QSAR and chemometric approaches for setting water quality objectives for dangerous chemicals

In order to evaluate environmentally safe levels of dangerous chemicals, th ere is the need for a set of toxicological data on organisms representative of the ecosystems, which is often unavailable or inadequate. In this artic le, a predictive approach was applied to a set of 125 chemicals (derived fr om the European priority list in compliance with Directive 76/464/EEC), for which water quality objectives were available, Toxicological data on organ isms representative of the aquatic environment (algae, Daphnia, and fish) w ere taken from the literature or predicted by means of quantitative structu re-activity relationships, This provided toxicological data on all three or ganisms for 97 of 125 chemicals and on at least two organisms (Daphnia and fish) for the whole data set. Principal Component Analysis was applied in o rder to perform an a priori classification of chemicals based on toxicity d ata, Then several classification models, based on traditional and nontradit ional molecular descriptors, were applied. Classification models gave resul ts in agreement with the a priori classification as well as with the origin al water quality objectives classification, The behavior of some outliers w as explained, The approach described appears to be a useful tool for the pr eliminary classification of chemicals that are dangerous to the aquatic env ironment for which toxicological data are inadequate. (C) 2001 Academic Pre ss.