There have been many other reports based on studies using more complicated or larger molecules. These have usually reported a linear relation between log(PS) and either log[Kn-octanol/water] or log[Kn-octanol/water MW−1/2] but often with a slope substantially less than 1 (see e.g. [162, 163]). It should be emphasized that slope not equal to 1 means that the fluxes are not proportional to Kn-octanol/water MW−1/2 and thus, for at least some of the substances tested, simple diffusion and partition into an environment that looks like n-octanol are not the only important factors that need to be considered. The appropriate factors are considered further in Appendix C.