Effect Concentration (ppm)

References (embryo-larval)


Marine and Freshwater Resources Institute (1998)


Gulec and Holdaway (2000)f


Norwegian Institute for Water Research (1994)


Burridge and Shir (1995)


Fuller and Bonner (2001)f

In addition to acute toxicity, dispersants may have more subtle effects that influence organism health. Dispersant has been reported to significantly affect the uptake, but not necessarily bioaccumulation, of oil constituents (Wolfe et al., 1998a,b,c; 1999a,b; 2001). In addition, dispersants have been reported to have toxic effects on microbial processes that could potentially interfere with oil decomposition (Varadaraj et al., 1995), but this effect may be offset by other factors that appear to promote oil biodegradation (Swannell and Daniel, 1999). For further discussion on the effect of dispersants and dispersed oil on microbial processes, see section on Microbial Communities (found later in this chapter) and Chapter 4.


Oils are a complex mixture of literally thousands of compounds of varying volatility, water solubility, and toxicity. The purpose of chemical dispersants is to facilitate the movement of oil into the water column. The result is a complex, multi-phase mixture composed of dissolved dispersant, dissolved petroleum hydrocarbons, oil/dispersant droplets, and bulk, undispersed oil. Consequently, aquatic organisms are potentially exposed to many toxicants with different modes of action and through different

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