Development of short, acute exposure hazard estimates: A tool for assessing the effects of chemical spills in aquatic environments

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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

Section: Dispersant-ice Model Development and Verificationmentioning

confidence: 99%

Further Development and Refinement of Interspecies Correlation Estimation Models for Current-Use Dispersants

Bejarano¹

2019

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“…Dispersant-specific SSDs with data from at least 5 unique aquatic species were developed using the geometric mean of multiple reported toxicity values (LC50 and EC50) for single species based on similar exposure conditions (e.g., constant static) and durations (e.g., 96 h). All SSDs were assessed for goodness of fit (a ¼ 0.05) using the Kolmogorov-Smirnov, Anderson-Darling (n > 7 species), and Cramer-Von Mises (n > 7 species) test statistics (D' Agostino and Stephens 1986;Bejarano and Farr 2013). The SSDs and their fifth percentile HCs (HC5), or concentrations protective of 95% of the species assemblage, were estimated using the methodology outlined in detail elsewhere (Bejarano and Farr 2013).…”

Section: Comparative Assessments Of Toxicity Datamentioning

confidence: 99%

Critical review and analysis of aquatic toxicity data on oil spill dispersants

Bejarano¹

2018

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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.

Section: The Use Of Toxicity Data In Decision Makingmentioning

confidence: 99%

“…A tool that has gained acceptance among ecological risk assessors, and chemical and oil spill practitioners in particular, is the use of species sensitivity distributions (SSDs) . Species sensitivity distributions are cumulative distributions of laboratory‐derived toxicological endpoints (e.g., LC50, EC50; typically from the same exposure duration) for species used in testing programs that allow for comparisons of the relative sensitivities of several species to the same chemical .…”

Section: Introductionmentioning

confidence: 99%

“…These comparisons showed that LC50| EC50 values from 3-h exposures were between 3-fold and 981fold greater (less toxicity) than 96-h exposure values (most observations 60-fold greater), and between 2-fold and 62-fold greater than 24-h exposure values (most observations 12-fold greater). Related studies have also shown a negative decay relationship between time and toxicity endpoints [22,32,39] such that there are greater differences in effect concentrations at time steps under 24-h exposures, compared with time steps above 24 h, where toxicity values tend to stabilize. Consequent-ly, toxicity data from the more commonly tested standard exposure durations should be used with caution and, when possible, in combination with other data sources to make informed decisions regarding potential impacts of dispersant use that are not overly conservative.…”

mentioning

confidence: 96%

See 1 more Smart Citation

Issues and challenges with oil toxicity data and implications for their use in decision making: A quantitative review

Bejarano¹,

Clark²,

Coelho³

2014

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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. Environ Toxicol Chem 2014;33:732-742. # 2014 SETAC