Population growth impairment of sulfur-containing compounds to Tetrahymenapyriformis

A series of 37 aliphatic and aromatic sulfur-containing compounds were eval uated in 2-day Tetrahymena pyriformis population growth impairment assay. T he results indicate that, except for select compounds, the in-ring sulfur-c ontaining compounds, sulfates, sulfites, thiols, sulfones, and sulfoxides m odel as neutral and noncovalent-reacting narcotics. Abiotic loss due to vol atility appears to interfere in accurate model prediction because actual to xicity was less than predicted. Vinyl sulfones and sulfoxides are more toxi c than predicted using neutral narcosis. Tetrahymena exposed to methyl viny l sulfone exhibits a direct relationship between the exposure concentration and the generation times with no lag phase in growth. As such, these popul ation growth kinetics mimic those reported for hydrophilic neutral narcotic s (i.e., ethanol and acetone). Tetrahymena exposed to phenyl vinyl sulfone exhibit a long concentration-dependent lag phase, which is followed by popu lation growth at rates not different from controls. These population growth kinetics are similar but more dramatic than those reported for hydrophobic neutral narcotics (i.e., butylbenzene and 2-decanone). These results are u seful in that they imply that sulfur-containing compounds for the most part act as simple narcotics. Therefore, their toxicity can be modeled with sim ple structure-toxicity relationships without much fear of underestimation o f potency. (C) 2001 by John Wiley & Sons, Inc.