Water standards regulatory consideration

The compound-specific data required for exposure assessments comprise the 1-octanol/water partition coefficient (log water solubility (S ), vapour pressure (p ), Henry s law constant (H, H ), soil sorption coefficient hydrolysis half-life time, photolysis half-life time and information on biodegradability (OECD, 1993c). These parameters generally relate to steady-state conditions - conditions that are rarely met in the real environment. The experimental data underlying the QSAR models are preferably determined by standardized protocols, but, even then, the absolute values are of variable reliability and precision, which clearly affects the accuracy of the predictions based on the acquired QSARs. The endpoints discussed in the following sections were selected because of their consideration in regulatory evaluation schemes in, for example, the EU (EEC, 1990). 

---