BfR-Wissenschaft 
81 
12 Chemical dispersion as an oil pollution response solution - French Ap 
proach 
Gilbert Le Lann 
Centre of Documentation, Research and Experimentation on Accidental Water Pollution 
(Cedre), Brest, France 
Qualification of chemical dispersants for use in national waters 
The qualification of chemical dispersants for use in areas under French jurisdiction is based 
on three main tests: 
• a test of efficiency, whose objective is to verify that the product allows good disper 
sion of hydrocarbons in the water column, and that the dispersion remains relatively 
stable; 
• a toxicity test, to ensure that the product does not present a major hazard to the envi 
ronment; 
• and finally a biodegradability test to verify that the product will gradually disappear 
naturally from areas where it could be used. 
The efficiency test is based in France on national standard NF T 90-345. It is carried out in a 
tank equipped with a stirrer to generate the necessary mechanical energy for the dispersion 
to take place. A reference oil, in the case of the standard a refined product having a viscosity 
of about 1300 mPa.s and a density of 0.97 at 20 q C, is introduced into the tank with the dis 
persant to be tested in a ratio of 20 volumes of oil to one volume of a dispersant. After one 
hour of test, the hydrocarbon concentration in the water is measured. If there is more than 
60 % of the initial oil quantity dispersed in water, the dispersant is considered as efficient 
enough. Other dispersant efficiency tests exist. These include notably the WSL (Warren 
Spring Laboratories) test used in the UK and based on the use of rotating conical separatory 
funnels. There is also the MNS (Mackay - Nadeau - Steelman) test used in Canada where oil 
and dispersant are placed in a cylindrical tank and the mechanical energy is introduced by an 
air flow which rotates the water. Finally the test SFT (Swirling Flask Test) used in the US is 
based on using Erlenmeyer flasks placed on a rotary shaker table. Cedre has the ability to 
implement all of these tests. 
The toxicity test is currently performed in France on the basis of another national standard 
NF T 90-346. It involves comparing in a bench for measuring the LC50 toxicity of the disper 
sant with that of a reference surfactant, the N-alkyl dimethyl benzyl ammonium chloride 
(Noranium). The dispersant is considered as acceptable if its toxicity is at least 10 times low 
er than that of the reference toxic. Tests are conducted for six hours on shrimps. National 
considerations are currently underway to replace this purely national test by the OSPAR 
tests, respectively on juvenile turbot, copepods, amphipods and algae. These standardized 
tests have indeed broad international recognition and form the basis of toxicity studies on 
marine species in many countries. 
Lastly, France makes a biodegradability test of chemical dispersants according to national 
standard NF T90-349. This test is performed over a period of 28 days, and the dispersant is 
accepted if its degradation rate at the end of this period is greater than 50 %. However, dis 
cussions are ongoing on whether to continue the test because its relevance is not proven. 
Indeed, the dilution of the product after 28 days is very much higher than the level of biodeg 
radation, which calls into question the interest of this test that would apply more to the use of 
products in a confined environment, which is not the case in reality.