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Predictive QSAR models estimating ecotoxic hazard of plant-protecting agents - target and non-target toxicity

: Dittrich, B.; Wenzel, A.; Klein, W.; Nendza, M.

Science of the Total Environment (1991), Nr.109/110, S.527-535 : Abb.,Tab.
ISSN: 0048-9697
Fraunhofer IUCT ( IME) ()
algae; bacteria; fish; phenylurea herbicide; plant; QSAR; rat

Quantitative structure-activity relationships (QSARs) are evaluated for predicting pesticides' effects on non-target and target organisms: aquatic biota, mammals, soil microorganisms, and plants. Satisfactory estimates of pesticides' fish toxicity are obtained from log PsubOW-dependent QSARs derived using chemicals of similar polarity and reactivity. Algal toxicity of herbicidal compounds reflects interactions with the electron transport chain in photosystem 2 and can be modelled by QSARs describing the Hill reaction inhibition. The ranking in effects on soil micro- organisms is evaluated from models derived using in- vitro bacteria systems. Mammalian toxicity can be estimated by QSARs using the partition coefficient log PsubOW and electronic terms derived by MNDO quantum mechanical calculations. In general, the targets are more susceptible than the non-target species towards phenylurea herbicides. Plants and algae constitute the most sensitive populations, corresponding to the same mo de of action. Differences in mode of action towards bacteria, rats, and fish, which are similarly sensitive organisms, are revealed by QSAR analyses.