxide (PBO) on pyrethrins toxicity. PBO concentrations less than 4 µg/L caused no toxicity enhancement, while toxicity increased with PBO concentrations between 4 µg/L and 15 µg/L. Additive toxicity calculations showed that true synergism accounted for an increase in pyrethrins toxicity (decrease in median lethal concentration, LC50) of 1.4- to 1.6-fold and varied only slightly between 4 and 15 µg/L PBO, while direct toxicity of PBO accounted for an additional increase in mixture toxicity (up to 3.2-fold) that was proportional to PBO concentration. These results can be used to assess the risk of measured or predicted co-occurring concentrations of PBO and pyrethrins in surface waters. This article is protected by copyright. All rights reserved.
ABSTRACT A mesocosm study of pesticide effects was conducted between November 1987 and November 1... more ABSTRACT A mesocosm study of pesticide effects was conducted between November 1987 and November 1988 using 0 04-ha earthen ponds The bottoms of the ponds were covered with sediments from an old farm pond, filled with aged reservoir water, and stocked with fifty 11- to 17-cm blue-gill sunfish Importing mature communities rapidly produced taxonomically rich ecosystems Coefficients of variance among ponds for taxonomic richness and population densities were modest (typically 10–30%) and usually inversely related to abundance Unchecked bluegill reproduction resulted in expected effects on lower trophic levels Crustacean zooplankton were nearly eliminated, which led to poor growth of the juvenile bluegill Phytoplankton densities appeared to increase as grazing pressure from zooplankton was reduced Insect emergence was not obviously impacted by fish predation Potential indirect effects on fish, such as growth impairment caused by pesticide induced reduction of food supply, could be obscured if zooplankton were nearly eliminated by over-predation This suggests a need to control bluegill reproduction to achieve a more balanced ecosystem
Environmental Toxicology and Chemistry, May 1, 1996
... JEFFREY M. GIDDINGS,* RONALD C. BIEVER, MARIA F. ANNUNZIATO, and ALAN J. HOSMER Springbo... more ... JEFFREY M. GIDDINGS,* RONALD C. BIEVER, MARIA F. ANNUNZIATO, and ALAN J. HOSMER Springborn Laboratories, Inc., 790 Main Street, Wareham, Massachusetts 02571-1075, USA Ciba-Geigy Corporation, PO Box 18300 ... Phyto-plank-tonc Peri-phytond ...
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