Quantitative structure-activity relationships for the toxicity and bioconcentration factor of nitrobenzene derivatives towards the guppy (Poecilia reticulata)

Abstract

The acute toxicity and bioconcentration factor of a series of nitrobenzene derivatives was determined for the guppy. Toxicity is found to be determined by both hydrophobicity (expressed by the octanol/water partition coefficient) and rate of reduction of the nitro group (expressed by either electrochemical halfwave reduction potential or Hammett σ values). The acute toxicity of mononitro compounds can be adequately described by hydrophobicity, and their bioconcentration factor is found to be approximately equal to the octanol/water partition coefficient. The dinitro compounds that are likely to be most easily reduced are found to have substantially lower bioconcentration factors than expected, accompanied by a marked increase in toxicity. Electrochemical reduction potentials are found to be a better descriptor of toxicity than Hammett σ− values. Nitroanilines do not fit the QSARs established for nitrobenzene derivatives. These compounds are probably to be considered aniline derivatives.