Organic molecules show potential hazard to bio-accumulate over time in fat tissue of organisms. This could lead to an underestimation of the toxicity of the chemical, if the prediction of toxicity is based on short-term exposure only, i.e. acute eco-toxicity tests. The experimental determination of the bio-accumulation behavior (bio-concentration factor, BCF) of chemicals is very time- and cost intensive, therefore not many BCF data exist.
Nevertheless, a first indication of the bio-accumulation potential of a chemical can be obtained from its physico-chemical partitioning between octanol (representing the fat tissue) and water. In legislation (e.g. CLP, REACH), the log Kow is used as a descriptor to characterize bio-accumulation potential of a chemical substance. Due to the inherent molecular structure of surfactants resulting in its amphiphilic nature and the tendency to accumulate at interfaces, surfactants are outside the applicability domain of the standard methods for log Kow determination (i.e. the shake-flask OECD 107, and the HPLC OECD 117 method)
Due to the prominent role of the log Kow as a simple, cost-efficient screening test in legislation and the inherent difficulties caused by the properties of the surfactants molecule, the basic research to determine proper log Kow values using alternative methods deserves high attention.