The determination of toxicities of sulphonylurea and phenylurea herbicides with quantitative structure–toxicity relationship (QSTR) studies

Sulphonylurea and phenylurea herbicides are two groups of herbicides that are most commonly used worldwide. Quantitative structure–toxicity relationship models were derived for estimating the acute oral toxicity of these herbicides to male rats. The 20 chemicals of the training set and the seven compounds of external testing set were described by means of using descriptors for lipophilicity, polarity and molecular geometry, as well as the calculation of quantum chemical descriptors for energy. Model development to predict the toxicity of sulphonylurea and phenylurea herbicides in different matrices was carried out using multiple-linear regression. The model was validated internally and externally. In the present study, QSTR model was used for the first time to understand the inherent relationships between the sulphonyl and phenylurea-type herbicide molecules and their toxic behaviour. Such studies provide mechanistic insight about structure–toxicity relationships and assist in the design of less toxic herbicides.

► We produced a QSTR model of some herbicides by using experimental LD50 values.
► First time, the toxicity of phenyl and sulphonylurea type herbicides was estimated theoretically.
► The most effective parameter in the QSTR model was log P values of herbicides.
► Mass and dipole moment of herbicides have moderate affect on the QSTR model.
► The less effective parameter in the QSTR model was molar refractivity values of herbicides.