River waters and wastewater treatment plant effluents contain persistant, bioaccumulative and toxic hydrophobic organic compounds (HOCs). The biological risk assessment of HOCs requires the estimation of their bioavailable fraction in addition to their total concentration in the media. The bioavailability of HOCs is dependent on the aquatic environment characteristics. In particular, HOCs may be bounded by dissolved organic matter (DOM), which usually lead to a reduction of the HOCs bioavailability. The generally accepted assumption is that bound pollutants are too large and too polar to cross biological membranes. A passive sampler (Semi-Permeable Membrane Device (SPMD)) has been developed to evaluate bioavailable fractions of HOCs. It is a long, flat polyethylene (PET) tube containing lipid (triolein). PET allows contaminants to pass through, in the same way as the membranes of animal cells and the triolein was chosen to be like lipids in biological tissues. The great advantage of SPMD is their relative simplicity for in situ estimation of HOCs. We first successfully tested the ability of SPMD to sample HOCs in anthropic rivers as well as in wastewater effluents. Concentrations in SPMDs were relied to total concentrations in waters. Then, we compared the ability for SPMD to sample bioavailable fractions of HOCs. In the laboratory, the bioavailable fraction of some Polycyclic Aromatic Hydrocarbons could be modified by the presence of DOM. Therefore, the bioaccumulation of PAHs to Daphnia magna and Danio rerio in the presence of various natural or commercial DOM (with different binding capacities) was compared to the fraction of PAHs accumulated in SPMD, showing that in most cases SPMD are good surrogates for living organisms.