TBTO also has a tendency to bioaccumulate in marine animals. Bioaccumulation occurs when an organism takes up a substance faster than the substance is excreted. The substance subsequently ends up accumulating in the fats, muscles, and organs of the marine animal. This usually occurs when a compound is more soluble in the organic media of an organism’s tissue than it is in water. In a laboratory setting, bioaccumulation can be estimated by allowing the substance to equilibrate in a nixture of 1-octanol and water (a mixture of 1-octanol and water will separate into two layers). If the equilibrium is such that most of the substance is found in the less polar octanol layer, then it is likely that the substance will bioaccumulate.