Research into Environmental Effects of Dispersants

ITOPF has become a partner in a joint research project on dispersants, entitled ‘DISCOBIOL', under the leadership of the French association CEDRE (Centre of Documentation, Research and Experimentation on Accidental Water Pollution). Preliminary results of the research into short-term toxicity showed that, for the organisms tested (species found in coastal and estuarine areas), the lethal concentration of dispersed oil is far higher than concentrations of chemically dispersed oil typically found in the water column during actual oil spills. 

This project is due to conclude at the end of 2012, but most of the experimental work has already finished. The sub-lethal effects of dispersed oil were assessed over a two-week period by monitoring a series of ‘bio-markers' (biological measures used to assess health), the results of which indicate that the impacts of oil intoxication are reversible for the vast majority of the test organisms, at least according to the bio-markers studied. While these preliminary results may suggest that dispersants could be considered for use in near-shore waters, the results from all the experiments will need to be analysed before any final project conclusions are made.

 

The aim of the project is to provide decision makers with information on the net environmental benefit of using dispersants in near-shore areas and involves assessing the toxicity and impacts of dispersed oils on different habitats and resources found in coastal and estuarine environments of temperate climates.

 

The use of dispersants can be a very effective response to an oil spill. When dispersants are used offshore the depth and flow of water allow for rapid dilution so that concentrations of dispersed oil quickly reduce to levels that do not generally give rise to significant harm to the environment. However, in many countries, if an oil spill occurs close to the coast, limits are imposed on the use of dispersants because of concerns that the shallow waters will not allow for sufficient dilution of dispersed oil subsequently leading to adverse effects. Nevertheless, in certain circumstances, the need to protect highly sensitive coastal resources may warrant consideration of dispersants in near-shore waters, especially if biodegradation of the dispersed oil is likely to occur.