Quantitative structure-activity relationship physicochemical, environmental

Raevsky, O. A., Schaper, K.-J. Physicochemical descriptors governing the solubility and partitioning of chemicals in water-solvent-gas systems. In Abstracts of 12th International Workshop on Quantitative Structure-Activity Relationships in Environmental Toxicology, Lyon, France, 2006, p. 23. 

Structure-activity relationships (SARs) and quantitative structure-activity relationships (QSARs), referred to collectively as QSARs, can be used for the prediction of physicochemical properties, environmental fate parameters (e.g., accumulation and biodegradation), human health effects, and ecotoxicological effects. A SAR is a (qualitative) association between a chemical substructure and the potential of a chemical containing the substructure to exhibit a certain physical or biological effect. A QS AR is a mathematical model that relates a quantitative measure of chemical structure (e.g., a physicochemical property) to a physical property or to a biological effect (e.g., a toxicological endpoint). 

Brtlggemann, R., Altschuh, J. and Matthies, M. (1990). QSAR for Estimating Physicochemical Data. In Practical Applications of Quantitative Structure-Activity Relationships (QSAR) in Environmental Chemistry and Toxicology (Karcher, W. and Devillers, J., eds.), Kluwer, Dordrecht (The Netherlands), pp. 197-212. 

Fortunately, to overcome the different problems of laboratory testing, modeling approaches are being developed for estimating the toxicity of chemicals. QSARs (quantitative structure-activity relationships) are the fundamental basis of these approaches in environmental toxicology for predicting the toxicity of chemicals from their molecular structure and/or physicochemical properties. 

This information may derive from laboratory testing. Alternatively, toxicologists may predict hazards from a structure-activity relationship (SAR), which is "the relationship of the molecular structure of a chemical with a physicochemical property, environmental fate attribute, and/or specific effect on human health or an environmental species. These correlations may be qualitative (simple SAR) or quantitative (quantitative SAR, or QSAR)" [79, p. 1]. Both "read across" from the behavior of one chemical to that of a similar chemical and the practice of assessing chemicals by categories are forms of SAR [80,81]. 

Chemical reactivity and biological activity can be related to molecular structure and physicochemical properties. QSAR models can be established among hydrophobic-lipophilic, electronic, and steric properties, between quantum-mechanics-related parameters and toxicity and between environmental fate parameters such as sorption and tendency for bioaccumulation. The main objective of a QSAR study is to develop quantitative relationships between given properties of a set of chemicals and their molecular descriptors. To develop a valid QSAR model, the following steps are essential ... 

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