187 



.simulate field trials the dispersant was applied to the 

 oil by means of sprayers similar to those used in the 

 beach test. Because of the difficulty of adjusting the 

 sprsyers to deliver an accurate quantity of dispersant 

 directly onto the oil in the tanks, the nominal dis- 

 pers:int to oil ratios of 1:10 and 1:20 are only 

 approximate and no statistical analysis can be per- 

 formed on indh'idual results. However, there is some 

 suggestion that the use of neat concentrates may 

 generate a slightly more toxic dispersion than the 

 diluted dispersant. 



4. Beach test results 



4.1 Tests under standard conditions used for licensing 

 purposes 



The results of beach tests with a number of dispersants 

 using the standard test conditions as described in Section 

 2.3 are given in Table 10. In the series of tests reported, 

 exposure of the limpets to fresh Kuwait crude oil caused 

 mortalities of between 309c and 95%, and application of 

 dispersant led to a wider range of mortalities, varying from 



Table 10 ■ Beach tests results 



Type 



Dispersant 



Mean mortality (%) 



Conventional (hydrocarbon 

 solvent-based) dispersants 



Concentrates (tested as a 

 10% solution in sea water) 



•.Mortalit) significantly greater than oil control (Student's t-test ; P = <0.05) 



