In the summer of 1994, a group of organizations sponsoring research related to the environmental effects of chemical oil spill treating agents organized a working group to coordinate their research activities in this area. The purpose of Chemical Response to Oil Spills: Ecological Effects Research Forum (CROSERF), as defined at the first meeting, was to provide a mechanism for the exchange of ideas and coordination of research to state, federal, and international agencies; industry; academic researchers; and consultants engaged in research on the ecological effects of oil spill response chemicals, especially dispersants. Each of the primary sponsors had its own objectives for the program, and contributed to the design of the cooperative research efforts. Over the past 7 years, there have been nine CROSERF meetings, each serving to direct the research efforts and resolve issues of importance to all of the participants. Most of the program objectives were achieved, but declining research funds limited the scope of the toxicity-testing program. Nevertheless, the forum provided the means for resolving dispersant and dispersed oil toxicity issues and encouraging communication among participants. The laboratory toxicity data generated by CROSERF is the most complete information currently available for multiple oils and species.

We performed 20-d, flow-through exposures of lipid-containing semipermeable membrane devices (SPMDs) and Pacific oysters (Crassostrea gigas) to three concentrations (nominally 10, 100, and 250 ng/L) of a diverse mixture of polycyclic aromatic hydrocarbons (PAHs). Exposure water was seawater free of particulates larger than 0.1 microm. The results of these controlled laboratory studies demonstrated that SPMDs and oysters concentrate the same chemicals but that the relative amounts accumulated are different. For oysters, the 20-d mean (across treatments) concentration factors (CFs) of test compounds with log Kow < or = 4.8 were much lower (4.0- to 20-fold lower) than those of the same compounds in SPMDs. In contrast, the 20-d CFs of PAHs with log Kow > or = 5.6 in oysters from the low-level treatment were higher than the corresponding CFs for SPMDs. The CFs of these compounds in oysters from the low-level treatment ranged from approximately 3.0- to 13-fold higher than those in oysters from the high-level treatment. This physiologically mediated difference in oyster CFs appears to be linked to active feeding in the low-level treatment and to apparent toxicity-induced cessation of feeding (i.e., valve closure) in the high-level treatment. Because CFs for these compounds in oysters were not independent of exposure concentrations, it follows that tissue levels were not proportional to exposure concentration. However, both sampling approaches have advantages and disadvantages, and the appropriateness of their use depends on the goals of a given study.

Chemical dispersant use has been regarded in some areas of the world as a non-traditional response option for open water marine spills. This view is based on the historical prevalence of mechanical response and the additional regulatory or permitting requirements placed on organizations which wish to use dispersants. While such requirements may be a deterrent, the response community underestimates the actual frequency of dispersant use. Based on response reports for maritime spills, the frequency of worldwide dispersant use is summarized over the last four decades. Information is also summarized by the geographic region where the dispersant was applied and using any reports on effectiveness. Effectiveness reports are uneven in quality and, in many cases, absent. This situation underscores the importance of knowing if an oil is dispersible beforehand and monitoring the performance of a dispersant on a spilled oil afterward.

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When planning response activities for an oil spill, decision makers must react to a wide range of circumstances. Decisions will vary depending on the type of petroleum product spilled and the nature of the impacted habitat. Response decisions will be based on tradeoffs dealing with the environmental consequences of the spilled oil and the response method selected, as well as the efficiency and effectiveness of the method. A new manual, Marine Oil Spill Response Options for Minimizing Environmental Impacts, is being jointly produced by industry and government to facilitate decision making for both prespill planning and incident response. Guidance will be provided through matrix tables indicating the relative environmental consequences of the different response options used for various categories of oil in open water and shoreline habitats. This paper describes the contents of the new manual.