Classification and Quantification of the Toxicity of Chemicals to Guppy, Fathead Minnow and Rainbow Trout: Part 1. Nonpolar Narcosis Mode of Action

Abstract

Discrimination of the acute toxicity of chemicals to guppy (Poecilia reticulata), fathead minnow (Pimephales promelas) and rainbow trout (Oncorhynchus mykiss) with nonpolar narcosis and other Modes Of Action (MOA) was successfully carried out by means of discrimination analysis and structural similarity analysis. Good QSARs for acute aquatic toxicity of chemicals with nonpolar narcosis MOA for the three fish species were constructed, based on molecular polarizability and H-bond acceptor factors calculated by the HYBOT program. These latter relationships are useful alternatives to QSARs based on the experimental parameter log K o/w because they yield good statistics and because they are amenable to physicochemical interpretation. In this case, the acute aquatic toxicity of chemicals with nonpolar MOA is presented as the result of two contributions (molecular polarizability, which is volume-related, and hydrogen bonding) with opposite action: molecular polarizability increases acute nonpolar narcosis toxicity and H-bond acceptor ability decreases it.

Classification and Quantification of the Toxicity of Chemicals to Guppy, Fathead Minnow, and Rainbow Trout. Part 2. Polar Narcosis Mode of Action

“…The SS method gave 66.7% correct recognition of those chemicals in the guppy training set and 71.8% for the combined guppy and FHM training set (71.0% for the combined guppy and FHM test set). Because the SS method has already demonstrated its ability to classify different chemicals [4,5] it may be that unsuccessful classification of chemicals with specific toxicity is a consequence of the small number of such chemicals in the training sets, in which case additional diverse chemicals in the training sets should increase the probability of correct recognition.…”

“…The contributions of baseline toxicity [calculated based on Eqs. (14) [5], (18) [5], and (22) [5] for guppy, FHM, and RT, respectively] and polar narcosis [calculated on the basis of Eqs. (59, 38, and 60) for guppy, FHM, and RT, respectively] to the total toxicity for all the chemicals studied are presented in Table 1.…”

“…In further publications [4,5] the same topics were discussed on the basis of data on guppy (G), Fathead Minnow (FHM), and Rainbow Trout (RT) toxicity for chemicals with baseline toxicity and other MOAs. Excellent correlation of baseline toxicity [log (1/LC 50 ), LC 50 in mmol/L] was obtained by application not only of values of chemicals distribution in the octanol -water system as the only descriptor, but also by two HYBOT descriptors connected with molecular volume and hydrogen bond acceptor ability.…”

“…Furthermore, comparison of, for example, Eq. (50) with a corresponding equation for general narcotics [log (1/LC 50 ) ¼ À 1.70(0.05) þ 0.88(0.02) log K o/w [5]] shows that, for chemicals with the same log K o/w values, those with polar narcosis MOA are more toxic than are those with general narcosis MOA, up to log K o/w values of about 7. Nevertheless descriptor K o/w does not give information on mechanism of action, simply because K o/w is a composite descriptor incorporating several physicochemical descriptors [14].…”

Investigation of Critical Body Residues and Modes of Toxic Action Based on Injection and Aquatic Exposure in Fish

“…The LC50 values to the guppy (Poecilia reticulata) and rainbow trout (Oncorhynchus mykiss) were taken from Raevsky et al (2008Raevsky et al ( , 2009. The LC50 values to fathead minnow (Pimephales promelas) were taken from Russom et al (1997), Yuan et al (2007), Papa et al (2005), Eroglu et al (2007) and Raevsky et al (2008Raevsky et al ( , 2009. The LC50 values to Medaka (Oryzias latipes) were taken from the Japanese CHRIP (Chemical Risk Information Platform: http://www.safe.…”