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Coefficient of water/oil distribution
This is the ratio of the solubility of a product in oil
to its solubility in water when they are brought into
contact with the product.
A value below 1 indicates a better solubility of the
product in oils and greases. The product is therefore
likely to be absorbed by the skin. However, a value
greater than 1 indicates a better solubility in water.
This product could therefore be absorbed by the
mucous membranes. This information can be useful
in evaluating the first aid to be given and can facilitate the choice of protective equipment.
Example
Toluene has a coefficient of water/oil distribution of
0.0026. Therefore, toluene is more soluble in oil than
in water with a value of 0.0026 g in water to 1 g in
oil.
Note. – On some material safety data sheets, the
distribution coefficient is expressed as log Pow,
therefore as the logarithm of the n-octanol/water
partition coefficient. n-Octanol is in fact the reference substance that is closest to oil. The method for
converting log Pow into the coefficient of water/oil
distribution is described in the Conversion factors section of this guide.
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