A<unk>  factor greater than 1 is indicative of a hydrophobic or lipophilic chemical. It is an indicator of how probable a chemical is to bioaccumulate. These chemicals have high lipid affinities and will concentrate in tissues with high lipid content instead of in an aqueous environment like the cytosol. Models are used to predict chemical partitioning in the environment which in turn allows the prediction of the biological fate of lipophilic chemicals. Equilibrium partitioning models Based on an assumed steady state scenario, the fate of a chemical in a system is modeled giving predicted endpoint phases and concentrations. It needs to be considered that reaching steady state may need a substantial amount of time as estimated using the following equation (in hours). For a substance with a log(KOW) of 4, it thus takes approximately five days to reach effective steady state. For a log(KOW) of 6, the equilibrium time increases to nine months. Fugacity models Fugacity is another predictive criterion for equilibrium among phases that has units of pressure. It is equivalent to partial pressure for most environmental purposes. It is the absconding propensity of a material. BCF can be determined from output parameters of a fugacity model and thus used to predict the fraction of chemical immediately interacting with and possibly having an effect on an organism. Food web models If organism-specific fugacity values are available, it is possible to create a food web model which takes trophic webs into consideration. This is especially pertinent for conservative chemicals that are not easily metabolized into degradation products. Biomagnification of conservative chemicals such as toxic metals can be harmful to apex predators like orca whales, osprey, and bald eagles.
Bioconcentration
Countercurrent exchange
Selective reabsorption
Enhanced permeability and retention effect
Isobaric counterdiffusion
Augmented renal clearance
Reabsorption
Solvent drag