RESUMEN
Since recognizing the importance of bioavailability for understanding the toxicity of chemicals in sediments, mechanistic modeling has advanced over the last 40 years by building better tools for estimating exposure and making predictions of probable adverse effects. Our review provides an up-to-date survey of the status of mechanistic modeling in contaminated sediment toxicity assessments. Relative to exposure, advances have been most substantial for non-ionic organic contaminants (NOCs) and divalent cationic metals, with several equilibrium partitioning-based (Eq-P) models having been developed. This has included the use of Abraham equations to estimate partition coefficients for environmental media. As a result of the complexity of their partitioning behavior, progress has been less substantial for ionic/polar organic contaminants. When the EqP-based estimates of exposure and bioavailability are combined with water-only effects measurements, predictions of sediment toxicity can be successfully made for NOCs and selected metals. Both species sensitivity distributions and toxicokinetic and toxicodynamic models are increasingly being applied to better predict contaminated sediment toxicity. Furthermore, for some classes of contaminants, such as polycyclic aromatic hydrocarbons, adverse effects can be modeled as mixtures, making the models useful in real-world applications, where contaminants seldomly occur individually. Despite the impressive advances in the development and application of mechanistic models to predict sediment toxicity, several critical research needs remain to be addressed. These needs and others represent the next frontier in the continuing development and application of mechanistic models for informing environmental scientists, managers, and decisions makers of the risks associated with contaminated sediments. Environ Toxicol Chem 2023;00:1-17. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
RESUMEN
During toxicity testing, chemical analyses of oil and exposure media samples are needed to allow comparison of results between different tests as well as to assist with identification of the drivers and mechanisms for the toxic effects observed. However, to maximize the ability to compare results between different laboratories and biota, it has long been recognized that guidelines for standard protocols were needed. In 2005, the Chemical Response to Oil Spills: Ecological Effects Research Forum (CROSERF) protocol was developed with existing common analytical methods that described a standard method for reproducible preparation of exposure media as well as recommended specific analytical methods and analyte lists for comparative toxicity testing. At the time, the primary purpose for the data collected was to inform oil spill response and contingency planning. Since then, with improvements in both analytical equipment and methods, the use of toxicity data has expanded to include their integration into fate and effect models that aim to extend the applicability of lab-based study results to make predictions for field system-level impacts. This paper focuses on providing a summary of current chemical analyses for characterization of oil and exposure media used during aquatic toxicity testing and makes recommendations for the minimum analyses needed to allow for interpretation and modeling purposes.
Asunto(s)
Contaminación por Petróleo , Petróleo , Contaminantes Químicos del Agua , Petróleo/toxicidad , Contaminantes Químicos del Agua/toxicidad , Pruebas de Toxicidad/métodos , Contaminación por Petróleo/análisis , Agua/químicaRESUMEN
Photo-induced toxicity of petroleum products and polycyclic aromatic compounds (PACs) is the enhanced toxicity caused by their interaction with ultraviolet radiation and occurs by two distinct mechanisms: photosensitization and photomodification. Laboratory approaches for designing, conducting, and reporting of photo-induced toxicity studies are reviewed and recommended to enhance the original Chemical Response to Oil Spills: Ecological Research Forum (CROSERF) protocols which did not address photo-induced toxicity. Guidance is provided on conducting photo-induced toxicity tests, including test species, endpoints, experimental design and dosing, light sources, irradiance measurement, chemical characterization, and data reporting. Because of distinct mechanisms, aspects of photosensitization (change in compound energy state) and photomodification (change in compound structure) are addressed separately, and practical applications in laboratory and field studies and advances in predictive modeling are discussed. One goal for developing standardized testing protocols is to support lab-to-field extrapolations, which in the case of petroleum substances often requires a modeling framework to account for differential physicochemical properties of the constituents. Recommendations are provided to promote greater standardization of laboratory studies on photo-induced toxicity, thus facilitating comparisons across studies and generating data needed to improve models used in oil spill science.
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Contaminación por Petróleo , Petróleo , Hidrocarburos Policíclicos Aromáticos , Compuestos Policíclicos , Contaminantes Químicos del Agua , Petróleo/toxicidad , Petróleo/análisis , Rayos Ultravioleta , Contaminantes Químicos del Agua/toxicidad , Hidrocarburos Policíclicos Aromáticos/análisis , Compuestos Orgánicos , Contaminación por Petróleo/análisisRESUMEN
Standardized oil toxicity testing is important to ensure comparability of study results, and to generate information to support oil spill planning, response, and environmental assessments. Outcomes from toxicity tests are useful in the development, improvement and validation of effects models, and new or revised knowledge could be integrated into existing databases and related tools. To foster transparency, facilitate repeatability and maximize use and impact, outcomes from toxicity tests need to be clearly reported and communicated. This work is part of a series of reviews to support the modernization of the "Chemical Response to Oil Spills: Ecological Effects Research Forum" protocols focusing on technological advances and best toxicity testing practices. Thus, the primary motivation of the present work is to provide guidance and encourage detailed documentation of aquatic toxicity studies. Specific recommendations are provided regarding key reporting elements (i.e., experimental design, test substance and properties, test species and response endpoints, media preparation, exposure conditions, chemical characterization, reporting metric corresponding to the response endpoint, data quality standards, and statistical methods, and raw data), which along with a proposed checklist can be used to assess the completeness of reporting elements or to guide study conduct. When preparing journal publications, authors are encouraged to take advantage of the Supplementary Material section to enhance dissemination and access to key data and information that can be used by multiple end-users, including decision-makers, scientific support staff and modelers. Improving reporting, science communication, and access to critical information enable users to assess the reliability and relevance of study outcomes and increase incorporation of results gleaned from toxicity testing into tools and applications that support oil spill response decisions. Furthermore, improved reporting could be beneficial for audiences outside the oil spill response community, including peer reviewers, journal editors, aquatic toxicologists, researchers in other disciplines, and the public.
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Contaminación por Petróleo , Contaminantes Químicos del Agua , Humanos , Reproducibilidad de los Resultados , Contaminantes Químicos del Agua/toxicidad , Pruebas de Toxicidad , ComunicaciónRESUMEN
Biocides used in offshore oil and gas operations could be present in water discharges, and thus identifying such chemicals and their hazard could help address concerns regarding non-target organisms. Aquatic toxicity data, queried from different sources and augmented with predictive models, were used to develop species sensitivity distributions and their corresponding 5th percentile hazard concentrations (HC5s). Curated data, including over 1000 empirical records for 137 species, indicated no evidence of bias when comparing sensitivity between marine and freshwater species, even when predicted data were used. HC5s facilitated estimation of an acute-to-chronic ratio (ACR = 10), appropriate for most chemicals and useful in filling data gaps. Comparison of chronic-HC5s with the default approach for deriving predicted no effect concentrations showed that the latter systematically overstates aquatic hazard. The present approach shows promise of using acute-to-chronic HC5 ratios for defining assessment factors for different chemical classes, instead of the use of generic assessment factors.
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Desinfectantes , Contaminantes Químicos del Agua , Organismos Acuáticos , Desinfectantes/toxicidad , Agua Dulce , Medición de Riesgo , Especificidad de la Especie , Agua , Contaminantes Químicos del Agua/toxicidadRESUMEN
Predictive toxicity models, including interspecies correlation estimation (ICE) models, are reliable alternatives to animal toxicity testing. The ICE models describe mathematical relationships facilitating toxicity prediction from one surrogate test species to a species of unknown sensitivity. The ICE models were developed from curated aquatic toxicity data for 19 nonionic alcohol ethoxylate (AE) surfactants manufactured through the same process. Comparison of AE-ICE predictions with observed values from external validation datasets indicates a reasonable predictive accuracy. Model predictions were also closer to observed values than predictions from previously published ICE models for other substance groups. Comparison of acute fifth percentile hazard concentrations (HC5s) from species sensitivity distributions enhanced with AE-ICE predictions with chronic HC5s published elsewhere produced an acute-to-chronic ratio of 5, which was used to estimate chronic HC5s. With both acute and chronic HC5s for 14 AE substances, regressions were made relative to their respective liposome-water partitioning coefficients (log K lipw ), resulting in HC5-log K lipw relationships useful in estimating HC5s for AE substances with known composition but with limited or unavailable toxicity data. The findings from this case study further demonstrate that ICE models are viable alternatives to toxicity testing and could be used as weight of evidence in hazard assessment evaluations. Environ Toxicol Chem 2021;40:2073-2082. © 2021 SETAC.
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Contaminantes Químicos del Agua , Animales , Sensibilidad y Especificidad , Especificidad de la Especie , Tensoactivos/toxicidad , Pruebas de Toxicidad , Contaminantes Químicos del Agua/toxicidadRESUMEN
The Amphibian Metamorphosis Assay (AMA) is used to identify substances that potentially interfere with the normal function of the hypothalamic-pituitary-thyroid (HPT) axis. Although numerous AMA studies have been performed since the establishment of this assay a decade earlier, a comprehensive, large-scale examination of histopathology data obtained from control larvae has not been performed. The current investigation reviewed 51 AMA experiments conducted at 7 different laboratories in Europe and North America. Dilution water control and/or solvent control specimens from each study (1,335 animals total) had been evaluated microscopically by one of eight anatomic pathologists. In order of descending frequency, the most common findings in prometamorphic Xenopus laevis controls were the core criteria of follicular cell (FC) hypertrophy, FC hyperplasia, thyroid hypertrophy, and thyroid atrophy, respectively. Less frequently recorded were non-core and ad hoc diagnoses, the toxicological relevance and utility of which were in some cases uncertain. As anticipated, the prevalence of FC hypertrophy and FC hyperplasia diagnoses were at least partially dependent on the Nieuwkoop and Faber (NF) stage at sacrifice. The recorded frequencies of each of the four core diagnoses also differed according to pathologist, which suggests that pathologist diagnostic interpretation is a potential source of variability across AMA study outcomes. Based on the current examination of the AMA historical data, and further hands-on experience with this assay, diagnostic approaches to evaluating the histopathology endpoint are discussed, and several recommendations are proposed for the refinement of core diagnostic criteria assessment.
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Metadatos , Glándula Tiroides , Animales , Hiperplasia , Hipertrofia , Xenopus laevisRESUMEN
Routine whole effluent toxicity (WET) testing is commonly used to monitor effluent discharges for regulatory compliance in North America. However, the use of fish in WET testing raises ethical concerns and therefore an important question to be explored is whether invertebrates can be used to reduce and/or replace the need for vertebrate testing. The present study evaluated WET data collected for regulatory compliance between 2003 and 2019 (n = 2581 endpoints) from 20 different stationary onshore and offshore oil and gas facilities located across Canada and the United States. Our objective was to assess the relative sensitivity between vertebrates (i.e., fish) and invertebrates in paired samples and to evaluate trends in WET compliance. Despite the variability in testing endpoints, invertebrates displayed equal to or greater sensitivity to tested effluents than fish. For example, based on no-observed-effect concentrations for survival and growth, Americamysis bahia was found to be protective of Menidia beryllina in 90% of endpoint comparisons (n = 336). The results also indicated that regulatory compliance was high (94-100%), with most WET tests passing the established criteria by large margins (79-251%). The results of this comprehensive analysis of historical WET data can be used to improve future permit testing requirements and help answer the question of whether fish tests are needed for routine WET testing. Environ Toxicol Chem 2021;40:1255-1265. © 2020 SETAC.
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Contaminantes Químicos del Agua , Animales , Crustáceos , Peces , Invertebrados , Pruebas de Toxicidad , Estados Unidos , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidadRESUMEN
The majority of aquatic toxicity data for petroleum products has been limited to a few intensively studied crude oils and Corexit chemical dispersants, and acute toxicity testing in two standard estuarine test species: mysids (Americamysis bahia) and inland silversides (Menidia beryllina). This study compared the toxicity of two chemical dispersants commonly stock piled for spill response (Corexit EC9500A®, Finasol®OSR 52), three less studied agents (Accell Clean®DWD dispersant; CytoSol® surface washing agent; Gelco200® solidifier), and three crude oils differing in hydrocarbon composition (Dorado, Endicott, Alaska North Slope). Consistent with listings on the U.S. National Contingency Plan Product Schedule, general rank order toxicity was greatest for dispersants and lowest for the solidifier. The results indicate that freshwater species can have similar sensitivity as the conventionally tested mysids and silversides, and that the sea urchin (Arbacia punctulata) appears to be a reasonable addition to increase taxa diversity in standardized oil agent testing.
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Contaminación por Petróleo , Petróleo/toxicidad , Contaminantes Químicos del Agua/toxicidad , Alaska , Animales , Organismos Acuáticos/efectos de los fármacos , Tensoactivos/toxicidad , Pruebas de Toxicidad AgudaRESUMEN
Limited species diversity in aquatic toxicity data for most current-use dispersants leads to uncertainties in hazard assessments, which impacts the broader discussion on dispersant use. Sufficient toxicity data are available for a re-evaluation of previously developed dispersant-interspecies correlation estimation (ICE) models. These models increase species diversity because toxicity predictions for untested species are made from the known toxicity for surrogates. Data were used to refine 4 and develop 25 new dispersant-ICE models. Most of the new models are for species not included in the >2000 existing ICE models, and contain a higher species diversity than the original dispersant-ICE models (19 vs 7 species). Dispersant-ICE models predict toxicity with reasonably accuracy: predictions were within 3-fold of observed values (new models: 70% of 132 predictions; refined models: 88% of 83 predictions), and species sensitivity distributions developed with ICE-predicted data only were in most cases not statistically significantly different from those developed with empirical data (83% of 23 paired comparisons). Examples of the practical application of dispersant-ICE models, including laboratory-to-field comparisons within the context of operational dispersant application rates, are also presented. The significance of these results is that dispersant-ICE models could fill gaps in species diversity, and thus help to address concerns about species sensitivities related to the use of dispersants. Environ Toxicol Chem 2019;38:1682-1691. © 2019 SETAC.
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Organismos Acuáticos/efectos de los fármacos , Modelos Teóricos , Tensoactivos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Sensibilidad y Especificidad , Especificidad de la Especie , IncertidumbreRESUMEN
Oil spill response requires consideration of several countermeasures including chemical dispersants, but their potential toxicity to aquatic species poses a concern. Considerable in vivo aquatic toxicity data from laboratory exposures have been generated since 2010 for current-use dispersants. The objective of the present review is to provide a synthesis of these data to improve dispersant hazard assessments. Data from multiple studies were evaluated based on reliability criteria. Although procedures, standards, endpoints, and statistical approaches were usually described, nearly a quarter of sources did not provide sufficient information to judge study quality but were considered on a case-by-case basis. Data were used to develop dispersant-specific species sensitivity distributions and hazard concentrations protective of 95% of the species (HC5). Given data limitations, post-2010 toxicity data were augmented with pre-2010 data and model predictions. The HC5s calculated for 54 dispersants fell mostly within the moderate to slightly toxic range and were compared to field dispersant-only concentrations estimated from operational application rates under conservative assumptions. Based on available evidence, dispersants may not pose a significant risk under field conditions to most aquatic species, if proper application and dilution are taken into account. Recommendations on improved toxicity testing and reporting as well as research needs are also provided. Environ Toxicol Chem 2018;37:2989-3001. © 2018 SETAC.
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Organismos Acuáticos/efectos de los fármacos , Contaminación por Petróleo/análisis , Pruebas de Toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Especificidad de la Especie , Contaminantes Químicos del Agua/análisisRESUMEN
The risks to Arctic species from oil releases is a global concern, but their sensitivity to chemically dispersed oil has not been assessed using a curated and standardized dataset from spiked declining tests. Species sensitivity to dispersed oil was determined by their position within species sensitivity distributions (SSDs) using three measures of hydrocarbon toxicity: total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbon (PAHs), and naphthalenes. Comparisons of SSDs with Arctic/sub-Arctic versus non-Arctic species, and across SSDs of compositionally similar oils, showed that Arctic and non-Arctic species have comparable sensitivities even with the variability introduced by combining data across studies and oils. Regardless of hydrocarbon measure, hazard concentrations across SSDs were protective of sensitive Arctic species. While the sensitivities of Arctic species to oil exposures resemble those of commonly tested species, PAH-based toxicity data are needed for a greater species diversity including sensitive Arctic species.
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Naftalenos/toxicidad , Petróleo/toxicidad , Hidrocarburos Policíclicos Aromáticos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Regiones ÁrticasRESUMEN
The Chemical Aquatic Fate and Effects (CAFE) database is a tool that facilitates assessments of accidental chemical releases into aquatic environments. CAFE contains aquatic toxicity data used in the development of species sensitivity distributions (SSDs) and the estimation of hazard concentrations (HCs). For many chemicals, gaps in species diversity and toxicity data limit the development of SSDs, which may be filled with Interspecies Correlation Estimation (ICE) models. Optimization of ICE model selection and integration ICE-predicted values into CAFE required a multistep process that involved the use of different types of data to assess their influence on SSDs and HC estimates. Results from multiple analyses showed that SSDs supplemented with ICE-predicted values generally produced HC5 estimates that were within a 3-fold difference of estimates from measured SSDs (58%-82% of comparisons), but that were often more conservative (63%-76% of comparisons) and had lower uncertainty (90% of comparisons). ICE SSDs did not substantially underpredict toxicity (<10% of comparisons) when compared to estimates from measured SSD. The incorporation of ICE-predicted values into CAFE allowed the development of >800 new SSDs, increased diversity in SSDs by an average of 34 species, and augmented data for priority chemicals involved in accidental chemical releases.
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Bases de Datos Factuales , Especificidad de la Especie , Contaminantes Químicos del Agua/toxicidad , Medición de Riesgo , IncertidumbreRESUMEN
Sand beaches are highly dynamic habitats that can experience considerable impacts from oil spills. This review provides a synthesis of the scientific literature on major oil spills and their impacts on sand beaches, with emphasis on studies documenting effects and recoveries of intertidal invertebrate communities. One of the key observations arising from this review is that more attention has generally been given to studying the impacts of oil spills on invertebrates (mostly macrobenthos), and not to documenting their biological recovery. Biological recovery of sand beach invertebrates is highly dynamic, depending on several factors including site-specific physical properties and processes (e.g., sand grain size, beach exposure), the degree of oiling, depth of oil burial, and biological factors (e.g., species-specific life-history traits). Recovery of affected communities ranges from several weeks to several years, with longer recoveries generally associated with physical factors that facilitate oil persistence, or when cleanup activities are absent on heavily oiled beaches. There are considerable challenges in quantifying impacts from spills on sand beach invertebrates because of insufficient baseline information (e.g., distribution, abundance and composition), knowledge gaps in their natural variability (spatial and temporal), and inadequate sampling and replication during and after oil spills. Thus, environment assessments of impacts and recovery require a rigorous experimental design that controls for confounding sources of variability. General recommendations on sampling strategies and toxicity testing, and a preliminary framework for incorporating species-specific life history traits into future assessments are also provided.
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Ecosistema , Invertebrados/efectos de los fármacos , Contaminación por Petróleo/efectos adversos , Animales , Dióxido de SilicioRESUMEN
Interspecies correlation estimation (ICE) models were developed for 30 nonpolar aromatic compounds to allow comparison of prediction accuracy between 2 data compilation approaches. Type 1 models used data combined across studies, and type 2 models used data combined only within studies. Target lipid (TLM) ICE models were also developed using target lipid concentrations of the type 2 model dataset (type 2-TLM). Analyses were performed to assess model prediction uncertainty introduced by each approach. Most statistically significant models (90%; 266 models total) had mean square errors < 0.27 and adjusted coefficients of determination (adj R(2) ) > 0.59, with the lowest amount of variation in mean square errors noted for type 2-TLM followed by type 2 models. Cross-validation success (>0.62) across most models (86% of all models) confirmed the agreement between ICE predicted and observed values. Despite differences in model predictive ability, most predicted values across all 3 ICE model types were within a 2-fold difference of the observed values. As a result, no statistically significant differences (p > 0.05) were found between most ICE-based and empirical species sensitivity distributions (SSDs). In most cases hazard concentrations were within or below the 95% confidence intervals of the direct-empirical SSD-based values, regardless of model choice. Interspecies correlation estimation-based 5th percentile (HC5) values showed a 200- to 900-fold increase as the log KOW increased from 2 to 5.3. Results indicate that ICE models for aromatic compounds provide a statistically based approach for deriving conservative hazard estimates for protecting aquatic life.
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Hidrocarburos Aromáticos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Contaminación Química del Agua/efectos adversos , Algoritmos , Animales , Organismos Acuáticos , Monitoreo del Ambiente/métodos , Monitoreo del Ambiente/estadística & datos numéricos , Hidrocarburos Aromáticos/química , Dosificación Letal Mediana , Metabolismo de los Lípidos , Modelos Biológicos , Reproducibilidad de los Resultados , Especificidad de la Especie , Contaminantes Químicos del Agua/químicaRESUMEN
The Chemical Aquatic Fate and Effects (CAFE) database is a centralized repository that allows for rapid and unrestricted access to data. Information in CAFE is integrated into a user-friendly tool with modules containing fate and effects data for 32 377 and 4498 chemicals, respectively. Toxicity data are summarized in the form of species sensitivity distributions (SSDs) with associated 1st and 5th percentile hazard concentrations (HCs). An assessment of data availability relative to reported chemical incidents showed that CAFE had fate and toxicity data for 32 and 20 chemicals, respectively, of 55 chemicals reported in the US National Response Center database (2000-2014), and fate and toxicity data for 86 and 103, respectively, of 205 chemicals reported by the National Oceanic and Atmospheric Administration (2003-2014). Modeled environmental concentrations of 2 hypothetical spills (acrylonitrile, 625 barrels; and denatured ethanol, 857 barrels) were used to demonstrate CAFE's practical application. Most species in the 24-h SSD could be potentially impacted by acrylonitrile and denatured ethanol during the first 35 min and 15 h post spill, respectively, with concentrations falling below their HC5s (17 mg/L and 2676 mg/L) at 45 min and 60 h post spill, respectively. Comparisons of CAFE-based versus published HC5 values for 100 chemicals showed that nearly half of values were within a 2-fold difference, with a relatively small number of comparisons exceeding a 10-fold difference. The development of CAFE facilitates access to relevant environmental information, with potential uses likely expanding beyond those related to assessment of spills in aquatic environments. Environ Toxicol Chem 2016;35:1576-1586. © 2015 SETAC.
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Liberación de Peligros Químicos , Bases de Datos Factuales , Contaminantes Químicos del Agua/metabolismo , Acrilonitrilo/metabolismo , Acrilonitrilo/toxicidad , Animales , Organismos Acuáticos/efectos de los fármacos , Bases de Datos de Compuestos Químicos , Etanol/metabolismo , Etanol/toxicidad , Internet , Medición de Riesgo , Interfaz Usuario-Computador , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/toxicidadRESUMEN
A three dimensional (3D) trajectory model was used to simulate oil mass balance and environmental concentrations of two 795,000 L hypothetical oil spills modeled under physical and chemical dispersion scenarios. Species Sensitivity Distributions (SSD) for Total Hydrocarbon Concentrations (THCs) were developed, and Hazard Concentrations (HC) used as levels of concern. Potential consequences to entrained water column organisms were characterized by comparing model outputs with SSDs, and obtaining the proportion of species affected (PSA) and areas with oil concentrations exceeding HC5s (Area ⩾ HC5). Under the physically-dispersed oil scenario ⩽ 77% of the oil remains on the water surface and strands on shorelines, while with the chemically-dispersed oil scenario ⩽ 67% of the oil is entrained in the water column. For every 10% increase in chemical dispersion effectiveness, the average PSA and Area ⩾ HC5 increases (range: 0.01-0.06 and 0.50-2.9 km(2), respectively), while shoreline oiling decreases (⩽ 2919 L/km). Integrating SSDs into modeling may improve understanding of scales of potential impacts to water column organisms, while providing net environmental benefit comparison of oil spill response options.
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Monitoreo del Ambiente/métodos , Modelos Teóricos , Contaminación por Petróleo , Organismos Acuáticos/fisiología , Ambiente , Sensibilidad y Especificidad , Contaminantes Químicos del Agua/análisisRESUMEN
Assessing the acute toxicity of oil has generally relied on existing toxicological data for a relatively few standard test species, which has limited the ability to estimate the impacts of spilled oil on aquatic communities. Interspecies correlation estimation (ICE) models were developed for petroleum and dispersant products to facilitate the prediction of toxicity values to a broader range of species and to better understand taxonomic differences in species sensitivity. ICE models are log linear regressions that can be used to estimate toxicity to a diversity of taxa based on the known toxicity value for a surrogate tested species. ICE models have only previously been developed for nonpetroleum chemicals. Petroleum and dispersant ICE models were statistically significant for 93 and 16 unique surrogate-predicted species pairs, respectively. These models had adjusted coefficient of determinations (adj-R(2)), square errors (MSE) and positive slope ranging from 0.29 to 0.99, 0.0002 to 0.311, and 0.187 to 2.665, respectively. Based on model cross-validation, predicted toxicity values for most ICE models (>90%) were within 5-fold of the measured values, with no influence of taxonomic relatedness on prediction accuracy. A comparison between hazard concentrations (HC) derived from empirical and ICE-based species sensitivity distributions (SSDs) showed that HC values were within the same order of magnitude of each other. These results show that ICE-based SSDs provide a statistically valid approach to estimating toxicity to a range of petroleum and dispersant products with applicability to oil spill assessment.
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Organismos Acuáticos/metabolismo , Monitoreo del Ambiente , Modelos Teóricos , Petróleo/análisis , Animales , Reproducibilidad de los Resultados , Especificidad de la EspecieRESUMEN
Aquatic toxicity considerations are part of the net environmental benefit analysis and approval decision process on the use of dispersants in the event of an offshore oil spill. Substantial information is available on the acute toxicity of physically and chemically dispersed oil to a diverse subset of aquatic species generated under controlled laboratory conditions. However, most information has been generated following standard laboratory practices, which do not realistically represent oil spill conditions in the field. The goal of the present quantitative review is to evaluate the use of standard toxicity testing data to help inform decisions regarding dispersant use, recognizing some key issues with current practices, specifically, reporting toxicity metrics (nominal vs measured), exposure duration (standard durations vs short-term exposures), and exposure concentrations (constant vs spiked). Analytical chemistry data also were used to demonstrate the role of oil loading on acute toxicity and the influence of dispersants on chemical partitioning. The analyses presented here strongly suggest that decisions should be made, at a minimum, based on measured aqueous exposure concentrations and, ideally, using data from short-term exposure durations under spiked exposure concentrations. Available data sets are used to demonstrate how species sensitivity distribution curves can provide useful insights to the decision-making process on dispersant use. Finally, recommendations are provided, including the adoption of oil spill-appropriate toxicity testing practices.