Nas questões ambientais legais, muitas vezes a referência à toxicidade de uma substância é vaga. No entanto, essa informação é essencial para a determinação da extensão do dano. Para fazer a previsão desses valores para o benzeno e hidrocarbonetos policíclicos aromáticos (PAHs), componentes do petróleo, foi feito um estudo QSAR (Quantitative Structure Activity Relationship) por meio de cálculos de mecânica quântica e quimiometria. O objetivo foi construir modelos para prever os valores de coeficiente de partição n-octanol/água, Kow (n-octanol/water partition coefficient) além do estudo das toxicidades dos PAHs. Para este estudo, as geometrias de todas as moléculas foram otimizadas utilizando os métodos semiempíricos AM1, PM3, PM6 e PM7. Desses resultados ainda foram extraídos os descritores teóricos que foram utilizados para descrever os valores de log Kow. Entre todos aqueles calculados, os descritores: energia total, energia eletrônica, área, volume e massa molar foram escolhidos como os parâmetros para o estudo PLS (Partial Least Squares). Além disso, as toxicidades dos PAHs foram calculadas por meio do programa T.E.S.T (Toxicity Estimation Software Tool) disponibilizado gratuitamente pelo EPA (Environmental Protection Agency) e estimados por meio de modelo PLS e gráficos de correlação. Observou-se com esse estudo que todos os métodos apresentaram resultados bastante satisfatórios, uma vez que valores próximos de 1 foram obtidos tanto para o coeficiente de correlação interno, Q2, quanto para o externo, R2. / In the environmental legal issues, often the reference to toxicity of a substance is vague. However, this information is essential for determining the extent of damage. To forecast these values for benzene and polycyclic aromatic hydrocarbons (PAHs), petroleum components, one study QSAR (Quantitative Structure Activity Relationship) was done by calculation of quantum mechanics and chemometrics. The goal was to build models to predict the values of the partition coefficient n-octanol / water, Kow (n-octanol / water partition coefficient) beyond the study of the toxicity of PAHs. For this study, the geometries of all molecules were optimized using the semi-empirical methods AM1, PM3, PM6 and PM7. These theoretical results also descriptors that were used to describe the Log Kow values were extracted. Among those calculated descriptors: total energy, electronic energy, area, volume and molar mass were chosen as the parameters for the study PLS (Partial Least Squares). Furthermore, the toxicities of PAHs were calculated using the TEST (Toxicity Estimation Software Tool) program available free of charge by the EPA (Environmental Protection Agency) and estimated by PLS model and correlation charts. It was observed in this study that all the methods have shown promising results, since values near one were obtained for the standard and cross-validated correlation coefficients R2 and Q2.

Nas questões ambientais legais, muitas vezes a referência à toxicidade de uma substância é vaga. No entanto, essa informação é essencial para a determinação da extensão do dano. Para fazer a previsão desses valores para o benzeno e hidrocarbonetos policíclicos aromáticos (PAHs), componentes do petróleo, foi feito um estudo QSAR (Quantitative Structure Activity Relationship) por meio de cálculos de mecânica quântica e quimiometria. O objetivo foi construir modelos para prever os valores de coeficiente de partição n-octanol/água, Kow (n-octanol/water partition coefficient) além do estudo das toxicidades dos PAHs. Para este estudo, as geometrias de todas as moléculas foram otimizadas utilizando os métodos semiempíricos AM1, PM3, PM6 e PM7. Desses resultados ainda foram extraídos os descritores teóricos que foram utilizados para descrever os valores de log Kow. Entre todos aqueles calculados, os descritores: energia total, energia eletrônica, área, volume e massa molar foram escolhidos como os parâmetros para o estudo PLS (Partial Least Squares). Além disso, as toxicidades dos PAHs foram calculadas por meio do programa T.E.S.T (Toxicity Estimation Software Tool) disponibilizado gratuitamente pelo EPA (Environmental Protection Agency) e estimados por meio de modelo PLS e gráficos de correlação. Observou-se com esse estudo que todos os métodos apresentaram resultados bastante satisfatórios, uma vez que valores próximos de 1 foram obtidos tanto para o coeficiente de correlação interno, Q2, quanto para o externo, R2. / In the environmental legal issues, often the reference to toxicity of a substance is vague. However, this information is essential for determining the extent of damage. To forecast these values for benzene and polycyclic aromatic hydrocarbons (PAHs), petroleum components, one study QSAR (Quantitative Structure Activity Relationship) was done by calculation of quantum mechanics and chemometrics. The goal was to build models to predict the values of the partition coefficient n-octanol / water, Kow (n-octanol / water partition coefficient) beyond the study of the toxicity of PAHs. For this study, the geometries of all molecules were optimized using the semi-empirical methods AM1, PM3, PM6 and PM7. These theoretical results also descriptors that were used to describe the Log Kow values were extracted. Among those calculated descriptors: total energy, electronic energy, area, volume and molar mass were chosen as the parameters for the study PLS (Partial Least Squares). Furthermore, the toxicities of PAHs were calculated using the TEST (Toxicity Estimation Software Tool) program available free of charge by the EPA (Environmental Protection Agency) and estimated by PLS model and correlation charts. It was observed in this study that all the methods have shown promising results, since values near one were obtained for the standard and cross-validated correlation coefficients R2 and Q2.

Determining the root uptake of xenobiotic organic chemicals into plants is critical for assessing the human and ecological health risks associated with the consumption of plants growing in contaminated environments. Root uptake of xenobiotic organics occurs passively in conjunction with transpiration and the transport from root to shoot is ultimately controlled by passage through one or more lipid root membranes. The transpiration stream concentration factor (TSCF), the ratio between the concentration of a chemical in the xylem to that in the solution used by the roots, is used to describe the relative ability of an organic chemical to be passively transported from root to shoot. However, relatively few experimental TSCF values exist due to the cost and the lack of regulatory requirements for generating such data. Where literature data exist for chemicals having more than one TSCF, the variability is often large due to the lack of standardized methods and difficulty in accounting for metabolism and volatilization losses occurring during the uptake experiments. Because of the scarcity of experimental values, estimated TSCFs are often used. Widely cited estimation approaches relating TSCF and the logarithm octanol/water partition coefficient (log KOW) suggest that only compounds that are in the intermediate lipophilicity range (log KOW = 2) will be taken up and translocated by plants. However, recent data for highly water soluble compounds such as 1,4-dioxane, MTBE, and sulfolane suggest that these estimation techniques should be critically reviewed. To re-evaluate the relationship between TSCF and log Kow, TSCFs were measured for 25 organic chemicals ranging in log KOW from -0.8 to 5 using an improved pressure chamber technique. The technique provides an approach for efficiently generating consistent plant uptake data. By using this data, a new mass transfer model relating TSCF and log KOW was developed that indicates that neutral, polar organic compounds are most likely taken up by plant roots and translocated to shoot tissue. An extensive review of literature TSCF studies supports the updated model.