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The European Solvents Industry Group (ESIG) Generic Exposure Scenario (GES) Risk and Exposure Tool (EGRET) was developed to facilitate the safety evaluation of consumer uses of solvents, as required by the European Union Registration, Evaluation and Authorization of Chemicals (REACH) Regulation. This exposure-based risk assessment tool provides estimates of both exposure and risk characterization ratios for consumer uses. It builds upon the consumer portion of the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) Targeted Risk Assessment (TRA) tool by implementing refinements described in ECETOC TR107. Technical enhancements included the use of additional data to refine scenario defaults and the ability to include additional parameters in exposure calculations. Scenarios were also added to cover all frequently encountered consumer uses of solvents. The TRA tool structure was modified to automatically determine conditions necessary for safe use. EGRET reports results using specific standard phrases in a format consistent with REACH exposure scenario guidance, in order that the outputs can be readily assimilated within safety data sheets and similar information technology systems. Evaluation of tool predictions for a range of commonly encountered consumer uses of solvents found it provides reasonable yet still conservative exposure estimates.

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Recent inland spills in Latin America have generated interest in dispersant use for freshwater oil spills. However, oil spill dispersants primarily are formulated for use in marine waters. Dispersants that are designed for saltwater use show reduced effectiveness when applied in freshwater. The effectiveness of COREXIT® 9500 in low salinity waters varies with the type of oil, the dispersant-to-oil ratio (DOR), and other factors. The effectiveness of COREXIT® 9500 can decrease markedly at salinities of 15 ppt or less. The authors observed an increase in effectiveness of COREXIT® 9500 in freshwater when the dispersant was blended with an inorganic, divalent salt, such as calcium chloride, prior to use (patent pending). COREXIT® 9500* refers here to the blend of the salt and dispersant. The Exxon Dispersant Effectiveness Test (EXDET) was used to evaluate dispersant performance in deionized water and in river water samples from Rio de la Plata, Argentina. COREXIT® 9500 showed 22% effectiveness on Alaska North Slope (ANS) crude oil in deionized water, a value indicative of poor effectiveness. Depending on the amount of calcium chloride added, COREXIT® 9500* showed up to 63% effectiveness on ANS crude oil in deionized water, which indicates good effectiveness. The effectiveness of COREXIT® 9500* and COREXIT® 9500 was compared for three additional crude oils both in deionized water and in river water. In all cases, the effectiveness of COREXIT® 9500 was lower compared with COREXIT® 9500*.

Open marine water (salinity 30–35°/00) is the environment where dispersants are used most frequently in oil spill response. In the Azerbaijan sector of the Caspian Sea, offshore oil and gas reserves are being developed in areas where salinity ranges from 10 to 12 °loo. Because salinity can affect dispersant efficacy and toxicity, the effectiveness and aquatic toxicity of six commercially available dispersants were tested using Azerbaijan crude oil, Caspian species and 12°/oo seawater. Effectiveness for the dispersants tested with Chirag crude oil and Caspian seawater ranged from 72% to 86%, using USEPA's baffled flask method. Dispersant toxicities were in the ranges: diatom (Chaetoceros tenuissimus) 72 hr EC50 (effective concentrations inhibiting growth rate by 50%) 18 to > 100 mg/l; copepod (Calanipeda aquae dulcis) 48 hr LC50 (effective concentration for immobilizing 50% test organisms) 12 to 49 mg/l; amphipod (Pontogammarus maeoticus) 48 hr LC50 (concentration lethal to 50% test organisms) 50 to > 100 mg/l. For dispersant use, the key toxicity concern is that of dispersed oil, not dispersant. Aquatic toxicity was determined for water—accommodated fractions (WAFs) of Chirag crude in Caspian seawater. Toxicity results for the WAFs were: diatom 72 hr EC50 > 10,000 mg/l nominal; copepod 48 hr LC50 3.9 mg/l; amphipod 48 hr LC50 >15 mg/l. Chirag crude was mixed with dispersant at 20:1 oil: dispersant ratio and resulting WAFs were tested for toxicity. Results were: diatom 72 hr EC50 < 18 to 208 mg/l nominal; copepod 48 hr LC50 2.1 to 37 mg/l; amphipod 48 hr LC50 20 to 89 mg/l. Dispersant and dispersed oil toxicity for Caspian species are similar to published toxicity data for marine species tested at typical ocean salinity. Prolonged exposure (24 to 96hrs.) to constant concentrations of dispersant or dispersed oil used in laboratory tests may overestimate potential field toxicity, where dilution and mixing can decrease concentrations to low ppm's within hours of application. Dispersant use decisions for any Caspian Sea oil spills will focus on net environmental benefits of moving oil into the water column where it can be quickly diluted compared to potentially greater impacts from oil reaching nearshore environments.