No abstract

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

No abstract

Oil spill response can be highly affected by the perceived costs and benefits of a particular countermeasure. Responders' perceptions of these can be influenced by the means in which scientific data are collected and presented. To date, a large amount of information has been generated on the aquatic toxicity of oil, dispersants, and dispersed oil. Unfortunately, many of these data are not comparable because of differing toxicological and analytical methodologies, as well as frequent lack of analytical verification of exposures. Recently, a group of federal, state, academic, and industry representatives from North America and Europe have been working toward standardizing both biological and analytical methods used to produce acute toxicity estimates for complex mixtures such as oil, dispersants, and dispersed oil. This standardization provides guidelines for future investigations to be conducted in a sufficiently rigorous manner to allow both inter- and intra-laboratory dataset comparisons, thus providing a more coherent and robust database from which to derive response guidance. By encouraging the use of these standardizations, it is hoped that decision-makers can be provided with a clearer understanding of the acute toxicological results of oil dispersal, and that such information can be more properly integrated into the response planning and decision-making processes.

Abstract-This study was performed to evaluate ambient toxicity conditions in Chesapeake Bay tidal tributaries whose watersheds are impacted by urban development and to further evaluate an existing toxicological risk ranking model. A battery of water-column and sediment bioassays were employed with animals and plants. The study was conducted in coordination with a fish community sampling program. Tests were conducted monthly from April through August 1994 at five sample sites in each of four tidal tributaries. Mortality, reproduction, and growth rates in the water-column assays did not consistently indicate chemical contamination in any system. Chemical analyses did not indicate elevated levels of contaminants in the water column. Sediment bioassays demonstrated greater responses than water-column assays. Sediment in the upstream reaches of the South River demonstrated significant toxicity. Toxicity was also observed at the uppermost Severn River station and the middle Patuxent River station. Chemical analyses of composite sediment samples indicated elevated metals levels in the South River. Some metals were above threshold values in the Patuxent and Wicomico rivers. The AVS/SEM ratios in pore water were below 1 in all cases. Organic analyses demonstrated low level polycyclicaromatic hydrocarbon contamination in all four systems. The toxicological risk ranking model ranked the South River as the most contaminant-impacted site. The Patuxent and Severn rivers were ranked below the South River; however, the ranking model identified specific locations in the Severn and Patuxent rivers that indicate sediment contamination. The Wicomico River had the lowest overall risk score. The Patuxent River requires more intense sampling due to its relatively larger size. The toxicological risk ranking results for sediment were significantly correlated with species diversity for fish communities sampled by bottom trawl. Results were consistent with data from previous years. Regression analysis of 2 years of data indicate that fish community impairment can be predicted with ambient toxicity results.