title: Regression comparisons of Tetrahymena pyriformis and Poecilia reticulata toxicity.
abstract: The toxicity data of chemicals common to both the Poecilia reticulata mortality assay and the Tetrahymena pyriformis growth impairment assay were evaluated. Two chemicals were not toxic at saturation in the T. pyriformis assay. In addition, due to abiotic transformation, a third chemical was removed from further consideration. Each chemical was a priori assigned a mode of toxic action: neutral non-covalent, polar non-covalent, or electrophilic covalent toxicity. To further investigate comparisons between endpoints, polar and electrophilic chemicals were separated into class-based groups. The polar non-covalent chemicals were separated into phenols and anilines, while the electrophilic chemicals were separated into those reacting via Schiff-base formation (i.e., aldehydes) and those reacting via bimolecular substitution to a nucleophile (i.e., selected nitroaromatics). A comparison of toxic potency as a collective set was statistically described by the relationship; log(LC50(-1)) = 1.05(log(IGC50(-1))) + 0.56, n = 124; r2 = 0.85; s = 0.42; F = 682; Pr > F = 0.0001. The relationship between endpoints was inversely proportional to reactivity associated with the mode of action. While the comparative toxicity for neutral narcotics exhibited an excellent fit (r2 = 0.94), the fits for polar narcotics and electrophiles were poorer, r2 = 0.69 and 0.62, respectively. Investigations into class-based groupings indicated fit of toxic potency data for aldehydes (r2 = 0.85) and phenols (r2 = 0.81) were quite good. However, fits for anilines (r2 = 0.43) and nitroaromatics (r2 = 0.68) revealed that toxicity was not as well related between endpoints for these chemicals.
authors: Graduate Program in Ecology and Evolutionary Biology, The University of Tennessee, Knoxville 37996-4500, USA.
authors: Julie R
authors: JR
authors: Seward
authors: Elizabeth L
authors: EL
authors: Hamblen
authors: T Wayne
authors: TW
authors: Schultz
mesh_terms: D000447:Aldehydes / Q000633:toxicity; D000814:Aniline Compounds / Q000633:toxicity; D000818:Animals; D023381:Endpoint Determination; D005544:Forecasting; D010636:Phenols / Q000633:toxicity; D011036:Poecilia; D012044:Regression Analysis; D013769:Tetrahymena pyriformis; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000447:Aldehydes; D000814:Aniline Compounds; D010636:Phenols; D014874:Water Pollutants, Chemical